EWB practical workbook

Post on 20-May-2015

20135 Views

Category:

Education

10 Downloads

Preview:

Click to see full reader

DESCRIPTION

Workbook for Electronics Workbench. with

Transcript

Practical Workbook

Logic Design amp Switching Theory I

Name _____________________________ Year __________ Batch ____________ Roll No _____________________________ Group No ____________________________ Department ____________________________

Dept of Computer amp Information Systems Engineering NED University of Engineering amp Technology

Karachi ndash 75270 Pakistan

Practical Workbook

Logic Design amp Switching Theory I

Prepared By M Anwar Ali Khan (Asst Professor) amp Muhammad Mazher Alam (Ex - Asst Professor) Revised By Maria Waqas (Lecturer)

Second Edition

Fourth Reprint ndash 2010

Dept of Computer amp Information Systems Engineering NED University of Engineering amp Technology

Karachi ndash 75270 Pakistan

THE BITS AND PIECES PART CIRCUIT

SIGN WHAT IT DOES

Supplies a voltage which drives an electric current round the circuit from the positive (+) terminal of the battery to its negative (ndash) terminal Voltage is measured in volts (V) and current in amperes (A)

Allows current to flow through it easily because it is made of copper which is a good electrical conductor Insulators like PVC (polyvinyl chloride - a plastic) and enamel are used to cover connecting wires

Connects terminal A to terminal B or C ie it is a change-over switch

Reduces the current in a circuit because of its resistance The colored bands give the resistance in ohms

When light falls on it its resistance becomes small in the dark its resistance is high

3

PART CIRCUIT SIGN

WHAT IT DOES

Stores electricity the greater the capaci-tance the more does it store Capacitance values are measured in microfarads shortened to μF or less correctly to mfd On a capacitor 01 μF may be marked as l mfd and 001μF as 10n The greatest voltage it can stand is also shown eg 30V

Stores electricity values usually larger than 1μF Greatest voltage marked on it Must be connected the correct way round

Varies the capacitance in a circuit by mov-ing one set of metal plates in or out of a fixed set when the spindle is rotated The sets of plates are separated by sheets of an insulator (also called a dielectric)

Changes electric currents into sound

Changes radio waves into electric currents

Lets current flow in one direction but not in the other When it conducts light is emit-ted Must have a current limiting resistor in series with it The cathode lead is nearest the lsquoflatrsquo and may be shorter than the anode lead (but this is not always so) The arrow on the sign shows the conducting direction

4

PART CIRCUIT SIGN

WHAT IT DOES

Amplifies small currents into much larger copies Acts as a very fast switch It must be correctly connected with a positive voltage to the collector

Transistors diodes resistors and capacitors are connected together on a tiny lsquochiprsquo of silicon (sand is mostly silicon oxide) to give any desired circuit eg a multistage amplifier an astable bistable or monostable multivibrator a counter a logic gate for a computer several stages of a TRF (tuned radio frequency) radio

They must be correctly connected Pin 1 is next to the lsquotagrsquo in the can type and on the dil type it is identified from the lsquonotchrsquo or lsquosmall dotrsquo on the case CMOS lsquochipsrsquo (standing for Complementary Metal Oxide Semiconductors and pronounced lsquosee-mossrsquo) need special care

PRECAUTIONS WITH CMOS INTEGRATED CIRCUITS Damage occurs if static charges build up on input pins when for example they touch insulating materials (eg clothes plastic pen) in warm dry conditions 1 Keep the IC in the carrier in which it is supplied until it is inserted in the circuit 2 Do not finger the pins or hold them in contact with an insulator 3 Connect all unused inputs of the IC to either the positive or the negative of the battery

depending on the circuit

5

BUILDING CIRCUITS

The circuit board shown above accepts ICs as well as separate components It has 47 rows of 5 interconnected sockets on each side of a central channel across which dil ICs can be fitted A wire inserted in a socket in a certain row becomes connected to wires in any of the other 4 sockets in that row by a metal strip under the board For example wires in sockets B5 C5 D5 E5 and F5 (shown in color in the diagram) are all joined Metal strips under the board connect the sockets A row of 40 interconnected sockets along the top of the board and a similar row along the bottom act as the positive and negative power supply rails (called lsquobus barsrsquo) Various makes of circuit board are available some with vertically mounting removable panels for supporting controls

6

1 To make a connection push about 1 cm of the bare end of a wire (025 to 085 mm diameter) straight into the socket (not at an angle) so that it is gripped by the metal strip under the board Do not use wires that are dirty or have kinked ends Only put one wire in each socket

Bend leads on resistors etc as shown before inserting them in the board

2 Bare the ends of connecting wire (PVC-covered tinned copper wire 06 mm diameter) by

removing the insulation (PVC) either with wire strippers or using a pair of blunt-nosed pliers and a pair of side cutters as shown With practice you should be able to judge just how much the side cutters have to be squeezed and pulled to remove the insulation without cutting the wire

3 lsquoJoinrsquo wires to the lsquolugsrsquo on the loudspeaker and variable capacitor using a small length of

2 mm bore plastic sleeving - as shown by 1 and 2

7

RESISTOR COLOUR CODE Resistor values are given in ohms (shortened to Ω the Greek letter lsquoomegarsquo) They are marked on the resistor using a color code Three colored bands are painted round the resistor Each color stands for a number To read the color code start at the 1st band it is nearest the end Sometimes it is not clear which is the 1st band because there is a 4th band of gold or silver near the other end These two colors are not used for the 1st band they give the accuracy of the resistor (gold is plusmn 5 and silver plusmn 10) so you should not have too much trouble deciding where to start The 1st band gives the first number the 2nd band gives the second number and the 3rd band tells how many zeroes come after the first two numbers

8

INTRODUCTION

Digital Logic Design is concerned with the interconnection among digital components and modules and the area of Switching Theory that can be identified between circuit design and system formulation Logic design is the base of any computer system as every digital system consists of different ICrsquoS and ICs contain a large number of interconnected digital circuits within a small package MSI devices provide digital function while LSI device cover a complete computer modules These circuitries are widely used in digital system like digital voltmeter frequency meter calculating machines telephone-switching system etc In this Practical Workbook laboratory sessions based on both combinational and sequential logic are covered First laboratory session gives an introduction to the basic logic gates and fundamentals of circuit building The second laboratory session covers a CAD software ndash Electronics Workbench (EWB) EWB is excellent simulation software where circuits can be designed and tested before physical implementation Various laboratory sessions of this workbook provide activities and exercises on EWB Next eight laboratory sessions are based on combinational logic Here various MSI circuits like adders converters multiplexers decoders encoders etc are designed Some of these laboratory sessions also include testing of MSI ICs Next four laboratory sessions help in exploring various designs based on sequential logic Here a variety of circuits are designed form the testing of basic flip-flop ICs to registers and different types of counters Last laboratory session demonstrates how digital hardware can be interfaced with a personal computer via parallel port and can be controlled by software All laboratory sessions of this workbook incorporate brief theoretical backgrounds as details may be covered in the respective theory classes Exercises activities are included with almost all the sessions for the students to practice Two appendices are also included in this workbook The first one provides pin diagrams for all the ICs required for the laboratory work provided in this workbook It will help the students in preparing the pin diagrams for the circuits Second appendix discusses a hardware debouncing circuit for mechanical switches as such switches are extensively used for input purpose in logic circuits

9

CONTENTS Lab Session No Object Page No

1 2 3 4 5 6 7 8 9

10

11

12

13

14

15

To study the logic gates in the following TTL ICs

7400 Quad 2-input NAND gate 7402 Quad 2-input NOR gate

7404 Hex inverter 7408 Quad 2-input AND gate 7432 Quad 2-input OR gate

Also implementing and testing the given circuit on a bread board Working with Electronics Workbench Designing Half and Full Adder Circuits Use of Karnaugh Map (SOP-Expression) method Designing a BCD Adder Designing of a 4 x 1 Multiplexer Experimenting with 74150 IC Designing of a 2 x 4 Decoder 1 x 4 Demultiplexer Experimenting with 74138 IC Designing of a 4 x 2 Priority Encoder Experimenting with 74148 IC Designing an Odd Parity Generator and Checker for a 3-bit Data Driving a seven segment display using 7447 7448 driver IC Experimenting with different modes of JK-FF Designing sequential circuit for the given state diagram using D flip-flop Designing a modulus-5 asynchronous up-counter using JK-FF Experimenting with 74194 4-bit bidirectional universal shift register Experimenting with 74245 octal bus transceivers using parallel port PC interfacing Appendix A ndash Pin Diagrams of the ICs required for the laboratory sessions Appendix B ndash Debouncing circuitry for mechanical switches

13

17

19

22

28

30

34

38

42

45

48

50

54

56

59

66

69

11

Logic Design amp Switching Theory 1 Lab Session 01 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

Lab Session 01 OBJECT

bull To study the logic gates in the following TTL ICs

i) 7400 Quad 2-input NAND gate ii) 7402 Quad 2-input NOR gate iii) 7404 Hex inverter iv) 7408 Quad 2-input AND gate v) 7432 Quad 2-input OR gate

bull Implementing and testing the given circuit on a bread board

COMPONENTS REQUIRED 1 Bread board 2 5 V - power supply 3 Multimeter 4 Logic probe 5 LEDs with resistors 6 Connecting wires 7 Switches (optional) 8 Following ICs and their datasheets

bull 7408 quad 2 input AND gate bull 7432 quad 2 input OR gate bull 7404 hex inverter bull 7400 quad 2 input NAND gate bull 7402 quad 2 input NOR gate

THEORY

Logic Gates

Logic gates are the fundamental building blocks of digital systems These devices are able to make decisions in the sense that they produce one output level when some combinations of input levels are present and a different output when other combinations are applied hence given the name Logic Gates The two levels produced by digital circuitry are referred to variously as HIGH and LOW TRUE and FALSE ON and OFF or simply 1 and 0 There are only three basic gates AND OR and NOT The other gates are merely combinations of these basic gates Logic gates can be interconnected to perform a variety of logical operations This interconnection of gates to achieve prescribed outcomes is called logic design

1 The AND Gate ndash An AND gatersquos output is 1 if and only if all its inputs are 1 If A and B are two inputs to an AND gate then output F of the gate is given as F = AB

2 The OR Gate - An OR gatersquos output is 1 if at least one of its input is 1 If A and B are two inputs to an OR gate then output F of the gate is given as F = A+B

13

Logic Design amp Switching Theory 1 Lab Session 01 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering 3 The NOT Gate (Inverter) ndash Its output is 1 when its input is 0 and its output is 0 when

the input is 1 ie it complements a digital variable If A is the input to a NOT gate then output F of the gate is given as AF =

4 The NAND Gate ndash Its output is 1 if at least one of its input is 0 This gate performs the same logic as an AND gate followed by an inverter If A and B are two inputs to a NAND gate then output F of the gate is given as BAF =

5 The NOR Gate - The output of a NOR gate is 1 if and only if all its inputs are 0 This gate performs the same logic function as an OR gate followed by an inverter If A and B are two inputs to a NAND gate then output F of the gate is given as BAF +=

All the above gates have one output and two or more inputs except the NOT gate which has only one input

PROCEDURE FOR TESTING THE LOGIC GATES IN GIVEN ICs

1 Set the power supply to 5V With the help of a multimeter check the voltage at the output knobs of the power supply

2 Connect wires long enough to reach the breadboard with the two knobs of the power supply Again using multimeter check voltage at the non-connected end of the wires

3 Insert the 7408 quad 2 input AND gate IC on to the bread board and make supply and ground connections by joining 5V wire to pin 14 and 0V wire to pin 7

4 Consult ICrsquos internal connection diagram for input and output pins of the first AND gate Connect input pins to logic 0 (0V) and observe the output using LED or logic probe You can also connect switches at the input lines to facilitate toggling between 1 and 0

5 Try different combinations of logic levels at the two inputs Again observe the output 6 Repeat the last two steps for all other gates of the same IC Record the observations 7 Repeat this procedure for all other ICs

OBSERVATIONS

Gate Input A Input B Expected Output Observed Output

AND

0 0 0 1 1 0 1 1

OR

0 0 0 1 1 0 1 1

NOT 0 - 1 -

NAND

0 0 0 1 1 0 1 1

14

Logic Design amp Switching Theory 1 Lab Session 01 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

NOR

0 0 0 1 1 0 1 1

DATA SHEETS

Figure 11

15

Logic Design amp Switching Theory 1 Lab Session 01 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

16

GIVEN CIRCUIT

Figure 12

PROCEDURE FOR IMPLEMENTATION OF THE GIVEN CIRCUIT 1 Set the power supply 2 Insert ICs on the bread board and make their supply and ground connections 3 As given in the logic diagram make connections using wires and gates in the ICs 4 Apply different combinations at the three inputs and observe the output OBSERVATIONS Logic expression for the given logic diagram __________________________________

A B C Expected Output Observed Output 0 0 0 0 0 1 0 1 0 0 1 1 1 0 0 1 0 1 1 1 0 1 1 1

Logic Design amp Switching Theory 1 Lab Session 02 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

Lab Session 02

OBJECT

Working with Electronics Workbench

ELECTRONICS WORKBENCH - EWB Electronics Workbench is a computer aided design tool that provides you with all the components and instruments necessary to create board-level designs It has complete mixed analog and digital simulation and graphical waveform analysis allowing you to design your circuit and then analyze it using different simulated instruments and analysis options It is fully integrated and interactive thus you can change your circuits quickly allowing fast and repeated what-if analysis Electronics Workbench provides the following kind of components bull Sources parts bin (AC voltage source Vcc source ground battery etc) bull Basic parts bin (resistors capacitors transformers switches etc) bull Diodes parts bin bull Transistors parts bin bull Analog ICs parts bin (op-amps etc) bull Mixed ICs parts bin (ADCs DACs 555 timers etc) bull Digital ICs parts bin (AND OR adders multiplexers etc) bull Indicators parts bin (voltmeter ammeter probe displays etc) bull Controls parts bin (voltage differentiator multiplier etc) bull Instruments parts bin (multimeter oscilloscope function generator etc) bull Miscellaneous parts bin (write data textbox etc)

o Write data This component allows you to save simulation results as an ASCII file o Text Box Use this to add descriptive text anywhere in a circuit

ACTIVITY

Design circuit for the logic expression )( CBDCABAF ++=

Procedure 1 From Logic Gates Parts Bin Drag and drop the required logic gates on the design

area Use Component Properties dialog box to customize these gates 2 Connect the terminal of these gates according to the given expression Use additional

connectors form the Basic Parts Bin if you want to connect more than wire at a single node

3 Drag and drop a probe from Indicators Parts Bin Use Component Properties dialog box to customize the color and other properties of the probe Connect this probe at the output terminal of the circuit to indicate results

4 Select four switches form Basic Parts Bin Specify the key that controls the switch by typing its name in the Value tab of the Component Properties dialog box For

17

Logic Design amp Switching Theory 1 Lab Session 02 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

18

example if you want the switch to close or open when digit lsquo1rsquo is pressed type 1 in the Value tab then click OK Assign different keys to all the switches

5 Connect the output terminals of these switches to each of the four inputs A B C and D of the circuit

6 Drag and drop Vcc and Ground form the Sources Parts Bin 7 Connect Vcc terminal to one end and Ground terminal to the other end of all the

switches 8 Label the circuit properly using text boxes found in the miscellaneous parts bin 9 Run the circuit using the Activate Simulation switch Use the keys you have assigned

to the switches to toggle them between Vcc and Ground connections thus providing 1 or 0 respectively to the inputs Record the results as indicated by the probe for all possible combinations of 1s and 0s at the inputs

EWB Circuit

Figure 21

Observations

A B C D Expected Output Observed Output 0 0 0 0 0 0 0 1 0 0 1 0 0 0 1 1 0 1 0 0 0 1 0 1 0 1 1 0 0 1 1 1 1 0 0 0 1 0 0 1 1 0 1 0 1 0 1 1 1 1 0 0 1 1 0 1 1 1 1 0 1 1 1 1

Logic Design amp Switching Theory 1 Lab Session 03 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

Lab Session 03

OBJECT

Designing Half and Full Adder Circuits COMPONENTS AND APPARATUS REQUIRED 1 Following ICs and their Datasheets

bull 7408 Quad 2-input AND Gate bull 7432 Quad 2-input OR Gate bull 7486 Quad 2-input XOR Gate

2 Digital Trainer DT-01 or the following components Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches

THEORY Half Adder A combination circuit that performs the addition of two bits without accounting for the previous carry is called half adder It needs two binary inputs and two binary outputs The input variables designate the augend and addend bits The output variables produce the sum and carry The simplified sum of product expressions for a half adder are

yxyxyxS oplus=+= yxC =

Figure 31 Circuit diagram for Half Adder

19

Logic Design amp Switching Theory 1 Lab Session 03 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

bles produce the sum and carry The simplified sum of product expressions for a half adder are

Full Adder

A combinational circuit that performs the addition of three input bits It consist of three inputs and two outputs Two of the input variables represent the two significant bits to be added The third input represents the carry from the previous lower significant position The output varia

zyxzyxzyxzyxzyxS oplusoplus=+++= yxzyxzyzxxyC )( +oplus=++=

Figure 32 Circuit diagram for Full Adder

efer to laboratory session 01 for procedure) and record the observations in the following ta

alf Adde ull Adder Inputs u

IMPLEMENTATION AND OBSERVATIONS

Implement the half adder and full adder circuits on a bread board (prepare the pin diagram (use appendix A) and r

bles H r F

Inputs Outputs Outp ts x y Carry Su Carry Sum m x y z 0 0 0 0 0 0 1 0 0 1 1 0 0 1 0 1 1 0 1 1 1 0 0 1 0 1 1 1 0 1 1 1

20

Logic Design amp Switching Theory 1 Lab Session 03 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

at of your designed circuit Attach hardcopy of the output form electronic workbench

at of your designed circuit Attach hardcopy of the output form lectronic workbench here

ACTIVITY

1 Simulate half adder circuit using Electronics Workbench Compare the results of simulation with thhere

2 Design a full subtractor circuit and simulate it using Electronics Workbench Compare the results of simulation with the

21

Logic Design amp Switching Theory 1 Lab Session 04 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

Lab Session 04 OBJECT

Use of Karnaugh Map (SOP-Expression) method GIVEN LOGIC EXPRESSION

F (A B C D) = sum ( 0 1 2 4 5 6 8 9 12 13 14 ) COMPONENTS AND APPARATUS REQUIRED 1 Digital ICs and their Datasheets

bull 7408 Quad 2-input AND Gate bull 7432 Quad 2-input OR Gate bull 7404 Hex Inverter

2 Digital Trainer DT-01 or the following components Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches PROCEDURE 1 Use Karnaugh map to reduce the given function 2 Draw the circuit diagram for the obtained reduced function 3 Implement the reduced circuit using digital ICs on a bread board (prepare the pin

diagram (use appendix A) and refer to laboratory session 01 for procedure) and record the observations

REDUCTION OF LOGIC EXPRESSION USING KARNAUGH MAP F

CD

AB DC

DC DC

DC

BA0 1 3 2

BA4 5 7 6

BA12 13 15 14

BA8 9 11 10

Reduced form of the given logic expression is __________________________________

22

Logic Design amp Switching Theory 1 Lab Session 04 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

LOGIC DIAGRAM (REDUCED FORM) OBSERVATIONS

A B C D Output 0 0 0 0 0 0 0 1 0 0 1 0 0 0 1 1 0 1 0 0 0 1 0 1 0 1 1 0 0 1 1 1 1 0 0 0 1 0 0 1 1 0 1 0 1 0 1 1 1 1 0 0 1 1 0 1 1 1 1 0 1 1 1 1

RESULT The reduced form (SOP Expression) of the given logic function is

____________________________________________________________

The observation table reflects the given logic function

23

Logic Design amp Switching Theory 1 Lab Session 04 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

ACTIVITY 1 Using Electronics Workbench derive a truth table and logic circuit for the following logic expression

BAAF +=

Procedure 1 From the Instruments Parts Bin drag and drop Logic Converter on the design area 2 Double click the Logic Converter to reveal Logic Converter dialog box This dialog

box shows various conversion options between truth table logic expression and logic circuit

3 Enter the given logic expression in the edit box found at the end of the dialog box Use lsquo to represent invert of a variable For example A is written as Arsquo

4 Click the Boolean Expression to Truth Table button The truth table appears in the logic converters display

5 Now click the Boolean Expression to Circuit button This creates the logic circuit for the given expression in the design area Label the diagram if needed

Resulting Logic Circuit For the given expression the final circuit will look like

Figure 41

24

Logic Design amp Switching Theory 1 Lab Session 04 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

ACTIVITY 2

Using Electronics Workbench find a simplified logic expression and circuit for the following truth table

A B C Output 0 0 0 1 0 0 1 1 0 1 0 0 0 1 1 1 1 0 0 0 1 0 1 0 1 1 0 0 1 1 1 1

Procedure 1 Click three input channels from A to H across the top of the logic converter The

display area below the terminals fills up with the necessary combinations of ones and zeros to fulfill the input conditions The values in the output column on the right are initially set to 0

2 Edit the output column to specify the desired output for each input condition To change an output value select it and type a new value 1 0 or x An x indicates a donrsquot care condition

3 To convert this truth table to a Boolean expression click the Truth Table to Boolean Expression button The Boolean expression will be displayed at the bottom of the logic converter

4 Simplify the expression by clicking the Simplify button 5 Now click the Boolean Expression to Circuit button This creates the logic circuit for

the given expression in the design area Resulting Logic Circuit For the given truth table the final simplified circuit will look like

Figure 42

25

Logic Design amp Switching Theory 1 Lab Session 04 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

ACTIVITY 3

Using Electronics Workbench find the logic expression and truth table for the following logic circuit

Figure 43

Procedure 1 Attach the input terminals of the logic converter to up to four input points in the

circuit 2 Connect the single output of the circuit to the output terminal on the logic converter

icon 3 Click the Circuit to Truth Table button The truth table appears in the logic

converters display 4 To convert this truth table to a Boolean expression click the Truth Table to Boolean

Expression button The Boolean expression will be displayed at the bottom of the logic converter

Resulting Logic Expression Logic Expression for the given circuit is found to be _____________________________

26

Logic Design amp Switching Theory 1 Lab Session 04 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

27

For activities 1 2 and 3 attach hardcopy of the output (truth table logic expression and logic circuit) form electronic workbench here

Logic Design amp Switching Theory 1 Lab Session 05 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

Lab Session 05 Lab Session 05 OBJECT OBJECT

Designing a BCD Adder Designing a BCD Adder COMPONENTS AND APPARATUS REQUIRED COMPONENTS AND APPARATUS REQUIRED

1 Following ICs and their Datasheets 1 Following ICs and their Datasheets bull 7408 Quad 2-input AND Gate bull 7408 Quad 2-input AND Gate bull 7432 Quad 2-input OR Gate bull 7432 Quad 2-input OR Gate bull 7483 4-bit Binary Adder bull 7483 4-bit Binary Adder

2 Digital Trainer DT-01 or the following components 2 Digital Trainer DT-01 or the following components Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors (100 Ω) Connecting wires Switches (100 Ω) Connecting wires Switches

THEORY THEORY

A BCD Adder is a combinational circuit that adds two BCD digits in parallel and produces a sum digit also in BCD A BCD Adder is a combinational circuit that adds two BCD digits in parallel and produces a sum digit also in BCD

A4 A3 A2 A1 B4 B3 B2 B1

7483-BCD ADDER

Cout (C4 ) Z4 Z3 Z2 Z1 Cin(C0)

A4 A3 A2 A1 B4 B3 B2 B1

7483-BCD ADDER

Cout

(C4 ) Z4 Z3 Z2 Z1 Cin(C0)

Figure 51 BCD Adder Circuit

28

Logic Design amp Switching Theory 1 Lab Session 05 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

29

A BCD adder must include the correction logic in its internal construction The two BCD digits together with the input carry are first added using a 4-bit binary adder to produce the binary sum If no output carry is generated and the binary sum is less than or equal to 9 then the corresponding BCD sum is identical and therefore no conversion is needed When the output carry is equal to 1 or the binary sum is greater than 9 then a binary 0110 is added to the binary sum through another 4-bit binary adder If Cout is the carry output and Z4Z3Z2Z1 is the binary sum form the first 4-bit binary adder then the following equation indicates the condition when a binary 0110 is to be added

C = COUT + Z4Z2 + Z4Z3 IMPLEMENTATION AND OBSERVATIONS Implement the BCD adder circuit according to figure 51 on a bread board (prepare the pin diagram (use appendix A) and refer to laboratory session 01 for procedure) A BCD adder has nine input bits (two BCD digits and a carry bit) which can result in a total of 512 combinations of which 312 inputs are donrsquot care Since it is a very lengthy procedure to record results for 200 valid input combinations therefore for simplicity just record results for any eight combinations in the following table

Input Carry

BCD Digit 1 BCD Digit 2 Carry Output

BCD Sum A4 A3 A2 A1 B4 B3 B2 B1 Z4 Z3 Z2 Z1

Logic Design amp Switching Theory 1 lab Session 06 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

Lab Session 06

OBJECT

bull Designing of a 4 x 1 Multiplexer bull Experimenting with 74150 IC

COMPONENTS AND APPARATUS REQUIRED 1 Following ICs and their Datasheets

bull 7408 Quad 2-input AND Gates or 7411 Triple 3-input AND Gates bull 7432 Quad 2-input OR Gates bull 7404 Hex Inverter bull 74150 16 x 1 MUX

2 Digital Trainer DT-01 or the following components Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches THEORY

Multiplexers A digital data Multiplexer (MUX) is a combinational circuit having several data inputs and a single output A set of data-select inputs is used to control which of the data inputs is routed to the single output A multiplexer is also called a data selector because of this ability to select which data input is connected o the output Normally there are 2n input lines and n selection lines whose bit combination determine which input is selected DESIGN OF A 4 x 1 MULTIPLEXER A 4 x 1 multiplexer is capable of selecting one of four data inputs (see figure 61) The 2-bit binary number at the data select inputs S1 and S0 specifies which of the four data inputs is to be routed to the output Since there are two data select inputs therefore they can select 22 = 4 different data inputs lines

S0 S1 D0 D1

D2 D3

Data-select Inputs Output

Data Inputs

Figure 61 Block Diagram of a 4 x1 Multiplexer

30

Logic Design amp Switching Theory 1 lab Session 06 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

Figure 62 Circuit Diagram for 4 x 1 Multiplexer

Implementation and Observations

Implement the 4 x 1 Multiplexer circuit (figure 62) on a bread board (prepare the pin diagram (use appendix A) and refer to laboratory session 01 for implementation procedure) and record the observations in the following table For each data select combination specify the switch number as well as the binary value present on that selected switch

S1 S0 Output 0 0 0 1 1 0 1 1

TESTING OF 74150 - 16 x 1 MUX

The 74150 IC has sixteen data inputs and four data-selection lines Function of various pins of this IC is described below

bull E0 through E15 Data input lines

31

Logic Design amp Switching Theory 1 lab Session 06 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering bull A B C D Data select lines with D being the MSB bull W Active low output line bull Grsquo Active low enable line bull VCC and GND Supply connections lines

Circuit Diagram

Figure 63 Pin connections of 74150 for selecting E0

Testing Procedure

bull Make connections as shown in the circuit diagram bull Apply different data (1 or 0) at data inputs that are labeled as E0 to E15 Only

connection for E0 is shown is the figure for simplicity bull Select the data input E0 with the help of data selectors A B C and D bull Observe the output which shows the complement of the data from E0 bull Select all the sixteen data inputs one by one and record your observations in the

following table

32

Logic Design amp Switching Theory 1 lab Session 06 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

33

Observations

Grsquo D C B A W Grsquo D C B A W 0 0 0 0 0 0 1 0 0 0 0 0 0 0 1 0 1 0 0 1 0 0 0 1 0 0 1 0 1 0 0 0 0 1 1 0 1 0 1 1 0 0 1 0 0 0 1 1 0 0 0 0 1 0 1 0 1 1 0 1 0 0 1 1 0 0 1 1 1 0 0 0 1 1 1 0 1 1 1 1

ACTIVITY 1 Consider 4x1 Multiplexer Draw the output wave-form for the following data inputs

(E0 E1 E2 E3) and select lines A B (B being the MSB) Output is W

E3 E2 E1 E0 A B

W

2 Using the 4 x 1 MUX designed in this laboratory session implement the following logical function F (A B C) = Σ (0147)

Show your working and input connections in the following block diagram according to the circuit you have implemented

4 x 1 MUX

S0 S1

Output D0

D1

D2

D3

Logic Design amp Switching Theory 1 Lab Session 07 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

Lab Session 07

OBJECT

bull Designing of a 2 x 4 Decoder 1 x 4 Demultiplexer bull Experimenting with 74138 IC

COMPONENTS AND APPARATUS REQUIRED 1 Following ICs and their Datasheets

bull 7408 Quad 2-input or 7411 Triple 3-input AND Gates bull 7404 Hex Inverter bull 74138 3 x 8 Decoder

2 Digital Trainer DT-01 or the following components Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches THEORY

Decoder A Decoder is a combinational circuit that converts binary information form n input lines to a maximum of 2n unique output lines In practical applications decoders are often used for selecting one of several devices

Demultiplexer A decoder with an enable input can function as a Demultiplexer A Demultiplexer (DMUX) id a circuit that receives information on a single line and transmits this information on one of 2n possible output lines The selection of a specific output line is controlled by the bit values of n selection lines DESIGN OF A 2 x 4 DECODER 1 x 4 DEMULTIPLEXER A 2 x 4 decoder is capable of selecting one of four output lines (see figure 71 (a)) The 2-bit binary number at the data inputs S1 and S0 specifies which of the four data inputs is to be selected If we add an enable pin and use it as an input line then this decoder can be converted to a 1 x 4 Demultiplexer where S1 and S0 will select a line to which data input is to be routed (see figure 71 (b))

Select S0 S0 Inputs

S1 D0 D1

D2

D3

Enable (a) Block Diagram of a 2 x 4 Decoder

Figure 71

S1 D0 D1

D2

D3

Inputs

Data Input (b) Block Diagram of a 1 x 4 Demulptiplexer

34

Logic Design amp Switching Theory 1 Lab Session 07 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

Figure 72 Circuit Diagram for 2 x 4 Decoder 1 x 4 Demultiplexer

Implementation and Observations Implement the 2 x 4 Decoder 1 x 4 Demultiplexer circuit (figure 72) on a bread board (prepare the pin diagram (use appendix A) and refer to laboratory session 01 for implementation procedure) and record the observations in the following table

Enable Data Input S1 S0 D0 D1 D2 D3

0 0 0 0 0 1 0 1 0 0 1 1 1 0 0 1 0 1 1 1 0 1 1 1

TESTING OF 74138 3 x 8 Decoder The 74138 IC has three inputs and eight output lines It has three enable inputs and for the IC to function all three inputs need to be enabled Function of various pins of this IC is described below

35

Logic Design amp Switching Theory 1 Lab Session 07 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

bull Y0 through Y7 Active low data outputs bull A B C Input select lines with C being the MSB bull G1 Active high enable Input bull G2Arsquo and G2Brsquo Active low enable Inputs bull VCC and GND Supply connections lines Circuit Diagram

Figure 73 Pin connections of 74138

Testing Procedure

bull Make connections as shown in the circuit diagram bull Apply different combinations of 1s and 0s at data inputs bull Observe the output and record your observations in the following table

Observations

C B A Y0 Y1 Y2 Y3 Y4 Y5 Y6 Y7 0 0 0 0 0 1 0 1 0 0 1 1 1 0 0 1 0 1 1 1 0 1 1 1

36

Logic Design amp Switching Theory 1 Lab Session 07 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

37

ACTIVITY ACTIVITY 1 What will be the binary values at the outputs Y0 through Y7 of 74138 if 1 What will be the binary values at the outputs Y0 through Y7 of 74138 if

bull All three enable pins are connected to ground bull All three enable pins are connected to ground __________________________________________________________________________________________________________________________________________ __________________________________________________________________________________________________________________________________________ _____________________________________________________________________ _____________________________________________________________________

bull All three enable pins are connected to VCC bull All three enable pins are connected to VCC _______________________________________________________________________________________________________________________________________________________________________________________________________________

_______________________________________________________________________________________________________________________________________________________________________________________________________________

2 Show connections for 74138 in order to use it as a 1 x 8 Demultiplexer 2 Show connections for 74138 in order to use it as a 1 x 8 Demultiplexer

3 Consider a 2 x 4 Decoder with two enable inputs (one active high - G and one active low ndash Grsquo) Draw the output wave-forms for D0 D1 D2 and D3 if the two select inputs are A and B (B being the MSB) All outputs are active low

Grsquo

G

A B

D0 D1 D2

D3

Logic Design amp Switching Theory 1 Lab Session 08 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

Lab Session 08 OBJECT

bull Designing of a 4 x 2 Priority Encoder bull Experimenting with 74148 IC

COMPONENTS AND APPARATUS REQUIRED

1 Following ICs and their Datasheets

bull 7408 Quad 2-input or 7421 Dual 4-input AND Gates bull 7432 Quad 2-input OR Gates bull 7404 Hex Inverter bull 74148 Encoder

2 Digital Trainer DT-01 or the following components Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches

THEORY

Encoder An Encoder is a digital function that produces a reverse operation from that of a decoder An Encoder has 2n (or less) input lines and n output lines The output lines generate the binary code for the 2n input variables Priority Encoder

A simple encoder may produce an erroneous output if more than one of its inputs is high A Priority Encoder is one that responds to just one input among those that may be simultaneously high in accordance with some priority system The most common priority system is based on the relative magnitudes of the inputs whichever decimal input is largest is the one that is encoded

DESIGN OF A 4 x 2 Priority Encoder

The following equations represent the outputs of a 4 x 2 priority encoder 32 DDA +=

321 DDDB += As can be seen from the equations that input D0 which has a binary code 00 is not used in any equation A binary code 00 at the output indicates two conditions Either D0 is selected or no input is selected In order to differentiate these two conditions we will provide an additional output Z to indicate if at least one of the inputs is a 1 The equation for Z will be

4321 DDDDZ = If Z is 0 then the binary code 00 at the output indicates that D0 is selected and if Z is 1 then it indicates that no input line is selected

38

Logic Design amp Switching Theory 1 Lab Session 08 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

Figure 81 Circuit Diagram for 4 x 2 Priority Encoder

it (figure 81) on a bread board (prepare the to laboratory session 01 for implementation

Implementation a Implement the 4 x 2 Priority Encoder circu

ram (use appendix A) and refer

nd Observations

pin diagprocedure) and record the observations in the following table

D3 D2 D1 D0 A B 0 0 0 1 0 0 1 x 0 1 x x 1 x x x

TESTING OF 74148 8 x 3 Octal Priority Encoder

imal digits There are nine of which three represents

ing any of the inputs is high

then it shows that line 0 is selected and if e inputs selected E0 and GS

cannot be in the same state provided that E1 is enabled

The 74148 is a priority encoder with active-Low input for dec

input) and five output linesinputs lines (including an enablethe binary code for the octal digit Function of various pins of this IC is described below

bull 0 through 7 Active low data inputs representing the octal digits A2 A1 A0 Active low output lines representing the binary code bullbull E1 Active low enable Input bull E0 Active low output indicating none of the inputs is high bull GS Active low output indicatbull VCC and GND Supply connections lines Therefore if GS A2 A1 and A0 are all low

then it shows that none of thE0 A2 A1 and A0 are all low

39

Logic Design amp Switching Theory 1 Lab Session 08 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

Circuit Diagram

Figure 82 Pin connections of 74148

Testing Procedure bull Make connections as sho

binations of 1s and 0s at data inputs d record your observations in the following table

GS E0

wn in the circuit diagram bull Apply different combull Observe the output an Observations

0 1 2 3 4 5 6 7 A2 A1 A0 1 1 1 1 1 1 1 1 x x x x x x x 0 x x x x x x 0 1 x x x x x 0 1 1 x x x x 0 1 1 1 x x x 0 1 1 1 1 x x 0 1 1 1 1 1 x 0 1 1 1 1 1 1 0 1 1 1 1 1 1 1

40

Logic Design amp Switching Theory 1 Lab Session 08 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

41

CTIVITY

Cascade the following two 74148 8 x 3 Priority Encoders to form 16 x 4 Priority

A 1

Encoder

Logic Design amp Switching Theory 1 Lab Session 09 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering `

Lab Session 09 OBJECT

Designing an Odd Parity Generator and Checker for a 3-bit Data COMPONENTS AND APPARATUS REQUIRED

1 Following ICs and their Datasheets

bull 7486 Quad 2-input Exclusive-OR Gates bull 7404 Hex Inverter

2 Digital Trainer DT-01 or the following components Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches

THEORY

Parity Generator When binary data is transmitted and processed it is ndash as are all electrical signals ndash susceptible to noise that can either alter or distort its contents 1s may be effectively changed to 0s and 0s to 1s To overcome this problem one or more bits are often added to the data as an aid in detecting errors caused by noise The most common of these is a Parity bit that signifies whether the total number of 1s in a code group is odd or even In an Odd Parity system the parity bit is made 0 or 1 as necessary to make the total number 1s odd (counting the parity bit itself) In an Even Parity system the parity bit is chosen to make the total number of 1s even Table 91 shows how parity bits would be added to BCD code group in both systems

Decimal BCD Value Parity Bit ABCD Odd Parity Even Parity

0 0000 1 0 1 0001 0 1 2 0010 0 1 3 0011 1 0 4 0100 0 1 5 0101 1 0 6 0110 1 0 7 0111 0 1 8 1000 0 1 9 1001 1 0

Table 91 Odd and Even Parity in BCD

When digital data is received a parity checking circuit generates an error signal if the total number of 1s is odd in an even parity system or if it is even in an odd parity system Parity check always detects a single error (one bit change from 0 to 1 or 1 to 0) but may not detect

42

Logic Design amp Switching Theory 1 Lab Session 09 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering ` two or more errors Odd parity is used more often than even parity because even parity does not detect a situation where all 0s are created due to short circuit or other fault condition DESIGN OF A 3-BIT ODD PARITY GENERATOR AND CHECKER Let x y and z be the three bits that constitute the message and are the input to the Odd Parity Generator Circuit Since it is an odd parity system the bit P is generated so as to make the total number of 1s odd (including P) The function P can be expressed as follows P = x oplus y Ο z or P = x Ο y oplus z Since the IC available is 7486 which is quad 2input XOR IC therefore we will convert XNOR also to XOR

P = x oplus y Ο z

P = ( x oplus y ) Ο z Since for even number of variables ______

XOR = XNOR Therefore ___________ _________

P = ( x oplus y ) oplus z = x oplus y oplus z This logical expression can be implemented with two XOR gates and an inverter (see figure 91)

Figure 91 Circuit Diagram for a 3-bit Parity Generator

The 3-bit message and the parity bit are transmitted to their destination where they are applied to a Parity Checker Circuit An error occurs during transmission if the parity of the four bits received is even since the binary information transmitted was originally odd The output C of the parity checker should be a 1 when an error occurs ie when the number of 1s in the four inputs is even Therefore the function C can be expressed as

C = x Ο y Ο z Ο P

Using the same logic applied for the conversion of the equation of P

PzyxC oplusoplusoplus= This logical expression can be implemented with three XOR gates and an inverter (see figure 92)

43

Logic Design amp Switching Theory 1 Lab Session 09 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering `

44

Figure 92 Circuit Diagram for a 3-bit Parity Checker Implementation and Observations Implement the 3-bit Parity Generator and Checker circuits (figure 91 and 92) on a bread board (prepare the pin diagram (use appendix A) and refer to laboratory session 01 for implementation procedure) and record the observations in the following table

x y z P x y z P C x y z P C 0 0 0 0 0 0 0 1 0 0 0 0 0 1 0 0 0 1 1 0 0 1 0 1 0 0 0 1 0 1 0 1 0 0 1 1 0 0 1 1 1 0 1 1 1 0 0 0 1 0 0 1 1 0 0 1 0 1 0 1 0 1 1 1 0 1 1 1 0 0 1 1 0 1 1 1 0 1 1 1 0 1 1 1 1 1 1 1

Odd Parity Generation Odd Parity Check ACTIVITY 1 Try using the parity checker of figure 92 as 3-bit parity generator Write the details here

_____________________________________________________________________________________________________________________________________________________________________________________________________________________ ______________________________________________________________________________________________________________________________________________ _______________________________________________________________________ ______________________________________________________________________________________________________________________________________________

Logic Design amp Switching Theory 1 Lab Session 10 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

Lab Session 10 OBJECT

Driving a seven segment display using 7447 7448 driver IC COMPONENTS AND APPARATUS REQUIRED

1 Following ICs and their Datasheets

bull Seven Segment Displays (Common Anode Common Cathode) bull 7447 7448 BCD to Seven Segment Driver

2 Digital Trainer DT-01 or the following components Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches

THEORY Seven Segment Displays A Seven Segment Display consists of seven light-emitting segments The segments are designated by letters a through g (see figure 101) By illuminating various combinations of segments the numerals 0 through 9 can be displayed Seven Segment Displays are commonly constructed with light-emitting diodes (LEDs) and with liquid-crystal displays (LCDs) LEDs generally provide greater illumination levels but require much greater power than LCDs An LED display can be a common-anode type or common cathode type In common anode type a high voltage is applied at the common terminal of the display and low voltage is applied at a segmentrsquos terminal for illumination In the common-cathode type a low voltage is applied at the common terminal of the display and high voltage is applied at a segmentrsquos terminal for illumination

Figure 101 Seven Segment Display

a f b g

e c d

7447 7448 BCD to Seven Segment Driver 7447 7448 IC is particularly used to drive Seven Segment Its input is a BCD number and output drives a seven segment display 7447 is used to drive common-anode displays whereas 7448 is used to drive common cathode displays 7447 7448 is a 16 pin IC Function of various pins of these ICs is described below

bull A B C D Inputs representing BCD digits (D being the MSB)

45

Logic Design amp Switching Theory 1 Lab Session 10 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering bull OA through OG Outputs to drive segments a through g of the display (Active low

in 7447 and active high in 7448) bull RBI Ripple Blanking Input Turns off all the segments if kept low provided that LT

is kept high and all other inputs (A B C D BI) are kept low Should be kept high otherwise

bull BI RBO Wire-AND logic serving as a Blanking Input and or Ripple Blanking Output

o BI Turns off all the segments if low o RBO Goes to a low level (response condition) along with other outputs when

RBI and inputs A B C and D are low with LT input at high level bull LT Lamp Test input Tests whether all segments are working or not Illuminates all

segments if kept low provided that BI is kept high Should be kept high otherwise bull VCC and GND Supply connections lines CIRCUIT DIAGRAM

Figure 102 Circuit diagram for 7447driving a common-anode display

IMPLEMENTATION AND OBSERVATIONS

bull Make connections as shown in the circuit diagram (refer to laboratory session 01 for implementation procedure)

bull Apply different combinations of 1s and 0s at data inputs bull Observe the output and record your observations in the following table

46

Logic Design amp Switching Theory 1 Lab Session 10 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

47

Decimal Digit

BCD Inputs Seven Segment Outputs D C B A a b c d e f g

0 0 0 0 0 1 0 0 0 1 2 0 0 1 0 3 0 0 1 1 4 0 1 0 0 5 0 1 0 1 6 0 1 1 0 7 0 1 1 1 8 1 0 0 0 9 1 0 0 1

ACTIVITY 1 Perform the Lamp Test for the designed circuit and write your observations

____________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________

2 How can you use 7447 IC to drive a common-cathode display

____________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________

3 What symbols appear in the seven segment display if inputs DCBA are

DCBA Symbol

1010

1011

1100

1101

1110

1111

Logic Design amp Switching Theory 1 Lab Session 11 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

48

Lab Session 11 OBJECT

Testing different modes of JK-FF COMPONENTS AND APPARATUS REQUIRED 1 Following ICs and their Datasheets

bull 7473 7476 JK Flip-Flop 2 Digital Trainer DT-01 or the following components

Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches

THEORY

Flip-Flop A flip-flop circuit can maintain a binary state indefinitely (as long as the power is delivered to the circuit) until directed by an input signal to switch states The major differences among various types of flip-flops are in the number of inputs they possess and in the manner in which the inputs affect the binary state

JK Flip-Flop JK flip flop is an edge triggered device A typical JK flip flop has three inputs J K and a clock input The flip-flop can be either positive or negative edge triggered The output Q is available in complemented form as well Beside the usual inputs and output most of the flip-flop IC also possess two asynchronous inputs namely Preset and Clear These inputs are usually active low If used Preset and Clear inputs keep the flip-flop in set and reset state respectively irrespective of the other inputs Both of these inputs cannot be used simultaneously otherwise they will bring the flip-flop in unstable state

Figure 111 Symbol for JK flip-flop

(a) positive-edge triggering (b) active low Preset (PR) and Clear (CLR) with positive-edge triggering

(c) active low Preset (PR) and Clear (CLR) with negative-edge triggering

Logic Design amp Switching Theory 1 Lab Session 11 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

49

TESTING OF 7473 7476 DUAL JK FLIP-FLOP

Both the ICs 7473 and 7476 are similar in functionality except for one difference The flip-flops in 7473 have only one type of active low asynchronous input which is the Clear input whereas the flip-flops in 7476 have both Preset and Clear inputs Both these ICs have negative edge triggered flip-flops

Circuit Diagram

Figure 112 Pin connections of 7476

Testing Procedure

bull Make connections as shown in the circuit diagram (figure 112) bull Apply different combinations of 1s and 0s at J and K inputs bull Observe the output and record your observations in the following table

Observations

J

K Q

0 0 0 1 1 0 1 1

ACTIVITY

1 Observe the output Q of JK flip-flop if the clock input is connected to VCC or GND instead of a clock source Write your observations here __________________________________________________________________________________________________________________________________________ _______________________________________________________________________________________________________________________________________________________________________________________________________________

Logic Design amp Switching Theory 1 Lab Session 12 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

50

Lab Session 12 OBJECT

Designing sequential circuit for the given state diagram using D flip-flop GIVEN STATE DIAGRAM

00

11

Figure 121 State Diagram COMPONENTS AND APPARATUS REQUIRED 1 Following ICs and their Datasheets

bull 7474 D Flip-Flop bull ICs of basic gates (AND OR NOT XOR etc) as required

2 Digital Trainer DT-01 or the following components Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches

THEORY

Sequential Circuits In Sequential Circuits the output not only depends on the present inputs but also on previous states of the circuit These circuits use memory elements (latches flip-flops) and the binary information stored in the memory elements at any given time defines the state of the sequential circuit Analysis of a Sequential Circuit The behavior of a sequential circuit is determined from the inputs the outputs and the states of its flip-flops Both the outputs and next state are a function of the inputs and the

10

01

00 11 10

00

00 11 10 00

Logic Design amp Switching Theory 1 Lab Session 12 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

51

present state The analysis of a sequential circuit form a state diagram comprises of the following bull Selecting a particular flip-flop to design the circuit bull Obtaining state table from the state diagram bull Finding input equations for the selected flip-flop bull Finding state equations (not required for the construction of circuit) bull Implementing the circuit using selected flip-flops and their input equations ANALYZING THE GIVEN STATE DIAGRAM D Flip-Flop D flip-flop is also called transparent flip-flop as it simply transfers the input data to the output For our design we require the graphical symbol and excitation table of D flip-flop (see figure 122)

Qt Qt+1 T 0 0 0 0 1 1 1 0 0 1 1 1

(b) Excitation table of D Flip-Flop

(a) Graphical Symbol

Figure 122 Characteristic equation of D flip-flop is Q(t+1) = D State Table The given state diagram has four states so we will need two D flip-flops (FF-0 FF-1) Form state table form the given state diagram and record the results in the following table

Present State Input Next State Output Input to FF-0 D0

Input to FF-1 D1 Q1t Q0t x Q1(t+1) Q0(t+1) z

Logic Design amp Switching Theory 1 Lab Session 12 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

52

Input Equations Using Karnaugh map the input equations D0 and D1 for the two flip-flops can be found

D0 D1 Q0x

Q1

_ _ Q0x

_ Q0x

Q0x

_ Q0x

Q0x

Q1

_ _ Q0x

_ Q0x

Q0x

_ Q0x

_ Q1

_ Q1

Q1

Q1

D0 = _________________ D1 = _________________

State Equations Using the characteristic equation of D flip-flop we can find the state equations Q0(t+1) and Q1(t+1) for the to flip flops Q0(t+1) = _______________________ Q1(t+1) = _______________________ _______________________ _______________________ _______________________ _______________________ Circuit Diagram

Logic Design amp Switching Theory 1 Lab Session 12 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

53

Implementation Procedure and Observations

1 Implement the circuit using digital ICs on a bread board (prepare the pin diagram (use appendix A) and refer to laboratory session 01 for procedure)

2 Make the clear inputs of the flip-flops low (to clear the flip-flops) The flip-flops will remain in clear state as long as the clear inputs are connected to low level

3 Connect output Q0 and the clock pulse to an oscilloscope 4 Apply 0 to the input x 5 Now make the clear inputs to high 6 Observe the waveform for the first 5 clock pulses and record it 7 Repeat steps 2 to 6 keeping x=1 in step 4 this time 8 Repeat steps 2 to 7 this time connecting Q1 instead of Q0 to the oscilloscope in step

3 Record your observations (Keep frequency of the clock pulse low (eg1Hz) so that the output waveforms can be observed easily)

1 2 3 4 5 Clock Pulse

Output Waveform for Q0 when x=0

Output Waveform for Q0 when x=1

Output Waveform for Q1 when x=0

Output Waveform for Q1 when x=1

Logic Design amp Switching Theory 1 Lab Session 13 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

Lab Session 13 OBJECT

Designing a modulo-5 asynchronous up-counter using JK-FF COMPONENTS AND APPARATUS REQUIRED

1 Following ICs and their Datasheets

bull 7400 Quad 2-input or 7410 Triple 3-input NAND Gates bull 7476 7473 JK Flip-Flop

2 Digital Trainer DT-01 or the following components Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches

THEORY

Digital Counters A digital counter is a set of flip-flops whose states change in response to pulses applied at the input to the counter The flip-flops are interconnected so that their combined state at any time is the binary equivalent of the total number of pulses that have occurred up to that time Every counter resets after a certain number of clock pulses Thus as it name implies a counter is used to count pulses An n stage counter can count up to a maximum of 2n states n is equal to the number of flip-flops required for the construction of counter

Modulus Counters The number of input pulses that causes a counter to reset to its initial count is called the modulus of the counter Thus the modulus equals to total number of distinct states (counts) including zero that a counter can store A binary counter with n stages is a modulo-2n (or mod-2n) counter The largest count a mod-N counter can achieve is N-1 ie a mod-N counter never reaches the binary number equal to its modulus N is always equal to or less than 2n Counters can be classified as bull Synchronous Counters which are clock driven All the flip-flops are driven by a

single clock bull Asynchronous Counters which are event driven Clock input is given to the first

flip-flop only Rest of the flip-flops are driven by their preceding flip-flops

DESIGN OF A MOD-5 ASYNCHRONOUS UP COUNTER The number of flip-flops required to construct a mod-5 counter is 3 because 5 should be less than or equal to 2n This counter will count from 0 to 4 a total of 5 distinct states Since a 3-stage counter can count up to 8 states at maximum a NAND gate is used to reset it after 5 clock pulses Figure 131 shows the logic diagram

54

Logic Design amp Switching Theory 1 Lab Session 13 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

55

Figure 131 A Mod-5 Asynchronous Up Counter

Implementation and Observations

Implement the mod-5 counter circuit (figure 131) on a bread board (prepare the pin diagram (use appendix A) and refer to laboratory session 01 for implementation procedure) and record the observations in the following table

Clock Pulse Q2 Q1 Q0

0 1 2 3 4 5 6 7

ACTIVITY

Draw the timing diagram for mod-5 counter designed in this laboratory session

Logic Design amp Switching Theory 1 Lab Session 14 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

Lab Session 14 OBJECT

Experimenting with 74194 4-bit bidirectional universal shift register COMPONENTS AND APPARATUS REQUIRED

1 Following ICs and their Datasheets

bull 74194 4-bit bidirectional universal shift register 2 Digital Trainer DT-01 or the following components

Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches

THEORY

Shift Registers

A Register is a set of flip-flops used to store binary data A register which is capable of shifting its binary information either to the right or left is called a shift register The logical configuration of a register consists of a chain of flip-flops connected in cascade with the output of one flip-flop connected to the input of next flip-flop All flip-flops receive a common clock pulse which causes the shift from one stage to the next

Bidirectional Shift Registers A bi-directional shift register is one whose bits can be shifted from left to right or from right to left

Universal Shift Registers A universal shift register is a bi-directional register whose input can be in either serial or parallel form and whose output can be in either serial or parallel form

74194 4-BIT BIDIRECTIONAL UNIVERSAL SHIFT REGISTER

The 74194 register provides parallel as well as serial loading in both directions Function of various pins of this IC is described below

bull A B C and D Active high inputs for parallel loading bull QA QB QC and QD Active high outputs bull S0 and S1 Active high mode control inputs The following table shows combinations

of S1 and S0 to enable various modes

S1 S0 Clock Action 0 0 x No change 0 1 uarr Shift right 1 0 uarr Shift left 1 1 uarr Parallel load

uarr shows the rising edge of the clock pulse

56

Logic Design amp Switching Theory 1 Lab Session 14 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering bull SR Active high serial input for right shifting bull SL Active high serial input for left shifting bull CLR Active low input Clears all the flip-flops of the register if set to 0 should be

kept high otherwise bull CLK Clock input bull VCC and GND Supply connections lines Thus A B C and D are inputs for parallel loading whereas SR and SL are inputs for serial loading with right or left shifting respectively S1 and S0 are used to select the loading mode Circuit Diagram

Figure 141 Pin connections of 74194 Testing Procedure

bull Make connections as shown in the circuit diagram bull Observe the output for the input combinations given in the following table

57

Logic Design amp Switching Theory 1 Lab Session 14 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

58

Observations

S1 S0 SL SR A B C D QA QB QC QD 0 0 0 1 0 0 0 0 0 1 1 0 0 0 0 1 1 0 0 0 0 0 1 0 1 1 0 0 0 0 1 1 0 0 1 1 0 1 0 0 0 1 1 1 0 1 0 1 1 0 1 0 0 1 1 0 1 1 1 0 0 1 1 1 1 1 0 0 1 1 1 1

ACTIVITY 1 Show connections of 74194 to convert it into a ring counter with right shifting

Logic Design amp Switching Theory 1 Lab Session 15 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

Lab Session 15

OBJECT

Experimenting with 74245 octal bus transceivers using parallel port PC interfacing COMPONENTS AND APPARATUS REQUIRED 1 Parallel Port Connectors (DB-25) with Cable 2 Personal Computer with Windows 98 and TurboC Compiler Installed 3 Following ICs and their Datasheets

bull 74245 Octal Bus Transceivers with 3-State Outputs 4 Digital Trainer DT-01 or the following components

Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches

THEORY

3-State Logic Sometimes it is necessary to isolate one part of circuit from the other part For this purpose some TTL ICs are designed with 3-state logic Such devices have three possible output states high low and high impedance The device can be put into high impedance state by a control signal applied to an appropriate pin When such a device is in high impedance state there is very high impedance at its output effectively isolating the device from whatever circuitry the output normally drives 74245 Octal Bus Transceivers A bus is any conducting path or set of paths having electrical connections to one or more devices 74245 octal bus transceivers are mainly used to control connectivity between two devices or circuits It also provides direction control for signal flow Function of various pin of this IC is given below

bull A1 through A8 Bus A bull B1 through B8 Bus B bull G΄ Active low enable input When high sets all the bus pins to high impedance state bull DIR Direction control for signal flow When set to high logic level transfers bus A

data to B bus When set to low logic level transfers bus B data to A bus bull VCC and GND Supply connections lines Serial and Parallel Port Connectors A Parallel Port can consist of only 25 pin port adapter called a DB-25 and a serial port can consist of either a 25 pin port adapter called a DB-25 or 9 pin adapter called a DB-9 port adapter Whether the port is a 9 pin or 25 pin it can accomplish all of the same tasks that serial port communications have been designed for

59

Logic Design amp Switching Theory 1 Lab Session 15 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

60

Each adapter can be a male type connector with pins or a female type adapter with tiny holes Generally a PRINTER port (called LPT1) on the back of a computer is female type adapter and we need to use MALE DB-25 pin cable on it for PRINTER connection or for parallel LAPLINK cable And a COM port on the back of a computer is male for the serial ports but it may not necessarily be Parallel Port Connector ndash DB-25 The DB-25 connector (named for its B-size D-shaped shell and 25 pins) is practically ubiquitous in the electronics industry The DB-25 connector is used for a variety of purposes Two common applications are RS-232EIA-232 (serial) connections and the parallel printer interface on the IBM PC The DB-25 connector is also used for SCSI connections Normally the parallel port is used for output to a printer or other device It sends data 8-bits or one byte at a time in parallel The other lines available on the DB-25 connector are a combination of status lines control lines and ground lines The status and control lines are used for handshaking commands and feedback when we are talking to a printer

Figure 152 DB-25 Female Figure 151 DB-25 Male

Figure 153 Pin Layout for DB-25 As can be seen form figure 153 there are four types of pins in this connector

bull Data pins (8 pins - D0 to D7) Active high bidirectional lines

Logic Design amp Switching Theory 1 Lab Session 15 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering bull Control pins (4 pins - C0 to C3) C0 C1 and C3 are active low whereas C2 is active

high These lines also are bidirectional bull Status pins (5 pins ndash S3 to S7) Only S7 is active low rest are active high input lines bull Ground pins (8 pins) Used as a reference signal for the low (below 05 volts) charge

Parallel Port Addresses A DB-25 connector at a parallel port has three address one for each kind of pins register data status and control The first or base address generally refers to data register Second address is for status register and the third one is for control register In Windows 98 the base address is usually found to be 278H 378H or 3BCH Now if 378H is the base address then it refers to the data register whereas addresses for status and control register are respectively 379H and 37AH For Windows 98 the base address can be found as follows 1 On your Desktop right-click on My Computer and select Properties 2 Click on the Device Manager tab and find LPT1 under Plug and Play BIOS 3 After selecting LPT1 click the Properties button 4 Next select the Resources tab and the address should then appear next to InputOutput

Range Accessing parallel port through C Language Programming There are multiple functions in C Language for accessing external ports The most commonly used are listed below

bull unsigned char inportb(int portid) inportb reads a byte from a hardware port

bull int inport(int portid) reads a word from a hardware port

bull void outportb(int portid unsigned char value) outputs a byte to a hardware port

bull void outport(int portid int value) outputs a word to a hardware port

portid refers to the port address whereas value refers to the data to be sent TESTING 74245 USING PARALLEL PORT PC INTERFACING At one end the parallel port connector will be connected to the PC via parallel port cable and another connector (to be plugged into the PC parallel port slot) At the other end it will be connected to the buffer IC 74245 Data lines of the connector will be used to transfer 8-bit data between the PC and the buffer Out of the 8-bits of 74245 4-bits will be used to enter data which will be displayed at the monitor through a C language

61

Logic Design amp Switching Theory 1 Lab Session 15 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering program The remaining 4-bits will receive data from PC as entered by the user via keyboard

Circuit Diagram

Figure 154 Interface of 74245 to PC via Parallel Port

Procedure

1 Connect the DB-25 connector to the PC at one end and solder it to the circuit board at the other end

2 Connect various pins of the connector and 74245 according to the circuit diagram shown in figure 152

3 Using the functions listed in the previous section write a program in C language to operate various pins of the buffer The user interface of the program should provide option to the user whether to send or receive data from the port

4 Set DIR switch to 1 5 Try sending some data bits to the port The result should be displayed at the LEDs 6 Set DIR switch to 0 7 Set some binary 4-bit value through the switches Try reading it via parallel port

C Language Program

A program to access parallel port for data transfers

use header file include ltstdiohgt main program void main() define variable

62

Logic Design amp Switching Theory 1 Lab Session 15 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering unsigned int data=0 char choice while(1) printing option menu clrscr() printf(This program will send or receive a BCD digit from the parallel portn) printf(nPress your choice numbern) printf(n1 Send Data) printf(n2 Receive Data) printf(n3 Exitn) choice = getch() sending entered digit to the port if(choice == 1) input BCD digit printf(nEnter BCD digit to be sent to the port) data = getche() masking the first four bits data = data amp 0x0f sending to the port outportb(0x378data) printf(nThe BCD digit c has been sent to the port data) printing on screen the data received from the port else if(choice == 2) receiving data from the port data = inportb(0x378) masking the last four bits data = data amp 0xf0 shifting first four bits to make them the last four bits datagtgt=4 printf(nThe BCD digit set at the port is c data) exit else if(choice == 3) break key pressed is not in the menu else printf(nEnter valid choice number) printf(nnPress any key to continue) getch()

63

Logic Design amp Switching Theory 1 Lab Session 15 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

ACTIVITY 1 In the above circuit DIR and G΄ inputs are hardwired Connect them to status or

control pins of the parallel port connector and control their function through your software program Circuit Diagram Program Code ______________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________

___________________________________________________________________________________________________________________________________________________

64

Logic Design amp Switching Theory 1 Lab Session 15 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

65

_____________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ _____________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ _______________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ _________________________________________________ _________________________________________________

Logic Design amp Switching Theory 1 Appendix A NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

Appendix A

PIN DIAGRAMS OF THE ICS REQUIRED FOR THE LABORATORY SESSIONS Consult the TTLIC data book for internal diagrams and electrical characteristics of these ICs 7400 Quad 2-Input NAND 7402 Quad 2-Input NOR

7404 Hex Inverter 7408 Quad 2-Input AND

7410 Triple 3-Input NAND 7411 Triple 3-Input AND

7421 Dual 4-Input AND 7432 Quad 2-Input OR

66

Logic Design amp Switching Theory 1 Appendix A NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

BCD-to-Seven Segm 7448 BCD-to-Seven Segment 7447 ent

Decoder (15V OC) Decoder (2kΩ pull-up output)

7473 Dual JK Flip-Flop 7474 Dual D-Type Flip-Flop

7476 Dual JK Flop-Flop -Bit Binary Full Adder 7483 4 with Fast Carry

86 Quad 2-Inpu 74138 3-to-8 Line 74 t Exclusive OR Decoder Demultiplexer

67

Logic Design amp Switching Theory 1 Appendix A NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

68

74148 8-to-3 Line 16-to-1 Line Data

Priority Encoder 74150 Selector Multiplexer

74245 Oct nsceivers Universal Shift Register (PIPO) (3-State)

74194 4-Bit Bidirectional al Bus Tra

Logic Design amp Switching Theory 1 Appendix B NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

Appendix B

DEBOUNCING CIRCUITRY FOR MECHANICAL SWITCHES Mechanical switches form the interface between human beings and computers or other digital systems For example a keyboard is a matrix of switches used to supply alphanumeric data to a computer Whatever the switch design it is a potential source of problems due to contact bounce The contact bounce creates a sense of narrow pulses when a switch is opened or closed An example of device whose operation would be adversely affected by contact bounce is a digital counter used to count the number of times a switch is depressed Eliminating the effects of contact bounce is called debouncing When data is entered into a computer via a keyboard a software debounce is often used This type of debouncing is a program that causes the computer to sample the switch terminal (ie to input data from it) many times in succession during the interval of time that contact bounce occurs If the data is sensed to be 1s (or 0s) for a specific number of consecutive samples then it is assumed that contact bounce has ended and the last value sensed is valid Hardware debouncing is the use of electronic circuitry to eliminate the effects of contact bounce There are numerous versions of such circuitry including those that use monostable multivibrators (one-shots) but the most straightforward is simply an RS latch Figure B1 shows the circuit When the switch is in position 1 R = 0 and S = 1 so the latch is set and the output (Q) is 1 When the switch is in position 0 R = 1and S = 0 so the latch is reset and the output is 0 When the switch is moved form one position to the other the latch changes state and bouncing occurs at either the R or the S input The bouncing does not affect the latch after it has change state An RS latch will remain set for example when its R input is 0 and its S input is alternately changed form 1 to 0

Figure B1 Use of RS latch to debounce a mechanical switch

69

  • 01-ldst-Outer title
    • Practical Workbook
    • Logic Design amp Switching Theory I
      • Dept of Computer amp Information Systems Engineering
        • NED University of Engineering amp Technology
        • Karachi ndash 75270 Pakistan
          • 02-ldst-inner Title
            • Practical Workbook
            • Logic Design amp Switching Theory I
              • Dept of Computer amp Information Systems Engineering
                • NED University of Engineering amp Technology
                • Karachi ndash 75270 Pakistan
                  • 03-ldst-general info
                  • 04-ldst-introduction
                  • 05-Table of Contents
                    • CONTENTS
                      • Lab Session No Object Page No
                      • 1
                      • Also implementing and testing the given circuit on a bread board
                        • Working with Electronics Workbench
                          • Driving a seven segment display using 7447 7448 driver IC
                            • Designing a modulus-5 asynchronous up-counter using JK-FF
                              • Experimenting with 74194 4-bit bidirectional universal shift register
                                  • 13
                                      • 06-ldst-Exp01
                                        • Lab Session 01
                                        • OBJECT
                                          • 1 Bread board
                                          • 2 5 V - power supply
                                          • 3 Multimeter
                                          • 4 Logic probe
                                          • 5 LEDs with resistors
                                          • 6 Connecting wires
                                          • 8 Following ICs and their datasheets
                                            • THEORY
                                              • Logic Gates
                                              • 1 The AND Gate ndash An AND gatersquos output is 1 if and only if all its inputs are 1 If A and B are two inputs to an AND gate then output F of the gate is given as F = AB
                                              • 2 The OR Gate - An OR gatersquos output is 1 if at least one of its input is 1 If A and B are two inputs to an OR gate then output F of the gate is given as F = A+B
                                              • 3 The NOT Gate (Inverter) ndash Its output is 1 when its input is 0 and its output is 0 when the input is 1 ie it complements a digital variable If A is the input to a NOT gate then output F of the gate is given as
                                              • 4 The NAND Gate ndash Its output is 1 if at least one of its input is 0 This gate performs the same logic as an AND gate followed by an inverter If A and B are two inputs to a NAND gate then output F of the gate is given as
                                                • 5 The NOR Gate - The output of a NOR gate is 1 if and only if all its inputs are 0 This gate performs the same logic function as an OR gate followed by an inverter If A and B are two inputs to a NAND gate then output F of the gate is given as
                                                    • DATA SHEETS
                                                      • Logic expression for the given logic diagram __________________________________
                                                          • 07-ldst-exp02
                                                            • Working with Electronics Workbench
                                                              • 08-ldst-exp03
                                                                • Designing Half and Full Adder Circuits
                                                                  • COMPONENTS AND APPARATUS REQUIRED
                                                                    • 1 Following ICs and their Datasheets
                                                                    • 7408 Quad 2-input AND Gate
                                                                    • 2 Digital Trainer DT-01 or the following components
                                                                      • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                      • Connecting wires Switches
                                                                        • THEORY
                                                                            • IMPLEMENTATION AND OBSERVATIONS
                                                                              • 09-ldst-Exp04
                                                                                • Lab Session 04
                                                                                • 1 Digital ICs and their Datasheets
                                                                                • 7408 Quad 2-input AND Gate
                                                                                • 2 Digital Trainer DT-01 or the following components
                                                                                  • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                  • Connecting wires Switches
                                                                                  • PROCEDURE
                                                                                  • REDUCTION OF LOGIC EXPRESSION USING KARNAUGH MAP
                                                                                  • OBSERVATIONS
                                                                                  • RESULT
                                                                                      • 10-ldst-Exp05
                                                                                        • Lab Session 05
                                                                                        • 1 Following ICs and their Datasheets
                                                                                        • 7408 Quad 2-input AND Gate
                                                                                        • 2 Digital Trainer DT-01 or the following components
                                                                                          • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                          • (100 Ω) Connecting wires Switches
                                                                                          • THEORY
                                                                                            • IMPLEMENTATION AND OBSERVATIONS
                                                                                              • 11-ldst-Exp06
                                                                                                • OBJECT
                                                                                                • 1 Following ICs and their Datasheets
                                                                                                • 7408 Quad 2-input AND Gates or 7411 Triple 3-input AND Gates
                                                                                                • 2 Digital Trainer DT-01 or the following components
                                                                                                  • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                  • Connecting wires Switches
                                                                                                    • Figure 62 Circuit Diagram for 4 x 1 Multiplexer
                                                                                                    • Implementation and Observations
                                                                                                      • Circuit Diagram
                                                                                                        • ACTIVITY
                                                                                                          • 12-ldst-exp07
                                                                                                            • 1 Following ICs and their Datasheets
                                                                                                            • 7408 Quad 2-input or 7411 Triple 3-input AND Gates
                                                                                                            • 2 Digital Trainer DT-01 or the following components
                                                                                                              • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                              • Connecting wires Switches
                                                                                                                • THEORY
                                                                                                                    • Figure 72 Circuit Diagram for 2 x 4 Decoder 1 x 4 Demultiplexer
                                                                                                                    • Implementation and Observations
                                                                                                                      • Circuit Diagram
                                                                                                                        • ACTIVITY
                                                                                                                          • 13-ldst-Exp08
                                                                                                                            • OBJECT
                                                                                                                            • 1 Following ICs and their Datasheets
                                                                                                                            • 7408 Quad 2-input or 7421 Dual 4-input AND Gates
                                                                                                                            • 2 Digital Trainer DT-01 or the following components
                                                                                                                              • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                              • Connecting wires Switches
                                                                                                                                • THEORY
                                                                                                                                    • Figure 81 Circuit Diagram for 4 x 2 Priority Encoder
                                                                                                                                    • Implementation and Observations
                                                                                                                                      • Therefore if GS A2 A1 and A0 are all low then it shows that line 0 is selected and if E0 A2 A1 and A0 are all low then it shows that none of the inputs selected E0 and GS cannot be in the same state provided that E1 is enabled
                                                                                                                                      • Circuit Diagram
                                                                                                                                        • ACTIVITY
                                                                                                                                          • 14-ldst-exp09
                                                                                                                                            • OBJECT
                                                                                                                                            • 1 Following ICs and their Datasheets
                                                                                                                                            • 2 Digital Trainer DT-01 or the following components
                                                                                                                                              • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                              • Connecting wires Switches
                                                                                                                                                • THEORY
                                                                                                                                                  • Parity Generator
                                                                                                                                                    • Let x y and z be the three bits that constitute the message and are the input to the Odd Parity Generator Circuit Since it is an odd parity system the bit P is generated so as to make the total number of 1s odd (including P) The function P can be expressed as follows
                                                                                                                                                    • Figure 91 Circuit Diagram for a 3-bit Parity Generator
                                                                                                                                                      • C = x Ο y Ο z Ο P
                                                                                                                                                        • Implementation and Observations
                                                                                                                                                          • ACTIVITY
                                                                                                                                                              • 15-ldst-exp10
                                                                                                                                                                • Driving a seven segment display using 7447 7448 driver IC
                                                                                                                                                                • COMPONENTS AND APPARATUS REQUIRED
                                                                                                                                                                • 1 Following ICs and their Datasheets
                                                                                                                                                                • 7447 7448 BCD to Seven Segment Driver
                                                                                                                                                                • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                  • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches
                                                                                                                                                                    • THEORY
                                                                                                                                                                    • Seven Segment Displays
                                                                                                                                                                    • CIRCUIT DIAGRAM
                                                                                                                                                                    • Figure 102 Circuit diagram for 7447driving a common-anode display
                                                                                                                                                                        • IMPLEMENTATION AND OBSERVATIONS
                                                                                                                                                                          • Decimal Digit
                                                                                                                                                                          • BCD Inputs
                                                                                                                                                                          • Seven Segment Outputs
                                                                                                                                                                          • D
                                                                                                                                                                          • C
                                                                                                                                                                          • B
                                                                                                                                                                          • A
                                                                                                                                                                          • a
                                                                                                                                                                          • b
                                                                                                                                                                          • c
                                                                                                                                                                          • d
                                                                                                                                                                          • e
                                                                                                                                                                          • f
                                                                                                                                                                          • g
                                                                                                                                                                          • 0
                                                                                                                                                                          • 0
                                                                                                                                                                          • 0
                                                                                                                                                                          • 0
                                                                                                                                                                          • 0
                                                                                                                                                                          • 1
                                                                                                                                                                          • 0
                                                                                                                                                                          • 0
                                                                                                                                                                          • 0
                                                                                                                                                                          • 1
                                                                                                                                                                          • 2
                                                                                                                                                                          • 0
                                                                                                                                                                          • 0
                                                                                                                                                                          • 1
                                                                                                                                                                          • 0
                                                                                                                                                                          • 3
                                                                                                                                                                          • 0
                                                                                                                                                                          • 0
                                                                                                                                                                          • 1
                                                                                                                                                                          • 1
                                                                                                                                                                          • 4
                                                                                                                                                                          • 0
                                                                                                                                                                          • 1
                                                                                                                                                                          • 0
                                                                                                                                                                          • 0
                                                                                                                                                                          • 5
                                                                                                                                                                          • 0
                                                                                                                                                                          • 1
                                                                                                                                                                          • 0
                                                                                                                                                                          • 1
                                                                                                                                                                          • 6
                                                                                                                                                                          • 0
                                                                                                                                                                          • 1
                                                                                                                                                                          • 1
                                                                                                                                                                          • 0
                                                                                                                                                                          • 7
                                                                                                                                                                          • 0
                                                                                                                                                                          • 1
                                                                                                                                                                          • 1
                                                                                                                                                                          • 1
                                                                                                                                                                          • 8
                                                                                                                                                                          • 1
                                                                                                                                                                          • 0
                                                                                                                                                                          • 0
                                                                                                                                                                          • 0
                                                                                                                                                                          • 9
                                                                                                                                                                          • 1
                                                                                                                                                                          • 0
                                                                                                                                                                          • 0
                                                                                                                                                                          • 1
                                                                                                                                                                            • ACTIVITY
                                                                                                                                                                              • 16-ldst-exp11
                                                                                                                                                                                • Lab Session 11
                                                                                                                                                                                  • OBJECT
                                                                                                                                                                                  • COMPONENTS AND APPARATUS REQUIRED
                                                                                                                                                                                    • 1 Following ICs and their Datasheets
                                                                                                                                                                                    • 7473 7476 JK Flip-Flop
                                                                                                                                                                                    • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                      • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                      • Connecting wires Switches
                                                                                                                                                                                        • THEORY
                                                                                                                                                                                            • Flip-Flop
                                                                                                                                                                                            • JK Flip-Flop
                                                                                                                                                                                              • Circuit Diagram
                                                                                                                                                                                                • Observations
                                                                                                                                                                                                  • ACTIVITY
                                                                                                                                                                                                      • 17-ldst-exp12
                                                                                                                                                                                                        • Lab Session 12
                                                                                                                                                                                                          • OBJECT
                                                                                                                                                                                                          • GIVEN STATE DIAGRAM
                                                                                                                                                                                                          • Figure 121 State Diagram
                                                                                                                                                                                                          • COMPONENTS AND APPARATUS REQUIRED
                                                                                                                                                                                                            • 1 Following ICs and their Datasheets
                                                                                                                                                                                                            • 7474 D Flip-Flop
                                                                                                                                                                                                            • ICs of basic gates (AND OR NOT XOR etc) as required
                                                                                                                                                                                                            • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                              • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                              • Connecting wires Switches
                                                                                                                                                                                                                • THEORY
                                                                                                                                                                                                                    • Sequential Circuits
                                                                                                                                                                                                                      • 18-ldst-exp13
                                                                                                                                                                                                                        • Lab Session 13
                                                                                                                                                                                                                          • Designing a modulo-5 asynchronous up-counter using JK-FF
                                                                                                                                                                                                                            • 1 Following ICs and their Datasheets
                                                                                                                                                                                                                            • 7400 Quad 2-input or 7410 Triple 3-input NAND Gates
                                                                                                                                                                                                                            • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                              • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                                              • Connecting wires Switches
                                                                                                                                                                                                                                • THEORY
                                                                                                                                                                                                                                    • Figure 131 A Mod-5 Asynchronous Up Counter
                                                                                                                                                                                                                                    • Implementation and Observations
                                                                                                                                                                                                                                      • ACTIVITY
                                                                                                                                                                                                                                          • 19-ldst-exp14
                                                                                                                                                                                                                                            • Experimenting with 74194 4-bit bidirectional universal shift register
                                                                                                                                                                                                                                            • 1 Following ICs and their Datasheets
                                                                                                                                                                                                                                            • 74194 4-bit bidirectional universal shift register
                                                                                                                                                                                                                                            • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                                              • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                                                              • Connecting wires Switches
                                                                                                                                                                                                                                                • THEORY
                                                                                                                                                                                                                                                  • Shift Registers
                                                                                                                                                                                                                                                  • Bidirectional Shift Registers
                                                                                                                                                                                                                                                  • Universal Shift Registers
                                                                                                                                                                                                                                                    • S1
                                                                                                                                                                                                                                                      • Circuit Diagram
                                                                                                                                                                                                                                                      • ACTIVITY
                                                                                                                                                                                                                                                          • 20-ldst-exp15
                                                                                                                                                                                                                                                            • COMPONENTS AND APPARATUS REQUIRED
                                                                                                                                                                                                                                                            • 1 Parallel Port Connectors (DB-25) with Cable
                                                                                                                                                                                                                                                            • 2 Personal Computer with Windows 98 and TurboC Compiler Installed
                                                                                                                                                                                                                                                            • 3 Following ICs and their Datasheets
                                                                                                                                                                                                                                                            • 74245 Octal Bus Transceivers with 3-State Outputs
                                                                                                                                                                                                                                                            • 4 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                                                              • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                                                                                • Connecting wires Switches
                                                                                                                                                                                                                                                                  • THEORY
                                                                                                                                                                                                                                                                  • 3-State Logic
                                                                                                                                                                                                                                                                    • Serial and Parallel Port Connectors
                                                                                                                                                                                                                                                                    • Parallel Port Connector ndash DB-25
                                                                                                                                                                                                                                                                      • Accessing parallel port through C Language Programming
                                                                                                                                                                                                                                                                          • 21-ldst-appendixA
                                                                                                                                                                                                                                                                          • 22-ldst-appendixB
                                                                                                                                                                                                                                                                            • DEBOUNCING CIRCUITRY FOR MECHANICAL SWITCHES

    Practical Workbook

    Logic Design amp Switching Theory I

    Prepared By M Anwar Ali Khan (Asst Professor) amp Muhammad Mazher Alam (Ex - Asst Professor) Revised By Maria Waqas (Lecturer)

    Second Edition

    Fourth Reprint ndash 2010

    Dept of Computer amp Information Systems Engineering NED University of Engineering amp Technology

    Karachi ndash 75270 Pakistan

    THE BITS AND PIECES PART CIRCUIT

    SIGN WHAT IT DOES

    Supplies a voltage which drives an electric current round the circuit from the positive (+) terminal of the battery to its negative (ndash) terminal Voltage is measured in volts (V) and current in amperes (A)

    Allows current to flow through it easily because it is made of copper which is a good electrical conductor Insulators like PVC (polyvinyl chloride - a plastic) and enamel are used to cover connecting wires

    Connects terminal A to terminal B or C ie it is a change-over switch

    Reduces the current in a circuit because of its resistance The colored bands give the resistance in ohms

    When light falls on it its resistance becomes small in the dark its resistance is high

    3

    PART CIRCUIT SIGN

    WHAT IT DOES

    Stores electricity the greater the capaci-tance the more does it store Capacitance values are measured in microfarads shortened to μF or less correctly to mfd On a capacitor 01 μF may be marked as l mfd and 001μF as 10n The greatest voltage it can stand is also shown eg 30V

    Stores electricity values usually larger than 1μF Greatest voltage marked on it Must be connected the correct way round

    Varies the capacitance in a circuit by mov-ing one set of metal plates in or out of a fixed set when the spindle is rotated The sets of plates are separated by sheets of an insulator (also called a dielectric)

    Changes electric currents into sound

    Changes radio waves into electric currents

    Lets current flow in one direction but not in the other When it conducts light is emit-ted Must have a current limiting resistor in series with it The cathode lead is nearest the lsquoflatrsquo and may be shorter than the anode lead (but this is not always so) The arrow on the sign shows the conducting direction

    4

    PART CIRCUIT SIGN

    WHAT IT DOES

    Amplifies small currents into much larger copies Acts as a very fast switch It must be correctly connected with a positive voltage to the collector

    Transistors diodes resistors and capacitors are connected together on a tiny lsquochiprsquo of silicon (sand is mostly silicon oxide) to give any desired circuit eg a multistage amplifier an astable bistable or monostable multivibrator a counter a logic gate for a computer several stages of a TRF (tuned radio frequency) radio

    They must be correctly connected Pin 1 is next to the lsquotagrsquo in the can type and on the dil type it is identified from the lsquonotchrsquo or lsquosmall dotrsquo on the case CMOS lsquochipsrsquo (standing for Complementary Metal Oxide Semiconductors and pronounced lsquosee-mossrsquo) need special care

    PRECAUTIONS WITH CMOS INTEGRATED CIRCUITS Damage occurs if static charges build up on input pins when for example they touch insulating materials (eg clothes plastic pen) in warm dry conditions 1 Keep the IC in the carrier in which it is supplied until it is inserted in the circuit 2 Do not finger the pins or hold them in contact with an insulator 3 Connect all unused inputs of the IC to either the positive or the negative of the battery

    depending on the circuit

    5

    BUILDING CIRCUITS

    The circuit board shown above accepts ICs as well as separate components It has 47 rows of 5 interconnected sockets on each side of a central channel across which dil ICs can be fitted A wire inserted in a socket in a certain row becomes connected to wires in any of the other 4 sockets in that row by a metal strip under the board For example wires in sockets B5 C5 D5 E5 and F5 (shown in color in the diagram) are all joined Metal strips under the board connect the sockets A row of 40 interconnected sockets along the top of the board and a similar row along the bottom act as the positive and negative power supply rails (called lsquobus barsrsquo) Various makes of circuit board are available some with vertically mounting removable panels for supporting controls

    6

    1 To make a connection push about 1 cm of the bare end of a wire (025 to 085 mm diameter) straight into the socket (not at an angle) so that it is gripped by the metal strip under the board Do not use wires that are dirty or have kinked ends Only put one wire in each socket

    Bend leads on resistors etc as shown before inserting them in the board

    2 Bare the ends of connecting wire (PVC-covered tinned copper wire 06 mm diameter) by

    removing the insulation (PVC) either with wire strippers or using a pair of blunt-nosed pliers and a pair of side cutters as shown With practice you should be able to judge just how much the side cutters have to be squeezed and pulled to remove the insulation without cutting the wire

    3 lsquoJoinrsquo wires to the lsquolugsrsquo on the loudspeaker and variable capacitor using a small length of

    2 mm bore plastic sleeving - as shown by 1 and 2

    7

    RESISTOR COLOUR CODE Resistor values are given in ohms (shortened to Ω the Greek letter lsquoomegarsquo) They are marked on the resistor using a color code Three colored bands are painted round the resistor Each color stands for a number To read the color code start at the 1st band it is nearest the end Sometimes it is not clear which is the 1st band because there is a 4th band of gold or silver near the other end These two colors are not used for the 1st band they give the accuracy of the resistor (gold is plusmn 5 and silver plusmn 10) so you should not have too much trouble deciding where to start The 1st band gives the first number the 2nd band gives the second number and the 3rd band tells how many zeroes come after the first two numbers

    8

    INTRODUCTION

    Digital Logic Design is concerned with the interconnection among digital components and modules and the area of Switching Theory that can be identified between circuit design and system formulation Logic design is the base of any computer system as every digital system consists of different ICrsquoS and ICs contain a large number of interconnected digital circuits within a small package MSI devices provide digital function while LSI device cover a complete computer modules These circuitries are widely used in digital system like digital voltmeter frequency meter calculating machines telephone-switching system etc In this Practical Workbook laboratory sessions based on both combinational and sequential logic are covered First laboratory session gives an introduction to the basic logic gates and fundamentals of circuit building The second laboratory session covers a CAD software ndash Electronics Workbench (EWB) EWB is excellent simulation software where circuits can be designed and tested before physical implementation Various laboratory sessions of this workbook provide activities and exercises on EWB Next eight laboratory sessions are based on combinational logic Here various MSI circuits like adders converters multiplexers decoders encoders etc are designed Some of these laboratory sessions also include testing of MSI ICs Next four laboratory sessions help in exploring various designs based on sequential logic Here a variety of circuits are designed form the testing of basic flip-flop ICs to registers and different types of counters Last laboratory session demonstrates how digital hardware can be interfaced with a personal computer via parallel port and can be controlled by software All laboratory sessions of this workbook incorporate brief theoretical backgrounds as details may be covered in the respective theory classes Exercises activities are included with almost all the sessions for the students to practice Two appendices are also included in this workbook The first one provides pin diagrams for all the ICs required for the laboratory work provided in this workbook It will help the students in preparing the pin diagrams for the circuits Second appendix discusses a hardware debouncing circuit for mechanical switches as such switches are extensively used for input purpose in logic circuits

    9

    CONTENTS Lab Session No Object Page No

    1 2 3 4 5 6 7 8 9

    10

    11

    12

    13

    14

    15

    To study the logic gates in the following TTL ICs

    7400 Quad 2-input NAND gate 7402 Quad 2-input NOR gate

    7404 Hex inverter 7408 Quad 2-input AND gate 7432 Quad 2-input OR gate

    Also implementing and testing the given circuit on a bread board Working with Electronics Workbench Designing Half and Full Adder Circuits Use of Karnaugh Map (SOP-Expression) method Designing a BCD Adder Designing of a 4 x 1 Multiplexer Experimenting with 74150 IC Designing of a 2 x 4 Decoder 1 x 4 Demultiplexer Experimenting with 74138 IC Designing of a 4 x 2 Priority Encoder Experimenting with 74148 IC Designing an Odd Parity Generator and Checker for a 3-bit Data Driving a seven segment display using 7447 7448 driver IC Experimenting with different modes of JK-FF Designing sequential circuit for the given state diagram using D flip-flop Designing a modulus-5 asynchronous up-counter using JK-FF Experimenting with 74194 4-bit bidirectional universal shift register Experimenting with 74245 octal bus transceivers using parallel port PC interfacing Appendix A ndash Pin Diagrams of the ICs required for the laboratory sessions Appendix B ndash Debouncing circuitry for mechanical switches

    13

    17

    19

    22

    28

    30

    34

    38

    42

    45

    48

    50

    54

    56

    59

    66

    69

    11

    Logic Design amp Switching Theory 1 Lab Session 01 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

    Lab Session 01 OBJECT

    bull To study the logic gates in the following TTL ICs

    i) 7400 Quad 2-input NAND gate ii) 7402 Quad 2-input NOR gate iii) 7404 Hex inverter iv) 7408 Quad 2-input AND gate v) 7432 Quad 2-input OR gate

    bull Implementing and testing the given circuit on a bread board

    COMPONENTS REQUIRED 1 Bread board 2 5 V - power supply 3 Multimeter 4 Logic probe 5 LEDs with resistors 6 Connecting wires 7 Switches (optional) 8 Following ICs and their datasheets

    bull 7408 quad 2 input AND gate bull 7432 quad 2 input OR gate bull 7404 hex inverter bull 7400 quad 2 input NAND gate bull 7402 quad 2 input NOR gate

    THEORY

    Logic Gates

    Logic gates are the fundamental building blocks of digital systems These devices are able to make decisions in the sense that they produce one output level when some combinations of input levels are present and a different output when other combinations are applied hence given the name Logic Gates The two levels produced by digital circuitry are referred to variously as HIGH and LOW TRUE and FALSE ON and OFF or simply 1 and 0 There are only three basic gates AND OR and NOT The other gates are merely combinations of these basic gates Logic gates can be interconnected to perform a variety of logical operations This interconnection of gates to achieve prescribed outcomes is called logic design

    1 The AND Gate ndash An AND gatersquos output is 1 if and only if all its inputs are 1 If A and B are two inputs to an AND gate then output F of the gate is given as F = AB

    2 The OR Gate - An OR gatersquos output is 1 if at least one of its input is 1 If A and B are two inputs to an OR gate then output F of the gate is given as F = A+B

    13

    Logic Design amp Switching Theory 1 Lab Session 01 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering 3 The NOT Gate (Inverter) ndash Its output is 1 when its input is 0 and its output is 0 when

    the input is 1 ie it complements a digital variable If A is the input to a NOT gate then output F of the gate is given as AF =

    4 The NAND Gate ndash Its output is 1 if at least one of its input is 0 This gate performs the same logic as an AND gate followed by an inverter If A and B are two inputs to a NAND gate then output F of the gate is given as BAF =

    5 The NOR Gate - The output of a NOR gate is 1 if and only if all its inputs are 0 This gate performs the same logic function as an OR gate followed by an inverter If A and B are two inputs to a NAND gate then output F of the gate is given as BAF +=

    All the above gates have one output and two or more inputs except the NOT gate which has only one input

    PROCEDURE FOR TESTING THE LOGIC GATES IN GIVEN ICs

    1 Set the power supply to 5V With the help of a multimeter check the voltage at the output knobs of the power supply

    2 Connect wires long enough to reach the breadboard with the two knobs of the power supply Again using multimeter check voltage at the non-connected end of the wires

    3 Insert the 7408 quad 2 input AND gate IC on to the bread board and make supply and ground connections by joining 5V wire to pin 14 and 0V wire to pin 7

    4 Consult ICrsquos internal connection diagram for input and output pins of the first AND gate Connect input pins to logic 0 (0V) and observe the output using LED or logic probe You can also connect switches at the input lines to facilitate toggling between 1 and 0

    5 Try different combinations of logic levels at the two inputs Again observe the output 6 Repeat the last two steps for all other gates of the same IC Record the observations 7 Repeat this procedure for all other ICs

    OBSERVATIONS

    Gate Input A Input B Expected Output Observed Output

    AND

    0 0 0 1 1 0 1 1

    OR

    0 0 0 1 1 0 1 1

    NOT 0 - 1 -

    NAND

    0 0 0 1 1 0 1 1

    14

    Logic Design amp Switching Theory 1 Lab Session 01 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

    NOR

    0 0 0 1 1 0 1 1

    DATA SHEETS

    Figure 11

    15

    Logic Design amp Switching Theory 1 Lab Session 01 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

    16

    GIVEN CIRCUIT

    Figure 12

    PROCEDURE FOR IMPLEMENTATION OF THE GIVEN CIRCUIT 1 Set the power supply 2 Insert ICs on the bread board and make their supply and ground connections 3 As given in the logic diagram make connections using wires and gates in the ICs 4 Apply different combinations at the three inputs and observe the output OBSERVATIONS Logic expression for the given logic diagram __________________________________

    A B C Expected Output Observed Output 0 0 0 0 0 1 0 1 0 0 1 1 1 0 0 1 0 1 1 1 0 1 1 1

    Logic Design amp Switching Theory 1 Lab Session 02 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

    Lab Session 02

    OBJECT

    Working with Electronics Workbench

    ELECTRONICS WORKBENCH - EWB Electronics Workbench is a computer aided design tool that provides you with all the components and instruments necessary to create board-level designs It has complete mixed analog and digital simulation and graphical waveform analysis allowing you to design your circuit and then analyze it using different simulated instruments and analysis options It is fully integrated and interactive thus you can change your circuits quickly allowing fast and repeated what-if analysis Electronics Workbench provides the following kind of components bull Sources parts bin (AC voltage source Vcc source ground battery etc) bull Basic parts bin (resistors capacitors transformers switches etc) bull Diodes parts bin bull Transistors parts bin bull Analog ICs parts bin (op-amps etc) bull Mixed ICs parts bin (ADCs DACs 555 timers etc) bull Digital ICs parts bin (AND OR adders multiplexers etc) bull Indicators parts bin (voltmeter ammeter probe displays etc) bull Controls parts bin (voltage differentiator multiplier etc) bull Instruments parts bin (multimeter oscilloscope function generator etc) bull Miscellaneous parts bin (write data textbox etc)

    o Write data This component allows you to save simulation results as an ASCII file o Text Box Use this to add descriptive text anywhere in a circuit

    ACTIVITY

    Design circuit for the logic expression )( CBDCABAF ++=

    Procedure 1 From Logic Gates Parts Bin Drag and drop the required logic gates on the design

    area Use Component Properties dialog box to customize these gates 2 Connect the terminal of these gates according to the given expression Use additional

    connectors form the Basic Parts Bin if you want to connect more than wire at a single node

    3 Drag and drop a probe from Indicators Parts Bin Use Component Properties dialog box to customize the color and other properties of the probe Connect this probe at the output terminal of the circuit to indicate results

    4 Select four switches form Basic Parts Bin Specify the key that controls the switch by typing its name in the Value tab of the Component Properties dialog box For

    17

    Logic Design amp Switching Theory 1 Lab Session 02 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

    18

    example if you want the switch to close or open when digit lsquo1rsquo is pressed type 1 in the Value tab then click OK Assign different keys to all the switches

    5 Connect the output terminals of these switches to each of the four inputs A B C and D of the circuit

    6 Drag and drop Vcc and Ground form the Sources Parts Bin 7 Connect Vcc terminal to one end and Ground terminal to the other end of all the

    switches 8 Label the circuit properly using text boxes found in the miscellaneous parts bin 9 Run the circuit using the Activate Simulation switch Use the keys you have assigned

    to the switches to toggle them between Vcc and Ground connections thus providing 1 or 0 respectively to the inputs Record the results as indicated by the probe for all possible combinations of 1s and 0s at the inputs

    EWB Circuit

    Figure 21

    Observations

    A B C D Expected Output Observed Output 0 0 0 0 0 0 0 1 0 0 1 0 0 0 1 1 0 1 0 0 0 1 0 1 0 1 1 0 0 1 1 1 1 0 0 0 1 0 0 1 1 0 1 0 1 0 1 1 1 1 0 0 1 1 0 1 1 1 1 0 1 1 1 1

    Logic Design amp Switching Theory 1 Lab Session 03 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

    Lab Session 03

    OBJECT

    Designing Half and Full Adder Circuits COMPONENTS AND APPARATUS REQUIRED 1 Following ICs and their Datasheets

    bull 7408 Quad 2-input AND Gate bull 7432 Quad 2-input OR Gate bull 7486 Quad 2-input XOR Gate

    2 Digital Trainer DT-01 or the following components Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches

    THEORY Half Adder A combination circuit that performs the addition of two bits without accounting for the previous carry is called half adder It needs two binary inputs and two binary outputs The input variables designate the augend and addend bits The output variables produce the sum and carry The simplified sum of product expressions for a half adder are

    yxyxyxS oplus=+= yxC =

    Figure 31 Circuit diagram for Half Adder

    19

    Logic Design amp Switching Theory 1 Lab Session 03 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

    bles produce the sum and carry The simplified sum of product expressions for a half adder are

    Full Adder

    A combinational circuit that performs the addition of three input bits It consist of three inputs and two outputs Two of the input variables represent the two significant bits to be added The third input represents the carry from the previous lower significant position The output varia

    zyxzyxzyxzyxzyxS oplusoplus=+++= yxzyxzyzxxyC )( +oplus=++=

    Figure 32 Circuit diagram for Full Adder

    efer to laboratory session 01 for procedure) and record the observations in the following ta

    alf Adde ull Adder Inputs u

    IMPLEMENTATION AND OBSERVATIONS

    Implement the half adder and full adder circuits on a bread board (prepare the pin diagram (use appendix A) and r

    bles H r F

    Inputs Outputs Outp ts x y Carry Su Carry Sum m x y z 0 0 0 0 0 0 1 0 0 1 1 0 0 1 0 1 1 0 1 1 1 0 0 1 0 1 1 1 0 1 1 1

    20

    Logic Design amp Switching Theory 1 Lab Session 03 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

    at of your designed circuit Attach hardcopy of the output form electronic workbench

    at of your designed circuit Attach hardcopy of the output form lectronic workbench here

    ACTIVITY

    1 Simulate half adder circuit using Electronics Workbench Compare the results of simulation with thhere

    2 Design a full subtractor circuit and simulate it using Electronics Workbench Compare the results of simulation with the

    21

    Logic Design amp Switching Theory 1 Lab Session 04 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

    Lab Session 04 OBJECT

    Use of Karnaugh Map (SOP-Expression) method GIVEN LOGIC EXPRESSION

    F (A B C D) = sum ( 0 1 2 4 5 6 8 9 12 13 14 ) COMPONENTS AND APPARATUS REQUIRED 1 Digital ICs and their Datasheets

    bull 7408 Quad 2-input AND Gate bull 7432 Quad 2-input OR Gate bull 7404 Hex Inverter

    2 Digital Trainer DT-01 or the following components Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches PROCEDURE 1 Use Karnaugh map to reduce the given function 2 Draw the circuit diagram for the obtained reduced function 3 Implement the reduced circuit using digital ICs on a bread board (prepare the pin

    diagram (use appendix A) and refer to laboratory session 01 for procedure) and record the observations

    REDUCTION OF LOGIC EXPRESSION USING KARNAUGH MAP F

    CD

    AB DC

    DC DC

    DC

    BA0 1 3 2

    BA4 5 7 6

    BA12 13 15 14

    BA8 9 11 10

    Reduced form of the given logic expression is __________________________________

    22

    Logic Design amp Switching Theory 1 Lab Session 04 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

    LOGIC DIAGRAM (REDUCED FORM) OBSERVATIONS

    A B C D Output 0 0 0 0 0 0 0 1 0 0 1 0 0 0 1 1 0 1 0 0 0 1 0 1 0 1 1 0 0 1 1 1 1 0 0 0 1 0 0 1 1 0 1 0 1 0 1 1 1 1 0 0 1 1 0 1 1 1 1 0 1 1 1 1

    RESULT The reduced form (SOP Expression) of the given logic function is

    ____________________________________________________________

    The observation table reflects the given logic function

    23

    Logic Design amp Switching Theory 1 Lab Session 04 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

    ACTIVITY 1 Using Electronics Workbench derive a truth table and logic circuit for the following logic expression

    BAAF +=

    Procedure 1 From the Instruments Parts Bin drag and drop Logic Converter on the design area 2 Double click the Logic Converter to reveal Logic Converter dialog box This dialog

    box shows various conversion options between truth table logic expression and logic circuit

    3 Enter the given logic expression in the edit box found at the end of the dialog box Use lsquo to represent invert of a variable For example A is written as Arsquo

    4 Click the Boolean Expression to Truth Table button The truth table appears in the logic converters display

    5 Now click the Boolean Expression to Circuit button This creates the logic circuit for the given expression in the design area Label the diagram if needed

    Resulting Logic Circuit For the given expression the final circuit will look like

    Figure 41

    24

    Logic Design amp Switching Theory 1 Lab Session 04 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

    ACTIVITY 2

    Using Electronics Workbench find a simplified logic expression and circuit for the following truth table

    A B C Output 0 0 0 1 0 0 1 1 0 1 0 0 0 1 1 1 1 0 0 0 1 0 1 0 1 1 0 0 1 1 1 1

    Procedure 1 Click three input channels from A to H across the top of the logic converter The

    display area below the terminals fills up with the necessary combinations of ones and zeros to fulfill the input conditions The values in the output column on the right are initially set to 0

    2 Edit the output column to specify the desired output for each input condition To change an output value select it and type a new value 1 0 or x An x indicates a donrsquot care condition

    3 To convert this truth table to a Boolean expression click the Truth Table to Boolean Expression button The Boolean expression will be displayed at the bottom of the logic converter

    4 Simplify the expression by clicking the Simplify button 5 Now click the Boolean Expression to Circuit button This creates the logic circuit for

    the given expression in the design area Resulting Logic Circuit For the given truth table the final simplified circuit will look like

    Figure 42

    25

    Logic Design amp Switching Theory 1 Lab Session 04 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

    ACTIVITY 3

    Using Electronics Workbench find the logic expression and truth table for the following logic circuit

    Figure 43

    Procedure 1 Attach the input terminals of the logic converter to up to four input points in the

    circuit 2 Connect the single output of the circuit to the output terminal on the logic converter

    icon 3 Click the Circuit to Truth Table button The truth table appears in the logic

    converters display 4 To convert this truth table to a Boolean expression click the Truth Table to Boolean

    Expression button The Boolean expression will be displayed at the bottom of the logic converter

    Resulting Logic Expression Logic Expression for the given circuit is found to be _____________________________

    26

    Logic Design amp Switching Theory 1 Lab Session 04 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

    27

    For activities 1 2 and 3 attach hardcopy of the output (truth table logic expression and logic circuit) form electronic workbench here

    Logic Design amp Switching Theory 1 Lab Session 05 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

    Lab Session 05 Lab Session 05 OBJECT OBJECT

    Designing a BCD Adder Designing a BCD Adder COMPONENTS AND APPARATUS REQUIRED COMPONENTS AND APPARATUS REQUIRED

    1 Following ICs and their Datasheets 1 Following ICs and their Datasheets bull 7408 Quad 2-input AND Gate bull 7408 Quad 2-input AND Gate bull 7432 Quad 2-input OR Gate bull 7432 Quad 2-input OR Gate bull 7483 4-bit Binary Adder bull 7483 4-bit Binary Adder

    2 Digital Trainer DT-01 or the following components 2 Digital Trainer DT-01 or the following components Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors (100 Ω) Connecting wires Switches (100 Ω) Connecting wires Switches

    THEORY THEORY

    A BCD Adder is a combinational circuit that adds two BCD digits in parallel and produces a sum digit also in BCD A BCD Adder is a combinational circuit that adds two BCD digits in parallel and produces a sum digit also in BCD

    A4 A3 A2 A1 B4 B3 B2 B1

    7483-BCD ADDER

    Cout (C4 ) Z4 Z3 Z2 Z1 Cin(C0)

    A4 A3 A2 A1 B4 B3 B2 B1

    7483-BCD ADDER

    Cout

    (C4 ) Z4 Z3 Z2 Z1 Cin(C0)

    Figure 51 BCD Adder Circuit

    28

    Logic Design amp Switching Theory 1 Lab Session 05 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

    29

    A BCD adder must include the correction logic in its internal construction The two BCD digits together with the input carry are first added using a 4-bit binary adder to produce the binary sum If no output carry is generated and the binary sum is less than or equal to 9 then the corresponding BCD sum is identical and therefore no conversion is needed When the output carry is equal to 1 or the binary sum is greater than 9 then a binary 0110 is added to the binary sum through another 4-bit binary adder If Cout is the carry output and Z4Z3Z2Z1 is the binary sum form the first 4-bit binary adder then the following equation indicates the condition when a binary 0110 is to be added

    C = COUT + Z4Z2 + Z4Z3 IMPLEMENTATION AND OBSERVATIONS Implement the BCD adder circuit according to figure 51 on a bread board (prepare the pin diagram (use appendix A) and refer to laboratory session 01 for procedure) A BCD adder has nine input bits (two BCD digits and a carry bit) which can result in a total of 512 combinations of which 312 inputs are donrsquot care Since it is a very lengthy procedure to record results for 200 valid input combinations therefore for simplicity just record results for any eight combinations in the following table

    Input Carry

    BCD Digit 1 BCD Digit 2 Carry Output

    BCD Sum A4 A3 A2 A1 B4 B3 B2 B1 Z4 Z3 Z2 Z1

    Logic Design amp Switching Theory 1 lab Session 06 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

    Lab Session 06

    OBJECT

    bull Designing of a 4 x 1 Multiplexer bull Experimenting with 74150 IC

    COMPONENTS AND APPARATUS REQUIRED 1 Following ICs and their Datasheets

    bull 7408 Quad 2-input AND Gates or 7411 Triple 3-input AND Gates bull 7432 Quad 2-input OR Gates bull 7404 Hex Inverter bull 74150 16 x 1 MUX

    2 Digital Trainer DT-01 or the following components Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches THEORY

    Multiplexers A digital data Multiplexer (MUX) is a combinational circuit having several data inputs and a single output A set of data-select inputs is used to control which of the data inputs is routed to the single output A multiplexer is also called a data selector because of this ability to select which data input is connected o the output Normally there are 2n input lines and n selection lines whose bit combination determine which input is selected DESIGN OF A 4 x 1 MULTIPLEXER A 4 x 1 multiplexer is capable of selecting one of four data inputs (see figure 61) The 2-bit binary number at the data select inputs S1 and S0 specifies which of the four data inputs is to be routed to the output Since there are two data select inputs therefore they can select 22 = 4 different data inputs lines

    S0 S1 D0 D1

    D2 D3

    Data-select Inputs Output

    Data Inputs

    Figure 61 Block Diagram of a 4 x1 Multiplexer

    30

    Logic Design amp Switching Theory 1 lab Session 06 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

    Figure 62 Circuit Diagram for 4 x 1 Multiplexer

    Implementation and Observations

    Implement the 4 x 1 Multiplexer circuit (figure 62) on a bread board (prepare the pin diagram (use appendix A) and refer to laboratory session 01 for implementation procedure) and record the observations in the following table For each data select combination specify the switch number as well as the binary value present on that selected switch

    S1 S0 Output 0 0 0 1 1 0 1 1

    TESTING OF 74150 - 16 x 1 MUX

    The 74150 IC has sixteen data inputs and four data-selection lines Function of various pins of this IC is described below

    bull E0 through E15 Data input lines

    31

    Logic Design amp Switching Theory 1 lab Session 06 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering bull A B C D Data select lines with D being the MSB bull W Active low output line bull Grsquo Active low enable line bull VCC and GND Supply connections lines

    Circuit Diagram

    Figure 63 Pin connections of 74150 for selecting E0

    Testing Procedure

    bull Make connections as shown in the circuit diagram bull Apply different data (1 or 0) at data inputs that are labeled as E0 to E15 Only

    connection for E0 is shown is the figure for simplicity bull Select the data input E0 with the help of data selectors A B C and D bull Observe the output which shows the complement of the data from E0 bull Select all the sixteen data inputs one by one and record your observations in the

    following table

    32

    Logic Design amp Switching Theory 1 lab Session 06 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

    33

    Observations

    Grsquo D C B A W Grsquo D C B A W 0 0 0 0 0 0 1 0 0 0 0 0 0 0 1 0 1 0 0 1 0 0 0 1 0 0 1 0 1 0 0 0 0 1 1 0 1 0 1 1 0 0 1 0 0 0 1 1 0 0 0 0 1 0 1 0 1 1 0 1 0 0 1 1 0 0 1 1 1 0 0 0 1 1 1 0 1 1 1 1

    ACTIVITY 1 Consider 4x1 Multiplexer Draw the output wave-form for the following data inputs

    (E0 E1 E2 E3) and select lines A B (B being the MSB) Output is W

    E3 E2 E1 E0 A B

    W

    2 Using the 4 x 1 MUX designed in this laboratory session implement the following logical function F (A B C) = Σ (0147)

    Show your working and input connections in the following block diagram according to the circuit you have implemented

    4 x 1 MUX

    S0 S1

    Output D0

    D1

    D2

    D3

    Logic Design amp Switching Theory 1 Lab Session 07 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

    Lab Session 07

    OBJECT

    bull Designing of a 2 x 4 Decoder 1 x 4 Demultiplexer bull Experimenting with 74138 IC

    COMPONENTS AND APPARATUS REQUIRED 1 Following ICs and their Datasheets

    bull 7408 Quad 2-input or 7411 Triple 3-input AND Gates bull 7404 Hex Inverter bull 74138 3 x 8 Decoder

    2 Digital Trainer DT-01 or the following components Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches THEORY

    Decoder A Decoder is a combinational circuit that converts binary information form n input lines to a maximum of 2n unique output lines In practical applications decoders are often used for selecting one of several devices

    Demultiplexer A decoder with an enable input can function as a Demultiplexer A Demultiplexer (DMUX) id a circuit that receives information on a single line and transmits this information on one of 2n possible output lines The selection of a specific output line is controlled by the bit values of n selection lines DESIGN OF A 2 x 4 DECODER 1 x 4 DEMULTIPLEXER A 2 x 4 decoder is capable of selecting one of four output lines (see figure 71 (a)) The 2-bit binary number at the data inputs S1 and S0 specifies which of the four data inputs is to be selected If we add an enable pin and use it as an input line then this decoder can be converted to a 1 x 4 Demultiplexer where S1 and S0 will select a line to which data input is to be routed (see figure 71 (b))

    Select S0 S0 Inputs

    S1 D0 D1

    D2

    D3

    Enable (a) Block Diagram of a 2 x 4 Decoder

    Figure 71

    S1 D0 D1

    D2

    D3

    Inputs

    Data Input (b) Block Diagram of a 1 x 4 Demulptiplexer

    34

    Logic Design amp Switching Theory 1 Lab Session 07 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

    Figure 72 Circuit Diagram for 2 x 4 Decoder 1 x 4 Demultiplexer

    Implementation and Observations Implement the 2 x 4 Decoder 1 x 4 Demultiplexer circuit (figure 72) on a bread board (prepare the pin diagram (use appendix A) and refer to laboratory session 01 for implementation procedure) and record the observations in the following table

    Enable Data Input S1 S0 D0 D1 D2 D3

    0 0 0 0 0 1 0 1 0 0 1 1 1 0 0 1 0 1 1 1 0 1 1 1

    TESTING OF 74138 3 x 8 Decoder The 74138 IC has three inputs and eight output lines It has three enable inputs and for the IC to function all three inputs need to be enabled Function of various pins of this IC is described below

    35

    Logic Design amp Switching Theory 1 Lab Session 07 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

    bull Y0 through Y7 Active low data outputs bull A B C Input select lines with C being the MSB bull G1 Active high enable Input bull G2Arsquo and G2Brsquo Active low enable Inputs bull VCC and GND Supply connections lines Circuit Diagram

    Figure 73 Pin connections of 74138

    Testing Procedure

    bull Make connections as shown in the circuit diagram bull Apply different combinations of 1s and 0s at data inputs bull Observe the output and record your observations in the following table

    Observations

    C B A Y0 Y1 Y2 Y3 Y4 Y5 Y6 Y7 0 0 0 0 0 1 0 1 0 0 1 1 1 0 0 1 0 1 1 1 0 1 1 1

    36

    Logic Design amp Switching Theory 1 Lab Session 07 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

    37

    ACTIVITY ACTIVITY 1 What will be the binary values at the outputs Y0 through Y7 of 74138 if 1 What will be the binary values at the outputs Y0 through Y7 of 74138 if

    bull All three enable pins are connected to ground bull All three enable pins are connected to ground __________________________________________________________________________________________________________________________________________ __________________________________________________________________________________________________________________________________________ _____________________________________________________________________ _____________________________________________________________________

    bull All three enable pins are connected to VCC bull All three enable pins are connected to VCC _______________________________________________________________________________________________________________________________________________________________________________________________________________

    _______________________________________________________________________________________________________________________________________________________________________________________________________________

    2 Show connections for 74138 in order to use it as a 1 x 8 Demultiplexer 2 Show connections for 74138 in order to use it as a 1 x 8 Demultiplexer

    3 Consider a 2 x 4 Decoder with two enable inputs (one active high - G and one active low ndash Grsquo) Draw the output wave-forms for D0 D1 D2 and D3 if the two select inputs are A and B (B being the MSB) All outputs are active low

    Grsquo

    G

    A B

    D0 D1 D2

    D3

    Logic Design amp Switching Theory 1 Lab Session 08 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

    Lab Session 08 OBJECT

    bull Designing of a 4 x 2 Priority Encoder bull Experimenting with 74148 IC

    COMPONENTS AND APPARATUS REQUIRED

    1 Following ICs and their Datasheets

    bull 7408 Quad 2-input or 7421 Dual 4-input AND Gates bull 7432 Quad 2-input OR Gates bull 7404 Hex Inverter bull 74148 Encoder

    2 Digital Trainer DT-01 or the following components Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches

    THEORY

    Encoder An Encoder is a digital function that produces a reverse operation from that of a decoder An Encoder has 2n (or less) input lines and n output lines The output lines generate the binary code for the 2n input variables Priority Encoder

    A simple encoder may produce an erroneous output if more than one of its inputs is high A Priority Encoder is one that responds to just one input among those that may be simultaneously high in accordance with some priority system The most common priority system is based on the relative magnitudes of the inputs whichever decimal input is largest is the one that is encoded

    DESIGN OF A 4 x 2 Priority Encoder

    The following equations represent the outputs of a 4 x 2 priority encoder 32 DDA +=

    321 DDDB += As can be seen from the equations that input D0 which has a binary code 00 is not used in any equation A binary code 00 at the output indicates two conditions Either D0 is selected or no input is selected In order to differentiate these two conditions we will provide an additional output Z to indicate if at least one of the inputs is a 1 The equation for Z will be

    4321 DDDDZ = If Z is 0 then the binary code 00 at the output indicates that D0 is selected and if Z is 1 then it indicates that no input line is selected

    38

    Logic Design amp Switching Theory 1 Lab Session 08 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

    Figure 81 Circuit Diagram for 4 x 2 Priority Encoder

    it (figure 81) on a bread board (prepare the to laboratory session 01 for implementation

    Implementation a Implement the 4 x 2 Priority Encoder circu

    ram (use appendix A) and refer

    nd Observations

    pin diagprocedure) and record the observations in the following table

    D3 D2 D1 D0 A B 0 0 0 1 0 0 1 x 0 1 x x 1 x x x

    TESTING OF 74148 8 x 3 Octal Priority Encoder

    imal digits There are nine of which three represents

    ing any of the inputs is high

    then it shows that line 0 is selected and if e inputs selected E0 and GS

    cannot be in the same state provided that E1 is enabled

    The 74148 is a priority encoder with active-Low input for dec

    input) and five output linesinputs lines (including an enablethe binary code for the octal digit Function of various pins of this IC is described below

    bull 0 through 7 Active low data inputs representing the octal digits A2 A1 A0 Active low output lines representing the binary code bullbull E1 Active low enable Input bull E0 Active low output indicating none of the inputs is high bull GS Active low output indicatbull VCC and GND Supply connections lines Therefore if GS A2 A1 and A0 are all low

    then it shows that none of thE0 A2 A1 and A0 are all low

    39

    Logic Design amp Switching Theory 1 Lab Session 08 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

    Circuit Diagram

    Figure 82 Pin connections of 74148

    Testing Procedure bull Make connections as sho

    binations of 1s and 0s at data inputs d record your observations in the following table

    GS E0

    wn in the circuit diagram bull Apply different combull Observe the output an Observations

    0 1 2 3 4 5 6 7 A2 A1 A0 1 1 1 1 1 1 1 1 x x x x x x x 0 x x x x x x 0 1 x x x x x 0 1 1 x x x x 0 1 1 1 x x x 0 1 1 1 1 x x 0 1 1 1 1 1 x 0 1 1 1 1 1 1 0 1 1 1 1 1 1 1

    40

    Logic Design amp Switching Theory 1 Lab Session 08 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

    41

    CTIVITY

    Cascade the following two 74148 8 x 3 Priority Encoders to form 16 x 4 Priority

    A 1

    Encoder

    Logic Design amp Switching Theory 1 Lab Session 09 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering `

    Lab Session 09 OBJECT

    Designing an Odd Parity Generator and Checker for a 3-bit Data COMPONENTS AND APPARATUS REQUIRED

    1 Following ICs and their Datasheets

    bull 7486 Quad 2-input Exclusive-OR Gates bull 7404 Hex Inverter

    2 Digital Trainer DT-01 or the following components Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches

    THEORY

    Parity Generator When binary data is transmitted and processed it is ndash as are all electrical signals ndash susceptible to noise that can either alter or distort its contents 1s may be effectively changed to 0s and 0s to 1s To overcome this problem one or more bits are often added to the data as an aid in detecting errors caused by noise The most common of these is a Parity bit that signifies whether the total number of 1s in a code group is odd or even In an Odd Parity system the parity bit is made 0 or 1 as necessary to make the total number 1s odd (counting the parity bit itself) In an Even Parity system the parity bit is chosen to make the total number of 1s even Table 91 shows how parity bits would be added to BCD code group in both systems

    Decimal BCD Value Parity Bit ABCD Odd Parity Even Parity

    0 0000 1 0 1 0001 0 1 2 0010 0 1 3 0011 1 0 4 0100 0 1 5 0101 1 0 6 0110 1 0 7 0111 0 1 8 1000 0 1 9 1001 1 0

    Table 91 Odd and Even Parity in BCD

    When digital data is received a parity checking circuit generates an error signal if the total number of 1s is odd in an even parity system or if it is even in an odd parity system Parity check always detects a single error (one bit change from 0 to 1 or 1 to 0) but may not detect

    42

    Logic Design amp Switching Theory 1 Lab Session 09 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering ` two or more errors Odd parity is used more often than even parity because even parity does not detect a situation where all 0s are created due to short circuit or other fault condition DESIGN OF A 3-BIT ODD PARITY GENERATOR AND CHECKER Let x y and z be the three bits that constitute the message and are the input to the Odd Parity Generator Circuit Since it is an odd parity system the bit P is generated so as to make the total number of 1s odd (including P) The function P can be expressed as follows P = x oplus y Ο z or P = x Ο y oplus z Since the IC available is 7486 which is quad 2input XOR IC therefore we will convert XNOR also to XOR

    P = x oplus y Ο z

    P = ( x oplus y ) Ο z Since for even number of variables ______

    XOR = XNOR Therefore ___________ _________

    P = ( x oplus y ) oplus z = x oplus y oplus z This logical expression can be implemented with two XOR gates and an inverter (see figure 91)

    Figure 91 Circuit Diagram for a 3-bit Parity Generator

    The 3-bit message and the parity bit are transmitted to their destination where they are applied to a Parity Checker Circuit An error occurs during transmission if the parity of the four bits received is even since the binary information transmitted was originally odd The output C of the parity checker should be a 1 when an error occurs ie when the number of 1s in the four inputs is even Therefore the function C can be expressed as

    C = x Ο y Ο z Ο P

    Using the same logic applied for the conversion of the equation of P

    PzyxC oplusoplusoplus= This logical expression can be implemented with three XOR gates and an inverter (see figure 92)

    43

    Logic Design amp Switching Theory 1 Lab Session 09 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering `

    44

    Figure 92 Circuit Diagram for a 3-bit Parity Checker Implementation and Observations Implement the 3-bit Parity Generator and Checker circuits (figure 91 and 92) on a bread board (prepare the pin diagram (use appendix A) and refer to laboratory session 01 for implementation procedure) and record the observations in the following table

    x y z P x y z P C x y z P C 0 0 0 0 0 0 0 1 0 0 0 0 0 1 0 0 0 1 1 0 0 1 0 1 0 0 0 1 0 1 0 1 0 0 1 1 0 0 1 1 1 0 1 1 1 0 0 0 1 0 0 1 1 0 0 1 0 1 0 1 0 1 1 1 0 1 1 1 0 0 1 1 0 1 1 1 0 1 1 1 0 1 1 1 1 1 1 1

    Odd Parity Generation Odd Parity Check ACTIVITY 1 Try using the parity checker of figure 92 as 3-bit parity generator Write the details here

    _____________________________________________________________________________________________________________________________________________________________________________________________________________________ ______________________________________________________________________________________________________________________________________________ _______________________________________________________________________ ______________________________________________________________________________________________________________________________________________

    Logic Design amp Switching Theory 1 Lab Session 10 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

    Lab Session 10 OBJECT

    Driving a seven segment display using 7447 7448 driver IC COMPONENTS AND APPARATUS REQUIRED

    1 Following ICs and their Datasheets

    bull Seven Segment Displays (Common Anode Common Cathode) bull 7447 7448 BCD to Seven Segment Driver

    2 Digital Trainer DT-01 or the following components Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches

    THEORY Seven Segment Displays A Seven Segment Display consists of seven light-emitting segments The segments are designated by letters a through g (see figure 101) By illuminating various combinations of segments the numerals 0 through 9 can be displayed Seven Segment Displays are commonly constructed with light-emitting diodes (LEDs) and with liquid-crystal displays (LCDs) LEDs generally provide greater illumination levels but require much greater power than LCDs An LED display can be a common-anode type or common cathode type In common anode type a high voltage is applied at the common terminal of the display and low voltage is applied at a segmentrsquos terminal for illumination In the common-cathode type a low voltage is applied at the common terminal of the display and high voltage is applied at a segmentrsquos terminal for illumination

    Figure 101 Seven Segment Display

    a f b g

    e c d

    7447 7448 BCD to Seven Segment Driver 7447 7448 IC is particularly used to drive Seven Segment Its input is a BCD number and output drives a seven segment display 7447 is used to drive common-anode displays whereas 7448 is used to drive common cathode displays 7447 7448 is a 16 pin IC Function of various pins of these ICs is described below

    bull A B C D Inputs representing BCD digits (D being the MSB)

    45

    Logic Design amp Switching Theory 1 Lab Session 10 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering bull OA through OG Outputs to drive segments a through g of the display (Active low

    in 7447 and active high in 7448) bull RBI Ripple Blanking Input Turns off all the segments if kept low provided that LT

    is kept high and all other inputs (A B C D BI) are kept low Should be kept high otherwise

    bull BI RBO Wire-AND logic serving as a Blanking Input and or Ripple Blanking Output

    o BI Turns off all the segments if low o RBO Goes to a low level (response condition) along with other outputs when

    RBI and inputs A B C and D are low with LT input at high level bull LT Lamp Test input Tests whether all segments are working or not Illuminates all

    segments if kept low provided that BI is kept high Should be kept high otherwise bull VCC and GND Supply connections lines CIRCUIT DIAGRAM

    Figure 102 Circuit diagram for 7447driving a common-anode display

    IMPLEMENTATION AND OBSERVATIONS

    bull Make connections as shown in the circuit diagram (refer to laboratory session 01 for implementation procedure)

    bull Apply different combinations of 1s and 0s at data inputs bull Observe the output and record your observations in the following table

    46

    Logic Design amp Switching Theory 1 Lab Session 10 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

    47

    Decimal Digit

    BCD Inputs Seven Segment Outputs D C B A a b c d e f g

    0 0 0 0 0 1 0 0 0 1 2 0 0 1 0 3 0 0 1 1 4 0 1 0 0 5 0 1 0 1 6 0 1 1 0 7 0 1 1 1 8 1 0 0 0 9 1 0 0 1

    ACTIVITY 1 Perform the Lamp Test for the designed circuit and write your observations

    ____________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________

    2 How can you use 7447 IC to drive a common-cathode display

    ____________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________

    3 What symbols appear in the seven segment display if inputs DCBA are

    DCBA Symbol

    1010

    1011

    1100

    1101

    1110

    1111

    Logic Design amp Switching Theory 1 Lab Session 11 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

    48

    Lab Session 11 OBJECT

    Testing different modes of JK-FF COMPONENTS AND APPARATUS REQUIRED 1 Following ICs and their Datasheets

    bull 7473 7476 JK Flip-Flop 2 Digital Trainer DT-01 or the following components

    Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches

    THEORY

    Flip-Flop A flip-flop circuit can maintain a binary state indefinitely (as long as the power is delivered to the circuit) until directed by an input signal to switch states The major differences among various types of flip-flops are in the number of inputs they possess and in the manner in which the inputs affect the binary state

    JK Flip-Flop JK flip flop is an edge triggered device A typical JK flip flop has three inputs J K and a clock input The flip-flop can be either positive or negative edge triggered The output Q is available in complemented form as well Beside the usual inputs and output most of the flip-flop IC also possess two asynchronous inputs namely Preset and Clear These inputs are usually active low If used Preset and Clear inputs keep the flip-flop in set and reset state respectively irrespective of the other inputs Both of these inputs cannot be used simultaneously otherwise they will bring the flip-flop in unstable state

    Figure 111 Symbol for JK flip-flop

    (a) positive-edge triggering (b) active low Preset (PR) and Clear (CLR) with positive-edge triggering

    (c) active low Preset (PR) and Clear (CLR) with negative-edge triggering

    Logic Design amp Switching Theory 1 Lab Session 11 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

    49

    TESTING OF 7473 7476 DUAL JK FLIP-FLOP

    Both the ICs 7473 and 7476 are similar in functionality except for one difference The flip-flops in 7473 have only one type of active low asynchronous input which is the Clear input whereas the flip-flops in 7476 have both Preset and Clear inputs Both these ICs have negative edge triggered flip-flops

    Circuit Diagram

    Figure 112 Pin connections of 7476

    Testing Procedure

    bull Make connections as shown in the circuit diagram (figure 112) bull Apply different combinations of 1s and 0s at J and K inputs bull Observe the output and record your observations in the following table

    Observations

    J

    K Q

    0 0 0 1 1 0 1 1

    ACTIVITY

    1 Observe the output Q of JK flip-flop if the clock input is connected to VCC or GND instead of a clock source Write your observations here __________________________________________________________________________________________________________________________________________ _______________________________________________________________________________________________________________________________________________________________________________________________________________

    Logic Design amp Switching Theory 1 Lab Session 12 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

    50

    Lab Session 12 OBJECT

    Designing sequential circuit for the given state diagram using D flip-flop GIVEN STATE DIAGRAM

    00

    11

    Figure 121 State Diagram COMPONENTS AND APPARATUS REQUIRED 1 Following ICs and their Datasheets

    bull 7474 D Flip-Flop bull ICs of basic gates (AND OR NOT XOR etc) as required

    2 Digital Trainer DT-01 or the following components Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches

    THEORY

    Sequential Circuits In Sequential Circuits the output not only depends on the present inputs but also on previous states of the circuit These circuits use memory elements (latches flip-flops) and the binary information stored in the memory elements at any given time defines the state of the sequential circuit Analysis of a Sequential Circuit The behavior of a sequential circuit is determined from the inputs the outputs and the states of its flip-flops Both the outputs and next state are a function of the inputs and the

    10

    01

    00 11 10

    00

    00 11 10 00

    Logic Design amp Switching Theory 1 Lab Session 12 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

    51

    present state The analysis of a sequential circuit form a state diagram comprises of the following bull Selecting a particular flip-flop to design the circuit bull Obtaining state table from the state diagram bull Finding input equations for the selected flip-flop bull Finding state equations (not required for the construction of circuit) bull Implementing the circuit using selected flip-flops and their input equations ANALYZING THE GIVEN STATE DIAGRAM D Flip-Flop D flip-flop is also called transparent flip-flop as it simply transfers the input data to the output For our design we require the graphical symbol and excitation table of D flip-flop (see figure 122)

    Qt Qt+1 T 0 0 0 0 1 1 1 0 0 1 1 1

    (b) Excitation table of D Flip-Flop

    (a) Graphical Symbol

    Figure 122 Characteristic equation of D flip-flop is Q(t+1) = D State Table The given state diagram has four states so we will need two D flip-flops (FF-0 FF-1) Form state table form the given state diagram and record the results in the following table

    Present State Input Next State Output Input to FF-0 D0

    Input to FF-1 D1 Q1t Q0t x Q1(t+1) Q0(t+1) z

    Logic Design amp Switching Theory 1 Lab Session 12 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

    52

    Input Equations Using Karnaugh map the input equations D0 and D1 for the two flip-flops can be found

    D0 D1 Q0x

    Q1

    _ _ Q0x

    _ Q0x

    Q0x

    _ Q0x

    Q0x

    Q1

    _ _ Q0x

    _ Q0x

    Q0x

    _ Q0x

    _ Q1

    _ Q1

    Q1

    Q1

    D0 = _________________ D1 = _________________

    State Equations Using the characteristic equation of D flip-flop we can find the state equations Q0(t+1) and Q1(t+1) for the to flip flops Q0(t+1) = _______________________ Q1(t+1) = _______________________ _______________________ _______________________ _______________________ _______________________ Circuit Diagram

    Logic Design amp Switching Theory 1 Lab Session 12 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

    53

    Implementation Procedure and Observations

    1 Implement the circuit using digital ICs on a bread board (prepare the pin diagram (use appendix A) and refer to laboratory session 01 for procedure)

    2 Make the clear inputs of the flip-flops low (to clear the flip-flops) The flip-flops will remain in clear state as long as the clear inputs are connected to low level

    3 Connect output Q0 and the clock pulse to an oscilloscope 4 Apply 0 to the input x 5 Now make the clear inputs to high 6 Observe the waveform for the first 5 clock pulses and record it 7 Repeat steps 2 to 6 keeping x=1 in step 4 this time 8 Repeat steps 2 to 7 this time connecting Q1 instead of Q0 to the oscilloscope in step

    3 Record your observations (Keep frequency of the clock pulse low (eg1Hz) so that the output waveforms can be observed easily)

    1 2 3 4 5 Clock Pulse

    Output Waveform for Q0 when x=0

    Output Waveform for Q0 when x=1

    Output Waveform for Q1 when x=0

    Output Waveform for Q1 when x=1

    Logic Design amp Switching Theory 1 Lab Session 13 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

    Lab Session 13 OBJECT

    Designing a modulo-5 asynchronous up-counter using JK-FF COMPONENTS AND APPARATUS REQUIRED

    1 Following ICs and their Datasheets

    bull 7400 Quad 2-input or 7410 Triple 3-input NAND Gates bull 7476 7473 JK Flip-Flop

    2 Digital Trainer DT-01 or the following components Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches

    THEORY

    Digital Counters A digital counter is a set of flip-flops whose states change in response to pulses applied at the input to the counter The flip-flops are interconnected so that their combined state at any time is the binary equivalent of the total number of pulses that have occurred up to that time Every counter resets after a certain number of clock pulses Thus as it name implies a counter is used to count pulses An n stage counter can count up to a maximum of 2n states n is equal to the number of flip-flops required for the construction of counter

    Modulus Counters The number of input pulses that causes a counter to reset to its initial count is called the modulus of the counter Thus the modulus equals to total number of distinct states (counts) including zero that a counter can store A binary counter with n stages is a modulo-2n (or mod-2n) counter The largest count a mod-N counter can achieve is N-1 ie a mod-N counter never reaches the binary number equal to its modulus N is always equal to or less than 2n Counters can be classified as bull Synchronous Counters which are clock driven All the flip-flops are driven by a

    single clock bull Asynchronous Counters which are event driven Clock input is given to the first

    flip-flop only Rest of the flip-flops are driven by their preceding flip-flops

    DESIGN OF A MOD-5 ASYNCHRONOUS UP COUNTER The number of flip-flops required to construct a mod-5 counter is 3 because 5 should be less than or equal to 2n This counter will count from 0 to 4 a total of 5 distinct states Since a 3-stage counter can count up to 8 states at maximum a NAND gate is used to reset it after 5 clock pulses Figure 131 shows the logic diagram

    54

    Logic Design amp Switching Theory 1 Lab Session 13 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

    55

    Figure 131 A Mod-5 Asynchronous Up Counter

    Implementation and Observations

    Implement the mod-5 counter circuit (figure 131) on a bread board (prepare the pin diagram (use appendix A) and refer to laboratory session 01 for implementation procedure) and record the observations in the following table

    Clock Pulse Q2 Q1 Q0

    0 1 2 3 4 5 6 7

    ACTIVITY

    Draw the timing diagram for mod-5 counter designed in this laboratory session

    Logic Design amp Switching Theory 1 Lab Session 14 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

    Lab Session 14 OBJECT

    Experimenting with 74194 4-bit bidirectional universal shift register COMPONENTS AND APPARATUS REQUIRED

    1 Following ICs and their Datasheets

    bull 74194 4-bit bidirectional universal shift register 2 Digital Trainer DT-01 or the following components

    Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches

    THEORY

    Shift Registers

    A Register is a set of flip-flops used to store binary data A register which is capable of shifting its binary information either to the right or left is called a shift register The logical configuration of a register consists of a chain of flip-flops connected in cascade with the output of one flip-flop connected to the input of next flip-flop All flip-flops receive a common clock pulse which causes the shift from one stage to the next

    Bidirectional Shift Registers A bi-directional shift register is one whose bits can be shifted from left to right or from right to left

    Universal Shift Registers A universal shift register is a bi-directional register whose input can be in either serial or parallel form and whose output can be in either serial or parallel form

    74194 4-BIT BIDIRECTIONAL UNIVERSAL SHIFT REGISTER

    The 74194 register provides parallel as well as serial loading in both directions Function of various pins of this IC is described below

    bull A B C and D Active high inputs for parallel loading bull QA QB QC and QD Active high outputs bull S0 and S1 Active high mode control inputs The following table shows combinations

    of S1 and S0 to enable various modes

    S1 S0 Clock Action 0 0 x No change 0 1 uarr Shift right 1 0 uarr Shift left 1 1 uarr Parallel load

    uarr shows the rising edge of the clock pulse

    56

    Logic Design amp Switching Theory 1 Lab Session 14 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering bull SR Active high serial input for right shifting bull SL Active high serial input for left shifting bull CLR Active low input Clears all the flip-flops of the register if set to 0 should be

    kept high otherwise bull CLK Clock input bull VCC and GND Supply connections lines Thus A B C and D are inputs for parallel loading whereas SR and SL are inputs for serial loading with right or left shifting respectively S1 and S0 are used to select the loading mode Circuit Diagram

    Figure 141 Pin connections of 74194 Testing Procedure

    bull Make connections as shown in the circuit diagram bull Observe the output for the input combinations given in the following table

    57

    Logic Design amp Switching Theory 1 Lab Session 14 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

    58

    Observations

    S1 S0 SL SR A B C D QA QB QC QD 0 0 0 1 0 0 0 0 0 1 1 0 0 0 0 1 1 0 0 0 0 0 1 0 1 1 0 0 0 0 1 1 0 0 1 1 0 1 0 0 0 1 1 1 0 1 0 1 1 0 1 0 0 1 1 0 1 1 1 0 0 1 1 1 1 1 0 0 1 1 1 1

    ACTIVITY 1 Show connections of 74194 to convert it into a ring counter with right shifting

    Logic Design amp Switching Theory 1 Lab Session 15 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

    Lab Session 15

    OBJECT

    Experimenting with 74245 octal bus transceivers using parallel port PC interfacing COMPONENTS AND APPARATUS REQUIRED 1 Parallel Port Connectors (DB-25) with Cable 2 Personal Computer with Windows 98 and TurboC Compiler Installed 3 Following ICs and their Datasheets

    bull 74245 Octal Bus Transceivers with 3-State Outputs 4 Digital Trainer DT-01 or the following components

    Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches

    THEORY

    3-State Logic Sometimes it is necessary to isolate one part of circuit from the other part For this purpose some TTL ICs are designed with 3-state logic Such devices have three possible output states high low and high impedance The device can be put into high impedance state by a control signal applied to an appropriate pin When such a device is in high impedance state there is very high impedance at its output effectively isolating the device from whatever circuitry the output normally drives 74245 Octal Bus Transceivers A bus is any conducting path or set of paths having electrical connections to one or more devices 74245 octal bus transceivers are mainly used to control connectivity between two devices or circuits It also provides direction control for signal flow Function of various pin of this IC is given below

    bull A1 through A8 Bus A bull B1 through B8 Bus B bull G΄ Active low enable input When high sets all the bus pins to high impedance state bull DIR Direction control for signal flow When set to high logic level transfers bus A

    data to B bus When set to low logic level transfers bus B data to A bus bull VCC and GND Supply connections lines Serial and Parallel Port Connectors A Parallel Port can consist of only 25 pin port adapter called a DB-25 and a serial port can consist of either a 25 pin port adapter called a DB-25 or 9 pin adapter called a DB-9 port adapter Whether the port is a 9 pin or 25 pin it can accomplish all of the same tasks that serial port communications have been designed for

    59

    Logic Design amp Switching Theory 1 Lab Session 15 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

    60

    Each adapter can be a male type connector with pins or a female type adapter with tiny holes Generally a PRINTER port (called LPT1) on the back of a computer is female type adapter and we need to use MALE DB-25 pin cable on it for PRINTER connection or for parallel LAPLINK cable And a COM port on the back of a computer is male for the serial ports but it may not necessarily be Parallel Port Connector ndash DB-25 The DB-25 connector (named for its B-size D-shaped shell and 25 pins) is practically ubiquitous in the electronics industry The DB-25 connector is used for a variety of purposes Two common applications are RS-232EIA-232 (serial) connections and the parallel printer interface on the IBM PC The DB-25 connector is also used for SCSI connections Normally the parallel port is used for output to a printer or other device It sends data 8-bits or one byte at a time in parallel The other lines available on the DB-25 connector are a combination of status lines control lines and ground lines The status and control lines are used for handshaking commands and feedback when we are talking to a printer

    Figure 152 DB-25 Female Figure 151 DB-25 Male

    Figure 153 Pin Layout for DB-25 As can be seen form figure 153 there are four types of pins in this connector

    bull Data pins (8 pins - D0 to D7) Active high bidirectional lines

    Logic Design amp Switching Theory 1 Lab Session 15 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering bull Control pins (4 pins - C0 to C3) C0 C1 and C3 are active low whereas C2 is active

    high These lines also are bidirectional bull Status pins (5 pins ndash S3 to S7) Only S7 is active low rest are active high input lines bull Ground pins (8 pins) Used as a reference signal for the low (below 05 volts) charge

    Parallel Port Addresses A DB-25 connector at a parallel port has three address one for each kind of pins register data status and control The first or base address generally refers to data register Second address is for status register and the third one is for control register In Windows 98 the base address is usually found to be 278H 378H or 3BCH Now if 378H is the base address then it refers to the data register whereas addresses for status and control register are respectively 379H and 37AH For Windows 98 the base address can be found as follows 1 On your Desktop right-click on My Computer and select Properties 2 Click on the Device Manager tab and find LPT1 under Plug and Play BIOS 3 After selecting LPT1 click the Properties button 4 Next select the Resources tab and the address should then appear next to InputOutput

    Range Accessing parallel port through C Language Programming There are multiple functions in C Language for accessing external ports The most commonly used are listed below

    bull unsigned char inportb(int portid) inportb reads a byte from a hardware port

    bull int inport(int portid) reads a word from a hardware port

    bull void outportb(int portid unsigned char value) outputs a byte to a hardware port

    bull void outport(int portid int value) outputs a word to a hardware port

    portid refers to the port address whereas value refers to the data to be sent TESTING 74245 USING PARALLEL PORT PC INTERFACING At one end the parallel port connector will be connected to the PC via parallel port cable and another connector (to be plugged into the PC parallel port slot) At the other end it will be connected to the buffer IC 74245 Data lines of the connector will be used to transfer 8-bit data between the PC and the buffer Out of the 8-bits of 74245 4-bits will be used to enter data which will be displayed at the monitor through a C language

    61

    Logic Design amp Switching Theory 1 Lab Session 15 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering program The remaining 4-bits will receive data from PC as entered by the user via keyboard

    Circuit Diagram

    Figure 154 Interface of 74245 to PC via Parallel Port

    Procedure

    1 Connect the DB-25 connector to the PC at one end and solder it to the circuit board at the other end

    2 Connect various pins of the connector and 74245 according to the circuit diagram shown in figure 152

    3 Using the functions listed in the previous section write a program in C language to operate various pins of the buffer The user interface of the program should provide option to the user whether to send or receive data from the port

    4 Set DIR switch to 1 5 Try sending some data bits to the port The result should be displayed at the LEDs 6 Set DIR switch to 0 7 Set some binary 4-bit value through the switches Try reading it via parallel port

    C Language Program

    A program to access parallel port for data transfers

    use header file include ltstdiohgt main program void main() define variable

    62

    Logic Design amp Switching Theory 1 Lab Session 15 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering unsigned int data=0 char choice while(1) printing option menu clrscr() printf(This program will send or receive a BCD digit from the parallel portn) printf(nPress your choice numbern) printf(n1 Send Data) printf(n2 Receive Data) printf(n3 Exitn) choice = getch() sending entered digit to the port if(choice == 1) input BCD digit printf(nEnter BCD digit to be sent to the port) data = getche() masking the first four bits data = data amp 0x0f sending to the port outportb(0x378data) printf(nThe BCD digit c has been sent to the port data) printing on screen the data received from the port else if(choice == 2) receiving data from the port data = inportb(0x378) masking the last four bits data = data amp 0xf0 shifting first four bits to make them the last four bits datagtgt=4 printf(nThe BCD digit set at the port is c data) exit else if(choice == 3) break key pressed is not in the menu else printf(nEnter valid choice number) printf(nnPress any key to continue) getch()

    63

    Logic Design amp Switching Theory 1 Lab Session 15 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

    ACTIVITY 1 In the above circuit DIR and G΄ inputs are hardwired Connect them to status or

    control pins of the parallel port connector and control their function through your software program Circuit Diagram Program Code ______________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________

    ___________________________________________________________________________________________________________________________________________________

    64

    Logic Design amp Switching Theory 1 Lab Session 15 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

    65

    _____________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ _____________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ _______________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ _________________________________________________ _________________________________________________

    Logic Design amp Switching Theory 1 Appendix A NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

    Appendix A

    PIN DIAGRAMS OF THE ICS REQUIRED FOR THE LABORATORY SESSIONS Consult the TTLIC data book for internal diagrams and electrical characteristics of these ICs 7400 Quad 2-Input NAND 7402 Quad 2-Input NOR

    7404 Hex Inverter 7408 Quad 2-Input AND

    7410 Triple 3-Input NAND 7411 Triple 3-Input AND

    7421 Dual 4-Input AND 7432 Quad 2-Input OR

    66

    Logic Design amp Switching Theory 1 Appendix A NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

    BCD-to-Seven Segm 7448 BCD-to-Seven Segment 7447 ent

    Decoder (15V OC) Decoder (2kΩ pull-up output)

    7473 Dual JK Flip-Flop 7474 Dual D-Type Flip-Flop

    7476 Dual JK Flop-Flop -Bit Binary Full Adder 7483 4 with Fast Carry

    86 Quad 2-Inpu 74138 3-to-8 Line 74 t Exclusive OR Decoder Demultiplexer

    67

    Logic Design amp Switching Theory 1 Appendix A NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

    68

    74148 8-to-3 Line 16-to-1 Line Data

    Priority Encoder 74150 Selector Multiplexer

    74245 Oct nsceivers Universal Shift Register (PIPO) (3-State)

    74194 4-Bit Bidirectional al Bus Tra

    Logic Design amp Switching Theory 1 Appendix B NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

    Appendix B

    DEBOUNCING CIRCUITRY FOR MECHANICAL SWITCHES Mechanical switches form the interface between human beings and computers or other digital systems For example a keyboard is a matrix of switches used to supply alphanumeric data to a computer Whatever the switch design it is a potential source of problems due to contact bounce The contact bounce creates a sense of narrow pulses when a switch is opened or closed An example of device whose operation would be adversely affected by contact bounce is a digital counter used to count the number of times a switch is depressed Eliminating the effects of contact bounce is called debouncing When data is entered into a computer via a keyboard a software debounce is often used This type of debouncing is a program that causes the computer to sample the switch terminal (ie to input data from it) many times in succession during the interval of time that contact bounce occurs If the data is sensed to be 1s (or 0s) for a specific number of consecutive samples then it is assumed that contact bounce has ended and the last value sensed is valid Hardware debouncing is the use of electronic circuitry to eliminate the effects of contact bounce There are numerous versions of such circuitry including those that use monostable multivibrators (one-shots) but the most straightforward is simply an RS latch Figure B1 shows the circuit When the switch is in position 1 R = 0 and S = 1 so the latch is set and the output (Q) is 1 When the switch is in position 0 R = 1and S = 0 so the latch is reset and the output is 0 When the switch is moved form one position to the other the latch changes state and bouncing occurs at either the R or the S input The bouncing does not affect the latch after it has change state An RS latch will remain set for example when its R input is 0 and its S input is alternately changed form 1 to 0

    Figure B1 Use of RS latch to debounce a mechanical switch

    69

    • 01-ldst-Outer title
      • Practical Workbook
      • Logic Design amp Switching Theory I
        • Dept of Computer amp Information Systems Engineering
          • NED University of Engineering amp Technology
          • Karachi ndash 75270 Pakistan
            • 02-ldst-inner Title
              • Practical Workbook
              • Logic Design amp Switching Theory I
                • Dept of Computer amp Information Systems Engineering
                  • NED University of Engineering amp Technology
                  • Karachi ndash 75270 Pakistan
                    • 03-ldst-general info
                    • 04-ldst-introduction
                    • 05-Table of Contents
                      • CONTENTS
                        • Lab Session No Object Page No
                        • 1
                        • Also implementing and testing the given circuit on a bread board
                          • Working with Electronics Workbench
                            • Driving a seven segment display using 7447 7448 driver IC
                              • Designing a modulus-5 asynchronous up-counter using JK-FF
                                • Experimenting with 74194 4-bit bidirectional universal shift register
                                    • 13
                                        • 06-ldst-Exp01
                                          • Lab Session 01
                                          • OBJECT
                                            • 1 Bread board
                                            • 2 5 V - power supply
                                            • 3 Multimeter
                                            • 4 Logic probe
                                            • 5 LEDs with resistors
                                            • 6 Connecting wires
                                            • 8 Following ICs and their datasheets
                                              • THEORY
                                                • Logic Gates
                                                • 1 The AND Gate ndash An AND gatersquos output is 1 if and only if all its inputs are 1 If A and B are two inputs to an AND gate then output F of the gate is given as F = AB
                                                • 2 The OR Gate - An OR gatersquos output is 1 if at least one of its input is 1 If A and B are two inputs to an OR gate then output F of the gate is given as F = A+B
                                                • 3 The NOT Gate (Inverter) ndash Its output is 1 when its input is 0 and its output is 0 when the input is 1 ie it complements a digital variable If A is the input to a NOT gate then output F of the gate is given as
                                                • 4 The NAND Gate ndash Its output is 1 if at least one of its input is 0 This gate performs the same logic as an AND gate followed by an inverter If A and B are two inputs to a NAND gate then output F of the gate is given as
                                                  • 5 The NOR Gate - The output of a NOR gate is 1 if and only if all its inputs are 0 This gate performs the same logic function as an OR gate followed by an inverter If A and B are two inputs to a NAND gate then output F of the gate is given as
                                                      • DATA SHEETS
                                                        • Logic expression for the given logic diagram __________________________________
                                                            • 07-ldst-exp02
                                                              • Working with Electronics Workbench
                                                                • 08-ldst-exp03
                                                                  • Designing Half and Full Adder Circuits
                                                                    • COMPONENTS AND APPARATUS REQUIRED
                                                                      • 1 Following ICs and their Datasheets
                                                                      • 7408 Quad 2-input AND Gate
                                                                      • 2 Digital Trainer DT-01 or the following components
                                                                        • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                        • Connecting wires Switches
                                                                          • THEORY
                                                                              • IMPLEMENTATION AND OBSERVATIONS
                                                                                • 09-ldst-Exp04
                                                                                  • Lab Session 04
                                                                                  • 1 Digital ICs and their Datasheets
                                                                                  • 7408 Quad 2-input AND Gate
                                                                                  • 2 Digital Trainer DT-01 or the following components
                                                                                    • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                    • Connecting wires Switches
                                                                                    • PROCEDURE
                                                                                    • REDUCTION OF LOGIC EXPRESSION USING KARNAUGH MAP
                                                                                    • OBSERVATIONS
                                                                                    • RESULT
                                                                                        • 10-ldst-Exp05
                                                                                          • Lab Session 05
                                                                                          • 1 Following ICs and their Datasheets
                                                                                          • 7408 Quad 2-input AND Gate
                                                                                          • 2 Digital Trainer DT-01 or the following components
                                                                                            • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                            • (100 Ω) Connecting wires Switches
                                                                                            • THEORY
                                                                                              • IMPLEMENTATION AND OBSERVATIONS
                                                                                                • 11-ldst-Exp06
                                                                                                  • OBJECT
                                                                                                  • 1 Following ICs and their Datasheets
                                                                                                  • 7408 Quad 2-input AND Gates or 7411 Triple 3-input AND Gates
                                                                                                  • 2 Digital Trainer DT-01 or the following components
                                                                                                    • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                    • Connecting wires Switches
                                                                                                      • Figure 62 Circuit Diagram for 4 x 1 Multiplexer
                                                                                                      • Implementation and Observations
                                                                                                        • Circuit Diagram
                                                                                                          • ACTIVITY
                                                                                                            • 12-ldst-exp07
                                                                                                              • 1 Following ICs and their Datasheets
                                                                                                              • 7408 Quad 2-input or 7411 Triple 3-input AND Gates
                                                                                                              • 2 Digital Trainer DT-01 or the following components
                                                                                                                • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                • Connecting wires Switches
                                                                                                                  • THEORY
                                                                                                                      • Figure 72 Circuit Diagram for 2 x 4 Decoder 1 x 4 Demultiplexer
                                                                                                                      • Implementation and Observations
                                                                                                                        • Circuit Diagram
                                                                                                                          • ACTIVITY
                                                                                                                            • 13-ldst-Exp08
                                                                                                                              • OBJECT
                                                                                                                              • 1 Following ICs and their Datasheets
                                                                                                                              • 7408 Quad 2-input or 7421 Dual 4-input AND Gates
                                                                                                                              • 2 Digital Trainer DT-01 or the following components
                                                                                                                                • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                • Connecting wires Switches
                                                                                                                                  • THEORY
                                                                                                                                      • Figure 81 Circuit Diagram for 4 x 2 Priority Encoder
                                                                                                                                      • Implementation and Observations
                                                                                                                                        • Therefore if GS A2 A1 and A0 are all low then it shows that line 0 is selected and if E0 A2 A1 and A0 are all low then it shows that none of the inputs selected E0 and GS cannot be in the same state provided that E1 is enabled
                                                                                                                                        • Circuit Diagram
                                                                                                                                          • ACTIVITY
                                                                                                                                            • 14-ldst-exp09
                                                                                                                                              • OBJECT
                                                                                                                                              • 1 Following ICs and their Datasheets
                                                                                                                                              • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                • Connecting wires Switches
                                                                                                                                                  • THEORY
                                                                                                                                                    • Parity Generator
                                                                                                                                                      • Let x y and z be the three bits that constitute the message and are the input to the Odd Parity Generator Circuit Since it is an odd parity system the bit P is generated so as to make the total number of 1s odd (including P) The function P can be expressed as follows
                                                                                                                                                      • Figure 91 Circuit Diagram for a 3-bit Parity Generator
                                                                                                                                                        • C = x Ο y Ο z Ο P
                                                                                                                                                          • Implementation and Observations
                                                                                                                                                            • ACTIVITY
                                                                                                                                                                • 15-ldst-exp10
                                                                                                                                                                  • Driving a seven segment display using 7447 7448 driver IC
                                                                                                                                                                  • COMPONENTS AND APPARATUS REQUIRED
                                                                                                                                                                  • 1 Following ICs and their Datasheets
                                                                                                                                                                  • 7447 7448 BCD to Seven Segment Driver
                                                                                                                                                                  • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                    • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches
                                                                                                                                                                      • THEORY
                                                                                                                                                                      • Seven Segment Displays
                                                                                                                                                                      • CIRCUIT DIAGRAM
                                                                                                                                                                      • Figure 102 Circuit diagram for 7447driving a common-anode display
                                                                                                                                                                          • IMPLEMENTATION AND OBSERVATIONS
                                                                                                                                                                            • Decimal Digit
                                                                                                                                                                            • BCD Inputs
                                                                                                                                                                            • Seven Segment Outputs
                                                                                                                                                                            • D
                                                                                                                                                                            • C
                                                                                                                                                                            • B
                                                                                                                                                                            • A
                                                                                                                                                                            • a
                                                                                                                                                                            • b
                                                                                                                                                                            • c
                                                                                                                                                                            • d
                                                                                                                                                                            • e
                                                                                                                                                                            • f
                                                                                                                                                                            • g
                                                                                                                                                                            • 0
                                                                                                                                                                            • 0
                                                                                                                                                                            • 0
                                                                                                                                                                            • 0
                                                                                                                                                                            • 0
                                                                                                                                                                            • 1
                                                                                                                                                                            • 0
                                                                                                                                                                            • 0
                                                                                                                                                                            • 0
                                                                                                                                                                            • 1
                                                                                                                                                                            • 2
                                                                                                                                                                            • 0
                                                                                                                                                                            • 0
                                                                                                                                                                            • 1
                                                                                                                                                                            • 0
                                                                                                                                                                            • 3
                                                                                                                                                                            • 0
                                                                                                                                                                            • 0
                                                                                                                                                                            • 1
                                                                                                                                                                            • 1
                                                                                                                                                                            • 4
                                                                                                                                                                            • 0
                                                                                                                                                                            • 1
                                                                                                                                                                            • 0
                                                                                                                                                                            • 0
                                                                                                                                                                            • 5
                                                                                                                                                                            • 0
                                                                                                                                                                            • 1
                                                                                                                                                                            • 0
                                                                                                                                                                            • 1
                                                                                                                                                                            • 6
                                                                                                                                                                            • 0
                                                                                                                                                                            • 1
                                                                                                                                                                            • 1
                                                                                                                                                                            • 0
                                                                                                                                                                            • 7
                                                                                                                                                                            • 0
                                                                                                                                                                            • 1
                                                                                                                                                                            • 1
                                                                                                                                                                            • 1
                                                                                                                                                                            • 8
                                                                                                                                                                            • 1
                                                                                                                                                                            • 0
                                                                                                                                                                            • 0
                                                                                                                                                                            • 0
                                                                                                                                                                            • 9
                                                                                                                                                                            • 1
                                                                                                                                                                            • 0
                                                                                                                                                                            • 0
                                                                                                                                                                            • 1
                                                                                                                                                                              • ACTIVITY
                                                                                                                                                                                • 16-ldst-exp11
                                                                                                                                                                                  • Lab Session 11
                                                                                                                                                                                    • OBJECT
                                                                                                                                                                                    • COMPONENTS AND APPARATUS REQUIRED
                                                                                                                                                                                      • 1 Following ICs and their Datasheets
                                                                                                                                                                                      • 7473 7476 JK Flip-Flop
                                                                                                                                                                                      • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                        • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                        • Connecting wires Switches
                                                                                                                                                                                          • THEORY
                                                                                                                                                                                              • Flip-Flop
                                                                                                                                                                                              • JK Flip-Flop
                                                                                                                                                                                                • Circuit Diagram
                                                                                                                                                                                                  • Observations
                                                                                                                                                                                                    • ACTIVITY
                                                                                                                                                                                                        • 17-ldst-exp12
                                                                                                                                                                                                          • Lab Session 12
                                                                                                                                                                                                            • OBJECT
                                                                                                                                                                                                            • GIVEN STATE DIAGRAM
                                                                                                                                                                                                            • Figure 121 State Diagram
                                                                                                                                                                                                            • COMPONENTS AND APPARATUS REQUIRED
                                                                                                                                                                                                              • 1 Following ICs and their Datasheets
                                                                                                                                                                                                              • 7474 D Flip-Flop
                                                                                                                                                                                                              • ICs of basic gates (AND OR NOT XOR etc) as required
                                                                                                                                                                                                              • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                                • Connecting wires Switches
                                                                                                                                                                                                                  • THEORY
                                                                                                                                                                                                                      • Sequential Circuits
                                                                                                                                                                                                                        • 18-ldst-exp13
                                                                                                                                                                                                                          • Lab Session 13
                                                                                                                                                                                                                            • Designing a modulo-5 asynchronous up-counter using JK-FF
                                                                                                                                                                                                                              • 1 Following ICs and their Datasheets
                                                                                                                                                                                                                              • 7400 Quad 2-input or 7410 Triple 3-input NAND Gates
                                                                                                                                                                                                                              • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                                • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                                                • Connecting wires Switches
                                                                                                                                                                                                                                  • THEORY
                                                                                                                                                                                                                                      • Figure 131 A Mod-5 Asynchronous Up Counter
                                                                                                                                                                                                                                      • Implementation and Observations
                                                                                                                                                                                                                                        • ACTIVITY
                                                                                                                                                                                                                                            • 19-ldst-exp14
                                                                                                                                                                                                                                              • Experimenting with 74194 4-bit bidirectional universal shift register
                                                                                                                                                                                                                                              • 1 Following ICs and their Datasheets
                                                                                                                                                                                                                                              • 74194 4-bit bidirectional universal shift register
                                                                                                                                                                                                                                              • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                                                • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                                                                • Connecting wires Switches
                                                                                                                                                                                                                                                  • THEORY
                                                                                                                                                                                                                                                    • Shift Registers
                                                                                                                                                                                                                                                    • Bidirectional Shift Registers
                                                                                                                                                                                                                                                    • Universal Shift Registers
                                                                                                                                                                                                                                                      • S1
                                                                                                                                                                                                                                                        • Circuit Diagram
                                                                                                                                                                                                                                                        • ACTIVITY
                                                                                                                                                                                                                                                            • 20-ldst-exp15
                                                                                                                                                                                                                                                              • COMPONENTS AND APPARATUS REQUIRED
                                                                                                                                                                                                                                                              • 1 Parallel Port Connectors (DB-25) with Cable
                                                                                                                                                                                                                                                              • 2 Personal Computer with Windows 98 and TurboC Compiler Installed
                                                                                                                                                                                                                                                              • 3 Following ICs and their Datasheets
                                                                                                                                                                                                                                                              • 74245 Octal Bus Transceivers with 3-State Outputs
                                                                                                                                                                                                                                                              • 4 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                                                                • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                                                                                  • Connecting wires Switches
                                                                                                                                                                                                                                                                    • THEORY
                                                                                                                                                                                                                                                                    • 3-State Logic
                                                                                                                                                                                                                                                                      • Serial and Parallel Port Connectors
                                                                                                                                                                                                                                                                      • Parallel Port Connector ndash DB-25
                                                                                                                                                                                                                                                                        • Accessing parallel port through C Language Programming
                                                                                                                                                                                                                                                                            • 21-ldst-appendixA
                                                                                                                                                                                                                                                                            • 22-ldst-appendixB
                                                                                                                                                                                                                                                                              • DEBOUNCING CIRCUITRY FOR MECHANICAL SWITCHES

      THE BITS AND PIECES PART CIRCUIT

      SIGN WHAT IT DOES

      Supplies a voltage which drives an electric current round the circuit from the positive (+) terminal of the battery to its negative (ndash) terminal Voltage is measured in volts (V) and current in amperes (A)

      Allows current to flow through it easily because it is made of copper which is a good electrical conductor Insulators like PVC (polyvinyl chloride - a plastic) and enamel are used to cover connecting wires

      Connects terminal A to terminal B or C ie it is a change-over switch

      Reduces the current in a circuit because of its resistance The colored bands give the resistance in ohms

      When light falls on it its resistance becomes small in the dark its resistance is high

      3

      PART CIRCUIT SIGN

      WHAT IT DOES

      Stores electricity the greater the capaci-tance the more does it store Capacitance values are measured in microfarads shortened to μF or less correctly to mfd On a capacitor 01 μF may be marked as l mfd and 001μF as 10n The greatest voltage it can stand is also shown eg 30V

      Stores electricity values usually larger than 1μF Greatest voltage marked on it Must be connected the correct way round

      Varies the capacitance in a circuit by mov-ing one set of metal plates in or out of a fixed set when the spindle is rotated The sets of plates are separated by sheets of an insulator (also called a dielectric)

      Changes electric currents into sound

      Changes radio waves into electric currents

      Lets current flow in one direction but not in the other When it conducts light is emit-ted Must have a current limiting resistor in series with it The cathode lead is nearest the lsquoflatrsquo and may be shorter than the anode lead (but this is not always so) The arrow on the sign shows the conducting direction

      4

      PART CIRCUIT SIGN

      WHAT IT DOES

      Amplifies small currents into much larger copies Acts as a very fast switch It must be correctly connected with a positive voltage to the collector

      Transistors diodes resistors and capacitors are connected together on a tiny lsquochiprsquo of silicon (sand is mostly silicon oxide) to give any desired circuit eg a multistage amplifier an astable bistable or monostable multivibrator a counter a logic gate for a computer several stages of a TRF (tuned radio frequency) radio

      They must be correctly connected Pin 1 is next to the lsquotagrsquo in the can type and on the dil type it is identified from the lsquonotchrsquo or lsquosmall dotrsquo on the case CMOS lsquochipsrsquo (standing for Complementary Metal Oxide Semiconductors and pronounced lsquosee-mossrsquo) need special care

      PRECAUTIONS WITH CMOS INTEGRATED CIRCUITS Damage occurs if static charges build up on input pins when for example they touch insulating materials (eg clothes plastic pen) in warm dry conditions 1 Keep the IC in the carrier in which it is supplied until it is inserted in the circuit 2 Do not finger the pins or hold them in contact with an insulator 3 Connect all unused inputs of the IC to either the positive or the negative of the battery

      depending on the circuit

      5

      BUILDING CIRCUITS

      The circuit board shown above accepts ICs as well as separate components It has 47 rows of 5 interconnected sockets on each side of a central channel across which dil ICs can be fitted A wire inserted in a socket in a certain row becomes connected to wires in any of the other 4 sockets in that row by a metal strip under the board For example wires in sockets B5 C5 D5 E5 and F5 (shown in color in the diagram) are all joined Metal strips under the board connect the sockets A row of 40 interconnected sockets along the top of the board and a similar row along the bottom act as the positive and negative power supply rails (called lsquobus barsrsquo) Various makes of circuit board are available some with vertically mounting removable panels for supporting controls

      6

      1 To make a connection push about 1 cm of the bare end of a wire (025 to 085 mm diameter) straight into the socket (not at an angle) so that it is gripped by the metal strip under the board Do not use wires that are dirty or have kinked ends Only put one wire in each socket

      Bend leads on resistors etc as shown before inserting them in the board

      2 Bare the ends of connecting wire (PVC-covered tinned copper wire 06 mm diameter) by

      removing the insulation (PVC) either with wire strippers or using a pair of blunt-nosed pliers and a pair of side cutters as shown With practice you should be able to judge just how much the side cutters have to be squeezed and pulled to remove the insulation without cutting the wire

      3 lsquoJoinrsquo wires to the lsquolugsrsquo on the loudspeaker and variable capacitor using a small length of

      2 mm bore plastic sleeving - as shown by 1 and 2

      7

      RESISTOR COLOUR CODE Resistor values are given in ohms (shortened to Ω the Greek letter lsquoomegarsquo) They are marked on the resistor using a color code Three colored bands are painted round the resistor Each color stands for a number To read the color code start at the 1st band it is nearest the end Sometimes it is not clear which is the 1st band because there is a 4th band of gold or silver near the other end These two colors are not used for the 1st band they give the accuracy of the resistor (gold is plusmn 5 and silver plusmn 10) so you should not have too much trouble deciding where to start The 1st band gives the first number the 2nd band gives the second number and the 3rd band tells how many zeroes come after the first two numbers

      8

      INTRODUCTION

      Digital Logic Design is concerned with the interconnection among digital components and modules and the area of Switching Theory that can be identified between circuit design and system formulation Logic design is the base of any computer system as every digital system consists of different ICrsquoS and ICs contain a large number of interconnected digital circuits within a small package MSI devices provide digital function while LSI device cover a complete computer modules These circuitries are widely used in digital system like digital voltmeter frequency meter calculating machines telephone-switching system etc In this Practical Workbook laboratory sessions based on both combinational and sequential logic are covered First laboratory session gives an introduction to the basic logic gates and fundamentals of circuit building The second laboratory session covers a CAD software ndash Electronics Workbench (EWB) EWB is excellent simulation software where circuits can be designed and tested before physical implementation Various laboratory sessions of this workbook provide activities and exercises on EWB Next eight laboratory sessions are based on combinational logic Here various MSI circuits like adders converters multiplexers decoders encoders etc are designed Some of these laboratory sessions also include testing of MSI ICs Next four laboratory sessions help in exploring various designs based on sequential logic Here a variety of circuits are designed form the testing of basic flip-flop ICs to registers and different types of counters Last laboratory session demonstrates how digital hardware can be interfaced with a personal computer via parallel port and can be controlled by software All laboratory sessions of this workbook incorporate brief theoretical backgrounds as details may be covered in the respective theory classes Exercises activities are included with almost all the sessions for the students to practice Two appendices are also included in this workbook The first one provides pin diagrams for all the ICs required for the laboratory work provided in this workbook It will help the students in preparing the pin diagrams for the circuits Second appendix discusses a hardware debouncing circuit for mechanical switches as such switches are extensively used for input purpose in logic circuits

      9

      CONTENTS Lab Session No Object Page No

      1 2 3 4 5 6 7 8 9

      10

      11

      12

      13

      14

      15

      To study the logic gates in the following TTL ICs

      7400 Quad 2-input NAND gate 7402 Quad 2-input NOR gate

      7404 Hex inverter 7408 Quad 2-input AND gate 7432 Quad 2-input OR gate

      Also implementing and testing the given circuit on a bread board Working with Electronics Workbench Designing Half and Full Adder Circuits Use of Karnaugh Map (SOP-Expression) method Designing a BCD Adder Designing of a 4 x 1 Multiplexer Experimenting with 74150 IC Designing of a 2 x 4 Decoder 1 x 4 Demultiplexer Experimenting with 74138 IC Designing of a 4 x 2 Priority Encoder Experimenting with 74148 IC Designing an Odd Parity Generator and Checker for a 3-bit Data Driving a seven segment display using 7447 7448 driver IC Experimenting with different modes of JK-FF Designing sequential circuit for the given state diagram using D flip-flop Designing a modulus-5 asynchronous up-counter using JK-FF Experimenting with 74194 4-bit bidirectional universal shift register Experimenting with 74245 octal bus transceivers using parallel port PC interfacing Appendix A ndash Pin Diagrams of the ICs required for the laboratory sessions Appendix B ndash Debouncing circuitry for mechanical switches

      13

      17

      19

      22

      28

      30

      34

      38

      42

      45

      48

      50

      54

      56

      59

      66

      69

      11

      Logic Design amp Switching Theory 1 Lab Session 01 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

      Lab Session 01 OBJECT

      bull To study the logic gates in the following TTL ICs

      i) 7400 Quad 2-input NAND gate ii) 7402 Quad 2-input NOR gate iii) 7404 Hex inverter iv) 7408 Quad 2-input AND gate v) 7432 Quad 2-input OR gate

      bull Implementing and testing the given circuit on a bread board

      COMPONENTS REQUIRED 1 Bread board 2 5 V - power supply 3 Multimeter 4 Logic probe 5 LEDs with resistors 6 Connecting wires 7 Switches (optional) 8 Following ICs and their datasheets

      bull 7408 quad 2 input AND gate bull 7432 quad 2 input OR gate bull 7404 hex inverter bull 7400 quad 2 input NAND gate bull 7402 quad 2 input NOR gate

      THEORY

      Logic Gates

      Logic gates are the fundamental building blocks of digital systems These devices are able to make decisions in the sense that they produce one output level when some combinations of input levels are present and a different output when other combinations are applied hence given the name Logic Gates The two levels produced by digital circuitry are referred to variously as HIGH and LOW TRUE and FALSE ON and OFF or simply 1 and 0 There are only three basic gates AND OR and NOT The other gates are merely combinations of these basic gates Logic gates can be interconnected to perform a variety of logical operations This interconnection of gates to achieve prescribed outcomes is called logic design

      1 The AND Gate ndash An AND gatersquos output is 1 if and only if all its inputs are 1 If A and B are two inputs to an AND gate then output F of the gate is given as F = AB

      2 The OR Gate - An OR gatersquos output is 1 if at least one of its input is 1 If A and B are two inputs to an OR gate then output F of the gate is given as F = A+B

      13

      Logic Design amp Switching Theory 1 Lab Session 01 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering 3 The NOT Gate (Inverter) ndash Its output is 1 when its input is 0 and its output is 0 when

      the input is 1 ie it complements a digital variable If A is the input to a NOT gate then output F of the gate is given as AF =

      4 The NAND Gate ndash Its output is 1 if at least one of its input is 0 This gate performs the same logic as an AND gate followed by an inverter If A and B are two inputs to a NAND gate then output F of the gate is given as BAF =

      5 The NOR Gate - The output of a NOR gate is 1 if and only if all its inputs are 0 This gate performs the same logic function as an OR gate followed by an inverter If A and B are two inputs to a NAND gate then output F of the gate is given as BAF +=

      All the above gates have one output and two or more inputs except the NOT gate which has only one input

      PROCEDURE FOR TESTING THE LOGIC GATES IN GIVEN ICs

      1 Set the power supply to 5V With the help of a multimeter check the voltage at the output knobs of the power supply

      2 Connect wires long enough to reach the breadboard with the two knobs of the power supply Again using multimeter check voltage at the non-connected end of the wires

      3 Insert the 7408 quad 2 input AND gate IC on to the bread board and make supply and ground connections by joining 5V wire to pin 14 and 0V wire to pin 7

      4 Consult ICrsquos internal connection diagram for input and output pins of the first AND gate Connect input pins to logic 0 (0V) and observe the output using LED or logic probe You can also connect switches at the input lines to facilitate toggling between 1 and 0

      5 Try different combinations of logic levels at the two inputs Again observe the output 6 Repeat the last two steps for all other gates of the same IC Record the observations 7 Repeat this procedure for all other ICs

      OBSERVATIONS

      Gate Input A Input B Expected Output Observed Output

      AND

      0 0 0 1 1 0 1 1

      OR

      0 0 0 1 1 0 1 1

      NOT 0 - 1 -

      NAND

      0 0 0 1 1 0 1 1

      14

      Logic Design amp Switching Theory 1 Lab Session 01 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

      NOR

      0 0 0 1 1 0 1 1

      DATA SHEETS

      Figure 11

      15

      Logic Design amp Switching Theory 1 Lab Session 01 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

      16

      GIVEN CIRCUIT

      Figure 12

      PROCEDURE FOR IMPLEMENTATION OF THE GIVEN CIRCUIT 1 Set the power supply 2 Insert ICs on the bread board and make their supply and ground connections 3 As given in the logic diagram make connections using wires and gates in the ICs 4 Apply different combinations at the three inputs and observe the output OBSERVATIONS Logic expression for the given logic diagram __________________________________

      A B C Expected Output Observed Output 0 0 0 0 0 1 0 1 0 0 1 1 1 0 0 1 0 1 1 1 0 1 1 1

      Logic Design amp Switching Theory 1 Lab Session 02 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

      Lab Session 02

      OBJECT

      Working with Electronics Workbench

      ELECTRONICS WORKBENCH - EWB Electronics Workbench is a computer aided design tool that provides you with all the components and instruments necessary to create board-level designs It has complete mixed analog and digital simulation and graphical waveform analysis allowing you to design your circuit and then analyze it using different simulated instruments and analysis options It is fully integrated and interactive thus you can change your circuits quickly allowing fast and repeated what-if analysis Electronics Workbench provides the following kind of components bull Sources parts bin (AC voltage source Vcc source ground battery etc) bull Basic parts bin (resistors capacitors transformers switches etc) bull Diodes parts bin bull Transistors parts bin bull Analog ICs parts bin (op-amps etc) bull Mixed ICs parts bin (ADCs DACs 555 timers etc) bull Digital ICs parts bin (AND OR adders multiplexers etc) bull Indicators parts bin (voltmeter ammeter probe displays etc) bull Controls parts bin (voltage differentiator multiplier etc) bull Instruments parts bin (multimeter oscilloscope function generator etc) bull Miscellaneous parts bin (write data textbox etc)

      o Write data This component allows you to save simulation results as an ASCII file o Text Box Use this to add descriptive text anywhere in a circuit

      ACTIVITY

      Design circuit for the logic expression )( CBDCABAF ++=

      Procedure 1 From Logic Gates Parts Bin Drag and drop the required logic gates on the design

      area Use Component Properties dialog box to customize these gates 2 Connect the terminal of these gates according to the given expression Use additional

      connectors form the Basic Parts Bin if you want to connect more than wire at a single node

      3 Drag and drop a probe from Indicators Parts Bin Use Component Properties dialog box to customize the color and other properties of the probe Connect this probe at the output terminal of the circuit to indicate results

      4 Select four switches form Basic Parts Bin Specify the key that controls the switch by typing its name in the Value tab of the Component Properties dialog box For

      17

      Logic Design amp Switching Theory 1 Lab Session 02 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

      18

      example if you want the switch to close or open when digit lsquo1rsquo is pressed type 1 in the Value tab then click OK Assign different keys to all the switches

      5 Connect the output terminals of these switches to each of the four inputs A B C and D of the circuit

      6 Drag and drop Vcc and Ground form the Sources Parts Bin 7 Connect Vcc terminal to one end and Ground terminal to the other end of all the

      switches 8 Label the circuit properly using text boxes found in the miscellaneous parts bin 9 Run the circuit using the Activate Simulation switch Use the keys you have assigned

      to the switches to toggle them between Vcc and Ground connections thus providing 1 or 0 respectively to the inputs Record the results as indicated by the probe for all possible combinations of 1s and 0s at the inputs

      EWB Circuit

      Figure 21

      Observations

      A B C D Expected Output Observed Output 0 0 0 0 0 0 0 1 0 0 1 0 0 0 1 1 0 1 0 0 0 1 0 1 0 1 1 0 0 1 1 1 1 0 0 0 1 0 0 1 1 0 1 0 1 0 1 1 1 1 0 0 1 1 0 1 1 1 1 0 1 1 1 1

      Logic Design amp Switching Theory 1 Lab Session 03 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

      Lab Session 03

      OBJECT

      Designing Half and Full Adder Circuits COMPONENTS AND APPARATUS REQUIRED 1 Following ICs and their Datasheets

      bull 7408 Quad 2-input AND Gate bull 7432 Quad 2-input OR Gate bull 7486 Quad 2-input XOR Gate

      2 Digital Trainer DT-01 or the following components Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches

      THEORY Half Adder A combination circuit that performs the addition of two bits without accounting for the previous carry is called half adder It needs two binary inputs and two binary outputs The input variables designate the augend and addend bits The output variables produce the sum and carry The simplified sum of product expressions for a half adder are

      yxyxyxS oplus=+= yxC =

      Figure 31 Circuit diagram for Half Adder

      19

      Logic Design amp Switching Theory 1 Lab Session 03 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

      bles produce the sum and carry The simplified sum of product expressions for a half adder are

      Full Adder

      A combinational circuit that performs the addition of three input bits It consist of three inputs and two outputs Two of the input variables represent the two significant bits to be added The third input represents the carry from the previous lower significant position The output varia

      zyxzyxzyxzyxzyxS oplusoplus=+++= yxzyxzyzxxyC )( +oplus=++=

      Figure 32 Circuit diagram for Full Adder

      efer to laboratory session 01 for procedure) and record the observations in the following ta

      alf Adde ull Adder Inputs u

      IMPLEMENTATION AND OBSERVATIONS

      Implement the half adder and full adder circuits on a bread board (prepare the pin diagram (use appendix A) and r

      bles H r F

      Inputs Outputs Outp ts x y Carry Su Carry Sum m x y z 0 0 0 0 0 0 1 0 0 1 1 0 0 1 0 1 1 0 1 1 1 0 0 1 0 1 1 1 0 1 1 1

      20

      Logic Design amp Switching Theory 1 Lab Session 03 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

      at of your designed circuit Attach hardcopy of the output form electronic workbench

      at of your designed circuit Attach hardcopy of the output form lectronic workbench here

      ACTIVITY

      1 Simulate half adder circuit using Electronics Workbench Compare the results of simulation with thhere

      2 Design a full subtractor circuit and simulate it using Electronics Workbench Compare the results of simulation with the

      21

      Logic Design amp Switching Theory 1 Lab Session 04 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

      Lab Session 04 OBJECT

      Use of Karnaugh Map (SOP-Expression) method GIVEN LOGIC EXPRESSION

      F (A B C D) = sum ( 0 1 2 4 5 6 8 9 12 13 14 ) COMPONENTS AND APPARATUS REQUIRED 1 Digital ICs and their Datasheets

      bull 7408 Quad 2-input AND Gate bull 7432 Quad 2-input OR Gate bull 7404 Hex Inverter

      2 Digital Trainer DT-01 or the following components Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches PROCEDURE 1 Use Karnaugh map to reduce the given function 2 Draw the circuit diagram for the obtained reduced function 3 Implement the reduced circuit using digital ICs on a bread board (prepare the pin

      diagram (use appendix A) and refer to laboratory session 01 for procedure) and record the observations

      REDUCTION OF LOGIC EXPRESSION USING KARNAUGH MAP F

      CD

      AB DC

      DC DC

      DC

      BA0 1 3 2

      BA4 5 7 6

      BA12 13 15 14

      BA8 9 11 10

      Reduced form of the given logic expression is __________________________________

      22

      Logic Design amp Switching Theory 1 Lab Session 04 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

      LOGIC DIAGRAM (REDUCED FORM) OBSERVATIONS

      A B C D Output 0 0 0 0 0 0 0 1 0 0 1 0 0 0 1 1 0 1 0 0 0 1 0 1 0 1 1 0 0 1 1 1 1 0 0 0 1 0 0 1 1 0 1 0 1 0 1 1 1 1 0 0 1 1 0 1 1 1 1 0 1 1 1 1

      RESULT The reduced form (SOP Expression) of the given logic function is

      ____________________________________________________________

      The observation table reflects the given logic function

      23

      Logic Design amp Switching Theory 1 Lab Session 04 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

      ACTIVITY 1 Using Electronics Workbench derive a truth table and logic circuit for the following logic expression

      BAAF +=

      Procedure 1 From the Instruments Parts Bin drag and drop Logic Converter on the design area 2 Double click the Logic Converter to reveal Logic Converter dialog box This dialog

      box shows various conversion options between truth table logic expression and logic circuit

      3 Enter the given logic expression in the edit box found at the end of the dialog box Use lsquo to represent invert of a variable For example A is written as Arsquo

      4 Click the Boolean Expression to Truth Table button The truth table appears in the logic converters display

      5 Now click the Boolean Expression to Circuit button This creates the logic circuit for the given expression in the design area Label the diagram if needed

      Resulting Logic Circuit For the given expression the final circuit will look like

      Figure 41

      24

      Logic Design amp Switching Theory 1 Lab Session 04 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

      ACTIVITY 2

      Using Electronics Workbench find a simplified logic expression and circuit for the following truth table

      A B C Output 0 0 0 1 0 0 1 1 0 1 0 0 0 1 1 1 1 0 0 0 1 0 1 0 1 1 0 0 1 1 1 1

      Procedure 1 Click three input channels from A to H across the top of the logic converter The

      display area below the terminals fills up with the necessary combinations of ones and zeros to fulfill the input conditions The values in the output column on the right are initially set to 0

      2 Edit the output column to specify the desired output for each input condition To change an output value select it and type a new value 1 0 or x An x indicates a donrsquot care condition

      3 To convert this truth table to a Boolean expression click the Truth Table to Boolean Expression button The Boolean expression will be displayed at the bottom of the logic converter

      4 Simplify the expression by clicking the Simplify button 5 Now click the Boolean Expression to Circuit button This creates the logic circuit for

      the given expression in the design area Resulting Logic Circuit For the given truth table the final simplified circuit will look like

      Figure 42

      25

      Logic Design amp Switching Theory 1 Lab Session 04 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

      ACTIVITY 3

      Using Electronics Workbench find the logic expression and truth table for the following logic circuit

      Figure 43

      Procedure 1 Attach the input terminals of the logic converter to up to four input points in the

      circuit 2 Connect the single output of the circuit to the output terminal on the logic converter

      icon 3 Click the Circuit to Truth Table button The truth table appears in the logic

      converters display 4 To convert this truth table to a Boolean expression click the Truth Table to Boolean

      Expression button The Boolean expression will be displayed at the bottom of the logic converter

      Resulting Logic Expression Logic Expression for the given circuit is found to be _____________________________

      26

      Logic Design amp Switching Theory 1 Lab Session 04 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

      27

      For activities 1 2 and 3 attach hardcopy of the output (truth table logic expression and logic circuit) form electronic workbench here

      Logic Design amp Switching Theory 1 Lab Session 05 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

      Lab Session 05 Lab Session 05 OBJECT OBJECT

      Designing a BCD Adder Designing a BCD Adder COMPONENTS AND APPARATUS REQUIRED COMPONENTS AND APPARATUS REQUIRED

      1 Following ICs and their Datasheets 1 Following ICs and their Datasheets bull 7408 Quad 2-input AND Gate bull 7408 Quad 2-input AND Gate bull 7432 Quad 2-input OR Gate bull 7432 Quad 2-input OR Gate bull 7483 4-bit Binary Adder bull 7483 4-bit Binary Adder

      2 Digital Trainer DT-01 or the following components 2 Digital Trainer DT-01 or the following components Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors (100 Ω) Connecting wires Switches (100 Ω) Connecting wires Switches

      THEORY THEORY

      A BCD Adder is a combinational circuit that adds two BCD digits in parallel and produces a sum digit also in BCD A BCD Adder is a combinational circuit that adds two BCD digits in parallel and produces a sum digit also in BCD

      A4 A3 A2 A1 B4 B3 B2 B1

      7483-BCD ADDER

      Cout (C4 ) Z4 Z3 Z2 Z1 Cin(C0)

      A4 A3 A2 A1 B4 B3 B2 B1

      7483-BCD ADDER

      Cout

      (C4 ) Z4 Z3 Z2 Z1 Cin(C0)

      Figure 51 BCD Adder Circuit

      28

      Logic Design amp Switching Theory 1 Lab Session 05 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

      29

      A BCD adder must include the correction logic in its internal construction The two BCD digits together with the input carry are first added using a 4-bit binary adder to produce the binary sum If no output carry is generated and the binary sum is less than or equal to 9 then the corresponding BCD sum is identical and therefore no conversion is needed When the output carry is equal to 1 or the binary sum is greater than 9 then a binary 0110 is added to the binary sum through another 4-bit binary adder If Cout is the carry output and Z4Z3Z2Z1 is the binary sum form the first 4-bit binary adder then the following equation indicates the condition when a binary 0110 is to be added

      C = COUT + Z4Z2 + Z4Z3 IMPLEMENTATION AND OBSERVATIONS Implement the BCD adder circuit according to figure 51 on a bread board (prepare the pin diagram (use appendix A) and refer to laboratory session 01 for procedure) A BCD adder has nine input bits (two BCD digits and a carry bit) which can result in a total of 512 combinations of which 312 inputs are donrsquot care Since it is a very lengthy procedure to record results for 200 valid input combinations therefore for simplicity just record results for any eight combinations in the following table

      Input Carry

      BCD Digit 1 BCD Digit 2 Carry Output

      BCD Sum A4 A3 A2 A1 B4 B3 B2 B1 Z4 Z3 Z2 Z1

      Logic Design amp Switching Theory 1 lab Session 06 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

      Lab Session 06

      OBJECT

      bull Designing of a 4 x 1 Multiplexer bull Experimenting with 74150 IC

      COMPONENTS AND APPARATUS REQUIRED 1 Following ICs and their Datasheets

      bull 7408 Quad 2-input AND Gates or 7411 Triple 3-input AND Gates bull 7432 Quad 2-input OR Gates bull 7404 Hex Inverter bull 74150 16 x 1 MUX

      2 Digital Trainer DT-01 or the following components Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches THEORY

      Multiplexers A digital data Multiplexer (MUX) is a combinational circuit having several data inputs and a single output A set of data-select inputs is used to control which of the data inputs is routed to the single output A multiplexer is also called a data selector because of this ability to select which data input is connected o the output Normally there are 2n input lines and n selection lines whose bit combination determine which input is selected DESIGN OF A 4 x 1 MULTIPLEXER A 4 x 1 multiplexer is capable of selecting one of four data inputs (see figure 61) The 2-bit binary number at the data select inputs S1 and S0 specifies which of the four data inputs is to be routed to the output Since there are two data select inputs therefore they can select 22 = 4 different data inputs lines

      S0 S1 D0 D1

      D2 D3

      Data-select Inputs Output

      Data Inputs

      Figure 61 Block Diagram of a 4 x1 Multiplexer

      30

      Logic Design amp Switching Theory 1 lab Session 06 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

      Figure 62 Circuit Diagram for 4 x 1 Multiplexer

      Implementation and Observations

      Implement the 4 x 1 Multiplexer circuit (figure 62) on a bread board (prepare the pin diagram (use appendix A) and refer to laboratory session 01 for implementation procedure) and record the observations in the following table For each data select combination specify the switch number as well as the binary value present on that selected switch

      S1 S0 Output 0 0 0 1 1 0 1 1

      TESTING OF 74150 - 16 x 1 MUX

      The 74150 IC has sixteen data inputs and four data-selection lines Function of various pins of this IC is described below

      bull E0 through E15 Data input lines

      31

      Logic Design amp Switching Theory 1 lab Session 06 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering bull A B C D Data select lines with D being the MSB bull W Active low output line bull Grsquo Active low enable line bull VCC and GND Supply connections lines

      Circuit Diagram

      Figure 63 Pin connections of 74150 for selecting E0

      Testing Procedure

      bull Make connections as shown in the circuit diagram bull Apply different data (1 or 0) at data inputs that are labeled as E0 to E15 Only

      connection for E0 is shown is the figure for simplicity bull Select the data input E0 with the help of data selectors A B C and D bull Observe the output which shows the complement of the data from E0 bull Select all the sixteen data inputs one by one and record your observations in the

      following table

      32

      Logic Design amp Switching Theory 1 lab Session 06 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

      33

      Observations

      Grsquo D C B A W Grsquo D C B A W 0 0 0 0 0 0 1 0 0 0 0 0 0 0 1 0 1 0 0 1 0 0 0 1 0 0 1 0 1 0 0 0 0 1 1 0 1 0 1 1 0 0 1 0 0 0 1 1 0 0 0 0 1 0 1 0 1 1 0 1 0 0 1 1 0 0 1 1 1 0 0 0 1 1 1 0 1 1 1 1

      ACTIVITY 1 Consider 4x1 Multiplexer Draw the output wave-form for the following data inputs

      (E0 E1 E2 E3) and select lines A B (B being the MSB) Output is W

      E3 E2 E1 E0 A B

      W

      2 Using the 4 x 1 MUX designed in this laboratory session implement the following logical function F (A B C) = Σ (0147)

      Show your working and input connections in the following block diagram according to the circuit you have implemented

      4 x 1 MUX

      S0 S1

      Output D0

      D1

      D2

      D3

      Logic Design amp Switching Theory 1 Lab Session 07 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

      Lab Session 07

      OBJECT

      bull Designing of a 2 x 4 Decoder 1 x 4 Demultiplexer bull Experimenting with 74138 IC

      COMPONENTS AND APPARATUS REQUIRED 1 Following ICs and their Datasheets

      bull 7408 Quad 2-input or 7411 Triple 3-input AND Gates bull 7404 Hex Inverter bull 74138 3 x 8 Decoder

      2 Digital Trainer DT-01 or the following components Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches THEORY

      Decoder A Decoder is a combinational circuit that converts binary information form n input lines to a maximum of 2n unique output lines In practical applications decoders are often used for selecting one of several devices

      Demultiplexer A decoder with an enable input can function as a Demultiplexer A Demultiplexer (DMUX) id a circuit that receives information on a single line and transmits this information on one of 2n possible output lines The selection of a specific output line is controlled by the bit values of n selection lines DESIGN OF A 2 x 4 DECODER 1 x 4 DEMULTIPLEXER A 2 x 4 decoder is capable of selecting one of four output lines (see figure 71 (a)) The 2-bit binary number at the data inputs S1 and S0 specifies which of the four data inputs is to be selected If we add an enable pin and use it as an input line then this decoder can be converted to a 1 x 4 Demultiplexer where S1 and S0 will select a line to which data input is to be routed (see figure 71 (b))

      Select S0 S0 Inputs

      S1 D0 D1

      D2

      D3

      Enable (a) Block Diagram of a 2 x 4 Decoder

      Figure 71

      S1 D0 D1

      D2

      D3

      Inputs

      Data Input (b) Block Diagram of a 1 x 4 Demulptiplexer

      34

      Logic Design amp Switching Theory 1 Lab Session 07 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

      Figure 72 Circuit Diagram for 2 x 4 Decoder 1 x 4 Demultiplexer

      Implementation and Observations Implement the 2 x 4 Decoder 1 x 4 Demultiplexer circuit (figure 72) on a bread board (prepare the pin diagram (use appendix A) and refer to laboratory session 01 for implementation procedure) and record the observations in the following table

      Enable Data Input S1 S0 D0 D1 D2 D3

      0 0 0 0 0 1 0 1 0 0 1 1 1 0 0 1 0 1 1 1 0 1 1 1

      TESTING OF 74138 3 x 8 Decoder The 74138 IC has three inputs and eight output lines It has three enable inputs and for the IC to function all three inputs need to be enabled Function of various pins of this IC is described below

      35

      Logic Design amp Switching Theory 1 Lab Session 07 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

      bull Y0 through Y7 Active low data outputs bull A B C Input select lines with C being the MSB bull G1 Active high enable Input bull G2Arsquo and G2Brsquo Active low enable Inputs bull VCC and GND Supply connections lines Circuit Diagram

      Figure 73 Pin connections of 74138

      Testing Procedure

      bull Make connections as shown in the circuit diagram bull Apply different combinations of 1s and 0s at data inputs bull Observe the output and record your observations in the following table

      Observations

      C B A Y0 Y1 Y2 Y3 Y4 Y5 Y6 Y7 0 0 0 0 0 1 0 1 0 0 1 1 1 0 0 1 0 1 1 1 0 1 1 1

      36

      Logic Design amp Switching Theory 1 Lab Session 07 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

      37

      ACTIVITY ACTIVITY 1 What will be the binary values at the outputs Y0 through Y7 of 74138 if 1 What will be the binary values at the outputs Y0 through Y7 of 74138 if

      bull All three enable pins are connected to ground bull All three enable pins are connected to ground __________________________________________________________________________________________________________________________________________ __________________________________________________________________________________________________________________________________________ _____________________________________________________________________ _____________________________________________________________________

      bull All three enable pins are connected to VCC bull All three enable pins are connected to VCC _______________________________________________________________________________________________________________________________________________________________________________________________________________

      _______________________________________________________________________________________________________________________________________________________________________________________________________________

      2 Show connections for 74138 in order to use it as a 1 x 8 Demultiplexer 2 Show connections for 74138 in order to use it as a 1 x 8 Demultiplexer

      3 Consider a 2 x 4 Decoder with two enable inputs (one active high - G and one active low ndash Grsquo) Draw the output wave-forms for D0 D1 D2 and D3 if the two select inputs are A and B (B being the MSB) All outputs are active low

      Grsquo

      G

      A B

      D0 D1 D2

      D3

      Logic Design amp Switching Theory 1 Lab Session 08 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

      Lab Session 08 OBJECT

      bull Designing of a 4 x 2 Priority Encoder bull Experimenting with 74148 IC

      COMPONENTS AND APPARATUS REQUIRED

      1 Following ICs and their Datasheets

      bull 7408 Quad 2-input or 7421 Dual 4-input AND Gates bull 7432 Quad 2-input OR Gates bull 7404 Hex Inverter bull 74148 Encoder

      2 Digital Trainer DT-01 or the following components Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches

      THEORY

      Encoder An Encoder is a digital function that produces a reverse operation from that of a decoder An Encoder has 2n (or less) input lines and n output lines The output lines generate the binary code for the 2n input variables Priority Encoder

      A simple encoder may produce an erroneous output if more than one of its inputs is high A Priority Encoder is one that responds to just one input among those that may be simultaneously high in accordance with some priority system The most common priority system is based on the relative magnitudes of the inputs whichever decimal input is largest is the one that is encoded

      DESIGN OF A 4 x 2 Priority Encoder

      The following equations represent the outputs of a 4 x 2 priority encoder 32 DDA +=

      321 DDDB += As can be seen from the equations that input D0 which has a binary code 00 is not used in any equation A binary code 00 at the output indicates two conditions Either D0 is selected or no input is selected In order to differentiate these two conditions we will provide an additional output Z to indicate if at least one of the inputs is a 1 The equation for Z will be

      4321 DDDDZ = If Z is 0 then the binary code 00 at the output indicates that D0 is selected and if Z is 1 then it indicates that no input line is selected

      38

      Logic Design amp Switching Theory 1 Lab Session 08 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

      Figure 81 Circuit Diagram for 4 x 2 Priority Encoder

      it (figure 81) on a bread board (prepare the to laboratory session 01 for implementation

      Implementation a Implement the 4 x 2 Priority Encoder circu

      ram (use appendix A) and refer

      nd Observations

      pin diagprocedure) and record the observations in the following table

      D3 D2 D1 D0 A B 0 0 0 1 0 0 1 x 0 1 x x 1 x x x

      TESTING OF 74148 8 x 3 Octal Priority Encoder

      imal digits There are nine of which three represents

      ing any of the inputs is high

      then it shows that line 0 is selected and if e inputs selected E0 and GS

      cannot be in the same state provided that E1 is enabled

      The 74148 is a priority encoder with active-Low input for dec

      input) and five output linesinputs lines (including an enablethe binary code for the octal digit Function of various pins of this IC is described below

      bull 0 through 7 Active low data inputs representing the octal digits A2 A1 A0 Active low output lines representing the binary code bullbull E1 Active low enable Input bull E0 Active low output indicating none of the inputs is high bull GS Active low output indicatbull VCC and GND Supply connections lines Therefore if GS A2 A1 and A0 are all low

      then it shows that none of thE0 A2 A1 and A0 are all low

      39

      Logic Design amp Switching Theory 1 Lab Session 08 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

      Circuit Diagram

      Figure 82 Pin connections of 74148

      Testing Procedure bull Make connections as sho

      binations of 1s and 0s at data inputs d record your observations in the following table

      GS E0

      wn in the circuit diagram bull Apply different combull Observe the output an Observations

      0 1 2 3 4 5 6 7 A2 A1 A0 1 1 1 1 1 1 1 1 x x x x x x x 0 x x x x x x 0 1 x x x x x 0 1 1 x x x x 0 1 1 1 x x x 0 1 1 1 1 x x 0 1 1 1 1 1 x 0 1 1 1 1 1 1 0 1 1 1 1 1 1 1

      40

      Logic Design amp Switching Theory 1 Lab Session 08 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

      41

      CTIVITY

      Cascade the following two 74148 8 x 3 Priority Encoders to form 16 x 4 Priority

      A 1

      Encoder

      Logic Design amp Switching Theory 1 Lab Session 09 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering `

      Lab Session 09 OBJECT

      Designing an Odd Parity Generator and Checker for a 3-bit Data COMPONENTS AND APPARATUS REQUIRED

      1 Following ICs and their Datasheets

      bull 7486 Quad 2-input Exclusive-OR Gates bull 7404 Hex Inverter

      2 Digital Trainer DT-01 or the following components Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches

      THEORY

      Parity Generator When binary data is transmitted and processed it is ndash as are all electrical signals ndash susceptible to noise that can either alter or distort its contents 1s may be effectively changed to 0s and 0s to 1s To overcome this problem one or more bits are often added to the data as an aid in detecting errors caused by noise The most common of these is a Parity bit that signifies whether the total number of 1s in a code group is odd or even In an Odd Parity system the parity bit is made 0 or 1 as necessary to make the total number 1s odd (counting the parity bit itself) In an Even Parity system the parity bit is chosen to make the total number of 1s even Table 91 shows how parity bits would be added to BCD code group in both systems

      Decimal BCD Value Parity Bit ABCD Odd Parity Even Parity

      0 0000 1 0 1 0001 0 1 2 0010 0 1 3 0011 1 0 4 0100 0 1 5 0101 1 0 6 0110 1 0 7 0111 0 1 8 1000 0 1 9 1001 1 0

      Table 91 Odd and Even Parity in BCD

      When digital data is received a parity checking circuit generates an error signal if the total number of 1s is odd in an even parity system or if it is even in an odd parity system Parity check always detects a single error (one bit change from 0 to 1 or 1 to 0) but may not detect

      42

      Logic Design amp Switching Theory 1 Lab Session 09 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering ` two or more errors Odd parity is used more often than even parity because even parity does not detect a situation where all 0s are created due to short circuit or other fault condition DESIGN OF A 3-BIT ODD PARITY GENERATOR AND CHECKER Let x y and z be the three bits that constitute the message and are the input to the Odd Parity Generator Circuit Since it is an odd parity system the bit P is generated so as to make the total number of 1s odd (including P) The function P can be expressed as follows P = x oplus y Ο z or P = x Ο y oplus z Since the IC available is 7486 which is quad 2input XOR IC therefore we will convert XNOR also to XOR

      P = x oplus y Ο z

      P = ( x oplus y ) Ο z Since for even number of variables ______

      XOR = XNOR Therefore ___________ _________

      P = ( x oplus y ) oplus z = x oplus y oplus z This logical expression can be implemented with two XOR gates and an inverter (see figure 91)

      Figure 91 Circuit Diagram for a 3-bit Parity Generator

      The 3-bit message and the parity bit are transmitted to their destination where they are applied to a Parity Checker Circuit An error occurs during transmission if the parity of the four bits received is even since the binary information transmitted was originally odd The output C of the parity checker should be a 1 when an error occurs ie when the number of 1s in the four inputs is even Therefore the function C can be expressed as

      C = x Ο y Ο z Ο P

      Using the same logic applied for the conversion of the equation of P

      PzyxC oplusoplusoplus= This logical expression can be implemented with three XOR gates and an inverter (see figure 92)

      43

      Logic Design amp Switching Theory 1 Lab Session 09 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering `

      44

      Figure 92 Circuit Diagram for a 3-bit Parity Checker Implementation and Observations Implement the 3-bit Parity Generator and Checker circuits (figure 91 and 92) on a bread board (prepare the pin diagram (use appendix A) and refer to laboratory session 01 for implementation procedure) and record the observations in the following table

      x y z P x y z P C x y z P C 0 0 0 0 0 0 0 1 0 0 0 0 0 1 0 0 0 1 1 0 0 1 0 1 0 0 0 1 0 1 0 1 0 0 1 1 0 0 1 1 1 0 1 1 1 0 0 0 1 0 0 1 1 0 0 1 0 1 0 1 0 1 1 1 0 1 1 1 0 0 1 1 0 1 1 1 0 1 1 1 0 1 1 1 1 1 1 1

      Odd Parity Generation Odd Parity Check ACTIVITY 1 Try using the parity checker of figure 92 as 3-bit parity generator Write the details here

      _____________________________________________________________________________________________________________________________________________________________________________________________________________________ ______________________________________________________________________________________________________________________________________________ _______________________________________________________________________ ______________________________________________________________________________________________________________________________________________

      Logic Design amp Switching Theory 1 Lab Session 10 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

      Lab Session 10 OBJECT

      Driving a seven segment display using 7447 7448 driver IC COMPONENTS AND APPARATUS REQUIRED

      1 Following ICs and their Datasheets

      bull Seven Segment Displays (Common Anode Common Cathode) bull 7447 7448 BCD to Seven Segment Driver

      2 Digital Trainer DT-01 or the following components Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches

      THEORY Seven Segment Displays A Seven Segment Display consists of seven light-emitting segments The segments are designated by letters a through g (see figure 101) By illuminating various combinations of segments the numerals 0 through 9 can be displayed Seven Segment Displays are commonly constructed with light-emitting diodes (LEDs) and with liquid-crystal displays (LCDs) LEDs generally provide greater illumination levels but require much greater power than LCDs An LED display can be a common-anode type or common cathode type In common anode type a high voltage is applied at the common terminal of the display and low voltage is applied at a segmentrsquos terminal for illumination In the common-cathode type a low voltage is applied at the common terminal of the display and high voltage is applied at a segmentrsquos terminal for illumination

      Figure 101 Seven Segment Display

      a f b g

      e c d

      7447 7448 BCD to Seven Segment Driver 7447 7448 IC is particularly used to drive Seven Segment Its input is a BCD number and output drives a seven segment display 7447 is used to drive common-anode displays whereas 7448 is used to drive common cathode displays 7447 7448 is a 16 pin IC Function of various pins of these ICs is described below

      bull A B C D Inputs representing BCD digits (D being the MSB)

      45

      Logic Design amp Switching Theory 1 Lab Session 10 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering bull OA through OG Outputs to drive segments a through g of the display (Active low

      in 7447 and active high in 7448) bull RBI Ripple Blanking Input Turns off all the segments if kept low provided that LT

      is kept high and all other inputs (A B C D BI) are kept low Should be kept high otherwise

      bull BI RBO Wire-AND logic serving as a Blanking Input and or Ripple Blanking Output

      o BI Turns off all the segments if low o RBO Goes to a low level (response condition) along with other outputs when

      RBI and inputs A B C and D are low with LT input at high level bull LT Lamp Test input Tests whether all segments are working or not Illuminates all

      segments if kept low provided that BI is kept high Should be kept high otherwise bull VCC and GND Supply connections lines CIRCUIT DIAGRAM

      Figure 102 Circuit diagram for 7447driving a common-anode display

      IMPLEMENTATION AND OBSERVATIONS

      bull Make connections as shown in the circuit diagram (refer to laboratory session 01 for implementation procedure)

      bull Apply different combinations of 1s and 0s at data inputs bull Observe the output and record your observations in the following table

      46

      Logic Design amp Switching Theory 1 Lab Session 10 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

      47

      Decimal Digit

      BCD Inputs Seven Segment Outputs D C B A a b c d e f g

      0 0 0 0 0 1 0 0 0 1 2 0 0 1 0 3 0 0 1 1 4 0 1 0 0 5 0 1 0 1 6 0 1 1 0 7 0 1 1 1 8 1 0 0 0 9 1 0 0 1

      ACTIVITY 1 Perform the Lamp Test for the designed circuit and write your observations

      ____________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________

      2 How can you use 7447 IC to drive a common-cathode display

      ____________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________

      3 What symbols appear in the seven segment display if inputs DCBA are

      DCBA Symbol

      1010

      1011

      1100

      1101

      1110

      1111

      Logic Design amp Switching Theory 1 Lab Session 11 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

      48

      Lab Session 11 OBJECT

      Testing different modes of JK-FF COMPONENTS AND APPARATUS REQUIRED 1 Following ICs and their Datasheets

      bull 7473 7476 JK Flip-Flop 2 Digital Trainer DT-01 or the following components

      Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches

      THEORY

      Flip-Flop A flip-flop circuit can maintain a binary state indefinitely (as long as the power is delivered to the circuit) until directed by an input signal to switch states The major differences among various types of flip-flops are in the number of inputs they possess and in the manner in which the inputs affect the binary state

      JK Flip-Flop JK flip flop is an edge triggered device A typical JK flip flop has three inputs J K and a clock input The flip-flop can be either positive or negative edge triggered The output Q is available in complemented form as well Beside the usual inputs and output most of the flip-flop IC also possess two asynchronous inputs namely Preset and Clear These inputs are usually active low If used Preset and Clear inputs keep the flip-flop in set and reset state respectively irrespective of the other inputs Both of these inputs cannot be used simultaneously otherwise they will bring the flip-flop in unstable state

      Figure 111 Symbol for JK flip-flop

      (a) positive-edge triggering (b) active low Preset (PR) and Clear (CLR) with positive-edge triggering

      (c) active low Preset (PR) and Clear (CLR) with negative-edge triggering

      Logic Design amp Switching Theory 1 Lab Session 11 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

      49

      TESTING OF 7473 7476 DUAL JK FLIP-FLOP

      Both the ICs 7473 and 7476 are similar in functionality except for one difference The flip-flops in 7473 have only one type of active low asynchronous input which is the Clear input whereas the flip-flops in 7476 have both Preset and Clear inputs Both these ICs have negative edge triggered flip-flops

      Circuit Diagram

      Figure 112 Pin connections of 7476

      Testing Procedure

      bull Make connections as shown in the circuit diagram (figure 112) bull Apply different combinations of 1s and 0s at J and K inputs bull Observe the output and record your observations in the following table

      Observations

      J

      K Q

      0 0 0 1 1 0 1 1

      ACTIVITY

      1 Observe the output Q of JK flip-flop if the clock input is connected to VCC or GND instead of a clock source Write your observations here __________________________________________________________________________________________________________________________________________ _______________________________________________________________________________________________________________________________________________________________________________________________________________

      Logic Design amp Switching Theory 1 Lab Session 12 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

      50

      Lab Session 12 OBJECT

      Designing sequential circuit for the given state diagram using D flip-flop GIVEN STATE DIAGRAM

      00

      11

      Figure 121 State Diagram COMPONENTS AND APPARATUS REQUIRED 1 Following ICs and their Datasheets

      bull 7474 D Flip-Flop bull ICs of basic gates (AND OR NOT XOR etc) as required

      2 Digital Trainer DT-01 or the following components Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches

      THEORY

      Sequential Circuits In Sequential Circuits the output not only depends on the present inputs but also on previous states of the circuit These circuits use memory elements (latches flip-flops) and the binary information stored in the memory elements at any given time defines the state of the sequential circuit Analysis of a Sequential Circuit The behavior of a sequential circuit is determined from the inputs the outputs and the states of its flip-flops Both the outputs and next state are a function of the inputs and the

      10

      01

      00 11 10

      00

      00 11 10 00

      Logic Design amp Switching Theory 1 Lab Session 12 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

      51

      present state The analysis of a sequential circuit form a state diagram comprises of the following bull Selecting a particular flip-flop to design the circuit bull Obtaining state table from the state diagram bull Finding input equations for the selected flip-flop bull Finding state equations (not required for the construction of circuit) bull Implementing the circuit using selected flip-flops and their input equations ANALYZING THE GIVEN STATE DIAGRAM D Flip-Flop D flip-flop is also called transparent flip-flop as it simply transfers the input data to the output For our design we require the graphical symbol and excitation table of D flip-flop (see figure 122)

      Qt Qt+1 T 0 0 0 0 1 1 1 0 0 1 1 1

      (b) Excitation table of D Flip-Flop

      (a) Graphical Symbol

      Figure 122 Characteristic equation of D flip-flop is Q(t+1) = D State Table The given state diagram has four states so we will need two D flip-flops (FF-0 FF-1) Form state table form the given state diagram and record the results in the following table

      Present State Input Next State Output Input to FF-0 D0

      Input to FF-1 D1 Q1t Q0t x Q1(t+1) Q0(t+1) z

      Logic Design amp Switching Theory 1 Lab Session 12 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

      52

      Input Equations Using Karnaugh map the input equations D0 and D1 for the two flip-flops can be found

      D0 D1 Q0x

      Q1

      _ _ Q0x

      _ Q0x

      Q0x

      _ Q0x

      Q0x

      Q1

      _ _ Q0x

      _ Q0x

      Q0x

      _ Q0x

      _ Q1

      _ Q1

      Q1

      Q1

      D0 = _________________ D1 = _________________

      State Equations Using the characteristic equation of D flip-flop we can find the state equations Q0(t+1) and Q1(t+1) for the to flip flops Q0(t+1) = _______________________ Q1(t+1) = _______________________ _______________________ _______________________ _______________________ _______________________ Circuit Diagram

      Logic Design amp Switching Theory 1 Lab Session 12 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

      53

      Implementation Procedure and Observations

      1 Implement the circuit using digital ICs on a bread board (prepare the pin diagram (use appendix A) and refer to laboratory session 01 for procedure)

      2 Make the clear inputs of the flip-flops low (to clear the flip-flops) The flip-flops will remain in clear state as long as the clear inputs are connected to low level

      3 Connect output Q0 and the clock pulse to an oscilloscope 4 Apply 0 to the input x 5 Now make the clear inputs to high 6 Observe the waveform for the first 5 clock pulses and record it 7 Repeat steps 2 to 6 keeping x=1 in step 4 this time 8 Repeat steps 2 to 7 this time connecting Q1 instead of Q0 to the oscilloscope in step

      3 Record your observations (Keep frequency of the clock pulse low (eg1Hz) so that the output waveforms can be observed easily)

      1 2 3 4 5 Clock Pulse

      Output Waveform for Q0 when x=0

      Output Waveform for Q0 when x=1

      Output Waveform for Q1 when x=0

      Output Waveform for Q1 when x=1

      Logic Design amp Switching Theory 1 Lab Session 13 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

      Lab Session 13 OBJECT

      Designing a modulo-5 asynchronous up-counter using JK-FF COMPONENTS AND APPARATUS REQUIRED

      1 Following ICs and their Datasheets

      bull 7400 Quad 2-input or 7410 Triple 3-input NAND Gates bull 7476 7473 JK Flip-Flop

      2 Digital Trainer DT-01 or the following components Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches

      THEORY

      Digital Counters A digital counter is a set of flip-flops whose states change in response to pulses applied at the input to the counter The flip-flops are interconnected so that their combined state at any time is the binary equivalent of the total number of pulses that have occurred up to that time Every counter resets after a certain number of clock pulses Thus as it name implies a counter is used to count pulses An n stage counter can count up to a maximum of 2n states n is equal to the number of flip-flops required for the construction of counter

      Modulus Counters The number of input pulses that causes a counter to reset to its initial count is called the modulus of the counter Thus the modulus equals to total number of distinct states (counts) including zero that a counter can store A binary counter with n stages is a modulo-2n (or mod-2n) counter The largest count a mod-N counter can achieve is N-1 ie a mod-N counter never reaches the binary number equal to its modulus N is always equal to or less than 2n Counters can be classified as bull Synchronous Counters which are clock driven All the flip-flops are driven by a

      single clock bull Asynchronous Counters which are event driven Clock input is given to the first

      flip-flop only Rest of the flip-flops are driven by their preceding flip-flops

      DESIGN OF A MOD-5 ASYNCHRONOUS UP COUNTER The number of flip-flops required to construct a mod-5 counter is 3 because 5 should be less than or equal to 2n This counter will count from 0 to 4 a total of 5 distinct states Since a 3-stage counter can count up to 8 states at maximum a NAND gate is used to reset it after 5 clock pulses Figure 131 shows the logic diagram

      54

      Logic Design amp Switching Theory 1 Lab Session 13 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

      55

      Figure 131 A Mod-5 Asynchronous Up Counter

      Implementation and Observations

      Implement the mod-5 counter circuit (figure 131) on a bread board (prepare the pin diagram (use appendix A) and refer to laboratory session 01 for implementation procedure) and record the observations in the following table

      Clock Pulse Q2 Q1 Q0

      0 1 2 3 4 5 6 7

      ACTIVITY

      Draw the timing diagram for mod-5 counter designed in this laboratory session

      Logic Design amp Switching Theory 1 Lab Session 14 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

      Lab Session 14 OBJECT

      Experimenting with 74194 4-bit bidirectional universal shift register COMPONENTS AND APPARATUS REQUIRED

      1 Following ICs and their Datasheets

      bull 74194 4-bit bidirectional universal shift register 2 Digital Trainer DT-01 or the following components

      Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches

      THEORY

      Shift Registers

      A Register is a set of flip-flops used to store binary data A register which is capable of shifting its binary information either to the right or left is called a shift register The logical configuration of a register consists of a chain of flip-flops connected in cascade with the output of one flip-flop connected to the input of next flip-flop All flip-flops receive a common clock pulse which causes the shift from one stage to the next

      Bidirectional Shift Registers A bi-directional shift register is one whose bits can be shifted from left to right or from right to left

      Universal Shift Registers A universal shift register is a bi-directional register whose input can be in either serial or parallel form and whose output can be in either serial or parallel form

      74194 4-BIT BIDIRECTIONAL UNIVERSAL SHIFT REGISTER

      The 74194 register provides parallel as well as serial loading in both directions Function of various pins of this IC is described below

      bull A B C and D Active high inputs for parallel loading bull QA QB QC and QD Active high outputs bull S0 and S1 Active high mode control inputs The following table shows combinations

      of S1 and S0 to enable various modes

      S1 S0 Clock Action 0 0 x No change 0 1 uarr Shift right 1 0 uarr Shift left 1 1 uarr Parallel load

      uarr shows the rising edge of the clock pulse

      56

      Logic Design amp Switching Theory 1 Lab Session 14 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering bull SR Active high serial input for right shifting bull SL Active high serial input for left shifting bull CLR Active low input Clears all the flip-flops of the register if set to 0 should be

      kept high otherwise bull CLK Clock input bull VCC and GND Supply connections lines Thus A B C and D are inputs for parallel loading whereas SR and SL are inputs for serial loading with right or left shifting respectively S1 and S0 are used to select the loading mode Circuit Diagram

      Figure 141 Pin connections of 74194 Testing Procedure

      bull Make connections as shown in the circuit diagram bull Observe the output for the input combinations given in the following table

      57

      Logic Design amp Switching Theory 1 Lab Session 14 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

      58

      Observations

      S1 S0 SL SR A B C D QA QB QC QD 0 0 0 1 0 0 0 0 0 1 1 0 0 0 0 1 1 0 0 0 0 0 1 0 1 1 0 0 0 0 1 1 0 0 1 1 0 1 0 0 0 1 1 1 0 1 0 1 1 0 1 0 0 1 1 0 1 1 1 0 0 1 1 1 1 1 0 0 1 1 1 1

      ACTIVITY 1 Show connections of 74194 to convert it into a ring counter with right shifting

      Logic Design amp Switching Theory 1 Lab Session 15 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

      Lab Session 15

      OBJECT

      Experimenting with 74245 octal bus transceivers using parallel port PC interfacing COMPONENTS AND APPARATUS REQUIRED 1 Parallel Port Connectors (DB-25) with Cable 2 Personal Computer with Windows 98 and TurboC Compiler Installed 3 Following ICs and their Datasheets

      bull 74245 Octal Bus Transceivers with 3-State Outputs 4 Digital Trainer DT-01 or the following components

      Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches

      THEORY

      3-State Logic Sometimes it is necessary to isolate one part of circuit from the other part For this purpose some TTL ICs are designed with 3-state logic Such devices have three possible output states high low and high impedance The device can be put into high impedance state by a control signal applied to an appropriate pin When such a device is in high impedance state there is very high impedance at its output effectively isolating the device from whatever circuitry the output normally drives 74245 Octal Bus Transceivers A bus is any conducting path or set of paths having electrical connections to one or more devices 74245 octal bus transceivers are mainly used to control connectivity between two devices or circuits It also provides direction control for signal flow Function of various pin of this IC is given below

      bull A1 through A8 Bus A bull B1 through B8 Bus B bull G΄ Active low enable input When high sets all the bus pins to high impedance state bull DIR Direction control for signal flow When set to high logic level transfers bus A

      data to B bus When set to low logic level transfers bus B data to A bus bull VCC and GND Supply connections lines Serial and Parallel Port Connectors A Parallel Port can consist of only 25 pin port adapter called a DB-25 and a serial port can consist of either a 25 pin port adapter called a DB-25 or 9 pin adapter called a DB-9 port adapter Whether the port is a 9 pin or 25 pin it can accomplish all of the same tasks that serial port communications have been designed for

      59

      Logic Design amp Switching Theory 1 Lab Session 15 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

      60

      Each adapter can be a male type connector with pins or a female type adapter with tiny holes Generally a PRINTER port (called LPT1) on the back of a computer is female type adapter and we need to use MALE DB-25 pin cable on it for PRINTER connection or for parallel LAPLINK cable And a COM port on the back of a computer is male for the serial ports but it may not necessarily be Parallel Port Connector ndash DB-25 The DB-25 connector (named for its B-size D-shaped shell and 25 pins) is practically ubiquitous in the electronics industry The DB-25 connector is used for a variety of purposes Two common applications are RS-232EIA-232 (serial) connections and the parallel printer interface on the IBM PC The DB-25 connector is also used for SCSI connections Normally the parallel port is used for output to a printer or other device It sends data 8-bits or one byte at a time in parallel The other lines available on the DB-25 connector are a combination of status lines control lines and ground lines The status and control lines are used for handshaking commands and feedback when we are talking to a printer

      Figure 152 DB-25 Female Figure 151 DB-25 Male

      Figure 153 Pin Layout for DB-25 As can be seen form figure 153 there are four types of pins in this connector

      bull Data pins (8 pins - D0 to D7) Active high bidirectional lines

      Logic Design amp Switching Theory 1 Lab Session 15 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering bull Control pins (4 pins - C0 to C3) C0 C1 and C3 are active low whereas C2 is active

      high These lines also are bidirectional bull Status pins (5 pins ndash S3 to S7) Only S7 is active low rest are active high input lines bull Ground pins (8 pins) Used as a reference signal for the low (below 05 volts) charge

      Parallel Port Addresses A DB-25 connector at a parallel port has three address one for each kind of pins register data status and control The first or base address generally refers to data register Second address is for status register and the third one is for control register In Windows 98 the base address is usually found to be 278H 378H or 3BCH Now if 378H is the base address then it refers to the data register whereas addresses for status and control register are respectively 379H and 37AH For Windows 98 the base address can be found as follows 1 On your Desktop right-click on My Computer and select Properties 2 Click on the Device Manager tab and find LPT1 under Plug and Play BIOS 3 After selecting LPT1 click the Properties button 4 Next select the Resources tab and the address should then appear next to InputOutput

      Range Accessing parallel port through C Language Programming There are multiple functions in C Language for accessing external ports The most commonly used are listed below

      bull unsigned char inportb(int portid) inportb reads a byte from a hardware port

      bull int inport(int portid) reads a word from a hardware port

      bull void outportb(int portid unsigned char value) outputs a byte to a hardware port

      bull void outport(int portid int value) outputs a word to a hardware port

      portid refers to the port address whereas value refers to the data to be sent TESTING 74245 USING PARALLEL PORT PC INTERFACING At one end the parallel port connector will be connected to the PC via parallel port cable and another connector (to be plugged into the PC parallel port slot) At the other end it will be connected to the buffer IC 74245 Data lines of the connector will be used to transfer 8-bit data between the PC and the buffer Out of the 8-bits of 74245 4-bits will be used to enter data which will be displayed at the monitor through a C language

      61

      Logic Design amp Switching Theory 1 Lab Session 15 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering program The remaining 4-bits will receive data from PC as entered by the user via keyboard

      Circuit Diagram

      Figure 154 Interface of 74245 to PC via Parallel Port

      Procedure

      1 Connect the DB-25 connector to the PC at one end and solder it to the circuit board at the other end

      2 Connect various pins of the connector and 74245 according to the circuit diagram shown in figure 152

      3 Using the functions listed in the previous section write a program in C language to operate various pins of the buffer The user interface of the program should provide option to the user whether to send or receive data from the port

      4 Set DIR switch to 1 5 Try sending some data bits to the port The result should be displayed at the LEDs 6 Set DIR switch to 0 7 Set some binary 4-bit value through the switches Try reading it via parallel port

      C Language Program

      A program to access parallel port for data transfers

      use header file include ltstdiohgt main program void main() define variable

      62

      Logic Design amp Switching Theory 1 Lab Session 15 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering unsigned int data=0 char choice while(1) printing option menu clrscr() printf(This program will send or receive a BCD digit from the parallel portn) printf(nPress your choice numbern) printf(n1 Send Data) printf(n2 Receive Data) printf(n3 Exitn) choice = getch() sending entered digit to the port if(choice == 1) input BCD digit printf(nEnter BCD digit to be sent to the port) data = getche() masking the first four bits data = data amp 0x0f sending to the port outportb(0x378data) printf(nThe BCD digit c has been sent to the port data) printing on screen the data received from the port else if(choice == 2) receiving data from the port data = inportb(0x378) masking the last four bits data = data amp 0xf0 shifting first four bits to make them the last four bits datagtgt=4 printf(nThe BCD digit set at the port is c data) exit else if(choice == 3) break key pressed is not in the menu else printf(nEnter valid choice number) printf(nnPress any key to continue) getch()

      63

      Logic Design amp Switching Theory 1 Lab Session 15 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

      ACTIVITY 1 In the above circuit DIR and G΄ inputs are hardwired Connect them to status or

      control pins of the parallel port connector and control their function through your software program Circuit Diagram Program Code ______________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________

      ___________________________________________________________________________________________________________________________________________________

      64

      Logic Design amp Switching Theory 1 Lab Session 15 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

      65

      _____________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ _____________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ _______________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ _________________________________________________ _________________________________________________

      Logic Design amp Switching Theory 1 Appendix A NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

      Appendix A

      PIN DIAGRAMS OF THE ICS REQUIRED FOR THE LABORATORY SESSIONS Consult the TTLIC data book for internal diagrams and electrical characteristics of these ICs 7400 Quad 2-Input NAND 7402 Quad 2-Input NOR

      7404 Hex Inverter 7408 Quad 2-Input AND

      7410 Triple 3-Input NAND 7411 Triple 3-Input AND

      7421 Dual 4-Input AND 7432 Quad 2-Input OR

      66

      Logic Design amp Switching Theory 1 Appendix A NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

      BCD-to-Seven Segm 7448 BCD-to-Seven Segment 7447 ent

      Decoder (15V OC) Decoder (2kΩ pull-up output)

      7473 Dual JK Flip-Flop 7474 Dual D-Type Flip-Flop

      7476 Dual JK Flop-Flop -Bit Binary Full Adder 7483 4 with Fast Carry

      86 Quad 2-Inpu 74138 3-to-8 Line 74 t Exclusive OR Decoder Demultiplexer

      67

      Logic Design amp Switching Theory 1 Appendix A NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

      68

      74148 8-to-3 Line 16-to-1 Line Data

      Priority Encoder 74150 Selector Multiplexer

      74245 Oct nsceivers Universal Shift Register (PIPO) (3-State)

      74194 4-Bit Bidirectional al Bus Tra

      Logic Design amp Switching Theory 1 Appendix B NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

      Appendix B

      DEBOUNCING CIRCUITRY FOR MECHANICAL SWITCHES Mechanical switches form the interface between human beings and computers or other digital systems For example a keyboard is a matrix of switches used to supply alphanumeric data to a computer Whatever the switch design it is a potential source of problems due to contact bounce The contact bounce creates a sense of narrow pulses when a switch is opened or closed An example of device whose operation would be adversely affected by contact bounce is a digital counter used to count the number of times a switch is depressed Eliminating the effects of contact bounce is called debouncing When data is entered into a computer via a keyboard a software debounce is often used This type of debouncing is a program that causes the computer to sample the switch terminal (ie to input data from it) many times in succession during the interval of time that contact bounce occurs If the data is sensed to be 1s (or 0s) for a specific number of consecutive samples then it is assumed that contact bounce has ended and the last value sensed is valid Hardware debouncing is the use of electronic circuitry to eliminate the effects of contact bounce There are numerous versions of such circuitry including those that use monostable multivibrators (one-shots) but the most straightforward is simply an RS latch Figure B1 shows the circuit When the switch is in position 1 R = 0 and S = 1 so the latch is set and the output (Q) is 1 When the switch is in position 0 R = 1and S = 0 so the latch is reset and the output is 0 When the switch is moved form one position to the other the latch changes state and bouncing occurs at either the R or the S input The bouncing does not affect the latch after it has change state An RS latch will remain set for example when its R input is 0 and its S input is alternately changed form 1 to 0

      Figure B1 Use of RS latch to debounce a mechanical switch

      69

      • 01-ldst-Outer title
        • Practical Workbook
        • Logic Design amp Switching Theory I
          • Dept of Computer amp Information Systems Engineering
            • NED University of Engineering amp Technology
            • Karachi ndash 75270 Pakistan
              • 02-ldst-inner Title
                • Practical Workbook
                • Logic Design amp Switching Theory I
                  • Dept of Computer amp Information Systems Engineering
                    • NED University of Engineering amp Technology
                    • Karachi ndash 75270 Pakistan
                      • 03-ldst-general info
                      • 04-ldst-introduction
                      • 05-Table of Contents
                        • CONTENTS
                          • Lab Session No Object Page No
                          • 1
                          • Also implementing and testing the given circuit on a bread board
                            • Working with Electronics Workbench
                              • Driving a seven segment display using 7447 7448 driver IC
                                • Designing a modulus-5 asynchronous up-counter using JK-FF
                                  • Experimenting with 74194 4-bit bidirectional universal shift register
                                      • 13
                                          • 06-ldst-Exp01
                                            • Lab Session 01
                                            • OBJECT
                                              • 1 Bread board
                                              • 2 5 V - power supply
                                              • 3 Multimeter
                                              • 4 Logic probe
                                              • 5 LEDs with resistors
                                              • 6 Connecting wires
                                              • 8 Following ICs and their datasheets
                                                • THEORY
                                                  • Logic Gates
                                                  • 1 The AND Gate ndash An AND gatersquos output is 1 if and only if all its inputs are 1 If A and B are two inputs to an AND gate then output F of the gate is given as F = AB
                                                  • 2 The OR Gate - An OR gatersquos output is 1 if at least one of its input is 1 If A and B are two inputs to an OR gate then output F of the gate is given as F = A+B
                                                  • 3 The NOT Gate (Inverter) ndash Its output is 1 when its input is 0 and its output is 0 when the input is 1 ie it complements a digital variable If A is the input to a NOT gate then output F of the gate is given as
                                                  • 4 The NAND Gate ndash Its output is 1 if at least one of its input is 0 This gate performs the same logic as an AND gate followed by an inverter If A and B are two inputs to a NAND gate then output F of the gate is given as
                                                    • 5 The NOR Gate - The output of a NOR gate is 1 if and only if all its inputs are 0 This gate performs the same logic function as an OR gate followed by an inverter If A and B are two inputs to a NAND gate then output F of the gate is given as
                                                        • DATA SHEETS
                                                          • Logic expression for the given logic diagram __________________________________
                                                              • 07-ldst-exp02
                                                                • Working with Electronics Workbench
                                                                  • 08-ldst-exp03
                                                                    • Designing Half and Full Adder Circuits
                                                                      • COMPONENTS AND APPARATUS REQUIRED
                                                                        • 1 Following ICs and their Datasheets
                                                                        • 7408 Quad 2-input AND Gate
                                                                        • 2 Digital Trainer DT-01 or the following components
                                                                          • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                          • Connecting wires Switches
                                                                            • THEORY
                                                                                • IMPLEMENTATION AND OBSERVATIONS
                                                                                  • 09-ldst-Exp04
                                                                                    • Lab Session 04
                                                                                    • 1 Digital ICs and their Datasheets
                                                                                    • 7408 Quad 2-input AND Gate
                                                                                    • 2 Digital Trainer DT-01 or the following components
                                                                                      • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                      • Connecting wires Switches
                                                                                      • PROCEDURE
                                                                                      • REDUCTION OF LOGIC EXPRESSION USING KARNAUGH MAP
                                                                                      • OBSERVATIONS
                                                                                      • RESULT
                                                                                          • 10-ldst-Exp05
                                                                                            • Lab Session 05
                                                                                            • 1 Following ICs and their Datasheets
                                                                                            • 7408 Quad 2-input AND Gate
                                                                                            • 2 Digital Trainer DT-01 or the following components
                                                                                              • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                              • (100 Ω) Connecting wires Switches
                                                                                              • THEORY
                                                                                                • IMPLEMENTATION AND OBSERVATIONS
                                                                                                  • 11-ldst-Exp06
                                                                                                    • OBJECT
                                                                                                    • 1 Following ICs and their Datasheets
                                                                                                    • 7408 Quad 2-input AND Gates or 7411 Triple 3-input AND Gates
                                                                                                    • 2 Digital Trainer DT-01 or the following components
                                                                                                      • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                      • Connecting wires Switches
                                                                                                        • Figure 62 Circuit Diagram for 4 x 1 Multiplexer
                                                                                                        • Implementation and Observations
                                                                                                          • Circuit Diagram
                                                                                                            • ACTIVITY
                                                                                                              • 12-ldst-exp07
                                                                                                                • 1 Following ICs and their Datasheets
                                                                                                                • 7408 Quad 2-input or 7411 Triple 3-input AND Gates
                                                                                                                • 2 Digital Trainer DT-01 or the following components
                                                                                                                  • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                  • Connecting wires Switches
                                                                                                                    • THEORY
                                                                                                                        • Figure 72 Circuit Diagram for 2 x 4 Decoder 1 x 4 Demultiplexer
                                                                                                                        • Implementation and Observations
                                                                                                                          • Circuit Diagram
                                                                                                                            • ACTIVITY
                                                                                                                              • 13-ldst-Exp08
                                                                                                                                • OBJECT
                                                                                                                                • 1 Following ICs and their Datasheets
                                                                                                                                • 7408 Quad 2-input or 7421 Dual 4-input AND Gates
                                                                                                                                • 2 Digital Trainer DT-01 or the following components
                                                                                                                                  • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                  • Connecting wires Switches
                                                                                                                                    • THEORY
                                                                                                                                        • Figure 81 Circuit Diagram for 4 x 2 Priority Encoder
                                                                                                                                        • Implementation and Observations
                                                                                                                                          • Therefore if GS A2 A1 and A0 are all low then it shows that line 0 is selected and if E0 A2 A1 and A0 are all low then it shows that none of the inputs selected E0 and GS cannot be in the same state provided that E1 is enabled
                                                                                                                                          • Circuit Diagram
                                                                                                                                            • ACTIVITY
                                                                                                                                              • 14-ldst-exp09
                                                                                                                                                • OBJECT
                                                                                                                                                • 1 Following ICs and their Datasheets
                                                                                                                                                • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                  • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                  • Connecting wires Switches
                                                                                                                                                    • THEORY
                                                                                                                                                      • Parity Generator
                                                                                                                                                        • Let x y and z be the three bits that constitute the message and are the input to the Odd Parity Generator Circuit Since it is an odd parity system the bit P is generated so as to make the total number of 1s odd (including P) The function P can be expressed as follows
                                                                                                                                                        • Figure 91 Circuit Diagram for a 3-bit Parity Generator
                                                                                                                                                          • C = x Ο y Ο z Ο P
                                                                                                                                                            • Implementation and Observations
                                                                                                                                                              • ACTIVITY
                                                                                                                                                                  • 15-ldst-exp10
                                                                                                                                                                    • Driving a seven segment display using 7447 7448 driver IC
                                                                                                                                                                    • COMPONENTS AND APPARATUS REQUIRED
                                                                                                                                                                    • 1 Following ICs and their Datasheets
                                                                                                                                                                    • 7447 7448 BCD to Seven Segment Driver
                                                                                                                                                                    • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                      • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches
                                                                                                                                                                        • THEORY
                                                                                                                                                                        • Seven Segment Displays
                                                                                                                                                                        • CIRCUIT DIAGRAM
                                                                                                                                                                        • Figure 102 Circuit diagram for 7447driving a common-anode display
                                                                                                                                                                            • IMPLEMENTATION AND OBSERVATIONS
                                                                                                                                                                              • Decimal Digit
                                                                                                                                                                              • BCD Inputs
                                                                                                                                                                              • Seven Segment Outputs
                                                                                                                                                                              • D
                                                                                                                                                                              • C
                                                                                                                                                                              • B
                                                                                                                                                                              • A
                                                                                                                                                                              • a
                                                                                                                                                                              • b
                                                                                                                                                                              • c
                                                                                                                                                                              • d
                                                                                                                                                                              • e
                                                                                                                                                                              • f
                                                                                                                                                                              • g
                                                                                                                                                                              • 0
                                                                                                                                                                              • 0
                                                                                                                                                                              • 0
                                                                                                                                                                              • 0
                                                                                                                                                                              • 0
                                                                                                                                                                              • 1
                                                                                                                                                                              • 0
                                                                                                                                                                              • 0
                                                                                                                                                                              • 0
                                                                                                                                                                              • 1
                                                                                                                                                                              • 2
                                                                                                                                                                              • 0
                                                                                                                                                                              • 0
                                                                                                                                                                              • 1
                                                                                                                                                                              • 0
                                                                                                                                                                              • 3
                                                                                                                                                                              • 0
                                                                                                                                                                              • 0
                                                                                                                                                                              • 1
                                                                                                                                                                              • 1
                                                                                                                                                                              • 4
                                                                                                                                                                              • 0
                                                                                                                                                                              • 1
                                                                                                                                                                              • 0
                                                                                                                                                                              • 0
                                                                                                                                                                              • 5
                                                                                                                                                                              • 0
                                                                                                                                                                              • 1
                                                                                                                                                                              • 0
                                                                                                                                                                              • 1
                                                                                                                                                                              • 6
                                                                                                                                                                              • 0
                                                                                                                                                                              • 1
                                                                                                                                                                              • 1
                                                                                                                                                                              • 0
                                                                                                                                                                              • 7
                                                                                                                                                                              • 0
                                                                                                                                                                              • 1
                                                                                                                                                                              • 1
                                                                                                                                                                              • 1
                                                                                                                                                                              • 8
                                                                                                                                                                              • 1
                                                                                                                                                                              • 0
                                                                                                                                                                              • 0
                                                                                                                                                                              • 0
                                                                                                                                                                              • 9
                                                                                                                                                                              • 1
                                                                                                                                                                              • 0
                                                                                                                                                                              • 0
                                                                                                                                                                              • 1
                                                                                                                                                                                • ACTIVITY
                                                                                                                                                                                  • 16-ldst-exp11
                                                                                                                                                                                    • Lab Session 11
                                                                                                                                                                                      • OBJECT
                                                                                                                                                                                      • COMPONENTS AND APPARATUS REQUIRED
                                                                                                                                                                                        • 1 Following ICs and their Datasheets
                                                                                                                                                                                        • 7473 7476 JK Flip-Flop
                                                                                                                                                                                        • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                          • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                          • Connecting wires Switches
                                                                                                                                                                                            • THEORY
                                                                                                                                                                                                • Flip-Flop
                                                                                                                                                                                                • JK Flip-Flop
                                                                                                                                                                                                  • Circuit Diagram
                                                                                                                                                                                                    • Observations
                                                                                                                                                                                                      • ACTIVITY
                                                                                                                                                                                                          • 17-ldst-exp12
                                                                                                                                                                                                            • Lab Session 12
                                                                                                                                                                                                              • OBJECT
                                                                                                                                                                                                              • GIVEN STATE DIAGRAM
                                                                                                                                                                                                              • Figure 121 State Diagram
                                                                                                                                                                                                              • COMPONENTS AND APPARATUS REQUIRED
                                                                                                                                                                                                                • 1 Following ICs and their Datasheets
                                                                                                                                                                                                                • 7474 D Flip-Flop
                                                                                                                                                                                                                • ICs of basic gates (AND OR NOT XOR etc) as required
                                                                                                                                                                                                                • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                  • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                                  • Connecting wires Switches
                                                                                                                                                                                                                    • THEORY
                                                                                                                                                                                                                        • Sequential Circuits
                                                                                                                                                                                                                          • 18-ldst-exp13
                                                                                                                                                                                                                            • Lab Session 13
                                                                                                                                                                                                                              • Designing a modulo-5 asynchronous up-counter using JK-FF
                                                                                                                                                                                                                                • 1 Following ICs and their Datasheets
                                                                                                                                                                                                                                • 7400 Quad 2-input or 7410 Triple 3-input NAND Gates
                                                                                                                                                                                                                                • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                                  • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                                                  • Connecting wires Switches
                                                                                                                                                                                                                                    • THEORY
                                                                                                                                                                                                                                        • Figure 131 A Mod-5 Asynchronous Up Counter
                                                                                                                                                                                                                                        • Implementation and Observations
                                                                                                                                                                                                                                          • ACTIVITY
                                                                                                                                                                                                                                              • 19-ldst-exp14
                                                                                                                                                                                                                                                • Experimenting with 74194 4-bit bidirectional universal shift register
                                                                                                                                                                                                                                                • 1 Following ICs and their Datasheets
                                                                                                                                                                                                                                                • 74194 4-bit bidirectional universal shift register
                                                                                                                                                                                                                                                • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                                                  • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                                                                  • Connecting wires Switches
                                                                                                                                                                                                                                                    • THEORY
                                                                                                                                                                                                                                                      • Shift Registers
                                                                                                                                                                                                                                                      • Bidirectional Shift Registers
                                                                                                                                                                                                                                                      • Universal Shift Registers
                                                                                                                                                                                                                                                        • S1
                                                                                                                                                                                                                                                          • Circuit Diagram
                                                                                                                                                                                                                                                          • ACTIVITY
                                                                                                                                                                                                                                                              • 20-ldst-exp15
                                                                                                                                                                                                                                                                • COMPONENTS AND APPARATUS REQUIRED
                                                                                                                                                                                                                                                                • 1 Parallel Port Connectors (DB-25) with Cable
                                                                                                                                                                                                                                                                • 2 Personal Computer with Windows 98 and TurboC Compiler Installed
                                                                                                                                                                                                                                                                • 3 Following ICs and their Datasheets
                                                                                                                                                                                                                                                                • 74245 Octal Bus Transceivers with 3-State Outputs
                                                                                                                                                                                                                                                                • 4 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                                                                  • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                                                                                    • Connecting wires Switches
                                                                                                                                                                                                                                                                      • THEORY
                                                                                                                                                                                                                                                                      • 3-State Logic
                                                                                                                                                                                                                                                                        • Serial and Parallel Port Connectors
                                                                                                                                                                                                                                                                        • Parallel Port Connector ndash DB-25
                                                                                                                                                                                                                                                                          • Accessing parallel port through C Language Programming
                                                                                                                                                                                                                                                                              • 21-ldst-appendixA
                                                                                                                                                                                                                                                                              • 22-ldst-appendixB
                                                                                                                                                                                                                                                                                • DEBOUNCING CIRCUITRY FOR MECHANICAL SWITCHES

        PART CIRCUIT SIGN

        WHAT IT DOES

        Stores electricity the greater the capaci-tance the more does it store Capacitance values are measured in microfarads shortened to μF or less correctly to mfd On a capacitor 01 μF may be marked as l mfd and 001μF as 10n The greatest voltage it can stand is also shown eg 30V

        Stores electricity values usually larger than 1μF Greatest voltage marked on it Must be connected the correct way round

        Varies the capacitance in a circuit by mov-ing one set of metal plates in or out of a fixed set when the spindle is rotated The sets of plates are separated by sheets of an insulator (also called a dielectric)

        Changes electric currents into sound

        Changes radio waves into electric currents

        Lets current flow in one direction but not in the other When it conducts light is emit-ted Must have a current limiting resistor in series with it The cathode lead is nearest the lsquoflatrsquo and may be shorter than the anode lead (but this is not always so) The arrow on the sign shows the conducting direction

        4

        PART CIRCUIT SIGN

        WHAT IT DOES

        Amplifies small currents into much larger copies Acts as a very fast switch It must be correctly connected with a positive voltage to the collector

        Transistors diodes resistors and capacitors are connected together on a tiny lsquochiprsquo of silicon (sand is mostly silicon oxide) to give any desired circuit eg a multistage amplifier an astable bistable or monostable multivibrator a counter a logic gate for a computer several stages of a TRF (tuned radio frequency) radio

        They must be correctly connected Pin 1 is next to the lsquotagrsquo in the can type and on the dil type it is identified from the lsquonotchrsquo or lsquosmall dotrsquo on the case CMOS lsquochipsrsquo (standing for Complementary Metal Oxide Semiconductors and pronounced lsquosee-mossrsquo) need special care

        PRECAUTIONS WITH CMOS INTEGRATED CIRCUITS Damage occurs if static charges build up on input pins when for example they touch insulating materials (eg clothes plastic pen) in warm dry conditions 1 Keep the IC in the carrier in which it is supplied until it is inserted in the circuit 2 Do not finger the pins or hold them in contact with an insulator 3 Connect all unused inputs of the IC to either the positive or the negative of the battery

        depending on the circuit

        5

        BUILDING CIRCUITS

        The circuit board shown above accepts ICs as well as separate components It has 47 rows of 5 interconnected sockets on each side of a central channel across which dil ICs can be fitted A wire inserted in a socket in a certain row becomes connected to wires in any of the other 4 sockets in that row by a metal strip under the board For example wires in sockets B5 C5 D5 E5 and F5 (shown in color in the diagram) are all joined Metal strips under the board connect the sockets A row of 40 interconnected sockets along the top of the board and a similar row along the bottom act as the positive and negative power supply rails (called lsquobus barsrsquo) Various makes of circuit board are available some with vertically mounting removable panels for supporting controls

        6

        1 To make a connection push about 1 cm of the bare end of a wire (025 to 085 mm diameter) straight into the socket (not at an angle) so that it is gripped by the metal strip under the board Do not use wires that are dirty or have kinked ends Only put one wire in each socket

        Bend leads on resistors etc as shown before inserting them in the board

        2 Bare the ends of connecting wire (PVC-covered tinned copper wire 06 mm diameter) by

        removing the insulation (PVC) either with wire strippers or using a pair of blunt-nosed pliers and a pair of side cutters as shown With practice you should be able to judge just how much the side cutters have to be squeezed and pulled to remove the insulation without cutting the wire

        3 lsquoJoinrsquo wires to the lsquolugsrsquo on the loudspeaker and variable capacitor using a small length of

        2 mm bore plastic sleeving - as shown by 1 and 2

        7

        RESISTOR COLOUR CODE Resistor values are given in ohms (shortened to Ω the Greek letter lsquoomegarsquo) They are marked on the resistor using a color code Three colored bands are painted round the resistor Each color stands for a number To read the color code start at the 1st band it is nearest the end Sometimes it is not clear which is the 1st band because there is a 4th band of gold or silver near the other end These two colors are not used for the 1st band they give the accuracy of the resistor (gold is plusmn 5 and silver plusmn 10) so you should not have too much trouble deciding where to start The 1st band gives the first number the 2nd band gives the second number and the 3rd band tells how many zeroes come after the first two numbers

        8

        INTRODUCTION

        Digital Logic Design is concerned with the interconnection among digital components and modules and the area of Switching Theory that can be identified between circuit design and system formulation Logic design is the base of any computer system as every digital system consists of different ICrsquoS and ICs contain a large number of interconnected digital circuits within a small package MSI devices provide digital function while LSI device cover a complete computer modules These circuitries are widely used in digital system like digital voltmeter frequency meter calculating machines telephone-switching system etc In this Practical Workbook laboratory sessions based on both combinational and sequential logic are covered First laboratory session gives an introduction to the basic logic gates and fundamentals of circuit building The second laboratory session covers a CAD software ndash Electronics Workbench (EWB) EWB is excellent simulation software where circuits can be designed and tested before physical implementation Various laboratory sessions of this workbook provide activities and exercises on EWB Next eight laboratory sessions are based on combinational logic Here various MSI circuits like adders converters multiplexers decoders encoders etc are designed Some of these laboratory sessions also include testing of MSI ICs Next four laboratory sessions help in exploring various designs based on sequential logic Here a variety of circuits are designed form the testing of basic flip-flop ICs to registers and different types of counters Last laboratory session demonstrates how digital hardware can be interfaced with a personal computer via parallel port and can be controlled by software All laboratory sessions of this workbook incorporate brief theoretical backgrounds as details may be covered in the respective theory classes Exercises activities are included with almost all the sessions for the students to practice Two appendices are also included in this workbook The first one provides pin diagrams for all the ICs required for the laboratory work provided in this workbook It will help the students in preparing the pin diagrams for the circuits Second appendix discusses a hardware debouncing circuit for mechanical switches as such switches are extensively used for input purpose in logic circuits

        9

        CONTENTS Lab Session No Object Page No

        1 2 3 4 5 6 7 8 9

        10

        11

        12

        13

        14

        15

        To study the logic gates in the following TTL ICs

        7400 Quad 2-input NAND gate 7402 Quad 2-input NOR gate

        7404 Hex inverter 7408 Quad 2-input AND gate 7432 Quad 2-input OR gate

        Also implementing and testing the given circuit on a bread board Working with Electronics Workbench Designing Half and Full Adder Circuits Use of Karnaugh Map (SOP-Expression) method Designing a BCD Adder Designing of a 4 x 1 Multiplexer Experimenting with 74150 IC Designing of a 2 x 4 Decoder 1 x 4 Demultiplexer Experimenting with 74138 IC Designing of a 4 x 2 Priority Encoder Experimenting with 74148 IC Designing an Odd Parity Generator and Checker for a 3-bit Data Driving a seven segment display using 7447 7448 driver IC Experimenting with different modes of JK-FF Designing sequential circuit for the given state diagram using D flip-flop Designing a modulus-5 asynchronous up-counter using JK-FF Experimenting with 74194 4-bit bidirectional universal shift register Experimenting with 74245 octal bus transceivers using parallel port PC interfacing Appendix A ndash Pin Diagrams of the ICs required for the laboratory sessions Appendix B ndash Debouncing circuitry for mechanical switches

        13

        17

        19

        22

        28

        30

        34

        38

        42

        45

        48

        50

        54

        56

        59

        66

        69

        11

        Logic Design amp Switching Theory 1 Lab Session 01 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

        Lab Session 01 OBJECT

        bull To study the logic gates in the following TTL ICs

        i) 7400 Quad 2-input NAND gate ii) 7402 Quad 2-input NOR gate iii) 7404 Hex inverter iv) 7408 Quad 2-input AND gate v) 7432 Quad 2-input OR gate

        bull Implementing and testing the given circuit on a bread board

        COMPONENTS REQUIRED 1 Bread board 2 5 V - power supply 3 Multimeter 4 Logic probe 5 LEDs with resistors 6 Connecting wires 7 Switches (optional) 8 Following ICs and their datasheets

        bull 7408 quad 2 input AND gate bull 7432 quad 2 input OR gate bull 7404 hex inverter bull 7400 quad 2 input NAND gate bull 7402 quad 2 input NOR gate

        THEORY

        Logic Gates

        Logic gates are the fundamental building blocks of digital systems These devices are able to make decisions in the sense that they produce one output level when some combinations of input levels are present and a different output when other combinations are applied hence given the name Logic Gates The two levels produced by digital circuitry are referred to variously as HIGH and LOW TRUE and FALSE ON and OFF or simply 1 and 0 There are only three basic gates AND OR and NOT The other gates are merely combinations of these basic gates Logic gates can be interconnected to perform a variety of logical operations This interconnection of gates to achieve prescribed outcomes is called logic design

        1 The AND Gate ndash An AND gatersquos output is 1 if and only if all its inputs are 1 If A and B are two inputs to an AND gate then output F of the gate is given as F = AB

        2 The OR Gate - An OR gatersquos output is 1 if at least one of its input is 1 If A and B are two inputs to an OR gate then output F of the gate is given as F = A+B

        13

        Logic Design amp Switching Theory 1 Lab Session 01 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering 3 The NOT Gate (Inverter) ndash Its output is 1 when its input is 0 and its output is 0 when

        the input is 1 ie it complements a digital variable If A is the input to a NOT gate then output F of the gate is given as AF =

        4 The NAND Gate ndash Its output is 1 if at least one of its input is 0 This gate performs the same logic as an AND gate followed by an inverter If A and B are two inputs to a NAND gate then output F of the gate is given as BAF =

        5 The NOR Gate - The output of a NOR gate is 1 if and only if all its inputs are 0 This gate performs the same logic function as an OR gate followed by an inverter If A and B are two inputs to a NAND gate then output F of the gate is given as BAF +=

        All the above gates have one output and two or more inputs except the NOT gate which has only one input

        PROCEDURE FOR TESTING THE LOGIC GATES IN GIVEN ICs

        1 Set the power supply to 5V With the help of a multimeter check the voltage at the output knobs of the power supply

        2 Connect wires long enough to reach the breadboard with the two knobs of the power supply Again using multimeter check voltage at the non-connected end of the wires

        3 Insert the 7408 quad 2 input AND gate IC on to the bread board and make supply and ground connections by joining 5V wire to pin 14 and 0V wire to pin 7

        4 Consult ICrsquos internal connection diagram for input and output pins of the first AND gate Connect input pins to logic 0 (0V) and observe the output using LED or logic probe You can also connect switches at the input lines to facilitate toggling between 1 and 0

        5 Try different combinations of logic levels at the two inputs Again observe the output 6 Repeat the last two steps for all other gates of the same IC Record the observations 7 Repeat this procedure for all other ICs

        OBSERVATIONS

        Gate Input A Input B Expected Output Observed Output

        AND

        0 0 0 1 1 0 1 1

        OR

        0 0 0 1 1 0 1 1

        NOT 0 - 1 -

        NAND

        0 0 0 1 1 0 1 1

        14

        Logic Design amp Switching Theory 1 Lab Session 01 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

        NOR

        0 0 0 1 1 0 1 1

        DATA SHEETS

        Figure 11

        15

        Logic Design amp Switching Theory 1 Lab Session 01 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

        16

        GIVEN CIRCUIT

        Figure 12

        PROCEDURE FOR IMPLEMENTATION OF THE GIVEN CIRCUIT 1 Set the power supply 2 Insert ICs on the bread board and make their supply and ground connections 3 As given in the logic diagram make connections using wires and gates in the ICs 4 Apply different combinations at the three inputs and observe the output OBSERVATIONS Logic expression for the given logic diagram __________________________________

        A B C Expected Output Observed Output 0 0 0 0 0 1 0 1 0 0 1 1 1 0 0 1 0 1 1 1 0 1 1 1

        Logic Design amp Switching Theory 1 Lab Session 02 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

        Lab Session 02

        OBJECT

        Working with Electronics Workbench

        ELECTRONICS WORKBENCH - EWB Electronics Workbench is a computer aided design tool that provides you with all the components and instruments necessary to create board-level designs It has complete mixed analog and digital simulation and graphical waveform analysis allowing you to design your circuit and then analyze it using different simulated instruments and analysis options It is fully integrated and interactive thus you can change your circuits quickly allowing fast and repeated what-if analysis Electronics Workbench provides the following kind of components bull Sources parts bin (AC voltage source Vcc source ground battery etc) bull Basic parts bin (resistors capacitors transformers switches etc) bull Diodes parts bin bull Transistors parts bin bull Analog ICs parts bin (op-amps etc) bull Mixed ICs parts bin (ADCs DACs 555 timers etc) bull Digital ICs parts bin (AND OR adders multiplexers etc) bull Indicators parts bin (voltmeter ammeter probe displays etc) bull Controls parts bin (voltage differentiator multiplier etc) bull Instruments parts bin (multimeter oscilloscope function generator etc) bull Miscellaneous parts bin (write data textbox etc)

        o Write data This component allows you to save simulation results as an ASCII file o Text Box Use this to add descriptive text anywhere in a circuit

        ACTIVITY

        Design circuit for the logic expression )( CBDCABAF ++=

        Procedure 1 From Logic Gates Parts Bin Drag and drop the required logic gates on the design

        area Use Component Properties dialog box to customize these gates 2 Connect the terminal of these gates according to the given expression Use additional

        connectors form the Basic Parts Bin if you want to connect more than wire at a single node

        3 Drag and drop a probe from Indicators Parts Bin Use Component Properties dialog box to customize the color and other properties of the probe Connect this probe at the output terminal of the circuit to indicate results

        4 Select four switches form Basic Parts Bin Specify the key that controls the switch by typing its name in the Value tab of the Component Properties dialog box For

        17

        Logic Design amp Switching Theory 1 Lab Session 02 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

        18

        example if you want the switch to close or open when digit lsquo1rsquo is pressed type 1 in the Value tab then click OK Assign different keys to all the switches

        5 Connect the output terminals of these switches to each of the four inputs A B C and D of the circuit

        6 Drag and drop Vcc and Ground form the Sources Parts Bin 7 Connect Vcc terminal to one end and Ground terminal to the other end of all the

        switches 8 Label the circuit properly using text boxes found in the miscellaneous parts bin 9 Run the circuit using the Activate Simulation switch Use the keys you have assigned

        to the switches to toggle them between Vcc and Ground connections thus providing 1 or 0 respectively to the inputs Record the results as indicated by the probe for all possible combinations of 1s and 0s at the inputs

        EWB Circuit

        Figure 21

        Observations

        A B C D Expected Output Observed Output 0 0 0 0 0 0 0 1 0 0 1 0 0 0 1 1 0 1 0 0 0 1 0 1 0 1 1 0 0 1 1 1 1 0 0 0 1 0 0 1 1 0 1 0 1 0 1 1 1 1 0 0 1 1 0 1 1 1 1 0 1 1 1 1

        Logic Design amp Switching Theory 1 Lab Session 03 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

        Lab Session 03

        OBJECT

        Designing Half and Full Adder Circuits COMPONENTS AND APPARATUS REQUIRED 1 Following ICs and their Datasheets

        bull 7408 Quad 2-input AND Gate bull 7432 Quad 2-input OR Gate bull 7486 Quad 2-input XOR Gate

        2 Digital Trainer DT-01 or the following components Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches

        THEORY Half Adder A combination circuit that performs the addition of two bits without accounting for the previous carry is called half adder It needs two binary inputs and two binary outputs The input variables designate the augend and addend bits The output variables produce the sum and carry The simplified sum of product expressions for a half adder are

        yxyxyxS oplus=+= yxC =

        Figure 31 Circuit diagram for Half Adder

        19

        Logic Design amp Switching Theory 1 Lab Session 03 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

        bles produce the sum and carry The simplified sum of product expressions for a half adder are

        Full Adder

        A combinational circuit that performs the addition of three input bits It consist of three inputs and two outputs Two of the input variables represent the two significant bits to be added The third input represents the carry from the previous lower significant position The output varia

        zyxzyxzyxzyxzyxS oplusoplus=+++= yxzyxzyzxxyC )( +oplus=++=

        Figure 32 Circuit diagram for Full Adder

        efer to laboratory session 01 for procedure) and record the observations in the following ta

        alf Adde ull Adder Inputs u

        IMPLEMENTATION AND OBSERVATIONS

        Implement the half adder and full adder circuits on a bread board (prepare the pin diagram (use appendix A) and r

        bles H r F

        Inputs Outputs Outp ts x y Carry Su Carry Sum m x y z 0 0 0 0 0 0 1 0 0 1 1 0 0 1 0 1 1 0 1 1 1 0 0 1 0 1 1 1 0 1 1 1

        20

        Logic Design amp Switching Theory 1 Lab Session 03 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

        at of your designed circuit Attach hardcopy of the output form electronic workbench

        at of your designed circuit Attach hardcopy of the output form lectronic workbench here

        ACTIVITY

        1 Simulate half adder circuit using Electronics Workbench Compare the results of simulation with thhere

        2 Design a full subtractor circuit and simulate it using Electronics Workbench Compare the results of simulation with the

        21

        Logic Design amp Switching Theory 1 Lab Session 04 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

        Lab Session 04 OBJECT

        Use of Karnaugh Map (SOP-Expression) method GIVEN LOGIC EXPRESSION

        F (A B C D) = sum ( 0 1 2 4 5 6 8 9 12 13 14 ) COMPONENTS AND APPARATUS REQUIRED 1 Digital ICs and their Datasheets

        bull 7408 Quad 2-input AND Gate bull 7432 Quad 2-input OR Gate bull 7404 Hex Inverter

        2 Digital Trainer DT-01 or the following components Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches PROCEDURE 1 Use Karnaugh map to reduce the given function 2 Draw the circuit diagram for the obtained reduced function 3 Implement the reduced circuit using digital ICs on a bread board (prepare the pin

        diagram (use appendix A) and refer to laboratory session 01 for procedure) and record the observations

        REDUCTION OF LOGIC EXPRESSION USING KARNAUGH MAP F

        CD

        AB DC

        DC DC

        DC

        BA0 1 3 2

        BA4 5 7 6

        BA12 13 15 14

        BA8 9 11 10

        Reduced form of the given logic expression is __________________________________

        22

        Logic Design amp Switching Theory 1 Lab Session 04 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

        LOGIC DIAGRAM (REDUCED FORM) OBSERVATIONS

        A B C D Output 0 0 0 0 0 0 0 1 0 0 1 0 0 0 1 1 0 1 0 0 0 1 0 1 0 1 1 0 0 1 1 1 1 0 0 0 1 0 0 1 1 0 1 0 1 0 1 1 1 1 0 0 1 1 0 1 1 1 1 0 1 1 1 1

        RESULT The reduced form (SOP Expression) of the given logic function is

        ____________________________________________________________

        The observation table reflects the given logic function

        23

        Logic Design amp Switching Theory 1 Lab Session 04 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

        ACTIVITY 1 Using Electronics Workbench derive a truth table and logic circuit for the following logic expression

        BAAF +=

        Procedure 1 From the Instruments Parts Bin drag and drop Logic Converter on the design area 2 Double click the Logic Converter to reveal Logic Converter dialog box This dialog

        box shows various conversion options between truth table logic expression and logic circuit

        3 Enter the given logic expression in the edit box found at the end of the dialog box Use lsquo to represent invert of a variable For example A is written as Arsquo

        4 Click the Boolean Expression to Truth Table button The truth table appears in the logic converters display

        5 Now click the Boolean Expression to Circuit button This creates the logic circuit for the given expression in the design area Label the diagram if needed

        Resulting Logic Circuit For the given expression the final circuit will look like

        Figure 41

        24

        Logic Design amp Switching Theory 1 Lab Session 04 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

        ACTIVITY 2

        Using Electronics Workbench find a simplified logic expression and circuit for the following truth table

        A B C Output 0 0 0 1 0 0 1 1 0 1 0 0 0 1 1 1 1 0 0 0 1 0 1 0 1 1 0 0 1 1 1 1

        Procedure 1 Click three input channels from A to H across the top of the logic converter The

        display area below the terminals fills up with the necessary combinations of ones and zeros to fulfill the input conditions The values in the output column on the right are initially set to 0

        2 Edit the output column to specify the desired output for each input condition To change an output value select it and type a new value 1 0 or x An x indicates a donrsquot care condition

        3 To convert this truth table to a Boolean expression click the Truth Table to Boolean Expression button The Boolean expression will be displayed at the bottom of the logic converter

        4 Simplify the expression by clicking the Simplify button 5 Now click the Boolean Expression to Circuit button This creates the logic circuit for

        the given expression in the design area Resulting Logic Circuit For the given truth table the final simplified circuit will look like

        Figure 42

        25

        Logic Design amp Switching Theory 1 Lab Session 04 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

        ACTIVITY 3

        Using Electronics Workbench find the logic expression and truth table for the following logic circuit

        Figure 43

        Procedure 1 Attach the input terminals of the logic converter to up to four input points in the

        circuit 2 Connect the single output of the circuit to the output terminal on the logic converter

        icon 3 Click the Circuit to Truth Table button The truth table appears in the logic

        converters display 4 To convert this truth table to a Boolean expression click the Truth Table to Boolean

        Expression button The Boolean expression will be displayed at the bottom of the logic converter

        Resulting Logic Expression Logic Expression for the given circuit is found to be _____________________________

        26

        Logic Design amp Switching Theory 1 Lab Session 04 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

        27

        For activities 1 2 and 3 attach hardcopy of the output (truth table logic expression and logic circuit) form electronic workbench here

        Logic Design amp Switching Theory 1 Lab Session 05 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

        Lab Session 05 Lab Session 05 OBJECT OBJECT

        Designing a BCD Adder Designing a BCD Adder COMPONENTS AND APPARATUS REQUIRED COMPONENTS AND APPARATUS REQUIRED

        1 Following ICs and their Datasheets 1 Following ICs and their Datasheets bull 7408 Quad 2-input AND Gate bull 7408 Quad 2-input AND Gate bull 7432 Quad 2-input OR Gate bull 7432 Quad 2-input OR Gate bull 7483 4-bit Binary Adder bull 7483 4-bit Binary Adder

        2 Digital Trainer DT-01 or the following components 2 Digital Trainer DT-01 or the following components Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors (100 Ω) Connecting wires Switches (100 Ω) Connecting wires Switches

        THEORY THEORY

        A BCD Adder is a combinational circuit that adds two BCD digits in parallel and produces a sum digit also in BCD A BCD Adder is a combinational circuit that adds two BCD digits in parallel and produces a sum digit also in BCD

        A4 A3 A2 A1 B4 B3 B2 B1

        7483-BCD ADDER

        Cout (C4 ) Z4 Z3 Z2 Z1 Cin(C0)

        A4 A3 A2 A1 B4 B3 B2 B1

        7483-BCD ADDER

        Cout

        (C4 ) Z4 Z3 Z2 Z1 Cin(C0)

        Figure 51 BCD Adder Circuit

        28

        Logic Design amp Switching Theory 1 Lab Session 05 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

        29

        A BCD adder must include the correction logic in its internal construction The two BCD digits together with the input carry are first added using a 4-bit binary adder to produce the binary sum If no output carry is generated and the binary sum is less than or equal to 9 then the corresponding BCD sum is identical and therefore no conversion is needed When the output carry is equal to 1 or the binary sum is greater than 9 then a binary 0110 is added to the binary sum through another 4-bit binary adder If Cout is the carry output and Z4Z3Z2Z1 is the binary sum form the first 4-bit binary adder then the following equation indicates the condition when a binary 0110 is to be added

        C = COUT + Z4Z2 + Z4Z3 IMPLEMENTATION AND OBSERVATIONS Implement the BCD adder circuit according to figure 51 on a bread board (prepare the pin diagram (use appendix A) and refer to laboratory session 01 for procedure) A BCD adder has nine input bits (two BCD digits and a carry bit) which can result in a total of 512 combinations of which 312 inputs are donrsquot care Since it is a very lengthy procedure to record results for 200 valid input combinations therefore for simplicity just record results for any eight combinations in the following table

        Input Carry

        BCD Digit 1 BCD Digit 2 Carry Output

        BCD Sum A4 A3 A2 A1 B4 B3 B2 B1 Z4 Z3 Z2 Z1

        Logic Design amp Switching Theory 1 lab Session 06 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

        Lab Session 06

        OBJECT

        bull Designing of a 4 x 1 Multiplexer bull Experimenting with 74150 IC

        COMPONENTS AND APPARATUS REQUIRED 1 Following ICs and their Datasheets

        bull 7408 Quad 2-input AND Gates or 7411 Triple 3-input AND Gates bull 7432 Quad 2-input OR Gates bull 7404 Hex Inverter bull 74150 16 x 1 MUX

        2 Digital Trainer DT-01 or the following components Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches THEORY

        Multiplexers A digital data Multiplexer (MUX) is a combinational circuit having several data inputs and a single output A set of data-select inputs is used to control which of the data inputs is routed to the single output A multiplexer is also called a data selector because of this ability to select which data input is connected o the output Normally there are 2n input lines and n selection lines whose bit combination determine which input is selected DESIGN OF A 4 x 1 MULTIPLEXER A 4 x 1 multiplexer is capable of selecting one of four data inputs (see figure 61) The 2-bit binary number at the data select inputs S1 and S0 specifies which of the four data inputs is to be routed to the output Since there are two data select inputs therefore they can select 22 = 4 different data inputs lines

        S0 S1 D0 D1

        D2 D3

        Data-select Inputs Output

        Data Inputs

        Figure 61 Block Diagram of a 4 x1 Multiplexer

        30

        Logic Design amp Switching Theory 1 lab Session 06 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

        Figure 62 Circuit Diagram for 4 x 1 Multiplexer

        Implementation and Observations

        Implement the 4 x 1 Multiplexer circuit (figure 62) on a bread board (prepare the pin diagram (use appendix A) and refer to laboratory session 01 for implementation procedure) and record the observations in the following table For each data select combination specify the switch number as well as the binary value present on that selected switch

        S1 S0 Output 0 0 0 1 1 0 1 1

        TESTING OF 74150 - 16 x 1 MUX

        The 74150 IC has sixteen data inputs and four data-selection lines Function of various pins of this IC is described below

        bull E0 through E15 Data input lines

        31

        Logic Design amp Switching Theory 1 lab Session 06 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering bull A B C D Data select lines with D being the MSB bull W Active low output line bull Grsquo Active low enable line bull VCC and GND Supply connections lines

        Circuit Diagram

        Figure 63 Pin connections of 74150 for selecting E0

        Testing Procedure

        bull Make connections as shown in the circuit diagram bull Apply different data (1 or 0) at data inputs that are labeled as E0 to E15 Only

        connection for E0 is shown is the figure for simplicity bull Select the data input E0 with the help of data selectors A B C and D bull Observe the output which shows the complement of the data from E0 bull Select all the sixteen data inputs one by one and record your observations in the

        following table

        32

        Logic Design amp Switching Theory 1 lab Session 06 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

        33

        Observations

        Grsquo D C B A W Grsquo D C B A W 0 0 0 0 0 0 1 0 0 0 0 0 0 0 1 0 1 0 0 1 0 0 0 1 0 0 1 0 1 0 0 0 0 1 1 0 1 0 1 1 0 0 1 0 0 0 1 1 0 0 0 0 1 0 1 0 1 1 0 1 0 0 1 1 0 0 1 1 1 0 0 0 1 1 1 0 1 1 1 1

        ACTIVITY 1 Consider 4x1 Multiplexer Draw the output wave-form for the following data inputs

        (E0 E1 E2 E3) and select lines A B (B being the MSB) Output is W

        E3 E2 E1 E0 A B

        W

        2 Using the 4 x 1 MUX designed in this laboratory session implement the following logical function F (A B C) = Σ (0147)

        Show your working and input connections in the following block diagram according to the circuit you have implemented

        4 x 1 MUX

        S0 S1

        Output D0

        D1

        D2

        D3

        Logic Design amp Switching Theory 1 Lab Session 07 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

        Lab Session 07

        OBJECT

        bull Designing of a 2 x 4 Decoder 1 x 4 Demultiplexer bull Experimenting with 74138 IC

        COMPONENTS AND APPARATUS REQUIRED 1 Following ICs and their Datasheets

        bull 7408 Quad 2-input or 7411 Triple 3-input AND Gates bull 7404 Hex Inverter bull 74138 3 x 8 Decoder

        2 Digital Trainer DT-01 or the following components Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches THEORY

        Decoder A Decoder is a combinational circuit that converts binary information form n input lines to a maximum of 2n unique output lines In practical applications decoders are often used for selecting one of several devices

        Demultiplexer A decoder with an enable input can function as a Demultiplexer A Demultiplexer (DMUX) id a circuit that receives information on a single line and transmits this information on one of 2n possible output lines The selection of a specific output line is controlled by the bit values of n selection lines DESIGN OF A 2 x 4 DECODER 1 x 4 DEMULTIPLEXER A 2 x 4 decoder is capable of selecting one of four output lines (see figure 71 (a)) The 2-bit binary number at the data inputs S1 and S0 specifies which of the four data inputs is to be selected If we add an enable pin and use it as an input line then this decoder can be converted to a 1 x 4 Demultiplexer where S1 and S0 will select a line to which data input is to be routed (see figure 71 (b))

        Select S0 S0 Inputs

        S1 D0 D1

        D2

        D3

        Enable (a) Block Diagram of a 2 x 4 Decoder

        Figure 71

        S1 D0 D1

        D2

        D3

        Inputs

        Data Input (b) Block Diagram of a 1 x 4 Demulptiplexer

        34

        Logic Design amp Switching Theory 1 Lab Session 07 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

        Figure 72 Circuit Diagram for 2 x 4 Decoder 1 x 4 Demultiplexer

        Implementation and Observations Implement the 2 x 4 Decoder 1 x 4 Demultiplexer circuit (figure 72) on a bread board (prepare the pin diagram (use appendix A) and refer to laboratory session 01 for implementation procedure) and record the observations in the following table

        Enable Data Input S1 S0 D0 D1 D2 D3

        0 0 0 0 0 1 0 1 0 0 1 1 1 0 0 1 0 1 1 1 0 1 1 1

        TESTING OF 74138 3 x 8 Decoder The 74138 IC has three inputs and eight output lines It has three enable inputs and for the IC to function all three inputs need to be enabled Function of various pins of this IC is described below

        35

        Logic Design amp Switching Theory 1 Lab Session 07 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

        bull Y0 through Y7 Active low data outputs bull A B C Input select lines with C being the MSB bull G1 Active high enable Input bull G2Arsquo and G2Brsquo Active low enable Inputs bull VCC and GND Supply connections lines Circuit Diagram

        Figure 73 Pin connections of 74138

        Testing Procedure

        bull Make connections as shown in the circuit diagram bull Apply different combinations of 1s and 0s at data inputs bull Observe the output and record your observations in the following table

        Observations

        C B A Y0 Y1 Y2 Y3 Y4 Y5 Y6 Y7 0 0 0 0 0 1 0 1 0 0 1 1 1 0 0 1 0 1 1 1 0 1 1 1

        36

        Logic Design amp Switching Theory 1 Lab Session 07 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

        37

        ACTIVITY ACTIVITY 1 What will be the binary values at the outputs Y0 through Y7 of 74138 if 1 What will be the binary values at the outputs Y0 through Y7 of 74138 if

        bull All three enable pins are connected to ground bull All three enable pins are connected to ground __________________________________________________________________________________________________________________________________________ __________________________________________________________________________________________________________________________________________ _____________________________________________________________________ _____________________________________________________________________

        bull All three enable pins are connected to VCC bull All three enable pins are connected to VCC _______________________________________________________________________________________________________________________________________________________________________________________________________________

        _______________________________________________________________________________________________________________________________________________________________________________________________________________

        2 Show connections for 74138 in order to use it as a 1 x 8 Demultiplexer 2 Show connections for 74138 in order to use it as a 1 x 8 Demultiplexer

        3 Consider a 2 x 4 Decoder with two enable inputs (one active high - G and one active low ndash Grsquo) Draw the output wave-forms for D0 D1 D2 and D3 if the two select inputs are A and B (B being the MSB) All outputs are active low

        Grsquo

        G

        A B

        D0 D1 D2

        D3

        Logic Design amp Switching Theory 1 Lab Session 08 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

        Lab Session 08 OBJECT

        bull Designing of a 4 x 2 Priority Encoder bull Experimenting with 74148 IC

        COMPONENTS AND APPARATUS REQUIRED

        1 Following ICs and their Datasheets

        bull 7408 Quad 2-input or 7421 Dual 4-input AND Gates bull 7432 Quad 2-input OR Gates bull 7404 Hex Inverter bull 74148 Encoder

        2 Digital Trainer DT-01 or the following components Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches

        THEORY

        Encoder An Encoder is a digital function that produces a reverse operation from that of a decoder An Encoder has 2n (or less) input lines and n output lines The output lines generate the binary code for the 2n input variables Priority Encoder

        A simple encoder may produce an erroneous output if more than one of its inputs is high A Priority Encoder is one that responds to just one input among those that may be simultaneously high in accordance with some priority system The most common priority system is based on the relative magnitudes of the inputs whichever decimal input is largest is the one that is encoded

        DESIGN OF A 4 x 2 Priority Encoder

        The following equations represent the outputs of a 4 x 2 priority encoder 32 DDA +=

        321 DDDB += As can be seen from the equations that input D0 which has a binary code 00 is not used in any equation A binary code 00 at the output indicates two conditions Either D0 is selected or no input is selected In order to differentiate these two conditions we will provide an additional output Z to indicate if at least one of the inputs is a 1 The equation for Z will be

        4321 DDDDZ = If Z is 0 then the binary code 00 at the output indicates that D0 is selected and if Z is 1 then it indicates that no input line is selected

        38

        Logic Design amp Switching Theory 1 Lab Session 08 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

        Figure 81 Circuit Diagram for 4 x 2 Priority Encoder

        it (figure 81) on a bread board (prepare the to laboratory session 01 for implementation

        Implementation a Implement the 4 x 2 Priority Encoder circu

        ram (use appendix A) and refer

        nd Observations

        pin diagprocedure) and record the observations in the following table

        D3 D2 D1 D0 A B 0 0 0 1 0 0 1 x 0 1 x x 1 x x x

        TESTING OF 74148 8 x 3 Octal Priority Encoder

        imal digits There are nine of which three represents

        ing any of the inputs is high

        then it shows that line 0 is selected and if e inputs selected E0 and GS

        cannot be in the same state provided that E1 is enabled

        The 74148 is a priority encoder with active-Low input for dec

        input) and five output linesinputs lines (including an enablethe binary code for the octal digit Function of various pins of this IC is described below

        bull 0 through 7 Active low data inputs representing the octal digits A2 A1 A0 Active low output lines representing the binary code bullbull E1 Active low enable Input bull E0 Active low output indicating none of the inputs is high bull GS Active low output indicatbull VCC and GND Supply connections lines Therefore if GS A2 A1 and A0 are all low

        then it shows that none of thE0 A2 A1 and A0 are all low

        39

        Logic Design amp Switching Theory 1 Lab Session 08 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

        Circuit Diagram

        Figure 82 Pin connections of 74148

        Testing Procedure bull Make connections as sho

        binations of 1s and 0s at data inputs d record your observations in the following table

        GS E0

        wn in the circuit diagram bull Apply different combull Observe the output an Observations

        0 1 2 3 4 5 6 7 A2 A1 A0 1 1 1 1 1 1 1 1 x x x x x x x 0 x x x x x x 0 1 x x x x x 0 1 1 x x x x 0 1 1 1 x x x 0 1 1 1 1 x x 0 1 1 1 1 1 x 0 1 1 1 1 1 1 0 1 1 1 1 1 1 1

        40

        Logic Design amp Switching Theory 1 Lab Session 08 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

        41

        CTIVITY

        Cascade the following two 74148 8 x 3 Priority Encoders to form 16 x 4 Priority

        A 1

        Encoder

        Logic Design amp Switching Theory 1 Lab Session 09 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering `

        Lab Session 09 OBJECT

        Designing an Odd Parity Generator and Checker for a 3-bit Data COMPONENTS AND APPARATUS REQUIRED

        1 Following ICs and their Datasheets

        bull 7486 Quad 2-input Exclusive-OR Gates bull 7404 Hex Inverter

        2 Digital Trainer DT-01 or the following components Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches

        THEORY

        Parity Generator When binary data is transmitted and processed it is ndash as are all electrical signals ndash susceptible to noise that can either alter or distort its contents 1s may be effectively changed to 0s and 0s to 1s To overcome this problem one or more bits are often added to the data as an aid in detecting errors caused by noise The most common of these is a Parity bit that signifies whether the total number of 1s in a code group is odd or even In an Odd Parity system the parity bit is made 0 or 1 as necessary to make the total number 1s odd (counting the parity bit itself) In an Even Parity system the parity bit is chosen to make the total number of 1s even Table 91 shows how parity bits would be added to BCD code group in both systems

        Decimal BCD Value Parity Bit ABCD Odd Parity Even Parity

        0 0000 1 0 1 0001 0 1 2 0010 0 1 3 0011 1 0 4 0100 0 1 5 0101 1 0 6 0110 1 0 7 0111 0 1 8 1000 0 1 9 1001 1 0

        Table 91 Odd and Even Parity in BCD

        When digital data is received a parity checking circuit generates an error signal if the total number of 1s is odd in an even parity system or if it is even in an odd parity system Parity check always detects a single error (one bit change from 0 to 1 or 1 to 0) but may not detect

        42

        Logic Design amp Switching Theory 1 Lab Session 09 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering ` two or more errors Odd parity is used more often than even parity because even parity does not detect a situation where all 0s are created due to short circuit or other fault condition DESIGN OF A 3-BIT ODD PARITY GENERATOR AND CHECKER Let x y and z be the three bits that constitute the message and are the input to the Odd Parity Generator Circuit Since it is an odd parity system the bit P is generated so as to make the total number of 1s odd (including P) The function P can be expressed as follows P = x oplus y Ο z or P = x Ο y oplus z Since the IC available is 7486 which is quad 2input XOR IC therefore we will convert XNOR also to XOR

        P = x oplus y Ο z

        P = ( x oplus y ) Ο z Since for even number of variables ______

        XOR = XNOR Therefore ___________ _________

        P = ( x oplus y ) oplus z = x oplus y oplus z This logical expression can be implemented with two XOR gates and an inverter (see figure 91)

        Figure 91 Circuit Diagram for a 3-bit Parity Generator

        The 3-bit message and the parity bit are transmitted to their destination where they are applied to a Parity Checker Circuit An error occurs during transmission if the parity of the four bits received is even since the binary information transmitted was originally odd The output C of the parity checker should be a 1 when an error occurs ie when the number of 1s in the four inputs is even Therefore the function C can be expressed as

        C = x Ο y Ο z Ο P

        Using the same logic applied for the conversion of the equation of P

        PzyxC oplusoplusoplus= This logical expression can be implemented with three XOR gates and an inverter (see figure 92)

        43

        Logic Design amp Switching Theory 1 Lab Session 09 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering `

        44

        Figure 92 Circuit Diagram for a 3-bit Parity Checker Implementation and Observations Implement the 3-bit Parity Generator and Checker circuits (figure 91 and 92) on a bread board (prepare the pin diagram (use appendix A) and refer to laboratory session 01 for implementation procedure) and record the observations in the following table

        x y z P x y z P C x y z P C 0 0 0 0 0 0 0 1 0 0 0 0 0 1 0 0 0 1 1 0 0 1 0 1 0 0 0 1 0 1 0 1 0 0 1 1 0 0 1 1 1 0 1 1 1 0 0 0 1 0 0 1 1 0 0 1 0 1 0 1 0 1 1 1 0 1 1 1 0 0 1 1 0 1 1 1 0 1 1 1 0 1 1 1 1 1 1 1

        Odd Parity Generation Odd Parity Check ACTIVITY 1 Try using the parity checker of figure 92 as 3-bit parity generator Write the details here

        _____________________________________________________________________________________________________________________________________________________________________________________________________________________ ______________________________________________________________________________________________________________________________________________ _______________________________________________________________________ ______________________________________________________________________________________________________________________________________________

        Logic Design amp Switching Theory 1 Lab Session 10 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

        Lab Session 10 OBJECT

        Driving a seven segment display using 7447 7448 driver IC COMPONENTS AND APPARATUS REQUIRED

        1 Following ICs and their Datasheets

        bull Seven Segment Displays (Common Anode Common Cathode) bull 7447 7448 BCD to Seven Segment Driver

        2 Digital Trainer DT-01 or the following components Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches

        THEORY Seven Segment Displays A Seven Segment Display consists of seven light-emitting segments The segments are designated by letters a through g (see figure 101) By illuminating various combinations of segments the numerals 0 through 9 can be displayed Seven Segment Displays are commonly constructed with light-emitting diodes (LEDs) and with liquid-crystal displays (LCDs) LEDs generally provide greater illumination levels but require much greater power than LCDs An LED display can be a common-anode type or common cathode type In common anode type a high voltage is applied at the common terminal of the display and low voltage is applied at a segmentrsquos terminal for illumination In the common-cathode type a low voltage is applied at the common terminal of the display and high voltage is applied at a segmentrsquos terminal for illumination

        Figure 101 Seven Segment Display

        a f b g

        e c d

        7447 7448 BCD to Seven Segment Driver 7447 7448 IC is particularly used to drive Seven Segment Its input is a BCD number and output drives a seven segment display 7447 is used to drive common-anode displays whereas 7448 is used to drive common cathode displays 7447 7448 is a 16 pin IC Function of various pins of these ICs is described below

        bull A B C D Inputs representing BCD digits (D being the MSB)

        45

        Logic Design amp Switching Theory 1 Lab Session 10 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering bull OA through OG Outputs to drive segments a through g of the display (Active low

        in 7447 and active high in 7448) bull RBI Ripple Blanking Input Turns off all the segments if kept low provided that LT

        is kept high and all other inputs (A B C D BI) are kept low Should be kept high otherwise

        bull BI RBO Wire-AND logic serving as a Blanking Input and or Ripple Blanking Output

        o BI Turns off all the segments if low o RBO Goes to a low level (response condition) along with other outputs when

        RBI and inputs A B C and D are low with LT input at high level bull LT Lamp Test input Tests whether all segments are working or not Illuminates all

        segments if kept low provided that BI is kept high Should be kept high otherwise bull VCC and GND Supply connections lines CIRCUIT DIAGRAM

        Figure 102 Circuit diagram for 7447driving a common-anode display

        IMPLEMENTATION AND OBSERVATIONS

        bull Make connections as shown in the circuit diagram (refer to laboratory session 01 for implementation procedure)

        bull Apply different combinations of 1s and 0s at data inputs bull Observe the output and record your observations in the following table

        46

        Logic Design amp Switching Theory 1 Lab Session 10 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

        47

        Decimal Digit

        BCD Inputs Seven Segment Outputs D C B A a b c d e f g

        0 0 0 0 0 1 0 0 0 1 2 0 0 1 0 3 0 0 1 1 4 0 1 0 0 5 0 1 0 1 6 0 1 1 0 7 0 1 1 1 8 1 0 0 0 9 1 0 0 1

        ACTIVITY 1 Perform the Lamp Test for the designed circuit and write your observations

        ____________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________

        2 How can you use 7447 IC to drive a common-cathode display

        ____________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________

        3 What symbols appear in the seven segment display if inputs DCBA are

        DCBA Symbol

        1010

        1011

        1100

        1101

        1110

        1111

        Logic Design amp Switching Theory 1 Lab Session 11 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

        48

        Lab Session 11 OBJECT

        Testing different modes of JK-FF COMPONENTS AND APPARATUS REQUIRED 1 Following ICs and their Datasheets

        bull 7473 7476 JK Flip-Flop 2 Digital Trainer DT-01 or the following components

        Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches

        THEORY

        Flip-Flop A flip-flop circuit can maintain a binary state indefinitely (as long as the power is delivered to the circuit) until directed by an input signal to switch states The major differences among various types of flip-flops are in the number of inputs they possess and in the manner in which the inputs affect the binary state

        JK Flip-Flop JK flip flop is an edge triggered device A typical JK flip flop has three inputs J K and a clock input The flip-flop can be either positive or negative edge triggered The output Q is available in complemented form as well Beside the usual inputs and output most of the flip-flop IC also possess two asynchronous inputs namely Preset and Clear These inputs are usually active low If used Preset and Clear inputs keep the flip-flop in set and reset state respectively irrespective of the other inputs Both of these inputs cannot be used simultaneously otherwise they will bring the flip-flop in unstable state

        Figure 111 Symbol for JK flip-flop

        (a) positive-edge triggering (b) active low Preset (PR) and Clear (CLR) with positive-edge triggering

        (c) active low Preset (PR) and Clear (CLR) with negative-edge triggering

        Logic Design amp Switching Theory 1 Lab Session 11 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

        49

        TESTING OF 7473 7476 DUAL JK FLIP-FLOP

        Both the ICs 7473 and 7476 are similar in functionality except for one difference The flip-flops in 7473 have only one type of active low asynchronous input which is the Clear input whereas the flip-flops in 7476 have both Preset and Clear inputs Both these ICs have negative edge triggered flip-flops

        Circuit Diagram

        Figure 112 Pin connections of 7476

        Testing Procedure

        bull Make connections as shown in the circuit diagram (figure 112) bull Apply different combinations of 1s and 0s at J and K inputs bull Observe the output and record your observations in the following table

        Observations

        J

        K Q

        0 0 0 1 1 0 1 1

        ACTIVITY

        1 Observe the output Q of JK flip-flop if the clock input is connected to VCC or GND instead of a clock source Write your observations here __________________________________________________________________________________________________________________________________________ _______________________________________________________________________________________________________________________________________________________________________________________________________________

        Logic Design amp Switching Theory 1 Lab Session 12 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

        50

        Lab Session 12 OBJECT

        Designing sequential circuit for the given state diagram using D flip-flop GIVEN STATE DIAGRAM

        00

        11

        Figure 121 State Diagram COMPONENTS AND APPARATUS REQUIRED 1 Following ICs and their Datasheets

        bull 7474 D Flip-Flop bull ICs of basic gates (AND OR NOT XOR etc) as required

        2 Digital Trainer DT-01 or the following components Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches

        THEORY

        Sequential Circuits In Sequential Circuits the output not only depends on the present inputs but also on previous states of the circuit These circuits use memory elements (latches flip-flops) and the binary information stored in the memory elements at any given time defines the state of the sequential circuit Analysis of a Sequential Circuit The behavior of a sequential circuit is determined from the inputs the outputs and the states of its flip-flops Both the outputs and next state are a function of the inputs and the

        10

        01

        00 11 10

        00

        00 11 10 00

        Logic Design amp Switching Theory 1 Lab Session 12 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

        51

        present state The analysis of a sequential circuit form a state diagram comprises of the following bull Selecting a particular flip-flop to design the circuit bull Obtaining state table from the state diagram bull Finding input equations for the selected flip-flop bull Finding state equations (not required for the construction of circuit) bull Implementing the circuit using selected flip-flops and their input equations ANALYZING THE GIVEN STATE DIAGRAM D Flip-Flop D flip-flop is also called transparent flip-flop as it simply transfers the input data to the output For our design we require the graphical symbol and excitation table of D flip-flop (see figure 122)

        Qt Qt+1 T 0 0 0 0 1 1 1 0 0 1 1 1

        (b) Excitation table of D Flip-Flop

        (a) Graphical Symbol

        Figure 122 Characteristic equation of D flip-flop is Q(t+1) = D State Table The given state diagram has four states so we will need two D flip-flops (FF-0 FF-1) Form state table form the given state diagram and record the results in the following table

        Present State Input Next State Output Input to FF-0 D0

        Input to FF-1 D1 Q1t Q0t x Q1(t+1) Q0(t+1) z

        Logic Design amp Switching Theory 1 Lab Session 12 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

        52

        Input Equations Using Karnaugh map the input equations D0 and D1 for the two flip-flops can be found

        D0 D1 Q0x

        Q1

        _ _ Q0x

        _ Q0x

        Q0x

        _ Q0x

        Q0x

        Q1

        _ _ Q0x

        _ Q0x

        Q0x

        _ Q0x

        _ Q1

        _ Q1

        Q1

        Q1

        D0 = _________________ D1 = _________________

        State Equations Using the characteristic equation of D flip-flop we can find the state equations Q0(t+1) and Q1(t+1) for the to flip flops Q0(t+1) = _______________________ Q1(t+1) = _______________________ _______________________ _______________________ _______________________ _______________________ Circuit Diagram

        Logic Design amp Switching Theory 1 Lab Session 12 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

        53

        Implementation Procedure and Observations

        1 Implement the circuit using digital ICs on a bread board (prepare the pin diagram (use appendix A) and refer to laboratory session 01 for procedure)

        2 Make the clear inputs of the flip-flops low (to clear the flip-flops) The flip-flops will remain in clear state as long as the clear inputs are connected to low level

        3 Connect output Q0 and the clock pulse to an oscilloscope 4 Apply 0 to the input x 5 Now make the clear inputs to high 6 Observe the waveform for the first 5 clock pulses and record it 7 Repeat steps 2 to 6 keeping x=1 in step 4 this time 8 Repeat steps 2 to 7 this time connecting Q1 instead of Q0 to the oscilloscope in step

        3 Record your observations (Keep frequency of the clock pulse low (eg1Hz) so that the output waveforms can be observed easily)

        1 2 3 4 5 Clock Pulse

        Output Waveform for Q0 when x=0

        Output Waveform for Q0 when x=1

        Output Waveform for Q1 when x=0

        Output Waveform for Q1 when x=1

        Logic Design amp Switching Theory 1 Lab Session 13 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

        Lab Session 13 OBJECT

        Designing a modulo-5 asynchronous up-counter using JK-FF COMPONENTS AND APPARATUS REQUIRED

        1 Following ICs and their Datasheets

        bull 7400 Quad 2-input or 7410 Triple 3-input NAND Gates bull 7476 7473 JK Flip-Flop

        2 Digital Trainer DT-01 or the following components Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches

        THEORY

        Digital Counters A digital counter is a set of flip-flops whose states change in response to pulses applied at the input to the counter The flip-flops are interconnected so that their combined state at any time is the binary equivalent of the total number of pulses that have occurred up to that time Every counter resets after a certain number of clock pulses Thus as it name implies a counter is used to count pulses An n stage counter can count up to a maximum of 2n states n is equal to the number of flip-flops required for the construction of counter

        Modulus Counters The number of input pulses that causes a counter to reset to its initial count is called the modulus of the counter Thus the modulus equals to total number of distinct states (counts) including zero that a counter can store A binary counter with n stages is a modulo-2n (or mod-2n) counter The largest count a mod-N counter can achieve is N-1 ie a mod-N counter never reaches the binary number equal to its modulus N is always equal to or less than 2n Counters can be classified as bull Synchronous Counters which are clock driven All the flip-flops are driven by a

        single clock bull Asynchronous Counters which are event driven Clock input is given to the first

        flip-flop only Rest of the flip-flops are driven by their preceding flip-flops

        DESIGN OF A MOD-5 ASYNCHRONOUS UP COUNTER The number of flip-flops required to construct a mod-5 counter is 3 because 5 should be less than or equal to 2n This counter will count from 0 to 4 a total of 5 distinct states Since a 3-stage counter can count up to 8 states at maximum a NAND gate is used to reset it after 5 clock pulses Figure 131 shows the logic diagram

        54

        Logic Design amp Switching Theory 1 Lab Session 13 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

        55

        Figure 131 A Mod-5 Asynchronous Up Counter

        Implementation and Observations

        Implement the mod-5 counter circuit (figure 131) on a bread board (prepare the pin diagram (use appendix A) and refer to laboratory session 01 for implementation procedure) and record the observations in the following table

        Clock Pulse Q2 Q1 Q0

        0 1 2 3 4 5 6 7

        ACTIVITY

        Draw the timing diagram for mod-5 counter designed in this laboratory session

        Logic Design amp Switching Theory 1 Lab Session 14 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

        Lab Session 14 OBJECT

        Experimenting with 74194 4-bit bidirectional universal shift register COMPONENTS AND APPARATUS REQUIRED

        1 Following ICs and their Datasheets

        bull 74194 4-bit bidirectional universal shift register 2 Digital Trainer DT-01 or the following components

        Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches

        THEORY

        Shift Registers

        A Register is a set of flip-flops used to store binary data A register which is capable of shifting its binary information either to the right or left is called a shift register The logical configuration of a register consists of a chain of flip-flops connected in cascade with the output of one flip-flop connected to the input of next flip-flop All flip-flops receive a common clock pulse which causes the shift from one stage to the next

        Bidirectional Shift Registers A bi-directional shift register is one whose bits can be shifted from left to right or from right to left

        Universal Shift Registers A universal shift register is a bi-directional register whose input can be in either serial or parallel form and whose output can be in either serial or parallel form

        74194 4-BIT BIDIRECTIONAL UNIVERSAL SHIFT REGISTER

        The 74194 register provides parallel as well as serial loading in both directions Function of various pins of this IC is described below

        bull A B C and D Active high inputs for parallel loading bull QA QB QC and QD Active high outputs bull S0 and S1 Active high mode control inputs The following table shows combinations

        of S1 and S0 to enable various modes

        S1 S0 Clock Action 0 0 x No change 0 1 uarr Shift right 1 0 uarr Shift left 1 1 uarr Parallel load

        uarr shows the rising edge of the clock pulse

        56

        Logic Design amp Switching Theory 1 Lab Session 14 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering bull SR Active high serial input for right shifting bull SL Active high serial input for left shifting bull CLR Active low input Clears all the flip-flops of the register if set to 0 should be

        kept high otherwise bull CLK Clock input bull VCC and GND Supply connections lines Thus A B C and D are inputs for parallel loading whereas SR and SL are inputs for serial loading with right or left shifting respectively S1 and S0 are used to select the loading mode Circuit Diagram

        Figure 141 Pin connections of 74194 Testing Procedure

        bull Make connections as shown in the circuit diagram bull Observe the output for the input combinations given in the following table

        57

        Logic Design amp Switching Theory 1 Lab Session 14 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

        58

        Observations

        S1 S0 SL SR A B C D QA QB QC QD 0 0 0 1 0 0 0 0 0 1 1 0 0 0 0 1 1 0 0 0 0 0 1 0 1 1 0 0 0 0 1 1 0 0 1 1 0 1 0 0 0 1 1 1 0 1 0 1 1 0 1 0 0 1 1 0 1 1 1 0 0 1 1 1 1 1 0 0 1 1 1 1

        ACTIVITY 1 Show connections of 74194 to convert it into a ring counter with right shifting

        Logic Design amp Switching Theory 1 Lab Session 15 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

        Lab Session 15

        OBJECT

        Experimenting with 74245 octal bus transceivers using parallel port PC interfacing COMPONENTS AND APPARATUS REQUIRED 1 Parallel Port Connectors (DB-25) with Cable 2 Personal Computer with Windows 98 and TurboC Compiler Installed 3 Following ICs and their Datasheets

        bull 74245 Octal Bus Transceivers with 3-State Outputs 4 Digital Trainer DT-01 or the following components

        Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches

        THEORY

        3-State Logic Sometimes it is necessary to isolate one part of circuit from the other part For this purpose some TTL ICs are designed with 3-state logic Such devices have three possible output states high low and high impedance The device can be put into high impedance state by a control signal applied to an appropriate pin When such a device is in high impedance state there is very high impedance at its output effectively isolating the device from whatever circuitry the output normally drives 74245 Octal Bus Transceivers A bus is any conducting path or set of paths having electrical connections to one or more devices 74245 octal bus transceivers are mainly used to control connectivity between two devices or circuits It also provides direction control for signal flow Function of various pin of this IC is given below

        bull A1 through A8 Bus A bull B1 through B8 Bus B bull G΄ Active low enable input When high sets all the bus pins to high impedance state bull DIR Direction control for signal flow When set to high logic level transfers bus A

        data to B bus When set to low logic level transfers bus B data to A bus bull VCC and GND Supply connections lines Serial and Parallel Port Connectors A Parallel Port can consist of only 25 pin port adapter called a DB-25 and a serial port can consist of either a 25 pin port adapter called a DB-25 or 9 pin adapter called a DB-9 port adapter Whether the port is a 9 pin or 25 pin it can accomplish all of the same tasks that serial port communications have been designed for

        59

        Logic Design amp Switching Theory 1 Lab Session 15 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

        60

        Each adapter can be a male type connector with pins or a female type adapter with tiny holes Generally a PRINTER port (called LPT1) on the back of a computer is female type adapter and we need to use MALE DB-25 pin cable on it for PRINTER connection or for parallel LAPLINK cable And a COM port on the back of a computer is male for the serial ports but it may not necessarily be Parallel Port Connector ndash DB-25 The DB-25 connector (named for its B-size D-shaped shell and 25 pins) is practically ubiquitous in the electronics industry The DB-25 connector is used for a variety of purposes Two common applications are RS-232EIA-232 (serial) connections and the parallel printer interface on the IBM PC The DB-25 connector is also used for SCSI connections Normally the parallel port is used for output to a printer or other device It sends data 8-bits or one byte at a time in parallel The other lines available on the DB-25 connector are a combination of status lines control lines and ground lines The status and control lines are used for handshaking commands and feedback when we are talking to a printer

        Figure 152 DB-25 Female Figure 151 DB-25 Male

        Figure 153 Pin Layout for DB-25 As can be seen form figure 153 there are four types of pins in this connector

        bull Data pins (8 pins - D0 to D7) Active high bidirectional lines

        Logic Design amp Switching Theory 1 Lab Session 15 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering bull Control pins (4 pins - C0 to C3) C0 C1 and C3 are active low whereas C2 is active

        high These lines also are bidirectional bull Status pins (5 pins ndash S3 to S7) Only S7 is active low rest are active high input lines bull Ground pins (8 pins) Used as a reference signal for the low (below 05 volts) charge

        Parallel Port Addresses A DB-25 connector at a parallel port has three address one for each kind of pins register data status and control The first or base address generally refers to data register Second address is for status register and the third one is for control register In Windows 98 the base address is usually found to be 278H 378H or 3BCH Now if 378H is the base address then it refers to the data register whereas addresses for status and control register are respectively 379H and 37AH For Windows 98 the base address can be found as follows 1 On your Desktop right-click on My Computer and select Properties 2 Click on the Device Manager tab and find LPT1 under Plug and Play BIOS 3 After selecting LPT1 click the Properties button 4 Next select the Resources tab and the address should then appear next to InputOutput

        Range Accessing parallel port through C Language Programming There are multiple functions in C Language for accessing external ports The most commonly used are listed below

        bull unsigned char inportb(int portid) inportb reads a byte from a hardware port

        bull int inport(int portid) reads a word from a hardware port

        bull void outportb(int portid unsigned char value) outputs a byte to a hardware port

        bull void outport(int portid int value) outputs a word to a hardware port

        portid refers to the port address whereas value refers to the data to be sent TESTING 74245 USING PARALLEL PORT PC INTERFACING At one end the parallel port connector will be connected to the PC via parallel port cable and another connector (to be plugged into the PC parallel port slot) At the other end it will be connected to the buffer IC 74245 Data lines of the connector will be used to transfer 8-bit data between the PC and the buffer Out of the 8-bits of 74245 4-bits will be used to enter data which will be displayed at the monitor through a C language

        61

        Logic Design amp Switching Theory 1 Lab Session 15 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering program The remaining 4-bits will receive data from PC as entered by the user via keyboard

        Circuit Diagram

        Figure 154 Interface of 74245 to PC via Parallel Port

        Procedure

        1 Connect the DB-25 connector to the PC at one end and solder it to the circuit board at the other end

        2 Connect various pins of the connector and 74245 according to the circuit diagram shown in figure 152

        3 Using the functions listed in the previous section write a program in C language to operate various pins of the buffer The user interface of the program should provide option to the user whether to send or receive data from the port

        4 Set DIR switch to 1 5 Try sending some data bits to the port The result should be displayed at the LEDs 6 Set DIR switch to 0 7 Set some binary 4-bit value through the switches Try reading it via parallel port

        C Language Program

        A program to access parallel port for data transfers

        use header file include ltstdiohgt main program void main() define variable

        62

        Logic Design amp Switching Theory 1 Lab Session 15 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering unsigned int data=0 char choice while(1) printing option menu clrscr() printf(This program will send or receive a BCD digit from the parallel portn) printf(nPress your choice numbern) printf(n1 Send Data) printf(n2 Receive Data) printf(n3 Exitn) choice = getch() sending entered digit to the port if(choice == 1) input BCD digit printf(nEnter BCD digit to be sent to the port) data = getche() masking the first four bits data = data amp 0x0f sending to the port outportb(0x378data) printf(nThe BCD digit c has been sent to the port data) printing on screen the data received from the port else if(choice == 2) receiving data from the port data = inportb(0x378) masking the last four bits data = data amp 0xf0 shifting first four bits to make them the last four bits datagtgt=4 printf(nThe BCD digit set at the port is c data) exit else if(choice == 3) break key pressed is not in the menu else printf(nEnter valid choice number) printf(nnPress any key to continue) getch()

        63

        Logic Design amp Switching Theory 1 Lab Session 15 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

        ACTIVITY 1 In the above circuit DIR and G΄ inputs are hardwired Connect them to status or

        control pins of the parallel port connector and control their function through your software program Circuit Diagram Program Code ______________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________

        ___________________________________________________________________________________________________________________________________________________

        64

        Logic Design amp Switching Theory 1 Lab Session 15 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

        65

        _____________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ _____________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ _______________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ _________________________________________________ _________________________________________________

        Logic Design amp Switching Theory 1 Appendix A NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

        Appendix A

        PIN DIAGRAMS OF THE ICS REQUIRED FOR THE LABORATORY SESSIONS Consult the TTLIC data book for internal diagrams and electrical characteristics of these ICs 7400 Quad 2-Input NAND 7402 Quad 2-Input NOR

        7404 Hex Inverter 7408 Quad 2-Input AND

        7410 Triple 3-Input NAND 7411 Triple 3-Input AND

        7421 Dual 4-Input AND 7432 Quad 2-Input OR

        66

        Logic Design amp Switching Theory 1 Appendix A NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

        BCD-to-Seven Segm 7448 BCD-to-Seven Segment 7447 ent

        Decoder (15V OC) Decoder (2kΩ pull-up output)

        7473 Dual JK Flip-Flop 7474 Dual D-Type Flip-Flop

        7476 Dual JK Flop-Flop -Bit Binary Full Adder 7483 4 with Fast Carry

        86 Quad 2-Inpu 74138 3-to-8 Line 74 t Exclusive OR Decoder Demultiplexer

        67

        Logic Design amp Switching Theory 1 Appendix A NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

        68

        74148 8-to-3 Line 16-to-1 Line Data

        Priority Encoder 74150 Selector Multiplexer

        74245 Oct nsceivers Universal Shift Register (PIPO) (3-State)

        74194 4-Bit Bidirectional al Bus Tra

        Logic Design amp Switching Theory 1 Appendix B NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

        Appendix B

        DEBOUNCING CIRCUITRY FOR MECHANICAL SWITCHES Mechanical switches form the interface between human beings and computers or other digital systems For example a keyboard is a matrix of switches used to supply alphanumeric data to a computer Whatever the switch design it is a potential source of problems due to contact bounce The contact bounce creates a sense of narrow pulses when a switch is opened or closed An example of device whose operation would be adversely affected by contact bounce is a digital counter used to count the number of times a switch is depressed Eliminating the effects of contact bounce is called debouncing When data is entered into a computer via a keyboard a software debounce is often used This type of debouncing is a program that causes the computer to sample the switch terminal (ie to input data from it) many times in succession during the interval of time that contact bounce occurs If the data is sensed to be 1s (or 0s) for a specific number of consecutive samples then it is assumed that contact bounce has ended and the last value sensed is valid Hardware debouncing is the use of electronic circuitry to eliminate the effects of contact bounce There are numerous versions of such circuitry including those that use monostable multivibrators (one-shots) but the most straightforward is simply an RS latch Figure B1 shows the circuit When the switch is in position 1 R = 0 and S = 1 so the latch is set and the output (Q) is 1 When the switch is in position 0 R = 1and S = 0 so the latch is reset and the output is 0 When the switch is moved form one position to the other the latch changes state and bouncing occurs at either the R or the S input The bouncing does not affect the latch after it has change state An RS latch will remain set for example when its R input is 0 and its S input is alternately changed form 1 to 0

        Figure B1 Use of RS latch to debounce a mechanical switch

        69

        • 01-ldst-Outer title
          • Practical Workbook
          • Logic Design amp Switching Theory I
            • Dept of Computer amp Information Systems Engineering
              • NED University of Engineering amp Technology
              • Karachi ndash 75270 Pakistan
                • 02-ldst-inner Title
                  • Practical Workbook
                  • Logic Design amp Switching Theory I
                    • Dept of Computer amp Information Systems Engineering
                      • NED University of Engineering amp Technology
                      • Karachi ndash 75270 Pakistan
                        • 03-ldst-general info
                        • 04-ldst-introduction
                        • 05-Table of Contents
                          • CONTENTS
                            • Lab Session No Object Page No
                            • 1
                            • Also implementing and testing the given circuit on a bread board
                              • Working with Electronics Workbench
                                • Driving a seven segment display using 7447 7448 driver IC
                                  • Designing a modulus-5 asynchronous up-counter using JK-FF
                                    • Experimenting with 74194 4-bit bidirectional universal shift register
                                        • 13
                                            • 06-ldst-Exp01
                                              • Lab Session 01
                                              • OBJECT
                                                • 1 Bread board
                                                • 2 5 V - power supply
                                                • 3 Multimeter
                                                • 4 Logic probe
                                                • 5 LEDs with resistors
                                                • 6 Connecting wires
                                                • 8 Following ICs and their datasheets
                                                  • THEORY
                                                    • Logic Gates
                                                    • 1 The AND Gate ndash An AND gatersquos output is 1 if and only if all its inputs are 1 If A and B are two inputs to an AND gate then output F of the gate is given as F = AB
                                                    • 2 The OR Gate - An OR gatersquos output is 1 if at least one of its input is 1 If A and B are two inputs to an OR gate then output F of the gate is given as F = A+B
                                                    • 3 The NOT Gate (Inverter) ndash Its output is 1 when its input is 0 and its output is 0 when the input is 1 ie it complements a digital variable If A is the input to a NOT gate then output F of the gate is given as
                                                    • 4 The NAND Gate ndash Its output is 1 if at least one of its input is 0 This gate performs the same logic as an AND gate followed by an inverter If A and B are two inputs to a NAND gate then output F of the gate is given as
                                                      • 5 The NOR Gate - The output of a NOR gate is 1 if and only if all its inputs are 0 This gate performs the same logic function as an OR gate followed by an inverter If A and B are two inputs to a NAND gate then output F of the gate is given as
                                                          • DATA SHEETS
                                                            • Logic expression for the given logic diagram __________________________________
                                                                • 07-ldst-exp02
                                                                  • Working with Electronics Workbench
                                                                    • 08-ldst-exp03
                                                                      • Designing Half and Full Adder Circuits
                                                                        • COMPONENTS AND APPARATUS REQUIRED
                                                                          • 1 Following ICs and their Datasheets
                                                                          • 7408 Quad 2-input AND Gate
                                                                          • 2 Digital Trainer DT-01 or the following components
                                                                            • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                            • Connecting wires Switches
                                                                              • THEORY
                                                                                  • IMPLEMENTATION AND OBSERVATIONS
                                                                                    • 09-ldst-Exp04
                                                                                      • Lab Session 04
                                                                                      • 1 Digital ICs and their Datasheets
                                                                                      • 7408 Quad 2-input AND Gate
                                                                                      • 2 Digital Trainer DT-01 or the following components
                                                                                        • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                        • Connecting wires Switches
                                                                                        • PROCEDURE
                                                                                        • REDUCTION OF LOGIC EXPRESSION USING KARNAUGH MAP
                                                                                        • OBSERVATIONS
                                                                                        • RESULT
                                                                                            • 10-ldst-Exp05
                                                                                              • Lab Session 05
                                                                                              • 1 Following ICs and their Datasheets
                                                                                              • 7408 Quad 2-input AND Gate
                                                                                              • 2 Digital Trainer DT-01 or the following components
                                                                                                • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                • (100 Ω) Connecting wires Switches
                                                                                                • THEORY
                                                                                                  • IMPLEMENTATION AND OBSERVATIONS
                                                                                                    • 11-ldst-Exp06
                                                                                                      • OBJECT
                                                                                                      • 1 Following ICs and their Datasheets
                                                                                                      • 7408 Quad 2-input AND Gates or 7411 Triple 3-input AND Gates
                                                                                                      • 2 Digital Trainer DT-01 or the following components
                                                                                                        • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                        • Connecting wires Switches
                                                                                                          • Figure 62 Circuit Diagram for 4 x 1 Multiplexer
                                                                                                          • Implementation and Observations
                                                                                                            • Circuit Diagram
                                                                                                              • ACTIVITY
                                                                                                                • 12-ldst-exp07
                                                                                                                  • 1 Following ICs and their Datasheets
                                                                                                                  • 7408 Quad 2-input or 7411 Triple 3-input AND Gates
                                                                                                                  • 2 Digital Trainer DT-01 or the following components
                                                                                                                    • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                    • Connecting wires Switches
                                                                                                                      • THEORY
                                                                                                                          • Figure 72 Circuit Diagram for 2 x 4 Decoder 1 x 4 Demultiplexer
                                                                                                                          • Implementation and Observations
                                                                                                                            • Circuit Diagram
                                                                                                                              • ACTIVITY
                                                                                                                                • 13-ldst-Exp08
                                                                                                                                  • OBJECT
                                                                                                                                  • 1 Following ICs and their Datasheets
                                                                                                                                  • 7408 Quad 2-input or 7421 Dual 4-input AND Gates
                                                                                                                                  • 2 Digital Trainer DT-01 or the following components
                                                                                                                                    • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                    • Connecting wires Switches
                                                                                                                                      • THEORY
                                                                                                                                          • Figure 81 Circuit Diagram for 4 x 2 Priority Encoder
                                                                                                                                          • Implementation and Observations
                                                                                                                                            • Therefore if GS A2 A1 and A0 are all low then it shows that line 0 is selected and if E0 A2 A1 and A0 are all low then it shows that none of the inputs selected E0 and GS cannot be in the same state provided that E1 is enabled
                                                                                                                                            • Circuit Diagram
                                                                                                                                              • ACTIVITY
                                                                                                                                                • 14-ldst-exp09
                                                                                                                                                  • OBJECT
                                                                                                                                                  • 1 Following ICs and their Datasheets
                                                                                                                                                  • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                    • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                    • Connecting wires Switches
                                                                                                                                                      • THEORY
                                                                                                                                                        • Parity Generator
                                                                                                                                                          • Let x y and z be the three bits that constitute the message and are the input to the Odd Parity Generator Circuit Since it is an odd parity system the bit P is generated so as to make the total number of 1s odd (including P) The function P can be expressed as follows
                                                                                                                                                          • Figure 91 Circuit Diagram for a 3-bit Parity Generator
                                                                                                                                                            • C = x Ο y Ο z Ο P
                                                                                                                                                              • Implementation and Observations
                                                                                                                                                                • ACTIVITY
                                                                                                                                                                    • 15-ldst-exp10
                                                                                                                                                                      • Driving a seven segment display using 7447 7448 driver IC
                                                                                                                                                                      • COMPONENTS AND APPARATUS REQUIRED
                                                                                                                                                                      • 1 Following ICs and their Datasheets
                                                                                                                                                                      • 7447 7448 BCD to Seven Segment Driver
                                                                                                                                                                      • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                        • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches
                                                                                                                                                                          • THEORY
                                                                                                                                                                          • Seven Segment Displays
                                                                                                                                                                          • CIRCUIT DIAGRAM
                                                                                                                                                                          • Figure 102 Circuit diagram for 7447driving a common-anode display
                                                                                                                                                                              • IMPLEMENTATION AND OBSERVATIONS
                                                                                                                                                                                • Decimal Digit
                                                                                                                                                                                • BCD Inputs
                                                                                                                                                                                • Seven Segment Outputs
                                                                                                                                                                                • D
                                                                                                                                                                                • C
                                                                                                                                                                                • B
                                                                                                                                                                                • A
                                                                                                                                                                                • a
                                                                                                                                                                                • b
                                                                                                                                                                                • c
                                                                                                                                                                                • d
                                                                                                                                                                                • e
                                                                                                                                                                                • f
                                                                                                                                                                                • g
                                                                                                                                                                                • 0
                                                                                                                                                                                • 0
                                                                                                                                                                                • 0
                                                                                                                                                                                • 0
                                                                                                                                                                                • 0
                                                                                                                                                                                • 1
                                                                                                                                                                                • 0
                                                                                                                                                                                • 0
                                                                                                                                                                                • 0
                                                                                                                                                                                • 1
                                                                                                                                                                                • 2
                                                                                                                                                                                • 0
                                                                                                                                                                                • 0
                                                                                                                                                                                • 1
                                                                                                                                                                                • 0
                                                                                                                                                                                • 3
                                                                                                                                                                                • 0
                                                                                                                                                                                • 0
                                                                                                                                                                                • 1
                                                                                                                                                                                • 1
                                                                                                                                                                                • 4
                                                                                                                                                                                • 0
                                                                                                                                                                                • 1
                                                                                                                                                                                • 0
                                                                                                                                                                                • 0
                                                                                                                                                                                • 5
                                                                                                                                                                                • 0
                                                                                                                                                                                • 1
                                                                                                                                                                                • 0
                                                                                                                                                                                • 1
                                                                                                                                                                                • 6
                                                                                                                                                                                • 0
                                                                                                                                                                                • 1
                                                                                                                                                                                • 1
                                                                                                                                                                                • 0
                                                                                                                                                                                • 7
                                                                                                                                                                                • 0
                                                                                                                                                                                • 1
                                                                                                                                                                                • 1
                                                                                                                                                                                • 1
                                                                                                                                                                                • 8
                                                                                                                                                                                • 1
                                                                                                                                                                                • 0
                                                                                                                                                                                • 0
                                                                                                                                                                                • 0
                                                                                                                                                                                • 9
                                                                                                                                                                                • 1
                                                                                                                                                                                • 0
                                                                                                                                                                                • 0
                                                                                                                                                                                • 1
                                                                                                                                                                                  • ACTIVITY
                                                                                                                                                                                    • 16-ldst-exp11
                                                                                                                                                                                      • Lab Session 11
                                                                                                                                                                                        • OBJECT
                                                                                                                                                                                        • COMPONENTS AND APPARATUS REQUIRED
                                                                                                                                                                                          • 1 Following ICs and their Datasheets
                                                                                                                                                                                          • 7473 7476 JK Flip-Flop
                                                                                                                                                                                          • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                            • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                            • Connecting wires Switches
                                                                                                                                                                                              • THEORY
                                                                                                                                                                                                  • Flip-Flop
                                                                                                                                                                                                  • JK Flip-Flop
                                                                                                                                                                                                    • Circuit Diagram
                                                                                                                                                                                                      • Observations
                                                                                                                                                                                                        • ACTIVITY
                                                                                                                                                                                                            • 17-ldst-exp12
                                                                                                                                                                                                              • Lab Session 12
                                                                                                                                                                                                                • OBJECT
                                                                                                                                                                                                                • GIVEN STATE DIAGRAM
                                                                                                                                                                                                                • Figure 121 State Diagram
                                                                                                                                                                                                                • COMPONENTS AND APPARATUS REQUIRED
                                                                                                                                                                                                                  • 1 Following ICs and their Datasheets
                                                                                                                                                                                                                  • 7474 D Flip-Flop
                                                                                                                                                                                                                  • ICs of basic gates (AND OR NOT XOR etc) as required
                                                                                                                                                                                                                  • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                    • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                                    • Connecting wires Switches
                                                                                                                                                                                                                      • THEORY
                                                                                                                                                                                                                          • Sequential Circuits
                                                                                                                                                                                                                            • 18-ldst-exp13
                                                                                                                                                                                                                              • Lab Session 13
                                                                                                                                                                                                                                • Designing a modulo-5 asynchronous up-counter using JK-FF
                                                                                                                                                                                                                                  • 1 Following ICs and their Datasheets
                                                                                                                                                                                                                                  • 7400 Quad 2-input or 7410 Triple 3-input NAND Gates
                                                                                                                                                                                                                                  • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                                    • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                                                    • Connecting wires Switches
                                                                                                                                                                                                                                      • THEORY
                                                                                                                                                                                                                                          • Figure 131 A Mod-5 Asynchronous Up Counter
                                                                                                                                                                                                                                          • Implementation and Observations
                                                                                                                                                                                                                                            • ACTIVITY
                                                                                                                                                                                                                                                • 19-ldst-exp14
                                                                                                                                                                                                                                                  • Experimenting with 74194 4-bit bidirectional universal shift register
                                                                                                                                                                                                                                                  • 1 Following ICs and their Datasheets
                                                                                                                                                                                                                                                  • 74194 4-bit bidirectional universal shift register
                                                                                                                                                                                                                                                  • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                                                    • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                                                                    • Connecting wires Switches
                                                                                                                                                                                                                                                      • THEORY
                                                                                                                                                                                                                                                        • Shift Registers
                                                                                                                                                                                                                                                        • Bidirectional Shift Registers
                                                                                                                                                                                                                                                        • Universal Shift Registers
                                                                                                                                                                                                                                                          • S1
                                                                                                                                                                                                                                                            • Circuit Diagram
                                                                                                                                                                                                                                                            • ACTIVITY
                                                                                                                                                                                                                                                                • 20-ldst-exp15
                                                                                                                                                                                                                                                                  • COMPONENTS AND APPARATUS REQUIRED
                                                                                                                                                                                                                                                                  • 1 Parallel Port Connectors (DB-25) with Cable
                                                                                                                                                                                                                                                                  • 2 Personal Computer with Windows 98 and TurboC Compiler Installed
                                                                                                                                                                                                                                                                  • 3 Following ICs and their Datasheets
                                                                                                                                                                                                                                                                  • 74245 Octal Bus Transceivers with 3-State Outputs
                                                                                                                                                                                                                                                                  • 4 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                                                                    • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                                                                                      • Connecting wires Switches
                                                                                                                                                                                                                                                                        • THEORY
                                                                                                                                                                                                                                                                        • 3-State Logic
                                                                                                                                                                                                                                                                          • Serial and Parallel Port Connectors
                                                                                                                                                                                                                                                                          • Parallel Port Connector ndash DB-25
                                                                                                                                                                                                                                                                            • Accessing parallel port through C Language Programming
                                                                                                                                                                                                                                                                                • 21-ldst-appendixA
                                                                                                                                                                                                                                                                                • 22-ldst-appendixB
                                                                                                                                                                                                                                                                                  • DEBOUNCING CIRCUITRY FOR MECHANICAL SWITCHES

          PART CIRCUIT SIGN

          WHAT IT DOES

          Amplifies small currents into much larger copies Acts as a very fast switch It must be correctly connected with a positive voltage to the collector

          Transistors diodes resistors and capacitors are connected together on a tiny lsquochiprsquo of silicon (sand is mostly silicon oxide) to give any desired circuit eg a multistage amplifier an astable bistable or monostable multivibrator a counter a logic gate for a computer several stages of a TRF (tuned radio frequency) radio

          They must be correctly connected Pin 1 is next to the lsquotagrsquo in the can type and on the dil type it is identified from the lsquonotchrsquo or lsquosmall dotrsquo on the case CMOS lsquochipsrsquo (standing for Complementary Metal Oxide Semiconductors and pronounced lsquosee-mossrsquo) need special care

          PRECAUTIONS WITH CMOS INTEGRATED CIRCUITS Damage occurs if static charges build up on input pins when for example they touch insulating materials (eg clothes plastic pen) in warm dry conditions 1 Keep the IC in the carrier in which it is supplied until it is inserted in the circuit 2 Do not finger the pins or hold them in contact with an insulator 3 Connect all unused inputs of the IC to either the positive or the negative of the battery

          depending on the circuit

          5

          BUILDING CIRCUITS

          The circuit board shown above accepts ICs as well as separate components It has 47 rows of 5 interconnected sockets on each side of a central channel across which dil ICs can be fitted A wire inserted in a socket in a certain row becomes connected to wires in any of the other 4 sockets in that row by a metal strip under the board For example wires in sockets B5 C5 D5 E5 and F5 (shown in color in the diagram) are all joined Metal strips under the board connect the sockets A row of 40 interconnected sockets along the top of the board and a similar row along the bottom act as the positive and negative power supply rails (called lsquobus barsrsquo) Various makes of circuit board are available some with vertically mounting removable panels for supporting controls

          6

          1 To make a connection push about 1 cm of the bare end of a wire (025 to 085 mm diameter) straight into the socket (not at an angle) so that it is gripped by the metal strip under the board Do not use wires that are dirty or have kinked ends Only put one wire in each socket

          Bend leads on resistors etc as shown before inserting them in the board

          2 Bare the ends of connecting wire (PVC-covered tinned copper wire 06 mm diameter) by

          removing the insulation (PVC) either with wire strippers or using a pair of blunt-nosed pliers and a pair of side cutters as shown With practice you should be able to judge just how much the side cutters have to be squeezed and pulled to remove the insulation without cutting the wire

          3 lsquoJoinrsquo wires to the lsquolugsrsquo on the loudspeaker and variable capacitor using a small length of

          2 mm bore plastic sleeving - as shown by 1 and 2

          7

          RESISTOR COLOUR CODE Resistor values are given in ohms (shortened to Ω the Greek letter lsquoomegarsquo) They are marked on the resistor using a color code Three colored bands are painted round the resistor Each color stands for a number To read the color code start at the 1st band it is nearest the end Sometimes it is not clear which is the 1st band because there is a 4th band of gold or silver near the other end These two colors are not used for the 1st band they give the accuracy of the resistor (gold is plusmn 5 and silver plusmn 10) so you should not have too much trouble deciding where to start The 1st band gives the first number the 2nd band gives the second number and the 3rd band tells how many zeroes come after the first two numbers

          8

          INTRODUCTION

          Digital Logic Design is concerned with the interconnection among digital components and modules and the area of Switching Theory that can be identified between circuit design and system formulation Logic design is the base of any computer system as every digital system consists of different ICrsquoS and ICs contain a large number of interconnected digital circuits within a small package MSI devices provide digital function while LSI device cover a complete computer modules These circuitries are widely used in digital system like digital voltmeter frequency meter calculating machines telephone-switching system etc In this Practical Workbook laboratory sessions based on both combinational and sequential logic are covered First laboratory session gives an introduction to the basic logic gates and fundamentals of circuit building The second laboratory session covers a CAD software ndash Electronics Workbench (EWB) EWB is excellent simulation software where circuits can be designed and tested before physical implementation Various laboratory sessions of this workbook provide activities and exercises on EWB Next eight laboratory sessions are based on combinational logic Here various MSI circuits like adders converters multiplexers decoders encoders etc are designed Some of these laboratory sessions also include testing of MSI ICs Next four laboratory sessions help in exploring various designs based on sequential logic Here a variety of circuits are designed form the testing of basic flip-flop ICs to registers and different types of counters Last laboratory session demonstrates how digital hardware can be interfaced with a personal computer via parallel port and can be controlled by software All laboratory sessions of this workbook incorporate brief theoretical backgrounds as details may be covered in the respective theory classes Exercises activities are included with almost all the sessions for the students to practice Two appendices are also included in this workbook The first one provides pin diagrams for all the ICs required for the laboratory work provided in this workbook It will help the students in preparing the pin diagrams for the circuits Second appendix discusses a hardware debouncing circuit for mechanical switches as such switches are extensively used for input purpose in logic circuits

          9

          CONTENTS Lab Session No Object Page No

          1 2 3 4 5 6 7 8 9

          10

          11

          12

          13

          14

          15

          To study the logic gates in the following TTL ICs

          7400 Quad 2-input NAND gate 7402 Quad 2-input NOR gate

          7404 Hex inverter 7408 Quad 2-input AND gate 7432 Quad 2-input OR gate

          Also implementing and testing the given circuit on a bread board Working with Electronics Workbench Designing Half and Full Adder Circuits Use of Karnaugh Map (SOP-Expression) method Designing a BCD Adder Designing of a 4 x 1 Multiplexer Experimenting with 74150 IC Designing of a 2 x 4 Decoder 1 x 4 Demultiplexer Experimenting with 74138 IC Designing of a 4 x 2 Priority Encoder Experimenting with 74148 IC Designing an Odd Parity Generator and Checker for a 3-bit Data Driving a seven segment display using 7447 7448 driver IC Experimenting with different modes of JK-FF Designing sequential circuit for the given state diagram using D flip-flop Designing a modulus-5 asynchronous up-counter using JK-FF Experimenting with 74194 4-bit bidirectional universal shift register Experimenting with 74245 octal bus transceivers using parallel port PC interfacing Appendix A ndash Pin Diagrams of the ICs required for the laboratory sessions Appendix B ndash Debouncing circuitry for mechanical switches

          13

          17

          19

          22

          28

          30

          34

          38

          42

          45

          48

          50

          54

          56

          59

          66

          69

          11

          Logic Design amp Switching Theory 1 Lab Session 01 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

          Lab Session 01 OBJECT

          bull To study the logic gates in the following TTL ICs

          i) 7400 Quad 2-input NAND gate ii) 7402 Quad 2-input NOR gate iii) 7404 Hex inverter iv) 7408 Quad 2-input AND gate v) 7432 Quad 2-input OR gate

          bull Implementing and testing the given circuit on a bread board

          COMPONENTS REQUIRED 1 Bread board 2 5 V - power supply 3 Multimeter 4 Logic probe 5 LEDs with resistors 6 Connecting wires 7 Switches (optional) 8 Following ICs and their datasheets

          bull 7408 quad 2 input AND gate bull 7432 quad 2 input OR gate bull 7404 hex inverter bull 7400 quad 2 input NAND gate bull 7402 quad 2 input NOR gate

          THEORY

          Logic Gates

          Logic gates are the fundamental building blocks of digital systems These devices are able to make decisions in the sense that they produce one output level when some combinations of input levels are present and a different output when other combinations are applied hence given the name Logic Gates The two levels produced by digital circuitry are referred to variously as HIGH and LOW TRUE and FALSE ON and OFF or simply 1 and 0 There are only three basic gates AND OR and NOT The other gates are merely combinations of these basic gates Logic gates can be interconnected to perform a variety of logical operations This interconnection of gates to achieve prescribed outcomes is called logic design

          1 The AND Gate ndash An AND gatersquos output is 1 if and only if all its inputs are 1 If A and B are two inputs to an AND gate then output F of the gate is given as F = AB

          2 The OR Gate - An OR gatersquos output is 1 if at least one of its input is 1 If A and B are two inputs to an OR gate then output F of the gate is given as F = A+B

          13

          Logic Design amp Switching Theory 1 Lab Session 01 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering 3 The NOT Gate (Inverter) ndash Its output is 1 when its input is 0 and its output is 0 when

          the input is 1 ie it complements a digital variable If A is the input to a NOT gate then output F of the gate is given as AF =

          4 The NAND Gate ndash Its output is 1 if at least one of its input is 0 This gate performs the same logic as an AND gate followed by an inverter If A and B are two inputs to a NAND gate then output F of the gate is given as BAF =

          5 The NOR Gate - The output of a NOR gate is 1 if and only if all its inputs are 0 This gate performs the same logic function as an OR gate followed by an inverter If A and B are two inputs to a NAND gate then output F of the gate is given as BAF +=

          All the above gates have one output and two or more inputs except the NOT gate which has only one input

          PROCEDURE FOR TESTING THE LOGIC GATES IN GIVEN ICs

          1 Set the power supply to 5V With the help of a multimeter check the voltage at the output knobs of the power supply

          2 Connect wires long enough to reach the breadboard with the two knobs of the power supply Again using multimeter check voltage at the non-connected end of the wires

          3 Insert the 7408 quad 2 input AND gate IC on to the bread board and make supply and ground connections by joining 5V wire to pin 14 and 0V wire to pin 7

          4 Consult ICrsquos internal connection diagram for input and output pins of the first AND gate Connect input pins to logic 0 (0V) and observe the output using LED or logic probe You can also connect switches at the input lines to facilitate toggling between 1 and 0

          5 Try different combinations of logic levels at the two inputs Again observe the output 6 Repeat the last two steps for all other gates of the same IC Record the observations 7 Repeat this procedure for all other ICs

          OBSERVATIONS

          Gate Input A Input B Expected Output Observed Output

          AND

          0 0 0 1 1 0 1 1

          OR

          0 0 0 1 1 0 1 1

          NOT 0 - 1 -

          NAND

          0 0 0 1 1 0 1 1

          14

          Logic Design amp Switching Theory 1 Lab Session 01 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

          NOR

          0 0 0 1 1 0 1 1

          DATA SHEETS

          Figure 11

          15

          Logic Design amp Switching Theory 1 Lab Session 01 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

          16

          GIVEN CIRCUIT

          Figure 12

          PROCEDURE FOR IMPLEMENTATION OF THE GIVEN CIRCUIT 1 Set the power supply 2 Insert ICs on the bread board and make their supply and ground connections 3 As given in the logic diagram make connections using wires and gates in the ICs 4 Apply different combinations at the three inputs and observe the output OBSERVATIONS Logic expression for the given logic diagram __________________________________

          A B C Expected Output Observed Output 0 0 0 0 0 1 0 1 0 0 1 1 1 0 0 1 0 1 1 1 0 1 1 1

          Logic Design amp Switching Theory 1 Lab Session 02 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

          Lab Session 02

          OBJECT

          Working with Electronics Workbench

          ELECTRONICS WORKBENCH - EWB Electronics Workbench is a computer aided design tool that provides you with all the components and instruments necessary to create board-level designs It has complete mixed analog and digital simulation and graphical waveform analysis allowing you to design your circuit and then analyze it using different simulated instruments and analysis options It is fully integrated and interactive thus you can change your circuits quickly allowing fast and repeated what-if analysis Electronics Workbench provides the following kind of components bull Sources parts bin (AC voltage source Vcc source ground battery etc) bull Basic parts bin (resistors capacitors transformers switches etc) bull Diodes parts bin bull Transistors parts bin bull Analog ICs parts bin (op-amps etc) bull Mixed ICs parts bin (ADCs DACs 555 timers etc) bull Digital ICs parts bin (AND OR adders multiplexers etc) bull Indicators parts bin (voltmeter ammeter probe displays etc) bull Controls parts bin (voltage differentiator multiplier etc) bull Instruments parts bin (multimeter oscilloscope function generator etc) bull Miscellaneous parts bin (write data textbox etc)

          o Write data This component allows you to save simulation results as an ASCII file o Text Box Use this to add descriptive text anywhere in a circuit

          ACTIVITY

          Design circuit for the logic expression )( CBDCABAF ++=

          Procedure 1 From Logic Gates Parts Bin Drag and drop the required logic gates on the design

          area Use Component Properties dialog box to customize these gates 2 Connect the terminal of these gates according to the given expression Use additional

          connectors form the Basic Parts Bin if you want to connect more than wire at a single node

          3 Drag and drop a probe from Indicators Parts Bin Use Component Properties dialog box to customize the color and other properties of the probe Connect this probe at the output terminal of the circuit to indicate results

          4 Select four switches form Basic Parts Bin Specify the key that controls the switch by typing its name in the Value tab of the Component Properties dialog box For

          17

          Logic Design amp Switching Theory 1 Lab Session 02 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

          18

          example if you want the switch to close or open when digit lsquo1rsquo is pressed type 1 in the Value tab then click OK Assign different keys to all the switches

          5 Connect the output terminals of these switches to each of the four inputs A B C and D of the circuit

          6 Drag and drop Vcc and Ground form the Sources Parts Bin 7 Connect Vcc terminal to one end and Ground terminal to the other end of all the

          switches 8 Label the circuit properly using text boxes found in the miscellaneous parts bin 9 Run the circuit using the Activate Simulation switch Use the keys you have assigned

          to the switches to toggle them between Vcc and Ground connections thus providing 1 or 0 respectively to the inputs Record the results as indicated by the probe for all possible combinations of 1s and 0s at the inputs

          EWB Circuit

          Figure 21

          Observations

          A B C D Expected Output Observed Output 0 0 0 0 0 0 0 1 0 0 1 0 0 0 1 1 0 1 0 0 0 1 0 1 0 1 1 0 0 1 1 1 1 0 0 0 1 0 0 1 1 0 1 0 1 0 1 1 1 1 0 0 1 1 0 1 1 1 1 0 1 1 1 1

          Logic Design amp Switching Theory 1 Lab Session 03 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

          Lab Session 03

          OBJECT

          Designing Half and Full Adder Circuits COMPONENTS AND APPARATUS REQUIRED 1 Following ICs and their Datasheets

          bull 7408 Quad 2-input AND Gate bull 7432 Quad 2-input OR Gate bull 7486 Quad 2-input XOR Gate

          2 Digital Trainer DT-01 or the following components Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches

          THEORY Half Adder A combination circuit that performs the addition of two bits without accounting for the previous carry is called half adder It needs two binary inputs and two binary outputs The input variables designate the augend and addend bits The output variables produce the sum and carry The simplified sum of product expressions for a half adder are

          yxyxyxS oplus=+= yxC =

          Figure 31 Circuit diagram for Half Adder

          19

          Logic Design amp Switching Theory 1 Lab Session 03 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

          bles produce the sum and carry The simplified sum of product expressions for a half adder are

          Full Adder

          A combinational circuit that performs the addition of three input bits It consist of three inputs and two outputs Two of the input variables represent the two significant bits to be added The third input represents the carry from the previous lower significant position The output varia

          zyxzyxzyxzyxzyxS oplusoplus=+++= yxzyxzyzxxyC )( +oplus=++=

          Figure 32 Circuit diagram for Full Adder

          efer to laboratory session 01 for procedure) and record the observations in the following ta

          alf Adde ull Adder Inputs u

          IMPLEMENTATION AND OBSERVATIONS

          Implement the half adder and full adder circuits on a bread board (prepare the pin diagram (use appendix A) and r

          bles H r F

          Inputs Outputs Outp ts x y Carry Su Carry Sum m x y z 0 0 0 0 0 0 1 0 0 1 1 0 0 1 0 1 1 0 1 1 1 0 0 1 0 1 1 1 0 1 1 1

          20

          Logic Design amp Switching Theory 1 Lab Session 03 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

          at of your designed circuit Attach hardcopy of the output form electronic workbench

          at of your designed circuit Attach hardcopy of the output form lectronic workbench here

          ACTIVITY

          1 Simulate half adder circuit using Electronics Workbench Compare the results of simulation with thhere

          2 Design a full subtractor circuit and simulate it using Electronics Workbench Compare the results of simulation with the

          21

          Logic Design amp Switching Theory 1 Lab Session 04 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

          Lab Session 04 OBJECT

          Use of Karnaugh Map (SOP-Expression) method GIVEN LOGIC EXPRESSION

          F (A B C D) = sum ( 0 1 2 4 5 6 8 9 12 13 14 ) COMPONENTS AND APPARATUS REQUIRED 1 Digital ICs and their Datasheets

          bull 7408 Quad 2-input AND Gate bull 7432 Quad 2-input OR Gate bull 7404 Hex Inverter

          2 Digital Trainer DT-01 or the following components Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches PROCEDURE 1 Use Karnaugh map to reduce the given function 2 Draw the circuit diagram for the obtained reduced function 3 Implement the reduced circuit using digital ICs on a bread board (prepare the pin

          diagram (use appendix A) and refer to laboratory session 01 for procedure) and record the observations

          REDUCTION OF LOGIC EXPRESSION USING KARNAUGH MAP F

          CD

          AB DC

          DC DC

          DC

          BA0 1 3 2

          BA4 5 7 6

          BA12 13 15 14

          BA8 9 11 10

          Reduced form of the given logic expression is __________________________________

          22

          Logic Design amp Switching Theory 1 Lab Session 04 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

          LOGIC DIAGRAM (REDUCED FORM) OBSERVATIONS

          A B C D Output 0 0 0 0 0 0 0 1 0 0 1 0 0 0 1 1 0 1 0 0 0 1 0 1 0 1 1 0 0 1 1 1 1 0 0 0 1 0 0 1 1 0 1 0 1 0 1 1 1 1 0 0 1 1 0 1 1 1 1 0 1 1 1 1

          RESULT The reduced form (SOP Expression) of the given logic function is

          ____________________________________________________________

          The observation table reflects the given logic function

          23

          Logic Design amp Switching Theory 1 Lab Session 04 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

          ACTIVITY 1 Using Electronics Workbench derive a truth table and logic circuit for the following logic expression

          BAAF +=

          Procedure 1 From the Instruments Parts Bin drag and drop Logic Converter on the design area 2 Double click the Logic Converter to reveal Logic Converter dialog box This dialog

          box shows various conversion options between truth table logic expression and logic circuit

          3 Enter the given logic expression in the edit box found at the end of the dialog box Use lsquo to represent invert of a variable For example A is written as Arsquo

          4 Click the Boolean Expression to Truth Table button The truth table appears in the logic converters display

          5 Now click the Boolean Expression to Circuit button This creates the logic circuit for the given expression in the design area Label the diagram if needed

          Resulting Logic Circuit For the given expression the final circuit will look like

          Figure 41

          24

          Logic Design amp Switching Theory 1 Lab Session 04 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

          ACTIVITY 2

          Using Electronics Workbench find a simplified logic expression and circuit for the following truth table

          A B C Output 0 0 0 1 0 0 1 1 0 1 0 0 0 1 1 1 1 0 0 0 1 0 1 0 1 1 0 0 1 1 1 1

          Procedure 1 Click three input channels from A to H across the top of the logic converter The

          display area below the terminals fills up with the necessary combinations of ones and zeros to fulfill the input conditions The values in the output column on the right are initially set to 0

          2 Edit the output column to specify the desired output for each input condition To change an output value select it and type a new value 1 0 or x An x indicates a donrsquot care condition

          3 To convert this truth table to a Boolean expression click the Truth Table to Boolean Expression button The Boolean expression will be displayed at the bottom of the logic converter

          4 Simplify the expression by clicking the Simplify button 5 Now click the Boolean Expression to Circuit button This creates the logic circuit for

          the given expression in the design area Resulting Logic Circuit For the given truth table the final simplified circuit will look like

          Figure 42

          25

          Logic Design amp Switching Theory 1 Lab Session 04 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

          ACTIVITY 3

          Using Electronics Workbench find the logic expression and truth table for the following logic circuit

          Figure 43

          Procedure 1 Attach the input terminals of the logic converter to up to four input points in the

          circuit 2 Connect the single output of the circuit to the output terminal on the logic converter

          icon 3 Click the Circuit to Truth Table button The truth table appears in the logic

          converters display 4 To convert this truth table to a Boolean expression click the Truth Table to Boolean

          Expression button The Boolean expression will be displayed at the bottom of the logic converter

          Resulting Logic Expression Logic Expression for the given circuit is found to be _____________________________

          26

          Logic Design amp Switching Theory 1 Lab Session 04 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

          27

          For activities 1 2 and 3 attach hardcopy of the output (truth table logic expression and logic circuit) form electronic workbench here

          Logic Design amp Switching Theory 1 Lab Session 05 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

          Lab Session 05 Lab Session 05 OBJECT OBJECT

          Designing a BCD Adder Designing a BCD Adder COMPONENTS AND APPARATUS REQUIRED COMPONENTS AND APPARATUS REQUIRED

          1 Following ICs and their Datasheets 1 Following ICs and their Datasheets bull 7408 Quad 2-input AND Gate bull 7408 Quad 2-input AND Gate bull 7432 Quad 2-input OR Gate bull 7432 Quad 2-input OR Gate bull 7483 4-bit Binary Adder bull 7483 4-bit Binary Adder

          2 Digital Trainer DT-01 or the following components 2 Digital Trainer DT-01 or the following components Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors (100 Ω) Connecting wires Switches (100 Ω) Connecting wires Switches

          THEORY THEORY

          A BCD Adder is a combinational circuit that adds two BCD digits in parallel and produces a sum digit also in BCD A BCD Adder is a combinational circuit that adds two BCD digits in parallel and produces a sum digit also in BCD

          A4 A3 A2 A1 B4 B3 B2 B1

          7483-BCD ADDER

          Cout (C4 ) Z4 Z3 Z2 Z1 Cin(C0)

          A4 A3 A2 A1 B4 B3 B2 B1

          7483-BCD ADDER

          Cout

          (C4 ) Z4 Z3 Z2 Z1 Cin(C0)

          Figure 51 BCD Adder Circuit

          28

          Logic Design amp Switching Theory 1 Lab Session 05 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

          29

          A BCD adder must include the correction logic in its internal construction The two BCD digits together with the input carry are first added using a 4-bit binary adder to produce the binary sum If no output carry is generated and the binary sum is less than or equal to 9 then the corresponding BCD sum is identical and therefore no conversion is needed When the output carry is equal to 1 or the binary sum is greater than 9 then a binary 0110 is added to the binary sum through another 4-bit binary adder If Cout is the carry output and Z4Z3Z2Z1 is the binary sum form the first 4-bit binary adder then the following equation indicates the condition when a binary 0110 is to be added

          C = COUT + Z4Z2 + Z4Z3 IMPLEMENTATION AND OBSERVATIONS Implement the BCD adder circuit according to figure 51 on a bread board (prepare the pin diagram (use appendix A) and refer to laboratory session 01 for procedure) A BCD adder has nine input bits (two BCD digits and a carry bit) which can result in a total of 512 combinations of which 312 inputs are donrsquot care Since it is a very lengthy procedure to record results for 200 valid input combinations therefore for simplicity just record results for any eight combinations in the following table

          Input Carry

          BCD Digit 1 BCD Digit 2 Carry Output

          BCD Sum A4 A3 A2 A1 B4 B3 B2 B1 Z4 Z3 Z2 Z1

          Logic Design amp Switching Theory 1 lab Session 06 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

          Lab Session 06

          OBJECT

          bull Designing of a 4 x 1 Multiplexer bull Experimenting with 74150 IC

          COMPONENTS AND APPARATUS REQUIRED 1 Following ICs and their Datasheets

          bull 7408 Quad 2-input AND Gates or 7411 Triple 3-input AND Gates bull 7432 Quad 2-input OR Gates bull 7404 Hex Inverter bull 74150 16 x 1 MUX

          2 Digital Trainer DT-01 or the following components Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches THEORY

          Multiplexers A digital data Multiplexer (MUX) is a combinational circuit having several data inputs and a single output A set of data-select inputs is used to control which of the data inputs is routed to the single output A multiplexer is also called a data selector because of this ability to select which data input is connected o the output Normally there are 2n input lines and n selection lines whose bit combination determine which input is selected DESIGN OF A 4 x 1 MULTIPLEXER A 4 x 1 multiplexer is capable of selecting one of four data inputs (see figure 61) The 2-bit binary number at the data select inputs S1 and S0 specifies which of the four data inputs is to be routed to the output Since there are two data select inputs therefore they can select 22 = 4 different data inputs lines

          S0 S1 D0 D1

          D2 D3

          Data-select Inputs Output

          Data Inputs

          Figure 61 Block Diagram of a 4 x1 Multiplexer

          30

          Logic Design amp Switching Theory 1 lab Session 06 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

          Figure 62 Circuit Diagram for 4 x 1 Multiplexer

          Implementation and Observations

          Implement the 4 x 1 Multiplexer circuit (figure 62) on a bread board (prepare the pin diagram (use appendix A) and refer to laboratory session 01 for implementation procedure) and record the observations in the following table For each data select combination specify the switch number as well as the binary value present on that selected switch

          S1 S0 Output 0 0 0 1 1 0 1 1

          TESTING OF 74150 - 16 x 1 MUX

          The 74150 IC has sixteen data inputs and four data-selection lines Function of various pins of this IC is described below

          bull E0 through E15 Data input lines

          31

          Logic Design amp Switching Theory 1 lab Session 06 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering bull A B C D Data select lines with D being the MSB bull W Active low output line bull Grsquo Active low enable line bull VCC and GND Supply connections lines

          Circuit Diagram

          Figure 63 Pin connections of 74150 for selecting E0

          Testing Procedure

          bull Make connections as shown in the circuit diagram bull Apply different data (1 or 0) at data inputs that are labeled as E0 to E15 Only

          connection for E0 is shown is the figure for simplicity bull Select the data input E0 with the help of data selectors A B C and D bull Observe the output which shows the complement of the data from E0 bull Select all the sixteen data inputs one by one and record your observations in the

          following table

          32

          Logic Design amp Switching Theory 1 lab Session 06 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

          33

          Observations

          Grsquo D C B A W Grsquo D C B A W 0 0 0 0 0 0 1 0 0 0 0 0 0 0 1 0 1 0 0 1 0 0 0 1 0 0 1 0 1 0 0 0 0 1 1 0 1 0 1 1 0 0 1 0 0 0 1 1 0 0 0 0 1 0 1 0 1 1 0 1 0 0 1 1 0 0 1 1 1 0 0 0 1 1 1 0 1 1 1 1

          ACTIVITY 1 Consider 4x1 Multiplexer Draw the output wave-form for the following data inputs

          (E0 E1 E2 E3) and select lines A B (B being the MSB) Output is W

          E3 E2 E1 E0 A B

          W

          2 Using the 4 x 1 MUX designed in this laboratory session implement the following logical function F (A B C) = Σ (0147)

          Show your working and input connections in the following block diagram according to the circuit you have implemented

          4 x 1 MUX

          S0 S1

          Output D0

          D1

          D2

          D3

          Logic Design amp Switching Theory 1 Lab Session 07 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

          Lab Session 07

          OBJECT

          bull Designing of a 2 x 4 Decoder 1 x 4 Demultiplexer bull Experimenting with 74138 IC

          COMPONENTS AND APPARATUS REQUIRED 1 Following ICs and their Datasheets

          bull 7408 Quad 2-input or 7411 Triple 3-input AND Gates bull 7404 Hex Inverter bull 74138 3 x 8 Decoder

          2 Digital Trainer DT-01 or the following components Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches THEORY

          Decoder A Decoder is a combinational circuit that converts binary information form n input lines to a maximum of 2n unique output lines In practical applications decoders are often used for selecting one of several devices

          Demultiplexer A decoder with an enable input can function as a Demultiplexer A Demultiplexer (DMUX) id a circuit that receives information on a single line and transmits this information on one of 2n possible output lines The selection of a specific output line is controlled by the bit values of n selection lines DESIGN OF A 2 x 4 DECODER 1 x 4 DEMULTIPLEXER A 2 x 4 decoder is capable of selecting one of four output lines (see figure 71 (a)) The 2-bit binary number at the data inputs S1 and S0 specifies which of the four data inputs is to be selected If we add an enable pin and use it as an input line then this decoder can be converted to a 1 x 4 Demultiplexer where S1 and S0 will select a line to which data input is to be routed (see figure 71 (b))

          Select S0 S0 Inputs

          S1 D0 D1

          D2

          D3

          Enable (a) Block Diagram of a 2 x 4 Decoder

          Figure 71

          S1 D0 D1

          D2

          D3

          Inputs

          Data Input (b) Block Diagram of a 1 x 4 Demulptiplexer

          34

          Logic Design amp Switching Theory 1 Lab Session 07 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

          Figure 72 Circuit Diagram for 2 x 4 Decoder 1 x 4 Demultiplexer

          Implementation and Observations Implement the 2 x 4 Decoder 1 x 4 Demultiplexer circuit (figure 72) on a bread board (prepare the pin diagram (use appendix A) and refer to laboratory session 01 for implementation procedure) and record the observations in the following table

          Enable Data Input S1 S0 D0 D1 D2 D3

          0 0 0 0 0 1 0 1 0 0 1 1 1 0 0 1 0 1 1 1 0 1 1 1

          TESTING OF 74138 3 x 8 Decoder The 74138 IC has three inputs and eight output lines It has three enable inputs and for the IC to function all three inputs need to be enabled Function of various pins of this IC is described below

          35

          Logic Design amp Switching Theory 1 Lab Session 07 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

          bull Y0 through Y7 Active low data outputs bull A B C Input select lines with C being the MSB bull G1 Active high enable Input bull G2Arsquo and G2Brsquo Active low enable Inputs bull VCC and GND Supply connections lines Circuit Diagram

          Figure 73 Pin connections of 74138

          Testing Procedure

          bull Make connections as shown in the circuit diagram bull Apply different combinations of 1s and 0s at data inputs bull Observe the output and record your observations in the following table

          Observations

          C B A Y0 Y1 Y2 Y3 Y4 Y5 Y6 Y7 0 0 0 0 0 1 0 1 0 0 1 1 1 0 0 1 0 1 1 1 0 1 1 1

          36

          Logic Design amp Switching Theory 1 Lab Session 07 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

          37

          ACTIVITY ACTIVITY 1 What will be the binary values at the outputs Y0 through Y7 of 74138 if 1 What will be the binary values at the outputs Y0 through Y7 of 74138 if

          bull All three enable pins are connected to ground bull All three enable pins are connected to ground __________________________________________________________________________________________________________________________________________ __________________________________________________________________________________________________________________________________________ _____________________________________________________________________ _____________________________________________________________________

          bull All three enable pins are connected to VCC bull All three enable pins are connected to VCC _______________________________________________________________________________________________________________________________________________________________________________________________________________

          _______________________________________________________________________________________________________________________________________________________________________________________________________________

          2 Show connections for 74138 in order to use it as a 1 x 8 Demultiplexer 2 Show connections for 74138 in order to use it as a 1 x 8 Demultiplexer

          3 Consider a 2 x 4 Decoder with two enable inputs (one active high - G and one active low ndash Grsquo) Draw the output wave-forms for D0 D1 D2 and D3 if the two select inputs are A and B (B being the MSB) All outputs are active low

          Grsquo

          G

          A B

          D0 D1 D2

          D3

          Logic Design amp Switching Theory 1 Lab Session 08 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

          Lab Session 08 OBJECT

          bull Designing of a 4 x 2 Priority Encoder bull Experimenting with 74148 IC

          COMPONENTS AND APPARATUS REQUIRED

          1 Following ICs and their Datasheets

          bull 7408 Quad 2-input or 7421 Dual 4-input AND Gates bull 7432 Quad 2-input OR Gates bull 7404 Hex Inverter bull 74148 Encoder

          2 Digital Trainer DT-01 or the following components Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches

          THEORY

          Encoder An Encoder is a digital function that produces a reverse operation from that of a decoder An Encoder has 2n (or less) input lines and n output lines The output lines generate the binary code for the 2n input variables Priority Encoder

          A simple encoder may produce an erroneous output if more than one of its inputs is high A Priority Encoder is one that responds to just one input among those that may be simultaneously high in accordance with some priority system The most common priority system is based on the relative magnitudes of the inputs whichever decimal input is largest is the one that is encoded

          DESIGN OF A 4 x 2 Priority Encoder

          The following equations represent the outputs of a 4 x 2 priority encoder 32 DDA +=

          321 DDDB += As can be seen from the equations that input D0 which has a binary code 00 is not used in any equation A binary code 00 at the output indicates two conditions Either D0 is selected or no input is selected In order to differentiate these two conditions we will provide an additional output Z to indicate if at least one of the inputs is a 1 The equation for Z will be

          4321 DDDDZ = If Z is 0 then the binary code 00 at the output indicates that D0 is selected and if Z is 1 then it indicates that no input line is selected

          38

          Logic Design amp Switching Theory 1 Lab Session 08 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

          Figure 81 Circuit Diagram for 4 x 2 Priority Encoder

          it (figure 81) on a bread board (prepare the to laboratory session 01 for implementation

          Implementation a Implement the 4 x 2 Priority Encoder circu

          ram (use appendix A) and refer

          nd Observations

          pin diagprocedure) and record the observations in the following table

          D3 D2 D1 D0 A B 0 0 0 1 0 0 1 x 0 1 x x 1 x x x

          TESTING OF 74148 8 x 3 Octal Priority Encoder

          imal digits There are nine of which three represents

          ing any of the inputs is high

          then it shows that line 0 is selected and if e inputs selected E0 and GS

          cannot be in the same state provided that E1 is enabled

          The 74148 is a priority encoder with active-Low input for dec

          input) and five output linesinputs lines (including an enablethe binary code for the octal digit Function of various pins of this IC is described below

          bull 0 through 7 Active low data inputs representing the octal digits A2 A1 A0 Active low output lines representing the binary code bullbull E1 Active low enable Input bull E0 Active low output indicating none of the inputs is high bull GS Active low output indicatbull VCC and GND Supply connections lines Therefore if GS A2 A1 and A0 are all low

          then it shows that none of thE0 A2 A1 and A0 are all low

          39

          Logic Design amp Switching Theory 1 Lab Session 08 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

          Circuit Diagram

          Figure 82 Pin connections of 74148

          Testing Procedure bull Make connections as sho

          binations of 1s and 0s at data inputs d record your observations in the following table

          GS E0

          wn in the circuit diagram bull Apply different combull Observe the output an Observations

          0 1 2 3 4 5 6 7 A2 A1 A0 1 1 1 1 1 1 1 1 x x x x x x x 0 x x x x x x 0 1 x x x x x 0 1 1 x x x x 0 1 1 1 x x x 0 1 1 1 1 x x 0 1 1 1 1 1 x 0 1 1 1 1 1 1 0 1 1 1 1 1 1 1

          40

          Logic Design amp Switching Theory 1 Lab Session 08 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

          41

          CTIVITY

          Cascade the following two 74148 8 x 3 Priority Encoders to form 16 x 4 Priority

          A 1

          Encoder

          Logic Design amp Switching Theory 1 Lab Session 09 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering `

          Lab Session 09 OBJECT

          Designing an Odd Parity Generator and Checker for a 3-bit Data COMPONENTS AND APPARATUS REQUIRED

          1 Following ICs and their Datasheets

          bull 7486 Quad 2-input Exclusive-OR Gates bull 7404 Hex Inverter

          2 Digital Trainer DT-01 or the following components Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches

          THEORY

          Parity Generator When binary data is transmitted and processed it is ndash as are all electrical signals ndash susceptible to noise that can either alter or distort its contents 1s may be effectively changed to 0s and 0s to 1s To overcome this problem one or more bits are often added to the data as an aid in detecting errors caused by noise The most common of these is a Parity bit that signifies whether the total number of 1s in a code group is odd or even In an Odd Parity system the parity bit is made 0 or 1 as necessary to make the total number 1s odd (counting the parity bit itself) In an Even Parity system the parity bit is chosen to make the total number of 1s even Table 91 shows how parity bits would be added to BCD code group in both systems

          Decimal BCD Value Parity Bit ABCD Odd Parity Even Parity

          0 0000 1 0 1 0001 0 1 2 0010 0 1 3 0011 1 0 4 0100 0 1 5 0101 1 0 6 0110 1 0 7 0111 0 1 8 1000 0 1 9 1001 1 0

          Table 91 Odd and Even Parity in BCD

          When digital data is received a parity checking circuit generates an error signal if the total number of 1s is odd in an even parity system or if it is even in an odd parity system Parity check always detects a single error (one bit change from 0 to 1 or 1 to 0) but may not detect

          42

          Logic Design amp Switching Theory 1 Lab Session 09 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering ` two or more errors Odd parity is used more often than even parity because even parity does not detect a situation where all 0s are created due to short circuit or other fault condition DESIGN OF A 3-BIT ODD PARITY GENERATOR AND CHECKER Let x y and z be the three bits that constitute the message and are the input to the Odd Parity Generator Circuit Since it is an odd parity system the bit P is generated so as to make the total number of 1s odd (including P) The function P can be expressed as follows P = x oplus y Ο z or P = x Ο y oplus z Since the IC available is 7486 which is quad 2input XOR IC therefore we will convert XNOR also to XOR

          P = x oplus y Ο z

          P = ( x oplus y ) Ο z Since for even number of variables ______

          XOR = XNOR Therefore ___________ _________

          P = ( x oplus y ) oplus z = x oplus y oplus z This logical expression can be implemented with two XOR gates and an inverter (see figure 91)

          Figure 91 Circuit Diagram for a 3-bit Parity Generator

          The 3-bit message and the parity bit are transmitted to their destination where they are applied to a Parity Checker Circuit An error occurs during transmission if the parity of the four bits received is even since the binary information transmitted was originally odd The output C of the parity checker should be a 1 when an error occurs ie when the number of 1s in the four inputs is even Therefore the function C can be expressed as

          C = x Ο y Ο z Ο P

          Using the same logic applied for the conversion of the equation of P

          PzyxC oplusoplusoplus= This logical expression can be implemented with three XOR gates and an inverter (see figure 92)

          43

          Logic Design amp Switching Theory 1 Lab Session 09 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering `

          44

          Figure 92 Circuit Diagram for a 3-bit Parity Checker Implementation and Observations Implement the 3-bit Parity Generator and Checker circuits (figure 91 and 92) on a bread board (prepare the pin diagram (use appendix A) and refer to laboratory session 01 for implementation procedure) and record the observations in the following table

          x y z P x y z P C x y z P C 0 0 0 0 0 0 0 1 0 0 0 0 0 1 0 0 0 1 1 0 0 1 0 1 0 0 0 1 0 1 0 1 0 0 1 1 0 0 1 1 1 0 1 1 1 0 0 0 1 0 0 1 1 0 0 1 0 1 0 1 0 1 1 1 0 1 1 1 0 0 1 1 0 1 1 1 0 1 1 1 0 1 1 1 1 1 1 1

          Odd Parity Generation Odd Parity Check ACTIVITY 1 Try using the parity checker of figure 92 as 3-bit parity generator Write the details here

          _____________________________________________________________________________________________________________________________________________________________________________________________________________________ ______________________________________________________________________________________________________________________________________________ _______________________________________________________________________ ______________________________________________________________________________________________________________________________________________

          Logic Design amp Switching Theory 1 Lab Session 10 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

          Lab Session 10 OBJECT

          Driving a seven segment display using 7447 7448 driver IC COMPONENTS AND APPARATUS REQUIRED

          1 Following ICs and their Datasheets

          bull Seven Segment Displays (Common Anode Common Cathode) bull 7447 7448 BCD to Seven Segment Driver

          2 Digital Trainer DT-01 or the following components Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches

          THEORY Seven Segment Displays A Seven Segment Display consists of seven light-emitting segments The segments are designated by letters a through g (see figure 101) By illuminating various combinations of segments the numerals 0 through 9 can be displayed Seven Segment Displays are commonly constructed with light-emitting diodes (LEDs) and with liquid-crystal displays (LCDs) LEDs generally provide greater illumination levels but require much greater power than LCDs An LED display can be a common-anode type or common cathode type In common anode type a high voltage is applied at the common terminal of the display and low voltage is applied at a segmentrsquos terminal for illumination In the common-cathode type a low voltage is applied at the common terminal of the display and high voltage is applied at a segmentrsquos terminal for illumination

          Figure 101 Seven Segment Display

          a f b g

          e c d

          7447 7448 BCD to Seven Segment Driver 7447 7448 IC is particularly used to drive Seven Segment Its input is a BCD number and output drives a seven segment display 7447 is used to drive common-anode displays whereas 7448 is used to drive common cathode displays 7447 7448 is a 16 pin IC Function of various pins of these ICs is described below

          bull A B C D Inputs representing BCD digits (D being the MSB)

          45

          Logic Design amp Switching Theory 1 Lab Session 10 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering bull OA through OG Outputs to drive segments a through g of the display (Active low

          in 7447 and active high in 7448) bull RBI Ripple Blanking Input Turns off all the segments if kept low provided that LT

          is kept high and all other inputs (A B C D BI) are kept low Should be kept high otherwise

          bull BI RBO Wire-AND logic serving as a Blanking Input and or Ripple Blanking Output

          o BI Turns off all the segments if low o RBO Goes to a low level (response condition) along with other outputs when

          RBI and inputs A B C and D are low with LT input at high level bull LT Lamp Test input Tests whether all segments are working or not Illuminates all

          segments if kept low provided that BI is kept high Should be kept high otherwise bull VCC and GND Supply connections lines CIRCUIT DIAGRAM

          Figure 102 Circuit diagram for 7447driving a common-anode display

          IMPLEMENTATION AND OBSERVATIONS

          bull Make connections as shown in the circuit diagram (refer to laboratory session 01 for implementation procedure)

          bull Apply different combinations of 1s and 0s at data inputs bull Observe the output and record your observations in the following table

          46

          Logic Design amp Switching Theory 1 Lab Session 10 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

          47

          Decimal Digit

          BCD Inputs Seven Segment Outputs D C B A a b c d e f g

          0 0 0 0 0 1 0 0 0 1 2 0 0 1 0 3 0 0 1 1 4 0 1 0 0 5 0 1 0 1 6 0 1 1 0 7 0 1 1 1 8 1 0 0 0 9 1 0 0 1

          ACTIVITY 1 Perform the Lamp Test for the designed circuit and write your observations

          ____________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________

          2 How can you use 7447 IC to drive a common-cathode display

          ____________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________

          3 What symbols appear in the seven segment display if inputs DCBA are

          DCBA Symbol

          1010

          1011

          1100

          1101

          1110

          1111

          Logic Design amp Switching Theory 1 Lab Session 11 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

          48

          Lab Session 11 OBJECT

          Testing different modes of JK-FF COMPONENTS AND APPARATUS REQUIRED 1 Following ICs and their Datasheets

          bull 7473 7476 JK Flip-Flop 2 Digital Trainer DT-01 or the following components

          Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches

          THEORY

          Flip-Flop A flip-flop circuit can maintain a binary state indefinitely (as long as the power is delivered to the circuit) until directed by an input signal to switch states The major differences among various types of flip-flops are in the number of inputs they possess and in the manner in which the inputs affect the binary state

          JK Flip-Flop JK flip flop is an edge triggered device A typical JK flip flop has three inputs J K and a clock input The flip-flop can be either positive or negative edge triggered The output Q is available in complemented form as well Beside the usual inputs and output most of the flip-flop IC also possess two asynchronous inputs namely Preset and Clear These inputs are usually active low If used Preset and Clear inputs keep the flip-flop in set and reset state respectively irrespective of the other inputs Both of these inputs cannot be used simultaneously otherwise they will bring the flip-flop in unstable state

          Figure 111 Symbol for JK flip-flop

          (a) positive-edge triggering (b) active low Preset (PR) and Clear (CLR) with positive-edge triggering

          (c) active low Preset (PR) and Clear (CLR) with negative-edge triggering

          Logic Design amp Switching Theory 1 Lab Session 11 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

          49

          TESTING OF 7473 7476 DUAL JK FLIP-FLOP

          Both the ICs 7473 and 7476 are similar in functionality except for one difference The flip-flops in 7473 have only one type of active low asynchronous input which is the Clear input whereas the flip-flops in 7476 have both Preset and Clear inputs Both these ICs have negative edge triggered flip-flops

          Circuit Diagram

          Figure 112 Pin connections of 7476

          Testing Procedure

          bull Make connections as shown in the circuit diagram (figure 112) bull Apply different combinations of 1s and 0s at J and K inputs bull Observe the output and record your observations in the following table

          Observations

          J

          K Q

          0 0 0 1 1 0 1 1

          ACTIVITY

          1 Observe the output Q of JK flip-flop if the clock input is connected to VCC or GND instead of a clock source Write your observations here __________________________________________________________________________________________________________________________________________ _______________________________________________________________________________________________________________________________________________________________________________________________________________

          Logic Design amp Switching Theory 1 Lab Session 12 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

          50

          Lab Session 12 OBJECT

          Designing sequential circuit for the given state diagram using D flip-flop GIVEN STATE DIAGRAM

          00

          11

          Figure 121 State Diagram COMPONENTS AND APPARATUS REQUIRED 1 Following ICs and their Datasheets

          bull 7474 D Flip-Flop bull ICs of basic gates (AND OR NOT XOR etc) as required

          2 Digital Trainer DT-01 or the following components Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches

          THEORY

          Sequential Circuits In Sequential Circuits the output not only depends on the present inputs but also on previous states of the circuit These circuits use memory elements (latches flip-flops) and the binary information stored in the memory elements at any given time defines the state of the sequential circuit Analysis of a Sequential Circuit The behavior of a sequential circuit is determined from the inputs the outputs and the states of its flip-flops Both the outputs and next state are a function of the inputs and the

          10

          01

          00 11 10

          00

          00 11 10 00

          Logic Design amp Switching Theory 1 Lab Session 12 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

          51

          present state The analysis of a sequential circuit form a state diagram comprises of the following bull Selecting a particular flip-flop to design the circuit bull Obtaining state table from the state diagram bull Finding input equations for the selected flip-flop bull Finding state equations (not required for the construction of circuit) bull Implementing the circuit using selected flip-flops and their input equations ANALYZING THE GIVEN STATE DIAGRAM D Flip-Flop D flip-flop is also called transparent flip-flop as it simply transfers the input data to the output For our design we require the graphical symbol and excitation table of D flip-flop (see figure 122)

          Qt Qt+1 T 0 0 0 0 1 1 1 0 0 1 1 1

          (b) Excitation table of D Flip-Flop

          (a) Graphical Symbol

          Figure 122 Characteristic equation of D flip-flop is Q(t+1) = D State Table The given state diagram has four states so we will need two D flip-flops (FF-0 FF-1) Form state table form the given state diagram and record the results in the following table

          Present State Input Next State Output Input to FF-0 D0

          Input to FF-1 D1 Q1t Q0t x Q1(t+1) Q0(t+1) z

          Logic Design amp Switching Theory 1 Lab Session 12 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

          52

          Input Equations Using Karnaugh map the input equations D0 and D1 for the two flip-flops can be found

          D0 D1 Q0x

          Q1

          _ _ Q0x

          _ Q0x

          Q0x

          _ Q0x

          Q0x

          Q1

          _ _ Q0x

          _ Q0x

          Q0x

          _ Q0x

          _ Q1

          _ Q1

          Q1

          Q1

          D0 = _________________ D1 = _________________

          State Equations Using the characteristic equation of D flip-flop we can find the state equations Q0(t+1) and Q1(t+1) for the to flip flops Q0(t+1) = _______________________ Q1(t+1) = _______________________ _______________________ _______________________ _______________________ _______________________ Circuit Diagram

          Logic Design amp Switching Theory 1 Lab Session 12 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

          53

          Implementation Procedure and Observations

          1 Implement the circuit using digital ICs on a bread board (prepare the pin diagram (use appendix A) and refer to laboratory session 01 for procedure)

          2 Make the clear inputs of the flip-flops low (to clear the flip-flops) The flip-flops will remain in clear state as long as the clear inputs are connected to low level

          3 Connect output Q0 and the clock pulse to an oscilloscope 4 Apply 0 to the input x 5 Now make the clear inputs to high 6 Observe the waveform for the first 5 clock pulses and record it 7 Repeat steps 2 to 6 keeping x=1 in step 4 this time 8 Repeat steps 2 to 7 this time connecting Q1 instead of Q0 to the oscilloscope in step

          3 Record your observations (Keep frequency of the clock pulse low (eg1Hz) so that the output waveforms can be observed easily)

          1 2 3 4 5 Clock Pulse

          Output Waveform for Q0 when x=0

          Output Waveform for Q0 when x=1

          Output Waveform for Q1 when x=0

          Output Waveform for Q1 when x=1

          Logic Design amp Switching Theory 1 Lab Session 13 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

          Lab Session 13 OBJECT

          Designing a modulo-5 asynchronous up-counter using JK-FF COMPONENTS AND APPARATUS REQUIRED

          1 Following ICs and their Datasheets

          bull 7400 Quad 2-input or 7410 Triple 3-input NAND Gates bull 7476 7473 JK Flip-Flop

          2 Digital Trainer DT-01 or the following components Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches

          THEORY

          Digital Counters A digital counter is a set of flip-flops whose states change in response to pulses applied at the input to the counter The flip-flops are interconnected so that their combined state at any time is the binary equivalent of the total number of pulses that have occurred up to that time Every counter resets after a certain number of clock pulses Thus as it name implies a counter is used to count pulses An n stage counter can count up to a maximum of 2n states n is equal to the number of flip-flops required for the construction of counter

          Modulus Counters The number of input pulses that causes a counter to reset to its initial count is called the modulus of the counter Thus the modulus equals to total number of distinct states (counts) including zero that a counter can store A binary counter with n stages is a modulo-2n (or mod-2n) counter The largest count a mod-N counter can achieve is N-1 ie a mod-N counter never reaches the binary number equal to its modulus N is always equal to or less than 2n Counters can be classified as bull Synchronous Counters which are clock driven All the flip-flops are driven by a

          single clock bull Asynchronous Counters which are event driven Clock input is given to the first

          flip-flop only Rest of the flip-flops are driven by their preceding flip-flops

          DESIGN OF A MOD-5 ASYNCHRONOUS UP COUNTER The number of flip-flops required to construct a mod-5 counter is 3 because 5 should be less than or equal to 2n This counter will count from 0 to 4 a total of 5 distinct states Since a 3-stage counter can count up to 8 states at maximum a NAND gate is used to reset it after 5 clock pulses Figure 131 shows the logic diagram

          54

          Logic Design amp Switching Theory 1 Lab Session 13 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

          55

          Figure 131 A Mod-5 Asynchronous Up Counter

          Implementation and Observations

          Implement the mod-5 counter circuit (figure 131) on a bread board (prepare the pin diagram (use appendix A) and refer to laboratory session 01 for implementation procedure) and record the observations in the following table

          Clock Pulse Q2 Q1 Q0

          0 1 2 3 4 5 6 7

          ACTIVITY

          Draw the timing diagram for mod-5 counter designed in this laboratory session

          Logic Design amp Switching Theory 1 Lab Session 14 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

          Lab Session 14 OBJECT

          Experimenting with 74194 4-bit bidirectional universal shift register COMPONENTS AND APPARATUS REQUIRED

          1 Following ICs and their Datasheets

          bull 74194 4-bit bidirectional universal shift register 2 Digital Trainer DT-01 or the following components

          Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches

          THEORY

          Shift Registers

          A Register is a set of flip-flops used to store binary data A register which is capable of shifting its binary information either to the right or left is called a shift register The logical configuration of a register consists of a chain of flip-flops connected in cascade with the output of one flip-flop connected to the input of next flip-flop All flip-flops receive a common clock pulse which causes the shift from one stage to the next

          Bidirectional Shift Registers A bi-directional shift register is one whose bits can be shifted from left to right or from right to left

          Universal Shift Registers A universal shift register is a bi-directional register whose input can be in either serial or parallel form and whose output can be in either serial or parallel form

          74194 4-BIT BIDIRECTIONAL UNIVERSAL SHIFT REGISTER

          The 74194 register provides parallel as well as serial loading in both directions Function of various pins of this IC is described below

          bull A B C and D Active high inputs for parallel loading bull QA QB QC and QD Active high outputs bull S0 and S1 Active high mode control inputs The following table shows combinations

          of S1 and S0 to enable various modes

          S1 S0 Clock Action 0 0 x No change 0 1 uarr Shift right 1 0 uarr Shift left 1 1 uarr Parallel load

          uarr shows the rising edge of the clock pulse

          56

          Logic Design amp Switching Theory 1 Lab Session 14 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering bull SR Active high serial input for right shifting bull SL Active high serial input for left shifting bull CLR Active low input Clears all the flip-flops of the register if set to 0 should be

          kept high otherwise bull CLK Clock input bull VCC and GND Supply connections lines Thus A B C and D are inputs for parallel loading whereas SR and SL are inputs for serial loading with right or left shifting respectively S1 and S0 are used to select the loading mode Circuit Diagram

          Figure 141 Pin connections of 74194 Testing Procedure

          bull Make connections as shown in the circuit diagram bull Observe the output for the input combinations given in the following table

          57

          Logic Design amp Switching Theory 1 Lab Session 14 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

          58

          Observations

          S1 S0 SL SR A B C D QA QB QC QD 0 0 0 1 0 0 0 0 0 1 1 0 0 0 0 1 1 0 0 0 0 0 1 0 1 1 0 0 0 0 1 1 0 0 1 1 0 1 0 0 0 1 1 1 0 1 0 1 1 0 1 0 0 1 1 0 1 1 1 0 0 1 1 1 1 1 0 0 1 1 1 1

          ACTIVITY 1 Show connections of 74194 to convert it into a ring counter with right shifting

          Logic Design amp Switching Theory 1 Lab Session 15 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

          Lab Session 15

          OBJECT

          Experimenting with 74245 octal bus transceivers using parallel port PC interfacing COMPONENTS AND APPARATUS REQUIRED 1 Parallel Port Connectors (DB-25) with Cable 2 Personal Computer with Windows 98 and TurboC Compiler Installed 3 Following ICs and their Datasheets

          bull 74245 Octal Bus Transceivers with 3-State Outputs 4 Digital Trainer DT-01 or the following components

          Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches

          THEORY

          3-State Logic Sometimes it is necessary to isolate one part of circuit from the other part For this purpose some TTL ICs are designed with 3-state logic Such devices have three possible output states high low and high impedance The device can be put into high impedance state by a control signal applied to an appropriate pin When such a device is in high impedance state there is very high impedance at its output effectively isolating the device from whatever circuitry the output normally drives 74245 Octal Bus Transceivers A bus is any conducting path or set of paths having electrical connections to one or more devices 74245 octal bus transceivers are mainly used to control connectivity between two devices or circuits It also provides direction control for signal flow Function of various pin of this IC is given below

          bull A1 through A8 Bus A bull B1 through B8 Bus B bull G΄ Active low enable input When high sets all the bus pins to high impedance state bull DIR Direction control for signal flow When set to high logic level transfers bus A

          data to B bus When set to low logic level transfers bus B data to A bus bull VCC and GND Supply connections lines Serial and Parallel Port Connectors A Parallel Port can consist of only 25 pin port adapter called a DB-25 and a serial port can consist of either a 25 pin port adapter called a DB-25 or 9 pin adapter called a DB-9 port adapter Whether the port is a 9 pin or 25 pin it can accomplish all of the same tasks that serial port communications have been designed for

          59

          Logic Design amp Switching Theory 1 Lab Session 15 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

          60

          Each adapter can be a male type connector with pins or a female type adapter with tiny holes Generally a PRINTER port (called LPT1) on the back of a computer is female type adapter and we need to use MALE DB-25 pin cable on it for PRINTER connection or for parallel LAPLINK cable And a COM port on the back of a computer is male for the serial ports but it may not necessarily be Parallel Port Connector ndash DB-25 The DB-25 connector (named for its B-size D-shaped shell and 25 pins) is practically ubiquitous in the electronics industry The DB-25 connector is used for a variety of purposes Two common applications are RS-232EIA-232 (serial) connections and the parallel printer interface on the IBM PC The DB-25 connector is also used for SCSI connections Normally the parallel port is used for output to a printer or other device It sends data 8-bits or one byte at a time in parallel The other lines available on the DB-25 connector are a combination of status lines control lines and ground lines The status and control lines are used for handshaking commands and feedback when we are talking to a printer

          Figure 152 DB-25 Female Figure 151 DB-25 Male

          Figure 153 Pin Layout for DB-25 As can be seen form figure 153 there are four types of pins in this connector

          bull Data pins (8 pins - D0 to D7) Active high bidirectional lines

          Logic Design amp Switching Theory 1 Lab Session 15 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering bull Control pins (4 pins - C0 to C3) C0 C1 and C3 are active low whereas C2 is active

          high These lines also are bidirectional bull Status pins (5 pins ndash S3 to S7) Only S7 is active low rest are active high input lines bull Ground pins (8 pins) Used as a reference signal for the low (below 05 volts) charge

          Parallel Port Addresses A DB-25 connector at a parallel port has three address one for each kind of pins register data status and control The first or base address generally refers to data register Second address is for status register and the third one is for control register In Windows 98 the base address is usually found to be 278H 378H or 3BCH Now if 378H is the base address then it refers to the data register whereas addresses for status and control register are respectively 379H and 37AH For Windows 98 the base address can be found as follows 1 On your Desktop right-click on My Computer and select Properties 2 Click on the Device Manager tab and find LPT1 under Plug and Play BIOS 3 After selecting LPT1 click the Properties button 4 Next select the Resources tab and the address should then appear next to InputOutput

          Range Accessing parallel port through C Language Programming There are multiple functions in C Language for accessing external ports The most commonly used are listed below

          bull unsigned char inportb(int portid) inportb reads a byte from a hardware port

          bull int inport(int portid) reads a word from a hardware port

          bull void outportb(int portid unsigned char value) outputs a byte to a hardware port

          bull void outport(int portid int value) outputs a word to a hardware port

          portid refers to the port address whereas value refers to the data to be sent TESTING 74245 USING PARALLEL PORT PC INTERFACING At one end the parallel port connector will be connected to the PC via parallel port cable and another connector (to be plugged into the PC parallel port slot) At the other end it will be connected to the buffer IC 74245 Data lines of the connector will be used to transfer 8-bit data between the PC and the buffer Out of the 8-bits of 74245 4-bits will be used to enter data which will be displayed at the monitor through a C language

          61

          Logic Design amp Switching Theory 1 Lab Session 15 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering program The remaining 4-bits will receive data from PC as entered by the user via keyboard

          Circuit Diagram

          Figure 154 Interface of 74245 to PC via Parallel Port

          Procedure

          1 Connect the DB-25 connector to the PC at one end and solder it to the circuit board at the other end

          2 Connect various pins of the connector and 74245 according to the circuit diagram shown in figure 152

          3 Using the functions listed in the previous section write a program in C language to operate various pins of the buffer The user interface of the program should provide option to the user whether to send or receive data from the port

          4 Set DIR switch to 1 5 Try sending some data bits to the port The result should be displayed at the LEDs 6 Set DIR switch to 0 7 Set some binary 4-bit value through the switches Try reading it via parallel port

          C Language Program

          A program to access parallel port for data transfers

          use header file include ltstdiohgt main program void main() define variable

          62

          Logic Design amp Switching Theory 1 Lab Session 15 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering unsigned int data=0 char choice while(1) printing option menu clrscr() printf(This program will send or receive a BCD digit from the parallel portn) printf(nPress your choice numbern) printf(n1 Send Data) printf(n2 Receive Data) printf(n3 Exitn) choice = getch() sending entered digit to the port if(choice == 1) input BCD digit printf(nEnter BCD digit to be sent to the port) data = getche() masking the first four bits data = data amp 0x0f sending to the port outportb(0x378data) printf(nThe BCD digit c has been sent to the port data) printing on screen the data received from the port else if(choice == 2) receiving data from the port data = inportb(0x378) masking the last four bits data = data amp 0xf0 shifting first four bits to make them the last four bits datagtgt=4 printf(nThe BCD digit set at the port is c data) exit else if(choice == 3) break key pressed is not in the menu else printf(nEnter valid choice number) printf(nnPress any key to continue) getch()

          63

          Logic Design amp Switching Theory 1 Lab Session 15 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

          ACTIVITY 1 In the above circuit DIR and G΄ inputs are hardwired Connect them to status or

          control pins of the parallel port connector and control their function through your software program Circuit Diagram Program Code ______________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________

          ___________________________________________________________________________________________________________________________________________________

          64

          Logic Design amp Switching Theory 1 Lab Session 15 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

          65

          _____________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ _____________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ _______________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ _________________________________________________ _________________________________________________

          Logic Design amp Switching Theory 1 Appendix A NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

          Appendix A

          PIN DIAGRAMS OF THE ICS REQUIRED FOR THE LABORATORY SESSIONS Consult the TTLIC data book for internal diagrams and electrical characteristics of these ICs 7400 Quad 2-Input NAND 7402 Quad 2-Input NOR

          7404 Hex Inverter 7408 Quad 2-Input AND

          7410 Triple 3-Input NAND 7411 Triple 3-Input AND

          7421 Dual 4-Input AND 7432 Quad 2-Input OR

          66

          Logic Design amp Switching Theory 1 Appendix A NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

          BCD-to-Seven Segm 7448 BCD-to-Seven Segment 7447 ent

          Decoder (15V OC) Decoder (2kΩ pull-up output)

          7473 Dual JK Flip-Flop 7474 Dual D-Type Flip-Flop

          7476 Dual JK Flop-Flop -Bit Binary Full Adder 7483 4 with Fast Carry

          86 Quad 2-Inpu 74138 3-to-8 Line 74 t Exclusive OR Decoder Demultiplexer

          67

          Logic Design amp Switching Theory 1 Appendix A NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

          68

          74148 8-to-3 Line 16-to-1 Line Data

          Priority Encoder 74150 Selector Multiplexer

          74245 Oct nsceivers Universal Shift Register (PIPO) (3-State)

          74194 4-Bit Bidirectional al Bus Tra

          Logic Design amp Switching Theory 1 Appendix B NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

          Appendix B

          DEBOUNCING CIRCUITRY FOR MECHANICAL SWITCHES Mechanical switches form the interface between human beings and computers or other digital systems For example a keyboard is a matrix of switches used to supply alphanumeric data to a computer Whatever the switch design it is a potential source of problems due to contact bounce The contact bounce creates a sense of narrow pulses when a switch is opened or closed An example of device whose operation would be adversely affected by contact bounce is a digital counter used to count the number of times a switch is depressed Eliminating the effects of contact bounce is called debouncing When data is entered into a computer via a keyboard a software debounce is often used This type of debouncing is a program that causes the computer to sample the switch terminal (ie to input data from it) many times in succession during the interval of time that contact bounce occurs If the data is sensed to be 1s (or 0s) for a specific number of consecutive samples then it is assumed that contact bounce has ended and the last value sensed is valid Hardware debouncing is the use of electronic circuitry to eliminate the effects of contact bounce There are numerous versions of such circuitry including those that use monostable multivibrators (one-shots) but the most straightforward is simply an RS latch Figure B1 shows the circuit When the switch is in position 1 R = 0 and S = 1 so the latch is set and the output (Q) is 1 When the switch is in position 0 R = 1and S = 0 so the latch is reset and the output is 0 When the switch is moved form one position to the other the latch changes state and bouncing occurs at either the R or the S input The bouncing does not affect the latch after it has change state An RS latch will remain set for example when its R input is 0 and its S input is alternately changed form 1 to 0

          Figure B1 Use of RS latch to debounce a mechanical switch

          69

          • 01-ldst-Outer title
            • Practical Workbook
            • Logic Design amp Switching Theory I
              • Dept of Computer amp Information Systems Engineering
                • NED University of Engineering amp Technology
                • Karachi ndash 75270 Pakistan
                  • 02-ldst-inner Title
                    • Practical Workbook
                    • Logic Design amp Switching Theory I
                      • Dept of Computer amp Information Systems Engineering
                        • NED University of Engineering amp Technology
                        • Karachi ndash 75270 Pakistan
                          • 03-ldst-general info
                          • 04-ldst-introduction
                          • 05-Table of Contents
                            • CONTENTS
                              • Lab Session No Object Page No
                              • 1
                              • Also implementing and testing the given circuit on a bread board
                                • Working with Electronics Workbench
                                  • Driving a seven segment display using 7447 7448 driver IC
                                    • Designing a modulus-5 asynchronous up-counter using JK-FF
                                      • Experimenting with 74194 4-bit bidirectional universal shift register
                                          • 13
                                              • 06-ldst-Exp01
                                                • Lab Session 01
                                                • OBJECT
                                                  • 1 Bread board
                                                  • 2 5 V - power supply
                                                  • 3 Multimeter
                                                  • 4 Logic probe
                                                  • 5 LEDs with resistors
                                                  • 6 Connecting wires
                                                  • 8 Following ICs and their datasheets
                                                    • THEORY
                                                      • Logic Gates
                                                      • 1 The AND Gate ndash An AND gatersquos output is 1 if and only if all its inputs are 1 If A and B are two inputs to an AND gate then output F of the gate is given as F = AB
                                                      • 2 The OR Gate - An OR gatersquos output is 1 if at least one of its input is 1 If A and B are two inputs to an OR gate then output F of the gate is given as F = A+B
                                                      • 3 The NOT Gate (Inverter) ndash Its output is 1 when its input is 0 and its output is 0 when the input is 1 ie it complements a digital variable If A is the input to a NOT gate then output F of the gate is given as
                                                      • 4 The NAND Gate ndash Its output is 1 if at least one of its input is 0 This gate performs the same logic as an AND gate followed by an inverter If A and B are two inputs to a NAND gate then output F of the gate is given as
                                                        • 5 The NOR Gate - The output of a NOR gate is 1 if and only if all its inputs are 0 This gate performs the same logic function as an OR gate followed by an inverter If A and B are two inputs to a NAND gate then output F of the gate is given as
                                                            • DATA SHEETS
                                                              • Logic expression for the given logic diagram __________________________________
                                                                  • 07-ldst-exp02
                                                                    • Working with Electronics Workbench
                                                                      • 08-ldst-exp03
                                                                        • Designing Half and Full Adder Circuits
                                                                          • COMPONENTS AND APPARATUS REQUIRED
                                                                            • 1 Following ICs and their Datasheets
                                                                            • 7408 Quad 2-input AND Gate
                                                                            • 2 Digital Trainer DT-01 or the following components
                                                                              • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                              • Connecting wires Switches
                                                                                • THEORY
                                                                                    • IMPLEMENTATION AND OBSERVATIONS
                                                                                      • 09-ldst-Exp04
                                                                                        • Lab Session 04
                                                                                        • 1 Digital ICs and their Datasheets
                                                                                        • 7408 Quad 2-input AND Gate
                                                                                        • 2 Digital Trainer DT-01 or the following components
                                                                                          • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                          • Connecting wires Switches
                                                                                          • PROCEDURE
                                                                                          • REDUCTION OF LOGIC EXPRESSION USING KARNAUGH MAP
                                                                                          • OBSERVATIONS
                                                                                          • RESULT
                                                                                              • 10-ldst-Exp05
                                                                                                • Lab Session 05
                                                                                                • 1 Following ICs and their Datasheets
                                                                                                • 7408 Quad 2-input AND Gate
                                                                                                • 2 Digital Trainer DT-01 or the following components
                                                                                                  • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                  • (100 Ω) Connecting wires Switches
                                                                                                  • THEORY
                                                                                                    • IMPLEMENTATION AND OBSERVATIONS
                                                                                                      • 11-ldst-Exp06
                                                                                                        • OBJECT
                                                                                                        • 1 Following ICs and their Datasheets
                                                                                                        • 7408 Quad 2-input AND Gates or 7411 Triple 3-input AND Gates
                                                                                                        • 2 Digital Trainer DT-01 or the following components
                                                                                                          • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                          • Connecting wires Switches
                                                                                                            • Figure 62 Circuit Diagram for 4 x 1 Multiplexer
                                                                                                            • Implementation and Observations
                                                                                                              • Circuit Diagram
                                                                                                                • ACTIVITY
                                                                                                                  • 12-ldst-exp07
                                                                                                                    • 1 Following ICs and their Datasheets
                                                                                                                    • 7408 Quad 2-input or 7411 Triple 3-input AND Gates
                                                                                                                    • 2 Digital Trainer DT-01 or the following components
                                                                                                                      • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                      • Connecting wires Switches
                                                                                                                        • THEORY
                                                                                                                            • Figure 72 Circuit Diagram for 2 x 4 Decoder 1 x 4 Demultiplexer
                                                                                                                            • Implementation and Observations
                                                                                                                              • Circuit Diagram
                                                                                                                                • ACTIVITY
                                                                                                                                  • 13-ldst-Exp08
                                                                                                                                    • OBJECT
                                                                                                                                    • 1 Following ICs and their Datasheets
                                                                                                                                    • 7408 Quad 2-input or 7421 Dual 4-input AND Gates
                                                                                                                                    • 2 Digital Trainer DT-01 or the following components
                                                                                                                                      • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                      • Connecting wires Switches
                                                                                                                                        • THEORY
                                                                                                                                            • Figure 81 Circuit Diagram for 4 x 2 Priority Encoder
                                                                                                                                            • Implementation and Observations
                                                                                                                                              • Therefore if GS A2 A1 and A0 are all low then it shows that line 0 is selected and if E0 A2 A1 and A0 are all low then it shows that none of the inputs selected E0 and GS cannot be in the same state provided that E1 is enabled
                                                                                                                                              • Circuit Diagram
                                                                                                                                                • ACTIVITY
                                                                                                                                                  • 14-ldst-exp09
                                                                                                                                                    • OBJECT
                                                                                                                                                    • 1 Following ICs and their Datasheets
                                                                                                                                                    • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                      • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                      • Connecting wires Switches
                                                                                                                                                        • THEORY
                                                                                                                                                          • Parity Generator
                                                                                                                                                            • Let x y and z be the three bits that constitute the message and are the input to the Odd Parity Generator Circuit Since it is an odd parity system the bit P is generated so as to make the total number of 1s odd (including P) The function P can be expressed as follows
                                                                                                                                                            • Figure 91 Circuit Diagram for a 3-bit Parity Generator
                                                                                                                                                              • C = x Ο y Ο z Ο P
                                                                                                                                                                • Implementation and Observations
                                                                                                                                                                  • ACTIVITY
                                                                                                                                                                      • 15-ldst-exp10
                                                                                                                                                                        • Driving a seven segment display using 7447 7448 driver IC
                                                                                                                                                                        • COMPONENTS AND APPARATUS REQUIRED
                                                                                                                                                                        • 1 Following ICs and their Datasheets
                                                                                                                                                                        • 7447 7448 BCD to Seven Segment Driver
                                                                                                                                                                        • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                          • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches
                                                                                                                                                                            • THEORY
                                                                                                                                                                            • Seven Segment Displays
                                                                                                                                                                            • CIRCUIT DIAGRAM
                                                                                                                                                                            • Figure 102 Circuit diagram for 7447driving a common-anode display
                                                                                                                                                                                • IMPLEMENTATION AND OBSERVATIONS
                                                                                                                                                                                  • Decimal Digit
                                                                                                                                                                                  • BCD Inputs
                                                                                                                                                                                  • Seven Segment Outputs
                                                                                                                                                                                  • D
                                                                                                                                                                                  • C
                                                                                                                                                                                  • B
                                                                                                                                                                                  • A
                                                                                                                                                                                  • a
                                                                                                                                                                                  • b
                                                                                                                                                                                  • c
                                                                                                                                                                                  • d
                                                                                                                                                                                  • e
                                                                                                                                                                                  • f
                                                                                                                                                                                  • g
                                                                                                                                                                                  • 0
                                                                                                                                                                                  • 0
                                                                                                                                                                                  • 0
                                                                                                                                                                                  • 0
                                                                                                                                                                                  • 0
                                                                                                                                                                                  • 1
                                                                                                                                                                                  • 0
                                                                                                                                                                                  • 0
                                                                                                                                                                                  • 0
                                                                                                                                                                                  • 1
                                                                                                                                                                                  • 2
                                                                                                                                                                                  • 0
                                                                                                                                                                                  • 0
                                                                                                                                                                                  • 1
                                                                                                                                                                                  • 0
                                                                                                                                                                                  • 3
                                                                                                                                                                                  • 0
                                                                                                                                                                                  • 0
                                                                                                                                                                                  • 1
                                                                                                                                                                                  • 1
                                                                                                                                                                                  • 4
                                                                                                                                                                                  • 0
                                                                                                                                                                                  • 1
                                                                                                                                                                                  • 0
                                                                                                                                                                                  • 0
                                                                                                                                                                                  • 5
                                                                                                                                                                                  • 0
                                                                                                                                                                                  • 1
                                                                                                                                                                                  • 0
                                                                                                                                                                                  • 1
                                                                                                                                                                                  • 6
                                                                                                                                                                                  • 0
                                                                                                                                                                                  • 1
                                                                                                                                                                                  • 1
                                                                                                                                                                                  • 0
                                                                                                                                                                                  • 7
                                                                                                                                                                                  • 0
                                                                                                                                                                                  • 1
                                                                                                                                                                                  • 1
                                                                                                                                                                                  • 1
                                                                                                                                                                                  • 8
                                                                                                                                                                                  • 1
                                                                                                                                                                                  • 0
                                                                                                                                                                                  • 0
                                                                                                                                                                                  • 0
                                                                                                                                                                                  • 9
                                                                                                                                                                                  • 1
                                                                                                                                                                                  • 0
                                                                                                                                                                                  • 0
                                                                                                                                                                                  • 1
                                                                                                                                                                                    • ACTIVITY
                                                                                                                                                                                      • 16-ldst-exp11
                                                                                                                                                                                        • Lab Session 11
                                                                                                                                                                                          • OBJECT
                                                                                                                                                                                          • COMPONENTS AND APPARATUS REQUIRED
                                                                                                                                                                                            • 1 Following ICs and their Datasheets
                                                                                                                                                                                            • 7473 7476 JK Flip-Flop
                                                                                                                                                                                            • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                              • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                              • Connecting wires Switches
                                                                                                                                                                                                • THEORY
                                                                                                                                                                                                    • Flip-Flop
                                                                                                                                                                                                    • JK Flip-Flop
                                                                                                                                                                                                      • Circuit Diagram
                                                                                                                                                                                                        • Observations
                                                                                                                                                                                                          • ACTIVITY
                                                                                                                                                                                                              • 17-ldst-exp12
                                                                                                                                                                                                                • Lab Session 12
                                                                                                                                                                                                                  • OBJECT
                                                                                                                                                                                                                  • GIVEN STATE DIAGRAM
                                                                                                                                                                                                                  • Figure 121 State Diagram
                                                                                                                                                                                                                  • COMPONENTS AND APPARATUS REQUIRED
                                                                                                                                                                                                                    • 1 Following ICs and their Datasheets
                                                                                                                                                                                                                    • 7474 D Flip-Flop
                                                                                                                                                                                                                    • ICs of basic gates (AND OR NOT XOR etc) as required
                                                                                                                                                                                                                    • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                      • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                                      • Connecting wires Switches
                                                                                                                                                                                                                        • THEORY
                                                                                                                                                                                                                            • Sequential Circuits
                                                                                                                                                                                                                              • 18-ldst-exp13
                                                                                                                                                                                                                                • Lab Session 13
                                                                                                                                                                                                                                  • Designing a modulo-5 asynchronous up-counter using JK-FF
                                                                                                                                                                                                                                    • 1 Following ICs and their Datasheets
                                                                                                                                                                                                                                    • 7400 Quad 2-input or 7410 Triple 3-input NAND Gates
                                                                                                                                                                                                                                    • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                                      • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                                                      • Connecting wires Switches
                                                                                                                                                                                                                                        • THEORY
                                                                                                                                                                                                                                            • Figure 131 A Mod-5 Asynchronous Up Counter
                                                                                                                                                                                                                                            • Implementation and Observations
                                                                                                                                                                                                                                              • ACTIVITY
                                                                                                                                                                                                                                                  • 19-ldst-exp14
                                                                                                                                                                                                                                                    • Experimenting with 74194 4-bit bidirectional universal shift register
                                                                                                                                                                                                                                                    • 1 Following ICs and their Datasheets
                                                                                                                                                                                                                                                    • 74194 4-bit bidirectional universal shift register
                                                                                                                                                                                                                                                    • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                                                      • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                                                                      • Connecting wires Switches
                                                                                                                                                                                                                                                        • THEORY
                                                                                                                                                                                                                                                          • Shift Registers
                                                                                                                                                                                                                                                          • Bidirectional Shift Registers
                                                                                                                                                                                                                                                          • Universal Shift Registers
                                                                                                                                                                                                                                                            • S1
                                                                                                                                                                                                                                                              • Circuit Diagram
                                                                                                                                                                                                                                                              • ACTIVITY
                                                                                                                                                                                                                                                                  • 20-ldst-exp15
                                                                                                                                                                                                                                                                    • COMPONENTS AND APPARATUS REQUIRED
                                                                                                                                                                                                                                                                    • 1 Parallel Port Connectors (DB-25) with Cable
                                                                                                                                                                                                                                                                    • 2 Personal Computer with Windows 98 and TurboC Compiler Installed
                                                                                                                                                                                                                                                                    • 3 Following ICs and their Datasheets
                                                                                                                                                                                                                                                                    • 74245 Octal Bus Transceivers with 3-State Outputs
                                                                                                                                                                                                                                                                    • 4 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                                                                      • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                                                                                        • Connecting wires Switches
                                                                                                                                                                                                                                                                          • THEORY
                                                                                                                                                                                                                                                                          • 3-State Logic
                                                                                                                                                                                                                                                                            • Serial and Parallel Port Connectors
                                                                                                                                                                                                                                                                            • Parallel Port Connector ndash DB-25
                                                                                                                                                                                                                                                                              • Accessing parallel port through C Language Programming
                                                                                                                                                                                                                                                                                  • 21-ldst-appendixA
                                                                                                                                                                                                                                                                                  • 22-ldst-appendixB
                                                                                                                                                                                                                                                                                    • DEBOUNCING CIRCUITRY FOR MECHANICAL SWITCHES

            BUILDING CIRCUITS

            The circuit board shown above accepts ICs as well as separate components It has 47 rows of 5 interconnected sockets on each side of a central channel across which dil ICs can be fitted A wire inserted in a socket in a certain row becomes connected to wires in any of the other 4 sockets in that row by a metal strip under the board For example wires in sockets B5 C5 D5 E5 and F5 (shown in color in the diagram) are all joined Metal strips under the board connect the sockets A row of 40 interconnected sockets along the top of the board and a similar row along the bottom act as the positive and negative power supply rails (called lsquobus barsrsquo) Various makes of circuit board are available some with vertically mounting removable panels for supporting controls

            6

            1 To make a connection push about 1 cm of the bare end of a wire (025 to 085 mm diameter) straight into the socket (not at an angle) so that it is gripped by the metal strip under the board Do not use wires that are dirty or have kinked ends Only put one wire in each socket

            Bend leads on resistors etc as shown before inserting them in the board

            2 Bare the ends of connecting wire (PVC-covered tinned copper wire 06 mm diameter) by

            removing the insulation (PVC) either with wire strippers or using a pair of blunt-nosed pliers and a pair of side cutters as shown With practice you should be able to judge just how much the side cutters have to be squeezed and pulled to remove the insulation without cutting the wire

            3 lsquoJoinrsquo wires to the lsquolugsrsquo on the loudspeaker and variable capacitor using a small length of

            2 mm bore plastic sleeving - as shown by 1 and 2

            7

            RESISTOR COLOUR CODE Resistor values are given in ohms (shortened to Ω the Greek letter lsquoomegarsquo) They are marked on the resistor using a color code Three colored bands are painted round the resistor Each color stands for a number To read the color code start at the 1st band it is nearest the end Sometimes it is not clear which is the 1st band because there is a 4th band of gold or silver near the other end These two colors are not used for the 1st band they give the accuracy of the resistor (gold is plusmn 5 and silver plusmn 10) so you should not have too much trouble deciding where to start The 1st band gives the first number the 2nd band gives the second number and the 3rd band tells how many zeroes come after the first two numbers

            8

            INTRODUCTION

            Digital Logic Design is concerned with the interconnection among digital components and modules and the area of Switching Theory that can be identified between circuit design and system formulation Logic design is the base of any computer system as every digital system consists of different ICrsquoS and ICs contain a large number of interconnected digital circuits within a small package MSI devices provide digital function while LSI device cover a complete computer modules These circuitries are widely used in digital system like digital voltmeter frequency meter calculating machines telephone-switching system etc In this Practical Workbook laboratory sessions based on both combinational and sequential logic are covered First laboratory session gives an introduction to the basic logic gates and fundamentals of circuit building The second laboratory session covers a CAD software ndash Electronics Workbench (EWB) EWB is excellent simulation software where circuits can be designed and tested before physical implementation Various laboratory sessions of this workbook provide activities and exercises on EWB Next eight laboratory sessions are based on combinational logic Here various MSI circuits like adders converters multiplexers decoders encoders etc are designed Some of these laboratory sessions also include testing of MSI ICs Next four laboratory sessions help in exploring various designs based on sequential logic Here a variety of circuits are designed form the testing of basic flip-flop ICs to registers and different types of counters Last laboratory session demonstrates how digital hardware can be interfaced with a personal computer via parallel port and can be controlled by software All laboratory sessions of this workbook incorporate brief theoretical backgrounds as details may be covered in the respective theory classes Exercises activities are included with almost all the sessions for the students to practice Two appendices are also included in this workbook The first one provides pin diagrams for all the ICs required for the laboratory work provided in this workbook It will help the students in preparing the pin diagrams for the circuits Second appendix discusses a hardware debouncing circuit for mechanical switches as such switches are extensively used for input purpose in logic circuits

            9

            CONTENTS Lab Session No Object Page No

            1 2 3 4 5 6 7 8 9

            10

            11

            12

            13

            14

            15

            To study the logic gates in the following TTL ICs

            7400 Quad 2-input NAND gate 7402 Quad 2-input NOR gate

            7404 Hex inverter 7408 Quad 2-input AND gate 7432 Quad 2-input OR gate

            Also implementing and testing the given circuit on a bread board Working with Electronics Workbench Designing Half and Full Adder Circuits Use of Karnaugh Map (SOP-Expression) method Designing a BCD Adder Designing of a 4 x 1 Multiplexer Experimenting with 74150 IC Designing of a 2 x 4 Decoder 1 x 4 Demultiplexer Experimenting with 74138 IC Designing of a 4 x 2 Priority Encoder Experimenting with 74148 IC Designing an Odd Parity Generator and Checker for a 3-bit Data Driving a seven segment display using 7447 7448 driver IC Experimenting with different modes of JK-FF Designing sequential circuit for the given state diagram using D flip-flop Designing a modulus-5 asynchronous up-counter using JK-FF Experimenting with 74194 4-bit bidirectional universal shift register Experimenting with 74245 octal bus transceivers using parallel port PC interfacing Appendix A ndash Pin Diagrams of the ICs required for the laboratory sessions Appendix B ndash Debouncing circuitry for mechanical switches

            13

            17

            19

            22

            28

            30

            34

            38

            42

            45

            48

            50

            54

            56

            59

            66

            69

            11

            Logic Design amp Switching Theory 1 Lab Session 01 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

            Lab Session 01 OBJECT

            bull To study the logic gates in the following TTL ICs

            i) 7400 Quad 2-input NAND gate ii) 7402 Quad 2-input NOR gate iii) 7404 Hex inverter iv) 7408 Quad 2-input AND gate v) 7432 Quad 2-input OR gate

            bull Implementing and testing the given circuit on a bread board

            COMPONENTS REQUIRED 1 Bread board 2 5 V - power supply 3 Multimeter 4 Logic probe 5 LEDs with resistors 6 Connecting wires 7 Switches (optional) 8 Following ICs and their datasheets

            bull 7408 quad 2 input AND gate bull 7432 quad 2 input OR gate bull 7404 hex inverter bull 7400 quad 2 input NAND gate bull 7402 quad 2 input NOR gate

            THEORY

            Logic Gates

            Logic gates are the fundamental building blocks of digital systems These devices are able to make decisions in the sense that they produce one output level when some combinations of input levels are present and a different output when other combinations are applied hence given the name Logic Gates The two levels produced by digital circuitry are referred to variously as HIGH and LOW TRUE and FALSE ON and OFF or simply 1 and 0 There are only three basic gates AND OR and NOT The other gates are merely combinations of these basic gates Logic gates can be interconnected to perform a variety of logical operations This interconnection of gates to achieve prescribed outcomes is called logic design

            1 The AND Gate ndash An AND gatersquos output is 1 if and only if all its inputs are 1 If A and B are two inputs to an AND gate then output F of the gate is given as F = AB

            2 The OR Gate - An OR gatersquos output is 1 if at least one of its input is 1 If A and B are two inputs to an OR gate then output F of the gate is given as F = A+B

            13

            Logic Design amp Switching Theory 1 Lab Session 01 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering 3 The NOT Gate (Inverter) ndash Its output is 1 when its input is 0 and its output is 0 when

            the input is 1 ie it complements a digital variable If A is the input to a NOT gate then output F of the gate is given as AF =

            4 The NAND Gate ndash Its output is 1 if at least one of its input is 0 This gate performs the same logic as an AND gate followed by an inverter If A and B are two inputs to a NAND gate then output F of the gate is given as BAF =

            5 The NOR Gate - The output of a NOR gate is 1 if and only if all its inputs are 0 This gate performs the same logic function as an OR gate followed by an inverter If A and B are two inputs to a NAND gate then output F of the gate is given as BAF +=

            All the above gates have one output and two or more inputs except the NOT gate which has only one input

            PROCEDURE FOR TESTING THE LOGIC GATES IN GIVEN ICs

            1 Set the power supply to 5V With the help of a multimeter check the voltage at the output knobs of the power supply

            2 Connect wires long enough to reach the breadboard with the two knobs of the power supply Again using multimeter check voltage at the non-connected end of the wires

            3 Insert the 7408 quad 2 input AND gate IC on to the bread board and make supply and ground connections by joining 5V wire to pin 14 and 0V wire to pin 7

            4 Consult ICrsquos internal connection diagram for input and output pins of the first AND gate Connect input pins to logic 0 (0V) and observe the output using LED or logic probe You can also connect switches at the input lines to facilitate toggling between 1 and 0

            5 Try different combinations of logic levels at the two inputs Again observe the output 6 Repeat the last two steps for all other gates of the same IC Record the observations 7 Repeat this procedure for all other ICs

            OBSERVATIONS

            Gate Input A Input B Expected Output Observed Output

            AND

            0 0 0 1 1 0 1 1

            OR

            0 0 0 1 1 0 1 1

            NOT 0 - 1 -

            NAND

            0 0 0 1 1 0 1 1

            14

            Logic Design amp Switching Theory 1 Lab Session 01 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

            NOR

            0 0 0 1 1 0 1 1

            DATA SHEETS

            Figure 11

            15

            Logic Design amp Switching Theory 1 Lab Session 01 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

            16

            GIVEN CIRCUIT

            Figure 12

            PROCEDURE FOR IMPLEMENTATION OF THE GIVEN CIRCUIT 1 Set the power supply 2 Insert ICs on the bread board and make their supply and ground connections 3 As given in the logic diagram make connections using wires and gates in the ICs 4 Apply different combinations at the three inputs and observe the output OBSERVATIONS Logic expression for the given logic diagram __________________________________

            A B C Expected Output Observed Output 0 0 0 0 0 1 0 1 0 0 1 1 1 0 0 1 0 1 1 1 0 1 1 1

            Logic Design amp Switching Theory 1 Lab Session 02 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

            Lab Session 02

            OBJECT

            Working with Electronics Workbench

            ELECTRONICS WORKBENCH - EWB Electronics Workbench is a computer aided design tool that provides you with all the components and instruments necessary to create board-level designs It has complete mixed analog and digital simulation and graphical waveform analysis allowing you to design your circuit and then analyze it using different simulated instruments and analysis options It is fully integrated and interactive thus you can change your circuits quickly allowing fast and repeated what-if analysis Electronics Workbench provides the following kind of components bull Sources parts bin (AC voltage source Vcc source ground battery etc) bull Basic parts bin (resistors capacitors transformers switches etc) bull Diodes parts bin bull Transistors parts bin bull Analog ICs parts bin (op-amps etc) bull Mixed ICs parts bin (ADCs DACs 555 timers etc) bull Digital ICs parts bin (AND OR adders multiplexers etc) bull Indicators parts bin (voltmeter ammeter probe displays etc) bull Controls parts bin (voltage differentiator multiplier etc) bull Instruments parts bin (multimeter oscilloscope function generator etc) bull Miscellaneous parts bin (write data textbox etc)

            o Write data This component allows you to save simulation results as an ASCII file o Text Box Use this to add descriptive text anywhere in a circuit

            ACTIVITY

            Design circuit for the logic expression )( CBDCABAF ++=

            Procedure 1 From Logic Gates Parts Bin Drag and drop the required logic gates on the design

            area Use Component Properties dialog box to customize these gates 2 Connect the terminal of these gates according to the given expression Use additional

            connectors form the Basic Parts Bin if you want to connect more than wire at a single node

            3 Drag and drop a probe from Indicators Parts Bin Use Component Properties dialog box to customize the color and other properties of the probe Connect this probe at the output terminal of the circuit to indicate results

            4 Select four switches form Basic Parts Bin Specify the key that controls the switch by typing its name in the Value tab of the Component Properties dialog box For

            17

            Logic Design amp Switching Theory 1 Lab Session 02 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

            18

            example if you want the switch to close or open when digit lsquo1rsquo is pressed type 1 in the Value tab then click OK Assign different keys to all the switches

            5 Connect the output terminals of these switches to each of the four inputs A B C and D of the circuit

            6 Drag and drop Vcc and Ground form the Sources Parts Bin 7 Connect Vcc terminal to one end and Ground terminal to the other end of all the

            switches 8 Label the circuit properly using text boxes found in the miscellaneous parts bin 9 Run the circuit using the Activate Simulation switch Use the keys you have assigned

            to the switches to toggle them between Vcc and Ground connections thus providing 1 or 0 respectively to the inputs Record the results as indicated by the probe for all possible combinations of 1s and 0s at the inputs

            EWB Circuit

            Figure 21

            Observations

            A B C D Expected Output Observed Output 0 0 0 0 0 0 0 1 0 0 1 0 0 0 1 1 0 1 0 0 0 1 0 1 0 1 1 0 0 1 1 1 1 0 0 0 1 0 0 1 1 0 1 0 1 0 1 1 1 1 0 0 1 1 0 1 1 1 1 0 1 1 1 1

            Logic Design amp Switching Theory 1 Lab Session 03 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

            Lab Session 03

            OBJECT

            Designing Half and Full Adder Circuits COMPONENTS AND APPARATUS REQUIRED 1 Following ICs and their Datasheets

            bull 7408 Quad 2-input AND Gate bull 7432 Quad 2-input OR Gate bull 7486 Quad 2-input XOR Gate

            2 Digital Trainer DT-01 or the following components Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches

            THEORY Half Adder A combination circuit that performs the addition of two bits without accounting for the previous carry is called half adder It needs two binary inputs and two binary outputs The input variables designate the augend and addend bits The output variables produce the sum and carry The simplified sum of product expressions for a half adder are

            yxyxyxS oplus=+= yxC =

            Figure 31 Circuit diagram for Half Adder

            19

            Logic Design amp Switching Theory 1 Lab Session 03 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

            bles produce the sum and carry The simplified sum of product expressions for a half adder are

            Full Adder

            A combinational circuit that performs the addition of three input bits It consist of three inputs and two outputs Two of the input variables represent the two significant bits to be added The third input represents the carry from the previous lower significant position The output varia

            zyxzyxzyxzyxzyxS oplusoplus=+++= yxzyxzyzxxyC )( +oplus=++=

            Figure 32 Circuit diagram for Full Adder

            efer to laboratory session 01 for procedure) and record the observations in the following ta

            alf Adde ull Adder Inputs u

            IMPLEMENTATION AND OBSERVATIONS

            Implement the half adder and full adder circuits on a bread board (prepare the pin diagram (use appendix A) and r

            bles H r F

            Inputs Outputs Outp ts x y Carry Su Carry Sum m x y z 0 0 0 0 0 0 1 0 0 1 1 0 0 1 0 1 1 0 1 1 1 0 0 1 0 1 1 1 0 1 1 1

            20

            Logic Design amp Switching Theory 1 Lab Session 03 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

            at of your designed circuit Attach hardcopy of the output form electronic workbench

            at of your designed circuit Attach hardcopy of the output form lectronic workbench here

            ACTIVITY

            1 Simulate half adder circuit using Electronics Workbench Compare the results of simulation with thhere

            2 Design a full subtractor circuit and simulate it using Electronics Workbench Compare the results of simulation with the

            21

            Logic Design amp Switching Theory 1 Lab Session 04 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

            Lab Session 04 OBJECT

            Use of Karnaugh Map (SOP-Expression) method GIVEN LOGIC EXPRESSION

            F (A B C D) = sum ( 0 1 2 4 5 6 8 9 12 13 14 ) COMPONENTS AND APPARATUS REQUIRED 1 Digital ICs and their Datasheets

            bull 7408 Quad 2-input AND Gate bull 7432 Quad 2-input OR Gate bull 7404 Hex Inverter

            2 Digital Trainer DT-01 or the following components Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches PROCEDURE 1 Use Karnaugh map to reduce the given function 2 Draw the circuit diagram for the obtained reduced function 3 Implement the reduced circuit using digital ICs on a bread board (prepare the pin

            diagram (use appendix A) and refer to laboratory session 01 for procedure) and record the observations

            REDUCTION OF LOGIC EXPRESSION USING KARNAUGH MAP F

            CD

            AB DC

            DC DC

            DC

            BA0 1 3 2

            BA4 5 7 6

            BA12 13 15 14

            BA8 9 11 10

            Reduced form of the given logic expression is __________________________________

            22

            Logic Design amp Switching Theory 1 Lab Session 04 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

            LOGIC DIAGRAM (REDUCED FORM) OBSERVATIONS

            A B C D Output 0 0 0 0 0 0 0 1 0 0 1 0 0 0 1 1 0 1 0 0 0 1 0 1 0 1 1 0 0 1 1 1 1 0 0 0 1 0 0 1 1 0 1 0 1 0 1 1 1 1 0 0 1 1 0 1 1 1 1 0 1 1 1 1

            RESULT The reduced form (SOP Expression) of the given logic function is

            ____________________________________________________________

            The observation table reflects the given logic function

            23

            Logic Design amp Switching Theory 1 Lab Session 04 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

            ACTIVITY 1 Using Electronics Workbench derive a truth table and logic circuit for the following logic expression

            BAAF +=

            Procedure 1 From the Instruments Parts Bin drag and drop Logic Converter on the design area 2 Double click the Logic Converter to reveal Logic Converter dialog box This dialog

            box shows various conversion options between truth table logic expression and logic circuit

            3 Enter the given logic expression in the edit box found at the end of the dialog box Use lsquo to represent invert of a variable For example A is written as Arsquo

            4 Click the Boolean Expression to Truth Table button The truth table appears in the logic converters display

            5 Now click the Boolean Expression to Circuit button This creates the logic circuit for the given expression in the design area Label the diagram if needed

            Resulting Logic Circuit For the given expression the final circuit will look like

            Figure 41

            24

            Logic Design amp Switching Theory 1 Lab Session 04 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

            ACTIVITY 2

            Using Electronics Workbench find a simplified logic expression and circuit for the following truth table

            A B C Output 0 0 0 1 0 0 1 1 0 1 0 0 0 1 1 1 1 0 0 0 1 0 1 0 1 1 0 0 1 1 1 1

            Procedure 1 Click three input channels from A to H across the top of the logic converter The

            display area below the terminals fills up with the necessary combinations of ones and zeros to fulfill the input conditions The values in the output column on the right are initially set to 0

            2 Edit the output column to specify the desired output for each input condition To change an output value select it and type a new value 1 0 or x An x indicates a donrsquot care condition

            3 To convert this truth table to a Boolean expression click the Truth Table to Boolean Expression button The Boolean expression will be displayed at the bottom of the logic converter

            4 Simplify the expression by clicking the Simplify button 5 Now click the Boolean Expression to Circuit button This creates the logic circuit for

            the given expression in the design area Resulting Logic Circuit For the given truth table the final simplified circuit will look like

            Figure 42

            25

            Logic Design amp Switching Theory 1 Lab Session 04 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

            ACTIVITY 3

            Using Electronics Workbench find the logic expression and truth table for the following logic circuit

            Figure 43

            Procedure 1 Attach the input terminals of the logic converter to up to four input points in the

            circuit 2 Connect the single output of the circuit to the output terminal on the logic converter

            icon 3 Click the Circuit to Truth Table button The truth table appears in the logic

            converters display 4 To convert this truth table to a Boolean expression click the Truth Table to Boolean

            Expression button The Boolean expression will be displayed at the bottom of the logic converter

            Resulting Logic Expression Logic Expression for the given circuit is found to be _____________________________

            26

            Logic Design amp Switching Theory 1 Lab Session 04 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

            27

            For activities 1 2 and 3 attach hardcopy of the output (truth table logic expression and logic circuit) form electronic workbench here

            Logic Design amp Switching Theory 1 Lab Session 05 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

            Lab Session 05 Lab Session 05 OBJECT OBJECT

            Designing a BCD Adder Designing a BCD Adder COMPONENTS AND APPARATUS REQUIRED COMPONENTS AND APPARATUS REQUIRED

            1 Following ICs and their Datasheets 1 Following ICs and their Datasheets bull 7408 Quad 2-input AND Gate bull 7408 Quad 2-input AND Gate bull 7432 Quad 2-input OR Gate bull 7432 Quad 2-input OR Gate bull 7483 4-bit Binary Adder bull 7483 4-bit Binary Adder

            2 Digital Trainer DT-01 or the following components 2 Digital Trainer DT-01 or the following components Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors (100 Ω) Connecting wires Switches (100 Ω) Connecting wires Switches

            THEORY THEORY

            A BCD Adder is a combinational circuit that adds two BCD digits in parallel and produces a sum digit also in BCD A BCD Adder is a combinational circuit that adds two BCD digits in parallel and produces a sum digit also in BCD

            A4 A3 A2 A1 B4 B3 B2 B1

            7483-BCD ADDER

            Cout (C4 ) Z4 Z3 Z2 Z1 Cin(C0)

            A4 A3 A2 A1 B4 B3 B2 B1

            7483-BCD ADDER

            Cout

            (C4 ) Z4 Z3 Z2 Z1 Cin(C0)

            Figure 51 BCD Adder Circuit

            28

            Logic Design amp Switching Theory 1 Lab Session 05 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

            29

            A BCD adder must include the correction logic in its internal construction The two BCD digits together with the input carry are first added using a 4-bit binary adder to produce the binary sum If no output carry is generated and the binary sum is less than or equal to 9 then the corresponding BCD sum is identical and therefore no conversion is needed When the output carry is equal to 1 or the binary sum is greater than 9 then a binary 0110 is added to the binary sum through another 4-bit binary adder If Cout is the carry output and Z4Z3Z2Z1 is the binary sum form the first 4-bit binary adder then the following equation indicates the condition when a binary 0110 is to be added

            C = COUT + Z4Z2 + Z4Z3 IMPLEMENTATION AND OBSERVATIONS Implement the BCD adder circuit according to figure 51 on a bread board (prepare the pin diagram (use appendix A) and refer to laboratory session 01 for procedure) A BCD adder has nine input bits (two BCD digits and a carry bit) which can result in a total of 512 combinations of which 312 inputs are donrsquot care Since it is a very lengthy procedure to record results for 200 valid input combinations therefore for simplicity just record results for any eight combinations in the following table

            Input Carry

            BCD Digit 1 BCD Digit 2 Carry Output

            BCD Sum A4 A3 A2 A1 B4 B3 B2 B1 Z4 Z3 Z2 Z1

            Logic Design amp Switching Theory 1 lab Session 06 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

            Lab Session 06

            OBJECT

            bull Designing of a 4 x 1 Multiplexer bull Experimenting with 74150 IC

            COMPONENTS AND APPARATUS REQUIRED 1 Following ICs and their Datasheets

            bull 7408 Quad 2-input AND Gates or 7411 Triple 3-input AND Gates bull 7432 Quad 2-input OR Gates bull 7404 Hex Inverter bull 74150 16 x 1 MUX

            2 Digital Trainer DT-01 or the following components Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches THEORY

            Multiplexers A digital data Multiplexer (MUX) is a combinational circuit having several data inputs and a single output A set of data-select inputs is used to control which of the data inputs is routed to the single output A multiplexer is also called a data selector because of this ability to select which data input is connected o the output Normally there are 2n input lines and n selection lines whose bit combination determine which input is selected DESIGN OF A 4 x 1 MULTIPLEXER A 4 x 1 multiplexer is capable of selecting one of four data inputs (see figure 61) The 2-bit binary number at the data select inputs S1 and S0 specifies which of the four data inputs is to be routed to the output Since there are two data select inputs therefore they can select 22 = 4 different data inputs lines

            S0 S1 D0 D1

            D2 D3

            Data-select Inputs Output

            Data Inputs

            Figure 61 Block Diagram of a 4 x1 Multiplexer

            30

            Logic Design amp Switching Theory 1 lab Session 06 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

            Figure 62 Circuit Diagram for 4 x 1 Multiplexer

            Implementation and Observations

            Implement the 4 x 1 Multiplexer circuit (figure 62) on a bread board (prepare the pin diagram (use appendix A) and refer to laboratory session 01 for implementation procedure) and record the observations in the following table For each data select combination specify the switch number as well as the binary value present on that selected switch

            S1 S0 Output 0 0 0 1 1 0 1 1

            TESTING OF 74150 - 16 x 1 MUX

            The 74150 IC has sixteen data inputs and four data-selection lines Function of various pins of this IC is described below

            bull E0 through E15 Data input lines

            31

            Logic Design amp Switching Theory 1 lab Session 06 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering bull A B C D Data select lines with D being the MSB bull W Active low output line bull Grsquo Active low enable line bull VCC and GND Supply connections lines

            Circuit Diagram

            Figure 63 Pin connections of 74150 for selecting E0

            Testing Procedure

            bull Make connections as shown in the circuit diagram bull Apply different data (1 or 0) at data inputs that are labeled as E0 to E15 Only

            connection for E0 is shown is the figure for simplicity bull Select the data input E0 with the help of data selectors A B C and D bull Observe the output which shows the complement of the data from E0 bull Select all the sixteen data inputs one by one and record your observations in the

            following table

            32

            Logic Design amp Switching Theory 1 lab Session 06 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

            33

            Observations

            Grsquo D C B A W Grsquo D C B A W 0 0 0 0 0 0 1 0 0 0 0 0 0 0 1 0 1 0 0 1 0 0 0 1 0 0 1 0 1 0 0 0 0 1 1 0 1 0 1 1 0 0 1 0 0 0 1 1 0 0 0 0 1 0 1 0 1 1 0 1 0 0 1 1 0 0 1 1 1 0 0 0 1 1 1 0 1 1 1 1

            ACTIVITY 1 Consider 4x1 Multiplexer Draw the output wave-form for the following data inputs

            (E0 E1 E2 E3) and select lines A B (B being the MSB) Output is W

            E3 E2 E1 E0 A B

            W

            2 Using the 4 x 1 MUX designed in this laboratory session implement the following logical function F (A B C) = Σ (0147)

            Show your working and input connections in the following block diagram according to the circuit you have implemented

            4 x 1 MUX

            S0 S1

            Output D0

            D1

            D2

            D3

            Logic Design amp Switching Theory 1 Lab Session 07 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

            Lab Session 07

            OBJECT

            bull Designing of a 2 x 4 Decoder 1 x 4 Demultiplexer bull Experimenting with 74138 IC

            COMPONENTS AND APPARATUS REQUIRED 1 Following ICs and their Datasheets

            bull 7408 Quad 2-input or 7411 Triple 3-input AND Gates bull 7404 Hex Inverter bull 74138 3 x 8 Decoder

            2 Digital Trainer DT-01 or the following components Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches THEORY

            Decoder A Decoder is a combinational circuit that converts binary information form n input lines to a maximum of 2n unique output lines In practical applications decoders are often used for selecting one of several devices

            Demultiplexer A decoder with an enable input can function as a Demultiplexer A Demultiplexer (DMUX) id a circuit that receives information on a single line and transmits this information on one of 2n possible output lines The selection of a specific output line is controlled by the bit values of n selection lines DESIGN OF A 2 x 4 DECODER 1 x 4 DEMULTIPLEXER A 2 x 4 decoder is capable of selecting one of four output lines (see figure 71 (a)) The 2-bit binary number at the data inputs S1 and S0 specifies which of the four data inputs is to be selected If we add an enable pin and use it as an input line then this decoder can be converted to a 1 x 4 Demultiplexer where S1 and S0 will select a line to which data input is to be routed (see figure 71 (b))

            Select S0 S0 Inputs

            S1 D0 D1

            D2

            D3

            Enable (a) Block Diagram of a 2 x 4 Decoder

            Figure 71

            S1 D0 D1

            D2

            D3

            Inputs

            Data Input (b) Block Diagram of a 1 x 4 Demulptiplexer

            34

            Logic Design amp Switching Theory 1 Lab Session 07 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

            Figure 72 Circuit Diagram for 2 x 4 Decoder 1 x 4 Demultiplexer

            Implementation and Observations Implement the 2 x 4 Decoder 1 x 4 Demultiplexer circuit (figure 72) on a bread board (prepare the pin diagram (use appendix A) and refer to laboratory session 01 for implementation procedure) and record the observations in the following table

            Enable Data Input S1 S0 D0 D1 D2 D3

            0 0 0 0 0 1 0 1 0 0 1 1 1 0 0 1 0 1 1 1 0 1 1 1

            TESTING OF 74138 3 x 8 Decoder The 74138 IC has three inputs and eight output lines It has three enable inputs and for the IC to function all three inputs need to be enabled Function of various pins of this IC is described below

            35

            Logic Design amp Switching Theory 1 Lab Session 07 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

            bull Y0 through Y7 Active low data outputs bull A B C Input select lines with C being the MSB bull G1 Active high enable Input bull G2Arsquo and G2Brsquo Active low enable Inputs bull VCC and GND Supply connections lines Circuit Diagram

            Figure 73 Pin connections of 74138

            Testing Procedure

            bull Make connections as shown in the circuit diagram bull Apply different combinations of 1s and 0s at data inputs bull Observe the output and record your observations in the following table

            Observations

            C B A Y0 Y1 Y2 Y3 Y4 Y5 Y6 Y7 0 0 0 0 0 1 0 1 0 0 1 1 1 0 0 1 0 1 1 1 0 1 1 1

            36

            Logic Design amp Switching Theory 1 Lab Session 07 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

            37

            ACTIVITY ACTIVITY 1 What will be the binary values at the outputs Y0 through Y7 of 74138 if 1 What will be the binary values at the outputs Y0 through Y7 of 74138 if

            bull All three enable pins are connected to ground bull All three enable pins are connected to ground __________________________________________________________________________________________________________________________________________ __________________________________________________________________________________________________________________________________________ _____________________________________________________________________ _____________________________________________________________________

            bull All three enable pins are connected to VCC bull All three enable pins are connected to VCC _______________________________________________________________________________________________________________________________________________________________________________________________________________

            _______________________________________________________________________________________________________________________________________________________________________________________________________________

            2 Show connections for 74138 in order to use it as a 1 x 8 Demultiplexer 2 Show connections for 74138 in order to use it as a 1 x 8 Demultiplexer

            3 Consider a 2 x 4 Decoder with two enable inputs (one active high - G and one active low ndash Grsquo) Draw the output wave-forms for D0 D1 D2 and D3 if the two select inputs are A and B (B being the MSB) All outputs are active low

            Grsquo

            G

            A B

            D0 D1 D2

            D3

            Logic Design amp Switching Theory 1 Lab Session 08 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

            Lab Session 08 OBJECT

            bull Designing of a 4 x 2 Priority Encoder bull Experimenting with 74148 IC

            COMPONENTS AND APPARATUS REQUIRED

            1 Following ICs and their Datasheets

            bull 7408 Quad 2-input or 7421 Dual 4-input AND Gates bull 7432 Quad 2-input OR Gates bull 7404 Hex Inverter bull 74148 Encoder

            2 Digital Trainer DT-01 or the following components Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches

            THEORY

            Encoder An Encoder is a digital function that produces a reverse operation from that of a decoder An Encoder has 2n (or less) input lines and n output lines The output lines generate the binary code for the 2n input variables Priority Encoder

            A simple encoder may produce an erroneous output if more than one of its inputs is high A Priority Encoder is one that responds to just one input among those that may be simultaneously high in accordance with some priority system The most common priority system is based on the relative magnitudes of the inputs whichever decimal input is largest is the one that is encoded

            DESIGN OF A 4 x 2 Priority Encoder

            The following equations represent the outputs of a 4 x 2 priority encoder 32 DDA +=

            321 DDDB += As can be seen from the equations that input D0 which has a binary code 00 is not used in any equation A binary code 00 at the output indicates two conditions Either D0 is selected or no input is selected In order to differentiate these two conditions we will provide an additional output Z to indicate if at least one of the inputs is a 1 The equation for Z will be

            4321 DDDDZ = If Z is 0 then the binary code 00 at the output indicates that D0 is selected and if Z is 1 then it indicates that no input line is selected

            38

            Logic Design amp Switching Theory 1 Lab Session 08 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

            Figure 81 Circuit Diagram for 4 x 2 Priority Encoder

            it (figure 81) on a bread board (prepare the to laboratory session 01 for implementation

            Implementation a Implement the 4 x 2 Priority Encoder circu

            ram (use appendix A) and refer

            nd Observations

            pin diagprocedure) and record the observations in the following table

            D3 D2 D1 D0 A B 0 0 0 1 0 0 1 x 0 1 x x 1 x x x

            TESTING OF 74148 8 x 3 Octal Priority Encoder

            imal digits There are nine of which three represents

            ing any of the inputs is high

            then it shows that line 0 is selected and if e inputs selected E0 and GS

            cannot be in the same state provided that E1 is enabled

            The 74148 is a priority encoder with active-Low input for dec

            input) and five output linesinputs lines (including an enablethe binary code for the octal digit Function of various pins of this IC is described below

            bull 0 through 7 Active low data inputs representing the octal digits A2 A1 A0 Active low output lines representing the binary code bullbull E1 Active low enable Input bull E0 Active low output indicating none of the inputs is high bull GS Active low output indicatbull VCC and GND Supply connections lines Therefore if GS A2 A1 and A0 are all low

            then it shows that none of thE0 A2 A1 and A0 are all low

            39

            Logic Design amp Switching Theory 1 Lab Session 08 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

            Circuit Diagram

            Figure 82 Pin connections of 74148

            Testing Procedure bull Make connections as sho

            binations of 1s and 0s at data inputs d record your observations in the following table

            GS E0

            wn in the circuit diagram bull Apply different combull Observe the output an Observations

            0 1 2 3 4 5 6 7 A2 A1 A0 1 1 1 1 1 1 1 1 x x x x x x x 0 x x x x x x 0 1 x x x x x 0 1 1 x x x x 0 1 1 1 x x x 0 1 1 1 1 x x 0 1 1 1 1 1 x 0 1 1 1 1 1 1 0 1 1 1 1 1 1 1

            40

            Logic Design amp Switching Theory 1 Lab Session 08 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

            41

            CTIVITY

            Cascade the following two 74148 8 x 3 Priority Encoders to form 16 x 4 Priority

            A 1

            Encoder

            Logic Design amp Switching Theory 1 Lab Session 09 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering `

            Lab Session 09 OBJECT

            Designing an Odd Parity Generator and Checker for a 3-bit Data COMPONENTS AND APPARATUS REQUIRED

            1 Following ICs and their Datasheets

            bull 7486 Quad 2-input Exclusive-OR Gates bull 7404 Hex Inverter

            2 Digital Trainer DT-01 or the following components Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches

            THEORY

            Parity Generator When binary data is transmitted and processed it is ndash as are all electrical signals ndash susceptible to noise that can either alter or distort its contents 1s may be effectively changed to 0s and 0s to 1s To overcome this problem one or more bits are often added to the data as an aid in detecting errors caused by noise The most common of these is a Parity bit that signifies whether the total number of 1s in a code group is odd or even In an Odd Parity system the parity bit is made 0 or 1 as necessary to make the total number 1s odd (counting the parity bit itself) In an Even Parity system the parity bit is chosen to make the total number of 1s even Table 91 shows how parity bits would be added to BCD code group in both systems

            Decimal BCD Value Parity Bit ABCD Odd Parity Even Parity

            0 0000 1 0 1 0001 0 1 2 0010 0 1 3 0011 1 0 4 0100 0 1 5 0101 1 0 6 0110 1 0 7 0111 0 1 8 1000 0 1 9 1001 1 0

            Table 91 Odd and Even Parity in BCD

            When digital data is received a parity checking circuit generates an error signal if the total number of 1s is odd in an even parity system or if it is even in an odd parity system Parity check always detects a single error (one bit change from 0 to 1 or 1 to 0) but may not detect

            42

            Logic Design amp Switching Theory 1 Lab Session 09 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering ` two or more errors Odd parity is used more often than even parity because even parity does not detect a situation where all 0s are created due to short circuit or other fault condition DESIGN OF A 3-BIT ODD PARITY GENERATOR AND CHECKER Let x y and z be the three bits that constitute the message and are the input to the Odd Parity Generator Circuit Since it is an odd parity system the bit P is generated so as to make the total number of 1s odd (including P) The function P can be expressed as follows P = x oplus y Ο z or P = x Ο y oplus z Since the IC available is 7486 which is quad 2input XOR IC therefore we will convert XNOR also to XOR

            P = x oplus y Ο z

            P = ( x oplus y ) Ο z Since for even number of variables ______

            XOR = XNOR Therefore ___________ _________

            P = ( x oplus y ) oplus z = x oplus y oplus z This logical expression can be implemented with two XOR gates and an inverter (see figure 91)

            Figure 91 Circuit Diagram for a 3-bit Parity Generator

            The 3-bit message and the parity bit are transmitted to their destination where they are applied to a Parity Checker Circuit An error occurs during transmission if the parity of the four bits received is even since the binary information transmitted was originally odd The output C of the parity checker should be a 1 when an error occurs ie when the number of 1s in the four inputs is even Therefore the function C can be expressed as

            C = x Ο y Ο z Ο P

            Using the same logic applied for the conversion of the equation of P

            PzyxC oplusoplusoplus= This logical expression can be implemented with three XOR gates and an inverter (see figure 92)

            43

            Logic Design amp Switching Theory 1 Lab Session 09 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering `

            44

            Figure 92 Circuit Diagram for a 3-bit Parity Checker Implementation and Observations Implement the 3-bit Parity Generator and Checker circuits (figure 91 and 92) on a bread board (prepare the pin diagram (use appendix A) and refer to laboratory session 01 for implementation procedure) and record the observations in the following table

            x y z P x y z P C x y z P C 0 0 0 0 0 0 0 1 0 0 0 0 0 1 0 0 0 1 1 0 0 1 0 1 0 0 0 1 0 1 0 1 0 0 1 1 0 0 1 1 1 0 1 1 1 0 0 0 1 0 0 1 1 0 0 1 0 1 0 1 0 1 1 1 0 1 1 1 0 0 1 1 0 1 1 1 0 1 1 1 0 1 1 1 1 1 1 1

            Odd Parity Generation Odd Parity Check ACTIVITY 1 Try using the parity checker of figure 92 as 3-bit parity generator Write the details here

            _____________________________________________________________________________________________________________________________________________________________________________________________________________________ ______________________________________________________________________________________________________________________________________________ _______________________________________________________________________ ______________________________________________________________________________________________________________________________________________

            Logic Design amp Switching Theory 1 Lab Session 10 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

            Lab Session 10 OBJECT

            Driving a seven segment display using 7447 7448 driver IC COMPONENTS AND APPARATUS REQUIRED

            1 Following ICs and their Datasheets

            bull Seven Segment Displays (Common Anode Common Cathode) bull 7447 7448 BCD to Seven Segment Driver

            2 Digital Trainer DT-01 or the following components Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches

            THEORY Seven Segment Displays A Seven Segment Display consists of seven light-emitting segments The segments are designated by letters a through g (see figure 101) By illuminating various combinations of segments the numerals 0 through 9 can be displayed Seven Segment Displays are commonly constructed with light-emitting diodes (LEDs) and with liquid-crystal displays (LCDs) LEDs generally provide greater illumination levels but require much greater power than LCDs An LED display can be a common-anode type or common cathode type In common anode type a high voltage is applied at the common terminal of the display and low voltage is applied at a segmentrsquos terminal for illumination In the common-cathode type a low voltage is applied at the common terminal of the display and high voltage is applied at a segmentrsquos terminal for illumination

            Figure 101 Seven Segment Display

            a f b g

            e c d

            7447 7448 BCD to Seven Segment Driver 7447 7448 IC is particularly used to drive Seven Segment Its input is a BCD number and output drives a seven segment display 7447 is used to drive common-anode displays whereas 7448 is used to drive common cathode displays 7447 7448 is a 16 pin IC Function of various pins of these ICs is described below

            bull A B C D Inputs representing BCD digits (D being the MSB)

            45

            Logic Design amp Switching Theory 1 Lab Session 10 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering bull OA through OG Outputs to drive segments a through g of the display (Active low

            in 7447 and active high in 7448) bull RBI Ripple Blanking Input Turns off all the segments if kept low provided that LT

            is kept high and all other inputs (A B C D BI) are kept low Should be kept high otherwise

            bull BI RBO Wire-AND logic serving as a Blanking Input and or Ripple Blanking Output

            o BI Turns off all the segments if low o RBO Goes to a low level (response condition) along with other outputs when

            RBI and inputs A B C and D are low with LT input at high level bull LT Lamp Test input Tests whether all segments are working or not Illuminates all

            segments if kept low provided that BI is kept high Should be kept high otherwise bull VCC and GND Supply connections lines CIRCUIT DIAGRAM

            Figure 102 Circuit diagram for 7447driving a common-anode display

            IMPLEMENTATION AND OBSERVATIONS

            bull Make connections as shown in the circuit diagram (refer to laboratory session 01 for implementation procedure)

            bull Apply different combinations of 1s and 0s at data inputs bull Observe the output and record your observations in the following table

            46

            Logic Design amp Switching Theory 1 Lab Session 10 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

            47

            Decimal Digit

            BCD Inputs Seven Segment Outputs D C B A a b c d e f g

            0 0 0 0 0 1 0 0 0 1 2 0 0 1 0 3 0 0 1 1 4 0 1 0 0 5 0 1 0 1 6 0 1 1 0 7 0 1 1 1 8 1 0 0 0 9 1 0 0 1

            ACTIVITY 1 Perform the Lamp Test for the designed circuit and write your observations

            ____________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________

            2 How can you use 7447 IC to drive a common-cathode display

            ____________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________

            3 What symbols appear in the seven segment display if inputs DCBA are

            DCBA Symbol

            1010

            1011

            1100

            1101

            1110

            1111

            Logic Design amp Switching Theory 1 Lab Session 11 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

            48

            Lab Session 11 OBJECT

            Testing different modes of JK-FF COMPONENTS AND APPARATUS REQUIRED 1 Following ICs and their Datasheets

            bull 7473 7476 JK Flip-Flop 2 Digital Trainer DT-01 or the following components

            Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches

            THEORY

            Flip-Flop A flip-flop circuit can maintain a binary state indefinitely (as long as the power is delivered to the circuit) until directed by an input signal to switch states The major differences among various types of flip-flops are in the number of inputs they possess and in the manner in which the inputs affect the binary state

            JK Flip-Flop JK flip flop is an edge triggered device A typical JK flip flop has three inputs J K and a clock input The flip-flop can be either positive or negative edge triggered The output Q is available in complemented form as well Beside the usual inputs and output most of the flip-flop IC also possess two asynchronous inputs namely Preset and Clear These inputs are usually active low If used Preset and Clear inputs keep the flip-flop in set and reset state respectively irrespective of the other inputs Both of these inputs cannot be used simultaneously otherwise they will bring the flip-flop in unstable state

            Figure 111 Symbol for JK flip-flop

            (a) positive-edge triggering (b) active low Preset (PR) and Clear (CLR) with positive-edge triggering

            (c) active low Preset (PR) and Clear (CLR) with negative-edge triggering

            Logic Design amp Switching Theory 1 Lab Session 11 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

            49

            TESTING OF 7473 7476 DUAL JK FLIP-FLOP

            Both the ICs 7473 and 7476 are similar in functionality except for one difference The flip-flops in 7473 have only one type of active low asynchronous input which is the Clear input whereas the flip-flops in 7476 have both Preset and Clear inputs Both these ICs have negative edge triggered flip-flops

            Circuit Diagram

            Figure 112 Pin connections of 7476

            Testing Procedure

            bull Make connections as shown in the circuit diagram (figure 112) bull Apply different combinations of 1s and 0s at J and K inputs bull Observe the output and record your observations in the following table

            Observations

            J

            K Q

            0 0 0 1 1 0 1 1

            ACTIVITY

            1 Observe the output Q of JK flip-flop if the clock input is connected to VCC or GND instead of a clock source Write your observations here __________________________________________________________________________________________________________________________________________ _______________________________________________________________________________________________________________________________________________________________________________________________________________

            Logic Design amp Switching Theory 1 Lab Session 12 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

            50

            Lab Session 12 OBJECT

            Designing sequential circuit for the given state diagram using D flip-flop GIVEN STATE DIAGRAM

            00

            11

            Figure 121 State Diagram COMPONENTS AND APPARATUS REQUIRED 1 Following ICs and their Datasheets

            bull 7474 D Flip-Flop bull ICs of basic gates (AND OR NOT XOR etc) as required

            2 Digital Trainer DT-01 or the following components Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches

            THEORY

            Sequential Circuits In Sequential Circuits the output not only depends on the present inputs but also on previous states of the circuit These circuits use memory elements (latches flip-flops) and the binary information stored in the memory elements at any given time defines the state of the sequential circuit Analysis of a Sequential Circuit The behavior of a sequential circuit is determined from the inputs the outputs and the states of its flip-flops Both the outputs and next state are a function of the inputs and the

            10

            01

            00 11 10

            00

            00 11 10 00

            Logic Design amp Switching Theory 1 Lab Session 12 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

            51

            present state The analysis of a sequential circuit form a state diagram comprises of the following bull Selecting a particular flip-flop to design the circuit bull Obtaining state table from the state diagram bull Finding input equations for the selected flip-flop bull Finding state equations (not required for the construction of circuit) bull Implementing the circuit using selected flip-flops and their input equations ANALYZING THE GIVEN STATE DIAGRAM D Flip-Flop D flip-flop is also called transparent flip-flop as it simply transfers the input data to the output For our design we require the graphical symbol and excitation table of D flip-flop (see figure 122)

            Qt Qt+1 T 0 0 0 0 1 1 1 0 0 1 1 1

            (b) Excitation table of D Flip-Flop

            (a) Graphical Symbol

            Figure 122 Characteristic equation of D flip-flop is Q(t+1) = D State Table The given state diagram has four states so we will need two D flip-flops (FF-0 FF-1) Form state table form the given state diagram and record the results in the following table

            Present State Input Next State Output Input to FF-0 D0

            Input to FF-1 D1 Q1t Q0t x Q1(t+1) Q0(t+1) z

            Logic Design amp Switching Theory 1 Lab Session 12 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

            52

            Input Equations Using Karnaugh map the input equations D0 and D1 for the two flip-flops can be found

            D0 D1 Q0x

            Q1

            _ _ Q0x

            _ Q0x

            Q0x

            _ Q0x

            Q0x

            Q1

            _ _ Q0x

            _ Q0x

            Q0x

            _ Q0x

            _ Q1

            _ Q1

            Q1

            Q1

            D0 = _________________ D1 = _________________

            State Equations Using the characteristic equation of D flip-flop we can find the state equations Q0(t+1) and Q1(t+1) for the to flip flops Q0(t+1) = _______________________ Q1(t+1) = _______________________ _______________________ _______________________ _______________________ _______________________ Circuit Diagram

            Logic Design amp Switching Theory 1 Lab Session 12 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

            53

            Implementation Procedure and Observations

            1 Implement the circuit using digital ICs on a bread board (prepare the pin diagram (use appendix A) and refer to laboratory session 01 for procedure)

            2 Make the clear inputs of the flip-flops low (to clear the flip-flops) The flip-flops will remain in clear state as long as the clear inputs are connected to low level

            3 Connect output Q0 and the clock pulse to an oscilloscope 4 Apply 0 to the input x 5 Now make the clear inputs to high 6 Observe the waveform for the first 5 clock pulses and record it 7 Repeat steps 2 to 6 keeping x=1 in step 4 this time 8 Repeat steps 2 to 7 this time connecting Q1 instead of Q0 to the oscilloscope in step

            3 Record your observations (Keep frequency of the clock pulse low (eg1Hz) so that the output waveforms can be observed easily)

            1 2 3 4 5 Clock Pulse

            Output Waveform for Q0 when x=0

            Output Waveform for Q0 when x=1

            Output Waveform for Q1 when x=0

            Output Waveform for Q1 when x=1

            Logic Design amp Switching Theory 1 Lab Session 13 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

            Lab Session 13 OBJECT

            Designing a modulo-5 asynchronous up-counter using JK-FF COMPONENTS AND APPARATUS REQUIRED

            1 Following ICs and their Datasheets

            bull 7400 Quad 2-input or 7410 Triple 3-input NAND Gates bull 7476 7473 JK Flip-Flop

            2 Digital Trainer DT-01 or the following components Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches

            THEORY

            Digital Counters A digital counter is a set of flip-flops whose states change in response to pulses applied at the input to the counter The flip-flops are interconnected so that their combined state at any time is the binary equivalent of the total number of pulses that have occurred up to that time Every counter resets after a certain number of clock pulses Thus as it name implies a counter is used to count pulses An n stage counter can count up to a maximum of 2n states n is equal to the number of flip-flops required for the construction of counter

            Modulus Counters The number of input pulses that causes a counter to reset to its initial count is called the modulus of the counter Thus the modulus equals to total number of distinct states (counts) including zero that a counter can store A binary counter with n stages is a modulo-2n (or mod-2n) counter The largest count a mod-N counter can achieve is N-1 ie a mod-N counter never reaches the binary number equal to its modulus N is always equal to or less than 2n Counters can be classified as bull Synchronous Counters which are clock driven All the flip-flops are driven by a

            single clock bull Asynchronous Counters which are event driven Clock input is given to the first

            flip-flop only Rest of the flip-flops are driven by their preceding flip-flops

            DESIGN OF A MOD-5 ASYNCHRONOUS UP COUNTER The number of flip-flops required to construct a mod-5 counter is 3 because 5 should be less than or equal to 2n This counter will count from 0 to 4 a total of 5 distinct states Since a 3-stage counter can count up to 8 states at maximum a NAND gate is used to reset it after 5 clock pulses Figure 131 shows the logic diagram

            54

            Logic Design amp Switching Theory 1 Lab Session 13 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

            55

            Figure 131 A Mod-5 Asynchronous Up Counter

            Implementation and Observations

            Implement the mod-5 counter circuit (figure 131) on a bread board (prepare the pin diagram (use appendix A) and refer to laboratory session 01 for implementation procedure) and record the observations in the following table

            Clock Pulse Q2 Q1 Q0

            0 1 2 3 4 5 6 7

            ACTIVITY

            Draw the timing diagram for mod-5 counter designed in this laboratory session

            Logic Design amp Switching Theory 1 Lab Session 14 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

            Lab Session 14 OBJECT

            Experimenting with 74194 4-bit bidirectional universal shift register COMPONENTS AND APPARATUS REQUIRED

            1 Following ICs and their Datasheets

            bull 74194 4-bit bidirectional universal shift register 2 Digital Trainer DT-01 or the following components

            Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches

            THEORY

            Shift Registers

            A Register is a set of flip-flops used to store binary data A register which is capable of shifting its binary information either to the right or left is called a shift register The logical configuration of a register consists of a chain of flip-flops connected in cascade with the output of one flip-flop connected to the input of next flip-flop All flip-flops receive a common clock pulse which causes the shift from one stage to the next

            Bidirectional Shift Registers A bi-directional shift register is one whose bits can be shifted from left to right or from right to left

            Universal Shift Registers A universal shift register is a bi-directional register whose input can be in either serial or parallel form and whose output can be in either serial or parallel form

            74194 4-BIT BIDIRECTIONAL UNIVERSAL SHIFT REGISTER

            The 74194 register provides parallel as well as serial loading in both directions Function of various pins of this IC is described below

            bull A B C and D Active high inputs for parallel loading bull QA QB QC and QD Active high outputs bull S0 and S1 Active high mode control inputs The following table shows combinations

            of S1 and S0 to enable various modes

            S1 S0 Clock Action 0 0 x No change 0 1 uarr Shift right 1 0 uarr Shift left 1 1 uarr Parallel load

            uarr shows the rising edge of the clock pulse

            56

            Logic Design amp Switching Theory 1 Lab Session 14 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering bull SR Active high serial input for right shifting bull SL Active high serial input for left shifting bull CLR Active low input Clears all the flip-flops of the register if set to 0 should be

            kept high otherwise bull CLK Clock input bull VCC and GND Supply connections lines Thus A B C and D are inputs for parallel loading whereas SR and SL are inputs for serial loading with right or left shifting respectively S1 and S0 are used to select the loading mode Circuit Diagram

            Figure 141 Pin connections of 74194 Testing Procedure

            bull Make connections as shown in the circuit diagram bull Observe the output for the input combinations given in the following table

            57

            Logic Design amp Switching Theory 1 Lab Session 14 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

            58

            Observations

            S1 S0 SL SR A B C D QA QB QC QD 0 0 0 1 0 0 0 0 0 1 1 0 0 0 0 1 1 0 0 0 0 0 1 0 1 1 0 0 0 0 1 1 0 0 1 1 0 1 0 0 0 1 1 1 0 1 0 1 1 0 1 0 0 1 1 0 1 1 1 0 0 1 1 1 1 1 0 0 1 1 1 1

            ACTIVITY 1 Show connections of 74194 to convert it into a ring counter with right shifting

            Logic Design amp Switching Theory 1 Lab Session 15 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

            Lab Session 15

            OBJECT

            Experimenting with 74245 octal bus transceivers using parallel port PC interfacing COMPONENTS AND APPARATUS REQUIRED 1 Parallel Port Connectors (DB-25) with Cable 2 Personal Computer with Windows 98 and TurboC Compiler Installed 3 Following ICs and their Datasheets

            bull 74245 Octal Bus Transceivers with 3-State Outputs 4 Digital Trainer DT-01 or the following components

            Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches

            THEORY

            3-State Logic Sometimes it is necessary to isolate one part of circuit from the other part For this purpose some TTL ICs are designed with 3-state logic Such devices have three possible output states high low and high impedance The device can be put into high impedance state by a control signal applied to an appropriate pin When such a device is in high impedance state there is very high impedance at its output effectively isolating the device from whatever circuitry the output normally drives 74245 Octal Bus Transceivers A bus is any conducting path or set of paths having electrical connections to one or more devices 74245 octal bus transceivers are mainly used to control connectivity between two devices or circuits It also provides direction control for signal flow Function of various pin of this IC is given below

            bull A1 through A8 Bus A bull B1 through B8 Bus B bull G΄ Active low enable input When high sets all the bus pins to high impedance state bull DIR Direction control for signal flow When set to high logic level transfers bus A

            data to B bus When set to low logic level transfers bus B data to A bus bull VCC and GND Supply connections lines Serial and Parallel Port Connectors A Parallel Port can consist of only 25 pin port adapter called a DB-25 and a serial port can consist of either a 25 pin port adapter called a DB-25 or 9 pin adapter called a DB-9 port adapter Whether the port is a 9 pin or 25 pin it can accomplish all of the same tasks that serial port communications have been designed for

            59

            Logic Design amp Switching Theory 1 Lab Session 15 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

            60

            Each adapter can be a male type connector with pins or a female type adapter with tiny holes Generally a PRINTER port (called LPT1) on the back of a computer is female type adapter and we need to use MALE DB-25 pin cable on it for PRINTER connection or for parallel LAPLINK cable And a COM port on the back of a computer is male for the serial ports but it may not necessarily be Parallel Port Connector ndash DB-25 The DB-25 connector (named for its B-size D-shaped shell and 25 pins) is practically ubiquitous in the electronics industry The DB-25 connector is used for a variety of purposes Two common applications are RS-232EIA-232 (serial) connections and the parallel printer interface on the IBM PC The DB-25 connector is also used for SCSI connections Normally the parallel port is used for output to a printer or other device It sends data 8-bits or one byte at a time in parallel The other lines available on the DB-25 connector are a combination of status lines control lines and ground lines The status and control lines are used for handshaking commands and feedback when we are talking to a printer

            Figure 152 DB-25 Female Figure 151 DB-25 Male

            Figure 153 Pin Layout for DB-25 As can be seen form figure 153 there are four types of pins in this connector

            bull Data pins (8 pins - D0 to D7) Active high bidirectional lines

            Logic Design amp Switching Theory 1 Lab Session 15 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering bull Control pins (4 pins - C0 to C3) C0 C1 and C3 are active low whereas C2 is active

            high These lines also are bidirectional bull Status pins (5 pins ndash S3 to S7) Only S7 is active low rest are active high input lines bull Ground pins (8 pins) Used as a reference signal for the low (below 05 volts) charge

            Parallel Port Addresses A DB-25 connector at a parallel port has three address one for each kind of pins register data status and control The first or base address generally refers to data register Second address is for status register and the third one is for control register In Windows 98 the base address is usually found to be 278H 378H or 3BCH Now if 378H is the base address then it refers to the data register whereas addresses for status and control register are respectively 379H and 37AH For Windows 98 the base address can be found as follows 1 On your Desktop right-click on My Computer and select Properties 2 Click on the Device Manager tab and find LPT1 under Plug and Play BIOS 3 After selecting LPT1 click the Properties button 4 Next select the Resources tab and the address should then appear next to InputOutput

            Range Accessing parallel port through C Language Programming There are multiple functions in C Language for accessing external ports The most commonly used are listed below

            bull unsigned char inportb(int portid) inportb reads a byte from a hardware port

            bull int inport(int portid) reads a word from a hardware port

            bull void outportb(int portid unsigned char value) outputs a byte to a hardware port

            bull void outport(int portid int value) outputs a word to a hardware port

            portid refers to the port address whereas value refers to the data to be sent TESTING 74245 USING PARALLEL PORT PC INTERFACING At one end the parallel port connector will be connected to the PC via parallel port cable and another connector (to be plugged into the PC parallel port slot) At the other end it will be connected to the buffer IC 74245 Data lines of the connector will be used to transfer 8-bit data between the PC and the buffer Out of the 8-bits of 74245 4-bits will be used to enter data which will be displayed at the monitor through a C language

            61

            Logic Design amp Switching Theory 1 Lab Session 15 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering program The remaining 4-bits will receive data from PC as entered by the user via keyboard

            Circuit Diagram

            Figure 154 Interface of 74245 to PC via Parallel Port

            Procedure

            1 Connect the DB-25 connector to the PC at one end and solder it to the circuit board at the other end

            2 Connect various pins of the connector and 74245 according to the circuit diagram shown in figure 152

            3 Using the functions listed in the previous section write a program in C language to operate various pins of the buffer The user interface of the program should provide option to the user whether to send or receive data from the port

            4 Set DIR switch to 1 5 Try sending some data bits to the port The result should be displayed at the LEDs 6 Set DIR switch to 0 7 Set some binary 4-bit value through the switches Try reading it via parallel port

            C Language Program

            A program to access parallel port for data transfers

            use header file include ltstdiohgt main program void main() define variable

            62

            Logic Design amp Switching Theory 1 Lab Session 15 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering unsigned int data=0 char choice while(1) printing option menu clrscr() printf(This program will send or receive a BCD digit from the parallel portn) printf(nPress your choice numbern) printf(n1 Send Data) printf(n2 Receive Data) printf(n3 Exitn) choice = getch() sending entered digit to the port if(choice == 1) input BCD digit printf(nEnter BCD digit to be sent to the port) data = getche() masking the first four bits data = data amp 0x0f sending to the port outportb(0x378data) printf(nThe BCD digit c has been sent to the port data) printing on screen the data received from the port else if(choice == 2) receiving data from the port data = inportb(0x378) masking the last four bits data = data amp 0xf0 shifting first four bits to make them the last four bits datagtgt=4 printf(nThe BCD digit set at the port is c data) exit else if(choice == 3) break key pressed is not in the menu else printf(nEnter valid choice number) printf(nnPress any key to continue) getch()

            63

            Logic Design amp Switching Theory 1 Lab Session 15 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

            ACTIVITY 1 In the above circuit DIR and G΄ inputs are hardwired Connect them to status or

            control pins of the parallel port connector and control their function through your software program Circuit Diagram Program Code ______________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________

            ___________________________________________________________________________________________________________________________________________________

            64

            Logic Design amp Switching Theory 1 Lab Session 15 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

            65

            _____________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ _____________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ _______________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ _________________________________________________ _________________________________________________

            Logic Design amp Switching Theory 1 Appendix A NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

            Appendix A

            PIN DIAGRAMS OF THE ICS REQUIRED FOR THE LABORATORY SESSIONS Consult the TTLIC data book for internal diagrams and electrical characteristics of these ICs 7400 Quad 2-Input NAND 7402 Quad 2-Input NOR

            7404 Hex Inverter 7408 Quad 2-Input AND

            7410 Triple 3-Input NAND 7411 Triple 3-Input AND

            7421 Dual 4-Input AND 7432 Quad 2-Input OR

            66

            Logic Design amp Switching Theory 1 Appendix A NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

            BCD-to-Seven Segm 7448 BCD-to-Seven Segment 7447 ent

            Decoder (15V OC) Decoder (2kΩ pull-up output)

            7473 Dual JK Flip-Flop 7474 Dual D-Type Flip-Flop

            7476 Dual JK Flop-Flop -Bit Binary Full Adder 7483 4 with Fast Carry

            86 Quad 2-Inpu 74138 3-to-8 Line 74 t Exclusive OR Decoder Demultiplexer

            67

            Logic Design amp Switching Theory 1 Appendix A NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

            68

            74148 8-to-3 Line 16-to-1 Line Data

            Priority Encoder 74150 Selector Multiplexer

            74245 Oct nsceivers Universal Shift Register (PIPO) (3-State)

            74194 4-Bit Bidirectional al Bus Tra

            Logic Design amp Switching Theory 1 Appendix B NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

            Appendix B

            DEBOUNCING CIRCUITRY FOR MECHANICAL SWITCHES Mechanical switches form the interface between human beings and computers or other digital systems For example a keyboard is a matrix of switches used to supply alphanumeric data to a computer Whatever the switch design it is a potential source of problems due to contact bounce The contact bounce creates a sense of narrow pulses when a switch is opened or closed An example of device whose operation would be adversely affected by contact bounce is a digital counter used to count the number of times a switch is depressed Eliminating the effects of contact bounce is called debouncing When data is entered into a computer via a keyboard a software debounce is often used This type of debouncing is a program that causes the computer to sample the switch terminal (ie to input data from it) many times in succession during the interval of time that contact bounce occurs If the data is sensed to be 1s (or 0s) for a specific number of consecutive samples then it is assumed that contact bounce has ended and the last value sensed is valid Hardware debouncing is the use of electronic circuitry to eliminate the effects of contact bounce There are numerous versions of such circuitry including those that use monostable multivibrators (one-shots) but the most straightforward is simply an RS latch Figure B1 shows the circuit When the switch is in position 1 R = 0 and S = 1 so the latch is set and the output (Q) is 1 When the switch is in position 0 R = 1and S = 0 so the latch is reset and the output is 0 When the switch is moved form one position to the other the latch changes state and bouncing occurs at either the R or the S input The bouncing does not affect the latch after it has change state An RS latch will remain set for example when its R input is 0 and its S input is alternately changed form 1 to 0

            Figure B1 Use of RS latch to debounce a mechanical switch

            69

            • 01-ldst-Outer title
              • Practical Workbook
              • Logic Design amp Switching Theory I
                • Dept of Computer amp Information Systems Engineering
                  • NED University of Engineering amp Technology
                  • Karachi ndash 75270 Pakistan
                    • 02-ldst-inner Title
                      • Practical Workbook
                      • Logic Design amp Switching Theory I
                        • Dept of Computer amp Information Systems Engineering
                          • NED University of Engineering amp Technology
                          • Karachi ndash 75270 Pakistan
                            • 03-ldst-general info
                            • 04-ldst-introduction
                            • 05-Table of Contents
                              • CONTENTS
                                • Lab Session No Object Page No
                                • 1
                                • Also implementing and testing the given circuit on a bread board
                                  • Working with Electronics Workbench
                                    • Driving a seven segment display using 7447 7448 driver IC
                                      • Designing a modulus-5 asynchronous up-counter using JK-FF
                                        • Experimenting with 74194 4-bit bidirectional universal shift register
                                            • 13
                                                • 06-ldst-Exp01
                                                  • Lab Session 01
                                                  • OBJECT
                                                    • 1 Bread board
                                                    • 2 5 V - power supply
                                                    • 3 Multimeter
                                                    • 4 Logic probe
                                                    • 5 LEDs with resistors
                                                    • 6 Connecting wires
                                                    • 8 Following ICs and their datasheets
                                                      • THEORY
                                                        • Logic Gates
                                                        • 1 The AND Gate ndash An AND gatersquos output is 1 if and only if all its inputs are 1 If A and B are two inputs to an AND gate then output F of the gate is given as F = AB
                                                        • 2 The OR Gate - An OR gatersquos output is 1 if at least one of its input is 1 If A and B are two inputs to an OR gate then output F of the gate is given as F = A+B
                                                        • 3 The NOT Gate (Inverter) ndash Its output is 1 when its input is 0 and its output is 0 when the input is 1 ie it complements a digital variable If A is the input to a NOT gate then output F of the gate is given as
                                                        • 4 The NAND Gate ndash Its output is 1 if at least one of its input is 0 This gate performs the same logic as an AND gate followed by an inverter If A and B are two inputs to a NAND gate then output F of the gate is given as
                                                          • 5 The NOR Gate - The output of a NOR gate is 1 if and only if all its inputs are 0 This gate performs the same logic function as an OR gate followed by an inverter If A and B are two inputs to a NAND gate then output F of the gate is given as
                                                              • DATA SHEETS
                                                                • Logic expression for the given logic diagram __________________________________
                                                                    • 07-ldst-exp02
                                                                      • Working with Electronics Workbench
                                                                        • 08-ldst-exp03
                                                                          • Designing Half and Full Adder Circuits
                                                                            • COMPONENTS AND APPARATUS REQUIRED
                                                                              • 1 Following ICs and their Datasheets
                                                                              • 7408 Quad 2-input AND Gate
                                                                              • 2 Digital Trainer DT-01 or the following components
                                                                                • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                • Connecting wires Switches
                                                                                  • THEORY
                                                                                      • IMPLEMENTATION AND OBSERVATIONS
                                                                                        • 09-ldst-Exp04
                                                                                          • Lab Session 04
                                                                                          • 1 Digital ICs and their Datasheets
                                                                                          • 7408 Quad 2-input AND Gate
                                                                                          • 2 Digital Trainer DT-01 or the following components
                                                                                            • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                            • Connecting wires Switches
                                                                                            • PROCEDURE
                                                                                            • REDUCTION OF LOGIC EXPRESSION USING KARNAUGH MAP
                                                                                            • OBSERVATIONS
                                                                                            • RESULT
                                                                                                • 10-ldst-Exp05
                                                                                                  • Lab Session 05
                                                                                                  • 1 Following ICs and their Datasheets
                                                                                                  • 7408 Quad 2-input AND Gate
                                                                                                  • 2 Digital Trainer DT-01 or the following components
                                                                                                    • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                    • (100 Ω) Connecting wires Switches
                                                                                                    • THEORY
                                                                                                      • IMPLEMENTATION AND OBSERVATIONS
                                                                                                        • 11-ldst-Exp06
                                                                                                          • OBJECT
                                                                                                          • 1 Following ICs and their Datasheets
                                                                                                          • 7408 Quad 2-input AND Gates or 7411 Triple 3-input AND Gates
                                                                                                          • 2 Digital Trainer DT-01 or the following components
                                                                                                            • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                            • Connecting wires Switches
                                                                                                              • Figure 62 Circuit Diagram for 4 x 1 Multiplexer
                                                                                                              • Implementation and Observations
                                                                                                                • Circuit Diagram
                                                                                                                  • ACTIVITY
                                                                                                                    • 12-ldst-exp07
                                                                                                                      • 1 Following ICs and their Datasheets
                                                                                                                      • 7408 Quad 2-input or 7411 Triple 3-input AND Gates
                                                                                                                      • 2 Digital Trainer DT-01 or the following components
                                                                                                                        • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                        • Connecting wires Switches
                                                                                                                          • THEORY
                                                                                                                              • Figure 72 Circuit Diagram for 2 x 4 Decoder 1 x 4 Demultiplexer
                                                                                                                              • Implementation and Observations
                                                                                                                                • Circuit Diagram
                                                                                                                                  • ACTIVITY
                                                                                                                                    • 13-ldst-Exp08
                                                                                                                                      • OBJECT
                                                                                                                                      • 1 Following ICs and their Datasheets
                                                                                                                                      • 7408 Quad 2-input or 7421 Dual 4-input AND Gates
                                                                                                                                      • 2 Digital Trainer DT-01 or the following components
                                                                                                                                        • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                        • Connecting wires Switches
                                                                                                                                          • THEORY
                                                                                                                                              • Figure 81 Circuit Diagram for 4 x 2 Priority Encoder
                                                                                                                                              • Implementation and Observations
                                                                                                                                                • Therefore if GS A2 A1 and A0 are all low then it shows that line 0 is selected and if E0 A2 A1 and A0 are all low then it shows that none of the inputs selected E0 and GS cannot be in the same state provided that E1 is enabled
                                                                                                                                                • Circuit Diagram
                                                                                                                                                  • ACTIVITY
                                                                                                                                                    • 14-ldst-exp09
                                                                                                                                                      • OBJECT
                                                                                                                                                      • 1 Following ICs and their Datasheets
                                                                                                                                                      • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                        • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                        • Connecting wires Switches
                                                                                                                                                          • THEORY
                                                                                                                                                            • Parity Generator
                                                                                                                                                              • Let x y and z be the three bits that constitute the message and are the input to the Odd Parity Generator Circuit Since it is an odd parity system the bit P is generated so as to make the total number of 1s odd (including P) The function P can be expressed as follows
                                                                                                                                                              • Figure 91 Circuit Diagram for a 3-bit Parity Generator
                                                                                                                                                                • C = x Ο y Ο z Ο P
                                                                                                                                                                  • Implementation and Observations
                                                                                                                                                                    • ACTIVITY
                                                                                                                                                                        • 15-ldst-exp10
                                                                                                                                                                          • Driving a seven segment display using 7447 7448 driver IC
                                                                                                                                                                          • COMPONENTS AND APPARATUS REQUIRED
                                                                                                                                                                          • 1 Following ICs and their Datasheets
                                                                                                                                                                          • 7447 7448 BCD to Seven Segment Driver
                                                                                                                                                                          • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                            • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches
                                                                                                                                                                              • THEORY
                                                                                                                                                                              • Seven Segment Displays
                                                                                                                                                                              • CIRCUIT DIAGRAM
                                                                                                                                                                              • Figure 102 Circuit diagram for 7447driving a common-anode display
                                                                                                                                                                                  • IMPLEMENTATION AND OBSERVATIONS
                                                                                                                                                                                    • Decimal Digit
                                                                                                                                                                                    • BCD Inputs
                                                                                                                                                                                    • Seven Segment Outputs
                                                                                                                                                                                    • D
                                                                                                                                                                                    • C
                                                                                                                                                                                    • B
                                                                                                                                                                                    • A
                                                                                                                                                                                    • a
                                                                                                                                                                                    • b
                                                                                                                                                                                    • c
                                                                                                                                                                                    • d
                                                                                                                                                                                    • e
                                                                                                                                                                                    • f
                                                                                                                                                                                    • g
                                                                                                                                                                                    • 0
                                                                                                                                                                                    • 0
                                                                                                                                                                                    • 0
                                                                                                                                                                                    • 0
                                                                                                                                                                                    • 0
                                                                                                                                                                                    • 1
                                                                                                                                                                                    • 0
                                                                                                                                                                                    • 0
                                                                                                                                                                                    • 0
                                                                                                                                                                                    • 1
                                                                                                                                                                                    • 2
                                                                                                                                                                                    • 0
                                                                                                                                                                                    • 0
                                                                                                                                                                                    • 1
                                                                                                                                                                                    • 0
                                                                                                                                                                                    • 3
                                                                                                                                                                                    • 0
                                                                                                                                                                                    • 0
                                                                                                                                                                                    • 1
                                                                                                                                                                                    • 1
                                                                                                                                                                                    • 4
                                                                                                                                                                                    • 0
                                                                                                                                                                                    • 1
                                                                                                                                                                                    • 0
                                                                                                                                                                                    • 0
                                                                                                                                                                                    • 5
                                                                                                                                                                                    • 0
                                                                                                                                                                                    • 1
                                                                                                                                                                                    • 0
                                                                                                                                                                                    • 1
                                                                                                                                                                                    • 6
                                                                                                                                                                                    • 0
                                                                                                                                                                                    • 1
                                                                                                                                                                                    • 1
                                                                                                                                                                                    • 0
                                                                                                                                                                                    • 7
                                                                                                                                                                                    • 0
                                                                                                                                                                                    • 1
                                                                                                                                                                                    • 1
                                                                                                                                                                                    • 1
                                                                                                                                                                                    • 8
                                                                                                                                                                                    • 1
                                                                                                                                                                                    • 0
                                                                                                                                                                                    • 0
                                                                                                                                                                                    • 0
                                                                                                                                                                                    • 9
                                                                                                                                                                                    • 1
                                                                                                                                                                                    • 0
                                                                                                                                                                                    • 0
                                                                                                                                                                                    • 1
                                                                                                                                                                                      • ACTIVITY
                                                                                                                                                                                        • 16-ldst-exp11
                                                                                                                                                                                          • Lab Session 11
                                                                                                                                                                                            • OBJECT
                                                                                                                                                                                            • COMPONENTS AND APPARATUS REQUIRED
                                                                                                                                                                                              • 1 Following ICs and their Datasheets
                                                                                                                                                                                              • 7473 7476 JK Flip-Flop
                                                                                                                                                                                              • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                • Connecting wires Switches
                                                                                                                                                                                                  • THEORY
                                                                                                                                                                                                      • Flip-Flop
                                                                                                                                                                                                      • JK Flip-Flop
                                                                                                                                                                                                        • Circuit Diagram
                                                                                                                                                                                                          • Observations
                                                                                                                                                                                                            • ACTIVITY
                                                                                                                                                                                                                • 17-ldst-exp12
                                                                                                                                                                                                                  • Lab Session 12
                                                                                                                                                                                                                    • OBJECT
                                                                                                                                                                                                                    • GIVEN STATE DIAGRAM
                                                                                                                                                                                                                    • Figure 121 State Diagram
                                                                                                                                                                                                                    • COMPONENTS AND APPARATUS REQUIRED
                                                                                                                                                                                                                      • 1 Following ICs and their Datasheets
                                                                                                                                                                                                                      • 7474 D Flip-Flop
                                                                                                                                                                                                                      • ICs of basic gates (AND OR NOT XOR etc) as required
                                                                                                                                                                                                                      • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                        • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                                        • Connecting wires Switches
                                                                                                                                                                                                                          • THEORY
                                                                                                                                                                                                                              • Sequential Circuits
                                                                                                                                                                                                                                • 18-ldst-exp13
                                                                                                                                                                                                                                  • Lab Session 13
                                                                                                                                                                                                                                    • Designing a modulo-5 asynchronous up-counter using JK-FF
                                                                                                                                                                                                                                      • 1 Following ICs and their Datasheets
                                                                                                                                                                                                                                      • 7400 Quad 2-input or 7410 Triple 3-input NAND Gates
                                                                                                                                                                                                                                      • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                                        • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                                                        • Connecting wires Switches
                                                                                                                                                                                                                                          • THEORY
                                                                                                                                                                                                                                              • Figure 131 A Mod-5 Asynchronous Up Counter
                                                                                                                                                                                                                                              • Implementation and Observations
                                                                                                                                                                                                                                                • ACTIVITY
                                                                                                                                                                                                                                                    • 19-ldst-exp14
                                                                                                                                                                                                                                                      • Experimenting with 74194 4-bit bidirectional universal shift register
                                                                                                                                                                                                                                                      • 1 Following ICs and their Datasheets
                                                                                                                                                                                                                                                      • 74194 4-bit bidirectional universal shift register
                                                                                                                                                                                                                                                      • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                                                        • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                                                                        • Connecting wires Switches
                                                                                                                                                                                                                                                          • THEORY
                                                                                                                                                                                                                                                            • Shift Registers
                                                                                                                                                                                                                                                            • Bidirectional Shift Registers
                                                                                                                                                                                                                                                            • Universal Shift Registers
                                                                                                                                                                                                                                                              • S1
                                                                                                                                                                                                                                                                • Circuit Diagram
                                                                                                                                                                                                                                                                • ACTIVITY
                                                                                                                                                                                                                                                                    • 20-ldst-exp15
                                                                                                                                                                                                                                                                      • COMPONENTS AND APPARATUS REQUIRED
                                                                                                                                                                                                                                                                      • 1 Parallel Port Connectors (DB-25) with Cable
                                                                                                                                                                                                                                                                      • 2 Personal Computer with Windows 98 and TurboC Compiler Installed
                                                                                                                                                                                                                                                                      • 3 Following ICs and their Datasheets
                                                                                                                                                                                                                                                                      • 74245 Octal Bus Transceivers with 3-State Outputs
                                                                                                                                                                                                                                                                      • 4 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                                                                        • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                                                                                          • Connecting wires Switches
                                                                                                                                                                                                                                                                            • THEORY
                                                                                                                                                                                                                                                                            • 3-State Logic
                                                                                                                                                                                                                                                                              • Serial and Parallel Port Connectors
                                                                                                                                                                                                                                                                              • Parallel Port Connector ndash DB-25
                                                                                                                                                                                                                                                                                • Accessing parallel port through C Language Programming
                                                                                                                                                                                                                                                                                    • 21-ldst-appendixA
                                                                                                                                                                                                                                                                                    • 22-ldst-appendixB
                                                                                                                                                                                                                                                                                      • DEBOUNCING CIRCUITRY FOR MECHANICAL SWITCHES

              1 To make a connection push about 1 cm of the bare end of a wire (025 to 085 mm diameter) straight into the socket (not at an angle) so that it is gripped by the metal strip under the board Do not use wires that are dirty or have kinked ends Only put one wire in each socket

              Bend leads on resistors etc as shown before inserting them in the board

              2 Bare the ends of connecting wire (PVC-covered tinned copper wire 06 mm diameter) by

              removing the insulation (PVC) either with wire strippers or using a pair of blunt-nosed pliers and a pair of side cutters as shown With practice you should be able to judge just how much the side cutters have to be squeezed and pulled to remove the insulation without cutting the wire

              3 lsquoJoinrsquo wires to the lsquolugsrsquo on the loudspeaker and variable capacitor using a small length of

              2 mm bore plastic sleeving - as shown by 1 and 2

              7

              RESISTOR COLOUR CODE Resistor values are given in ohms (shortened to Ω the Greek letter lsquoomegarsquo) They are marked on the resistor using a color code Three colored bands are painted round the resistor Each color stands for a number To read the color code start at the 1st band it is nearest the end Sometimes it is not clear which is the 1st band because there is a 4th band of gold or silver near the other end These two colors are not used for the 1st band they give the accuracy of the resistor (gold is plusmn 5 and silver plusmn 10) so you should not have too much trouble deciding where to start The 1st band gives the first number the 2nd band gives the second number and the 3rd band tells how many zeroes come after the first two numbers

              8

              INTRODUCTION

              Digital Logic Design is concerned with the interconnection among digital components and modules and the area of Switching Theory that can be identified between circuit design and system formulation Logic design is the base of any computer system as every digital system consists of different ICrsquoS and ICs contain a large number of interconnected digital circuits within a small package MSI devices provide digital function while LSI device cover a complete computer modules These circuitries are widely used in digital system like digital voltmeter frequency meter calculating machines telephone-switching system etc In this Practical Workbook laboratory sessions based on both combinational and sequential logic are covered First laboratory session gives an introduction to the basic logic gates and fundamentals of circuit building The second laboratory session covers a CAD software ndash Electronics Workbench (EWB) EWB is excellent simulation software where circuits can be designed and tested before physical implementation Various laboratory sessions of this workbook provide activities and exercises on EWB Next eight laboratory sessions are based on combinational logic Here various MSI circuits like adders converters multiplexers decoders encoders etc are designed Some of these laboratory sessions also include testing of MSI ICs Next four laboratory sessions help in exploring various designs based on sequential logic Here a variety of circuits are designed form the testing of basic flip-flop ICs to registers and different types of counters Last laboratory session demonstrates how digital hardware can be interfaced with a personal computer via parallel port and can be controlled by software All laboratory sessions of this workbook incorporate brief theoretical backgrounds as details may be covered in the respective theory classes Exercises activities are included with almost all the sessions for the students to practice Two appendices are also included in this workbook The first one provides pin diagrams for all the ICs required for the laboratory work provided in this workbook It will help the students in preparing the pin diagrams for the circuits Second appendix discusses a hardware debouncing circuit for mechanical switches as such switches are extensively used for input purpose in logic circuits

              9

              CONTENTS Lab Session No Object Page No

              1 2 3 4 5 6 7 8 9

              10

              11

              12

              13

              14

              15

              To study the logic gates in the following TTL ICs

              7400 Quad 2-input NAND gate 7402 Quad 2-input NOR gate

              7404 Hex inverter 7408 Quad 2-input AND gate 7432 Quad 2-input OR gate

              Also implementing and testing the given circuit on a bread board Working with Electronics Workbench Designing Half and Full Adder Circuits Use of Karnaugh Map (SOP-Expression) method Designing a BCD Adder Designing of a 4 x 1 Multiplexer Experimenting with 74150 IC Designing of a 2 x 4 Decoder 1 x 4 Demultiplexer Experimenting with 74138 IC Designing of a 4 x 2 Priority Encoder Experimenting with 74148 IC Designing an Odd Parity Generator and Checker for a 3-bit Data Driving a seven segment display using 7447 7448 driver IC Experimenting with different modes of JK-FF Designing sequential circuit for the given state diagram using D flip-flop Designing a modulus-5 asynchronous up-counter using JK-FF Experimenting with 74194 4-bit bidirectional universal shift register Experimenting with 74245 octal bus transceivers using parallel port PC interfacing Appendix A ndash Pin Diagrams of the ICs required for the laboratory sessions Appendix B ndash Debouncing circuitry for mechanical switches

              13

              17

              19

              22

              28

              30

              34

              38

              42

              45

              48

              50

              54

              56

              59

              66

              69

              11

              Logic Design amp Switching Theory 1 Lab Session 01 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

              Lab Session 01 OBJECT

              bull To study the logic gates in the following TTL ICs

              i) 7400 Quad 2-input NAND gate ii) 7402 Quad 2-input NOR gate iii) 7404 Hex inverter iv) 7408 Quad 2-input AND gate v) 7432 Quad 2-input OR gate

              bull Implementing and testing the given circuit on a bread board

              COMPONENTS REQUIRED 1 Bread board 2 5 V - power supply 3 Multimeter 4 Logic probe 5 LEDs with resistors 6 Connecting wires 7 Switches (optional) 8 Following ICs and their datasheets

              bull 7408 quad 2 input AND gate bull 7432 quad 2 input OR gate bull 7404 hex inverter bull 7400 quad 2 input NAND gate bull 7402 quad 2 input NOR gate

              THEORY

              Logic Gates

              Logic gates are the fundamental building blocks of digital systems These devices are able to make decisions in the sense that they produce one output level when some combinations of input levels are present and a different output when other combinations are applied hence given the name Logic Gates The two levels produced by digital circuitry are referred to variously as HIGH and LOW TRUE and FALSE ON and OFF or simply 1 and 0 There are only three basic gates AND OR and NOT The other gates are merely combinations of these basic gates Logic gates can be interconnected to perform a variety of logical operations This interconnection of gates to achieve prescribed outcomes is called logic design

              1 The AND Gate ndash An AND gatersquos output is 1 if and only if all its inputs are 1 If A and B are two inputs to an AND gate then output F of the gate is given as F = AB

              2 The OR Gate - An OR gatersquos output is 1 if at least one of its input is 1 If A and B are two inputs to an OR gate then output F of the gate is given as F = A+B

              13

              Logic Design amp Switching Theory 1 Lab Session 01 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering 3 The NOT Gate (Inverter) ndash Its output is 1 when its input is 0 and its output is 0 when

              the input is 1 ie it complements a digital variable If A is the input to a NOT gate then output F of the gate is given as AF =

              4 The NAND Gate ndash Its output is 1 if at least one of its input is 0 This gate performs the same logic as an AND gate followed by an inverter If A and B are two inputs to a NAND gate then output F of the gate is given as BAF =

              5 The NOR Gate - The output of a NOR gate is 1 if and only if all its inputs are 0 This gate performs the same logic function as an OR gate followed by an inverter If A and B are two inputs to a NAND gate then output F of the gate is given as BAF +=

              All the above gates have one output and two or more inputs except the NOT gate which has only one input

              PROCEDURE FOR TESTING THE LOGIC GATES IN GIVEN ICs

              1 Set the power supply to 5V With the help of a multimeter check the voltage at the output knobs of the power supply

              2 Connect wires long enough to reach the breadboard with the two knobs of the power supply Again using multimeter check voltage at the non-connected end of the wires

              3 Insert the 7408 quad 2 input AND gate IC on to the bread board and make supply and ground connections by joining 5V wire to pin 14 and 0V wire to pin 7

              4 Consult ICrsquos internal connection diagram for input and output pins of the first AND gate Connect input pins to logic 0 (0V) and observe the output using LED or logic probe You can also connect switches at the input lines to facilitate toggling between 1 and 0

              5 Try different combinations of logic levels at the two inputs Again observe the output 6 Repeat the last two steps for all other gates of the same IC Record the observations 7 Repeat this procedure for all other ICs

              OBSERVATIONS

              Gate Input A Input B Expected Output Observed Output

              AND

              0 0 0 1 1 0 1 1

              OR

              0 0 0 1 1 0 1 1

              NOT 0 - 1 -

              NAND

              0 0 0 1 1 0 1 1

              14

              Logic Design amp Switching Theory 1 Lab Session 01 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

              NOR

              0 0 0 1 1 0 1 1

              DATA SHEETS

              Figure 11

              15

              Logic Design amp Switching Theory 1 Lab Session 01 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

              16

              GIVEN CIRCUIT

              Figure 12

              PROCEDURE FOR IMPLEMENTATION OF THE GIVEN CIRCUIT 1 Set the power supply 2 Insert ICs on the bread board and make their supply and ground connections 3 As given in the logic diagram make connections using wires and gates in the ICs 4 Apply different combinations at the three inputs and observe the output OBSERVATIONS Logic expression for the given logic diagram __________________________________

              A B C Expected Output Observed Output 0 0 0 0 0 1 0 1 0 0 1 1 1 0 0 1 0 1 1 1 0 1 1 1

              Logic Design amp Switching Theory 1 Lab Session 02 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

              Lab Session 02

              OBJECT

              Working with Electronics Workbench

              ELECTRONICS WORKBENCH - EWB Electronics Workbench is a computer aided design tool that provides you with all the components and instruments necessary to create board-level designs It has complete mixed analog and digital simulation and graphical waveform analysis allowing you to design your circuit and then analyze it using different simulated instruments and analysis options It is fully integrated and interactive thus you can change your circuits quickly allowing fast and repeated what-if analysis Electronics Workbench provides the following kind of components bull Sources parts bin (AC voltage source Vcc source ground battery etc) bull Basic parts bin (resistors capacitors transformers switches etc) bull Diodes parts bin bull Transistors parts bin bull Analog ICs parts bin (op-amps etc) bull Mixed ICs parts bin (ADCs DACs 555 timers etc) bull Digital ICs parts bin (AND OR adders multiplexers etc) bull Indicators parts bin (voltmeter ammeter probe displays etc) bull Controls parts bin (voltage differentiator multiplier etc) bull Instruments parts bin (multimeter oscilloscope function generator etc) bull Miscellaneous parts bin (write data textbox etc)

              o Write data This component allows you to save simulation results as an ASCII file o Text Box Use this to add descriptive text anywhere in a circuit

              ACTIVITY

              Design circuit for the logic expression )( CBDCABAF ++=

              Procedure 1 From Logic Gates Parts Bin Drag and drop the required logic gates on the design

              area Use Component Properties dialog box to customize these gates 2 Connect the terminal of these gates according to the given expression Use additional

              connectors form the Basic Parts Bin if you want to connect more than wire at a single node

              3 Drag and drop a probe from Indicators Parts Bin Use Component Properties dialog box to customize the color and other properties of the probe Connect this probe at the output terminal of the circuit to indicate results

              4 Select four switches form Basic Parts Bin Specify the key that controls the switch by typing its name in the Value tab of the Component Properties dialog box For

              17

              Logic Design amp Switching Theory 1 Lab Session 02 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

              18

              example if you want the switch to close or open when digit lsquo1rsquo is pressed type 1 in the Value tab then click OK Assign different keys to all the switches

              5 Connect the output terminals of these switches to each of the four inputs A B C and D of the circuit

              6 Drag and drop Vcc and Ground form the Sources Parts Bin 7 Connect Vcc terminal to one end and Ground terminal to the other end of all the

              switches 8 Label the circuit properly using text boxes found in the miscellaneous parts bin 9 Run the circuit using the Activate Simulation switch Use the keys you have assigned

              to the switches to toggle them between Vcc and Ground connections thus providing 1 or 0 respectively to the inputs Record the results as indicated by the probe for all possible combinations of 1s and 0s at the inputs

              EWB Circuit

              Figure 21

              Observations

              A B C D Expected Output Observed Output 0 0 0 0 0 0 0 1 0 0 1 0 0 0 1 1 0 1 0 0 0 1 0 1 0 1 1 0 0 1 1 1 1 0 0 0 1 0 0 1 1 0 1 0 1 0 1 1 1 1 0 0 1 1 0 1 1 1 1 0 1 1 1 1

              Logic Design amp Switching Theory 1 Lab Session 03 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

              Lab Session 03

              OBJECT

              Designing Half and Full Adder Circuits COMPONENTS AND APPARATUS REQUIRED 1 Following ICs and their Datasheets

              bull 7408 Quad 2-input AND Gate bull 7432 Quad 2-input OR Gate bull 7486 Quad 2-input XOR Gate

              2 Digital Trainer DT-01 or the following components Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches

              THEORY Half Adder A combination circuit that performs the addition of two bits without accounting for the previous carry is called half adder It needs two binary inputs and two binary outputs The input variables designate the augend and addend bits The output variables produce the sum and carry The simplified sum of product expressions for a half adder are

              yxyxyxS oplus=+= yxC =

              Figure 31 Circuit diagram for Half Adder

              19

              Logic Design amp Switching Theory 1 Lab Session 03 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

              bles produce the sum and carry The simplified sum of product expressions for a half adder are

              Full Adder

              A combinational circuit that performs the addition of three input bits It consist of three inputs and two outputs Two of the input variables represent the two significant bits to be added The third input represents the carry from the previous lower significant position The output varia

              zyxzyxzyxzyxzyxS oplusoplus=+++= yxzyxzyzxxyC )( +oplus=++=

              Figure 32 Circuit diagram for Full Adder

              efer to laboratory session 01 for procedure) and record the observations in the following ta

              alf Adde ull Adder Inputs u

              IMPLEMENTATION AND OBSERVATIONS

              Implement the half adder and full adder circuits on a bread board (prepare the pin diagram (use appendix A) and r

              bles H r F

              Inputs Outputs Outp ts x y Carry Su Carry Sum m x y z 0 0 0 0 0 0 1 0 0 1 1 0 0 1 0 1 1 0 1 1 1 0 0 1 0 1 1 1 0 1 1 1

              20

              Logic Design amp Switching Theory 1 Lab Session 03 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

              at of your designed circuit Attach hardcopy of the output form electronic workbench

              at of your designed circuit Attach hardcopy of the output form lectronic workbench here

              ACTIVITY

              1 Simulate half adder circuit using Electronics Workbench Compare the results of simulation with thhere

              2 Design a full subtractor circuit and simulate it using Electronics Workbench Compare the results of simulation with the

              21

              Logic Design amp Switching Theory 1 Lab Session 04 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

              Lab Session 04 OBJECT

              Use of Karnaugh Map (SOP-Expression) method GIVEN LOGIC EXPRESSION

              F (A B C D) = sum ( 0 1 2 4 5 6 8 9 12 13 14 ) COMPONENTS AND APPARATUS REQUIRED 1 Digital ICs and their Datasheets

              bull 7408 Quad 2-input AND Gate bull 7432 Quad 2-input OR Gate bull 7404 Hex Inverter

              2 Digital Trainer DT-01 or the following components Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches PROCEDURE 1 Use Karnaugh map to reduce the given function 2 Draw the circuit diagram for the obtained reduced function 3 Implement the reduced circuit using digital ICs on a bread board (prepare the pin

              diagram (use appendix A) and refer to laboratory session 01 for procedure) and record the observations

              REDUCTION OF LOGIC EXPRESSION USING KARNAUGH MAP F

              CD

              AB DC

              DC DC

              DC

              BA0 1 3 2

              BA4 5 7 6

              BA12 13 15 14

              BA8 9 11 10

              Reduced form of the given logic expression is __________________________________

              22

              Logic Design amp Switching Theory 1 Lab Session 04 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

              LOGIC DIAGRAM (REDUCED FORM) OBSERVATIONS

              A B C D Output 0 0 0 0 0 0 0 1 0 0 1 0 0 0 1 1 0 1 0 0 0 1 0 1 0 1 1 0 0 1 1 1 1 0 0 0 1 0 0 1 1 0 1 0 1 0 1 1 1 1 0 0 1 1 0 1 1 1 1 0 1 1 1 1

              RESULT The reduced form (SOP Expression) of the given logic function is

              ____________________________________________________________

              The observation table reflects the given logic function

              23

              Logic Design amp Switching Theory 1 Lab Session 04 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

              ACTIVITY 1 Using Electronics Workbench derive a truth table and logic circuit for the following logic expression

              BAAF +=

              Procedure 1 From the Instruments Parts Bin drag and drop Logic Converter on the design area 2 Double click the Logic Converter to reveal Logic Converter dialog box This dialog

              box shows various conversion options between truth table logic expression and logic circuit

              3 Enter the given logic expression in the edit box found at the end of the dialog box Use lsquo to represent invert of a variable For example A is written as Arsquo

              4 Click the Boolean Expression to Truth Table button The truth table appears in the logic converters display

              5 Now click the Boolean Expression to Circuit button This creates the logic circuit for the given expression in the design area Label the diagram if needed

              Resulting Logic Circuit For the given expression the final circuit will look like

              Figure 41

              24

              Logic Design amp Switching Theory 1 Lab Session 04 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

              ACTIVITY 2

              Using Electronics Workbench find a simplified logic expression and circuit for the following truth table

              A B C Output 0 0 0 1 0 0 1 1 0 1 0 0 0 1 1 1 1 0 0 0 1 0 1 0 1 1 0 0 1 1 1 1

              Procedure 1 Click three input channels from A to H across the top of the logic converter The

              display area below the terminals fills up with the necessary combinations of ones and zeros to fulfill the input conditions The values in the output column on the right are initially set to 0

              2 Edit the output column to specify the desired output for each input condition To change an output value select it and type a new value 1 0 or x An x indicates a donrsquot care condition

              3 To convert this truth table to a Boolean expression click the Truth Table to Boolean Expression button The Boolean expression will be displayed at the bottom of the logic converter

              4 Simplify the expression by clicking the Simplify button 5 Now click the Boolean Expression to Circuit button This creates the logic circuit for

              the given expression in the design area Resulting Logic Circuit For the given truth table the final simplified circuit will look like

              Figure 42

              25

              Logic Design amp Switching Theory 1 Lab Session 04 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

              ACTIVITY 3

              Using Electronics Workbench find the logic expression and truth table for the following logic circuit

              Figure 43

              Procedure 1 Attach the input terminals of the logic converter to up to four input points in the

              circuit 2 Connect the single output of the circuit to the output terminal on the logic converter

              icon 3 Click the Circuit to Truth Table button The truth table appears in the logic

              converters display 4 To convert this truth table to a Boolean expression click the Truth Table to Boolean

              Expression button The Boolean expression will be displayed at the bottom of the logic converter

              Resulting Logic Expression Logic Expression for the given circuit is found to be _____________________________

              26

              Logic Design amp Switching Theory 1 Lab Session 04 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

              27

              For activities 1 2 and 3 attach hardcopy of the output (truth table logic expression and logic circuit) form electronic workbench here

              Logic Design amp Switching Theory 1 Lab Session 05 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

              Lab Session 05 Lab Session 05 OBJECT OBJECT

              Designing a BCD Adder Designing a BCD Adder COMPONENTS AND APPARATUS REQUIRED COMPONENTS AND APPARATUS REQUIRED

              1 Following ICs and their Datasheets 1 Following ICs and their Datasheets bull 7408 Quad 2-input AND Gate bull 7408 Quad 2-input AND Gate bull 7432 Quad 2-input OR Gate bull 7432 Quad 2-input OR Gate bull 7483 4-bit Binary Adder bull 7483 4-bit Binary Adder

              2 Digital Trainer DT-01 or the following components 2 Digital Trainer DT-01 or the following components Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors (100 Ω) Connecting wires Switches (100 Ω) Connecting wires Switches

              THEORY THEORY

              A BCD Adder is a combinational circuit that adds two BCD digits in parallel and produces a sum digit also in BCD A BCD Adder is a combinational circuit that adds two BCD digits in parallel and produces a sum digit also in BCD

              A4 A3 A2 A1 B4 B3 B2 B1

              7483-BCD ADDER

              Cout (C4 ) Z4 Z3 Z2 Z1 Cin(C0)

              A4 A3 A2 A1 B4 B3 B2 B1

              7483-BCD ADDER

              Cout

              (C4 ) Z4 Z3 Z2 Z1 Cin(C0)

              Figure 51 BCD Adder Circuit

              28

              Logic Design amp Switching Theory 1 Lab Session 05 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

              29

              A BCD adder must include the correction logic in its internal construction The two BCD digits together with the input carry are first added using a 4-bit binary adder to produce the binary sum If no output carry is generated and the binary sum is less than or equal to 9 then the corresponding BCD sum is identical and therefore no conversion is needed When the output carry is equal to 1 or the binary sum is greater than 9 then a binary 0110 is added to the binary sum through another 4-bit binary adder If Cout is the carry output and Z4Z3Z2Z1 is the binary sum form the first 4-bit binary adder then the following equation indicates the condition when a binary 0110 is to be added

              C = COUT + Z4Z2 + Z4Z3 IMPLEMENTATION AND OBSERVATIONS Implement the BCD adder circuit according to figure 51 on a bread board (prepare the pin diagram (use appendix A) and refer to laboratory session 01 for procedure) A BCD adder has nine input bits (two BCD digits and a carry bit) which can result in a total of 512 combinations of which 312 inputs are donrsquot care Since it is a very lengthy procedure to record results for 200 valid input combinations therefore for simplicity just record results for any eight combinations in the following table

              Input Carry

              BCD Digit 1 BCD Digit 2 Carry Output

              BCD Sum A4 A3 A2 A1 B4 B3 B2 B1 Z4 Z3 Z2 Z1

              Logic Design amp Switching Theory 1 lab Session 06 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

              Lab Session 06

              OBJECT

              bull Designing of a 4 x 1 Multiplexer bull Experimenting with 74150 IC

              COMPONENTS AND APPARATUS REQUIRED 1 Following ICs and their Datasheets

              bull 7408 Quad 2-input AND Gates or 7411 Triple 3-input AND Gates bull 7432 Quad 2-input OR Gates bull 7404 Hex Inverter bull 74150 16 x 1 MUX

              2 Digital Trainer DT-01 or the following components Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches THEORY

              Multiplexers A digital data Multiplexer (MUX) is a combinational circuit having several data inputs and a single output A set of data-select inputs is used to control which of the data inputs is routed to the single output A multiplexer is also called a data selector because of this ability to select which data input is connected o the output Normally there are 2n input lines and n selection lines whose bit combination determine which input is selected DESIGN OF A 4 x 1 MULTIPLEXER A 4 x 1 multiplexer is capable of selecting one of four data inputs (see figure 61) The 2-bit binary number at the data select inputs S1 and S0 specifies which of the four data inputs is to be routed to the output Since there are two data select inputs therefore they can select 22 = 4 different data inputs lines

              S0 S1 D0 D1

              D2 D3

              Data-select Inputs Output

              Data Inputs

              Figure 61 Block Diagram of a 4 x1 Multiplexer

              30

              Logic Design amp Switching Theory 1 lab Session 06 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

              Figure 62 Circuit Diagram for 4 x 1 Multiplexer

              Implementation and Observations

              Implement the 4 x 1 Multiplexer circuit (figure 62) on a bread board (prepare the pin diagram (use appendix A) and refer to laboratory session 01 for implementation procedure) and record the observations in the following table For each data select combination specify the switch number as well as the binary value present on that selected switch

              S1 S0 Output 0 0 0 1 1 0 1 1

              TESTING OF 74150 - 16 x 1 MUX

              The 74150 IC has sixteen data inputs and four data-selection lines Function of various pins of this IC is described below

              bull E0 through E15 Data input lines

              31

              Logic Design amp Switching Theory 1 lab Session 06 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering bull A B C D Data select lines with D being the MSB bull W Active low output line bull Grsquo Active low enable line bull VCC and GND Supply connections lines

              Circuit Diagram

              Figure 63 Pin connections of 74150 for selecting E0

              Testing Procedure

              bull Make connections as shown in the circuit diagram bull Apply different data (1 or 0) at data inputs that are labeled as E0 to E15 Only

              connection for E0 is shown is the figure for simplicity bull Select the data input E0 with the help of data selectors A B C and D bull Observe the output which shows the complement of the data from E0 bull Select all the sixteen data inputs one by one and record your observations in the

              following table

              32

              Logic Design amp Switching Theory 1 lab Session 06 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

              33

              Observations

              Grsquo D C B A W Grsquo D C B A W 0 0 0 0 0 0 1 0 0 0 0 0 0 0 1 0 1 0 0 1 0 0 0 1 0 0 1 0 1 0 0 0 0 1 1 0 1 0 1 1 0 0 1 0 0 0 1 1 0 0 0 0 1 0 1 0 1 1 0 1 0 0 1 1 0 0 1 1 1 0 0 0 1 1 1 0 1 1 1 1

              ACTIVITY 1 Consider 4x1 Multiplexer Draw the output wave-form for the following data inputs

              (E0 E1 E2 E3) and select lines A B (B being the MSB) Output is W

              E3 E2 E1 E0 A B

              W

              2 Using the 4 x 1 MUX designed in this laboratory session implement the following logical function F (A B C) = Σ (0147)

              Show your working and input connections in the following block diagram according to the circuit you have implemented

              4 x 1 MUX

              S0 S1

              Output D0

              D1

              D2

              D3

              Logic Design amp Switching Theory 1 Lab Session 07 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

              Lab Session 07

              OBJECT

              bull Designing of a 2 x 4 Decoder 1 x 4 Demultiplexer bull Experimenting with 74138 IC

              COMPONENTS AND APPARATUS REQUIRED 1 Following ICs and their Datasheets

              bull 7408 Quad 2-input or 7411 Triple 3-input AND Gates bull 7404 Hex Inverter bull 74138 3 x 8 Decoder

              2 Digital Trainer DT-01 or the following components Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches THEORY

              Decoder A Decoder is a combinational circuit that converts binary information form n input lines to a maximum of 2n unique output lines In practical applications decoders are often used for selecting one of several devices

              Demultiplexer A decoder with an enable input can function as a Demultiplexer A Demultiplexer (DMUX) id a circuit that receives information on a single line and transmits this information on one of 2n possible output lines The selection of a specific output line is controlled by the bit values of n selection lines DESIGN OF A 2 x 4 DECODER 1 x 4 DEMULTIPLEXER A 2 x 4 decoder is capable of selecting one of four output lines (see figure 71 (a)) The 2-bit binary number at the data inputs S1 and S0 specifies which of the four data inputs is to be selected If we add an enable pin and use it as an input line then this decoder can be converted to a 1 x 4 Demultiplexer where S1 and S0 will select a line to which data input is to be routed (see figure 71 (b))

              Select S0 S0 Inputs

              S1 D0 D1

              D2

              D3

              Enable (a) Block Diagram of a 2 x 4 Decoder

              Figure 71

              S1 D0 D1

              D2

              D3

              Inputs

              Data Input (b) Block Diagram of a 1 x 4 Demulptiplexer

              34

              Logic Design amp Switching Theory 1 Lab Session 07 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

              Figure 72 Circuit Diagram for 2 x 4 Decoder 1 x 4 Demultiplexer

              Implementation and Observations Implement the 2 x 4 Decoder 1 x 4 Demultiplexer circuit (figure 72) on a bread board (prepare the pin diagram (use appendix A) and refer to laboratory session 01 for implementation procedure) and record the observations in the following table

              Enable Data Input S1 S0 D0 D1 D2 D3

              0 0 0 0 0 1 0 1 0 0 1 1 1 0 0 1 0 1 1 1 0 1 1 1

              TESTING OF 74138 3 x 8 Decoder The 74138 IC has three inputs and eight output lines It has three enable inputs and for the IC to function all three inputs need to be enabled Function of various pins of this IC is described below

              35

              Logic Design amp Switching Theory 1 Lab Session 07 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

              bull Y0 through Y7 Active low data outputs bull A B C Input select lines with C being the MSB bull G1 Active high enable Input bull G2Arsquo and G2Brsquo Active low enable Inputs bull VCC and GND Supply connections lines Circuit Diagram

              Figure 73 Pin connections of 74138

              Testing Procedure

              bull Make connections as shown in the circuit diagram bull Apply different combinations of 1s and 0s at data inputs bull Observe the output and record your observations in the following table

              Observations

              C B A Y0 Y1 Y2 Y3 Y4 Y5 Y6 Y7 0 0 0 0 0 1 0 1 0 0 1 1 1 0 0 1 0 1 1 1 0 1 1 1

              36

              Logic Design amp Switching Theory 1 Lab Session 07 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

              37

              ACTIVITY ACTIVITY 1 What will be the binary values at the outputs Y0 through Y7 of 74138 if 1 What will be the binary values at the outputs Y0 through Y7 of 74138 if

              bull All three enable pins are connected to ground bull All three enable pins are connected to ground __________________________________________________________________________________________________________________________________________ __________________________________________________________________________________________________________________________________________ _____________________________________________________________________ _____________________________________________________________________

              bull All three enable pins are connected to VCC bull All three enable pins are connected to VCC _______________________________________________________________________________________________________________________________________________________________________________________________________________

              _______________________________________________________________________________________________________________________________________________________________________________________________________________

              2 Show connections for 74138 in order to use it as a 1 x 8 Demultiplexer 2 Show connections for 74138 in order to use it as a 1 x 8 Demultiplexer

              3 Consider a 2 x 4 Decoder with two enable inputs (one active high - G and one active low ndash Grsquo) Draw the output wave-forms for D0 D1 D2 and D3 if the two select inputs are A and B (B being the MSB) All outputs are active low

              Grsquo

              G

              A B

              D0 D1 D2

              D3

              Logic Design amp Switching Theory 1 Lab Session 08 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

              Lab Session 08 OBJECT

              bull Designing of a 4 x 2 Priority Encoder bull Experimenting with 74148 IC

              COMPONENTS AND APPARATUS REQUIRED

              1 Following ICs and their Datasheets

              bull 7408 Quad 2-input or 7421 Dual 4-input AND Gates bull 7432 Quad 2-input OR Gates bull 7404 Hex Inverter bull 74148 Encoder

              2 Digital Trainer DT-01 or the following components Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches

              THEORY

              Encoder An Encoder is a digital function that produces a reverse operation from that of a decoder An Encoder has 2n (or less) input lines and n output lines The output lines generate the binary code for the 2n input variables Priority Encoder

              A simple encoder may produce an erroneous output if more than one of its inputs is high A Priority Encoder is one that responds to just one input among those that may be simultaneously high in accordance with some priority system The most common priority system is based on the relative magnitudes of the inputs whichever decimal input is largest is the one that is encoded

              DESIGN OF A 4 x 2 Priority Encoder

              The following equations represent the outputs of a 4 x 2 priority encoder 32 DDA +=

              321 DDDB += As can be seen from the equations that input D0 which has a binary code 00 is not used in any equation A binary code 00 at the output indicates two conditions Either D0 is selected or no input is selected In order to differentiate these two conditions we will provide an additional output Z to indicate if at least one of the inputs is a 1 The equation for Z will be

              4321 DDDDZ = If Z is 0 then the binary code 00 at the output indicates that D0 is selected and if Z is 1 then it indicates that no input line is selected

              38

              Logic Design amp Switching Theory 1 Lab Session 08 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

              Figure 81 Circuit Diagram for 4 x 2 Priority Encoder

              it (figure 81) on a bread board (prepare the to laboratory session 01 for implementation

              Implementation a Implement the 4 x 2 Priority Encoder circu

              ram (use appendix A) and refer

              nd Observations

              pin diagprocedure) and record the observations in the following table

              D3 D2 D1 D0 A B 0 0 0 1 0 0 1 x 0 1 x x 1 x x x

              TESTING OF 74148 8 x 3 Octal Priority Encoder

              imal digits There are nine of which three represents

              ing any of the inputs is high

              then it shows that line 0 is selected and if e inputs selected E0 and GS

              cannot be in the same state provided that E1 is enabled

              The 74148 is a priority encoder with active-Low input for dec

              input) and five output linesinputs lines (including an enablethe binary code for the octal digit Function of various pins of this IC is described below

              bull 0 through 7 Active low data inputs representing the octal digits A2 A1 A0 Active low output lines representing the binary code bullbull E1 Active low enable Input bull E0 Active low output indicating none of the inputs is high bull GS Active low output indicatbull VCC and GND Supply connections lines Therefore if GS A2 A1 and A0 are all low

              then it shows that none of thE0 A2 A1 and A0 are all low

              39

              Logic Design amp Switching Theory 1 Lab Session 08 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

              Circuit Diagram

              Figure 82 Pin connections of 74148

              Testing Procedure bull Make connections as sho

              binations of 1s and 0s at data inputs d record your observations in the following table

              GS E0

              wn in the circuit diagram bull Apply different combull Observe the output an Observations

              0 1 2 3 4 5 6 7 A2 A1 A0 1 1 1 1 1 1 1 1 x x x x x x x 0 x x x x x x 0 1 x x x x x 0 1 1 x x x x 0 1 1 1 x x x 0 1 1 1 1 x x 0 1 1 1 1 1 x 0 1 1 1 1 1 1 0 1 1 1 1 1 1 1

              40

              Logic Design amp Switching Theory 1 Lab Session 08 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

              41

              CTIVITY

              Cascade the following two 74148 8 x 3 Priority Encoders to form 16 x 4 Priority

              A 1

              Encoder

              Logic Design amp Switching Theory 1 Lab Session 09 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering `

              Lab Session 09 OBJECT

              Designing an Odd Parity Generator and Checker for a 3-bit Data COMPONENTS AND APPARATUS REQUIRED

              1 Following ICs and their Datasheets

              bull 7486 Quad 2-input Exclusive-OR Gates bull 7404 Hex Inverter

              2 Digital Trainer DT-01 or the following components Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches

              THEORY

              Parity Generator When binary data is transmitted and processed it is ndash as are all electrical signals ndash susceptible to noise that can either alter or distort its contents 1s may be effectively changed to 0s and 0s to 1s To overcome this problem one or more bits are often added to the data as an aid in detecting errors caused by noise The most common of these is a Parity bit that signifies whether the total number of 1s in a code group is odd or even In an Odd Parity system the parity bit is made 0 or 1 as necessary to make the total number 1s odd (counting the parity bit itself) In an Even Parity system the parity bit is chosen to make the total number of 1s even Table 91 shows how parity bits would be added to BCD code group in both systems

              Decimal BCD Value Parity Bit ABCD Odd Parity Even Parity

              0 0000 1 0 1 0001 0 1 2 0010 0 1 3 0011 1 0 4 0100 0 1 5 0101 1 0 6 0110 1 0 7 0111 0 1 8 1000 0 1 9 1001 1 0

              Table 91 Odd and Even Parity in BCD

              When digital data is received a parity checking circuit generates an error signal if the total number of 1s is odd in an even parity system or if it is even in an odd parity system Parity check always detects a single error (one bit change from 0 to 1 or 1 to 0) but may not detect

              42

              Logic Design amp Switching Theory 1 Lab Session 09 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering ` two or more errors Odd parity is used more often than even parity because even parity does not detect a situation where all 0s are created due to short circuit or other fault condition DESIGN OF A 3-BIT ODD PARITY GENERATOR AND CHECKER Let x y and z be the three bits that constitute the message and are the input to the Odd Parity Generator Circuit Since it is an odd parity system the bit P is generated so as to make the total number of 1s odd (including P) The function P can be expressed as follows P = x oplus y Ο z or P = x Ο y oplus z Since the IC available is 7486 which is quad 2input XOR IC therefore we will convert XNOR also to XOR

              P = x oplus y Ο z

              P = ( x oplus y ) Ο z Since for even number of variables ______

              XOR = XNOR Therefore ___________ _________

              P = ( x oplus y ) oplus z = x oplus y oplus z This logical expression can be implemented with two XOR gates and an inverter (see figure 91)

              Figure 91 Circuit Diagram for a 3-bit Parity Generator

              The 3-bit message and the parity bit are transmitted to their destination where they are applied to a Parity Checker Circuit An error occurs during transmission if the parity of the four bits received is even since the binary information transmitted was originally odd The output C of the parity checker should be a 1 when an error occurs ie when the number of 1s in the four inputs is even Therefore the function C can be expressed as

              C = x Ο y Ο z Ο P

              Using the same logic applied for the conversion of the equation of P

              PzyxC oplusoplusoplus= This logical expression can be implemented with three XOR gates and an inverter (see figure 92)

              43

              Logic Design amp Switching Theory 1 Lab Session 09 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering `

              44

              Figure 92 Circuit Diagram for a 3-bit Parity Checker Implementation and Observations Implement the 3-bit Parity Generator and Checker circuits (figure 91 and 92) on a bread board (prepare the pin diagram (use appendix A) and refer to laboratory session 01 for implementation procedure) and record the observations in the following table

              x y z P x y z P C x y z P C 0 0 0 0 0 0 0 1 0 0 0 0 0 1 0 0 0 1 1 0 0 1 0 1 0 0 0 1 0 1 0 1 0 0 1 1 0 0 1 1 1 0 1 1 1 0 0 0 1 0 0 1 1 0 0 1 0 1 0 1 0 1 1 1 0 1 1 1 0 0 1 1 0 1 1 1 0 1 1 1 0 1 1 1 1 1 1 1

              Odd Parity Generation Odd Parity Check ACTIVITY 1 Try using the parity checker of figure 92 as 3-bit parity generator Write the details here

              _____________________________________________________________________________________________________________________________________________________________________________________________________________________ ______________________________________________________________________________________________________________________________________________ _______________________________________________________________________ ______________________________________________________________________________________________________________________________________________

              Logic Design amp Switching Theory 1 Lab Session 10 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

              Lab Session 10 OBJECT

              Driving a seven segment display using 7447 7448 driver IC COMPONENTS AND APPARATUS REQUIRED

              1 Following ICs and their Datasheets

              bull Seven Segment Displays (Common Anode Common Cathode) bull 7447 7448 BCD to Seven Segment Driver

              2 Digital Trainer DT-01 or the following components Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches

              THEORY Seven Segment Displays A Seven Segment Display consists of seven light-emitting segments The segments are designated by letters a through g (see figure 101) By illuminating various combinations of segments the numerals 0 through 9 can be displayed Seven Segment Displays are commonly constructed with light-emitting diodes (LEDs) and with liquid-crystal displays (LCDs) LEDs generally provide greater illumination levels but require much greater power than LCDs An LED display can be a common-anode type or common cathode type In common anode type a high voltage is applied at the common terminal of the display and low voltage is applied at a segmentrsquos terminal for illumination In the common-cathode type a low voltage is applied at the common terminal of the display and high voltage is applied at a segmentrsquos terminal for illumination

              Figure 101 Seven Segment Display

              a f b g

              e c d

              7447 7448 BCD to Seven Segment Driver 7447 7448 IC is particularly used to drive Seven Segment Its input is a BCD number and output drives a seven segment display 7447 is used to drive common-anode displays whereas 7448 is used to drive common cathode displays 7447 7448 is a 16 pin IC Function of various pins of these ICs is described below

              bull A B C D Inputs representing BCD digits (D being the MSB)

              45

              Logic Design amp Switching Theory 1 Lab Session 10 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering bull OA through OG Outputs to drive segments a through g of the display (Active low

              in 7447 and active high in 7448) bull RBI Ripple Blanking Input Turns off all the segments if kept low provided that LT

              is kept high and all other inputs (A B C D BI) are kept low Should be kept high otherwise

              bull BI RBO Wire-AND logic serving as a Blanking Input and or Ripple Blanking Output

              o BI Turns off all the segments if low o RBO Goes to a low level (response condition) along with other outputs when

              RBI and inputs A B C and D are low with LT input at high level bull LT Lamp Test input Tests whether all segments are working or not Illuminates all

              segments if kept low provided that BI is kept high Should be kept high otherwise bull VCC and GND Supply connections lines CIRCUIT DIAGRAM

              Figure 102 Circuit diagram for 7447driving a common-anode display

              IMPLEMENTATION AND OBSERVATIONS

              bull Make connections as shown in the circuit diagram (refer to laboratory session 01 for implementation procedure)

              bull Apply different combinations of 1s and 0s at data inputs bull Observe the output and record your observations in the following table

              46

              Logic Design amp Switching Theory 1 Lab Session 10 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

              47

              Decimal Digit

              BCD Inputs Seven Segment Outputs D C B A a b c d e f g

              0 0 0 0 0 1 0 0 0 1 2 0 0 1 0 3 0 0 1 1 4 0 1 0 0 5 0 1 0 1 6 0 1 1 0 7 0 1 1 1 8 1 0 0 0 9 1 0 0 1

              ACTIVITY 1 Perform the Lamp Test for the designed circuit and write your observations

              ____________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________

              2 How can you use 7447 IC to drive a common-cathode display

              ____________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________

              3 What symbols appear in the seven segment display if inputs DCBA are

              DCBA Symbol

              1010

              1011

              1100

              1101

              1110

              1111

              Logic Design amp Switching Theory 1 Lab Session 11 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

              48

              Lab Session 11 OBJECT

              Testing different modes of JK-FF COMPONENTS AND APPARATUS REQUIRED 1 Following ICs and their Datasheets

              bull 7473 7476 JK Flip-Flop 2 Digital Trainer DT-01 or the following components

              Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches

              THEORY

              Flip-Flop A flip-flop circuit can maintain a binary state indefinitely (as long as the power is delivered to the circuit) until directed by an input signal to switch states The major differences among various types of flip-flops are in the number of inputs they possess and in the manner in which the inputs affect the binary state

              JK Flip-Flop JK flip flop is an edge triggered device A typical JK flip flop has three inputs J K and a clock input The flip-flop can be either positive or negative edge triggered The output Q is available in complemented form as well Beside the usual inputs and output most of the flip-flop IC also possess two asynchronous inputs namely Preset and Clear These inputs are usually active low If used Preset and Clear inputs keep the flip-flop in set and reset state respectively irrespective of the other inputs Both of these inputs cannot be used simultaneously otherwise they will bring the flip-flop in unstable state

              Figure 111 Symbol for JK flip-flop

              (a) positive-edge triggering (b) active low Preset (PR) and Clear (CLR) with positive-edge triggering

              (c) active low Preset (PR) and Clear (CLR) with negative-edge triggering

              Logic Design amp Switching Theory 1 Lab Session 11 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

              49

              TESTING OF 7473 7476 DUAL JK FLIP-FLOP

              Both the ICs 7473 and 7476 are similar in functionality except for one difference The flip-flops in 7473 have only one type of active low asynchronous input which is the Clear input whereas the flip-flops in 7476 have both Preset and Clear inputs Both these ICs have negative edge triggered flip-flops

              Circuit Diagram

              Figure 112 Pin connections of 7476

              Testing Procedure

              bull Make connections as shown in the circuit diagram (figure 112) bull Apply different combinations of 1s and 0s at J and K inputs bull Observe the output and record your observations in the following table

              Observations

              J

              K Q

              0 0 0 1 1 0 1 1

              ACTIVITY

              1 Observe the output Q of JK flip-flop if the clock input is connected to VCC or GND instead of a clock source Write your observations here __________________________________________________________________________________________________________________________________________ _______________________________________________________________________________________________________________________________________________________________________________________________________________

              Logic Design amp Switching Theory 1 Lab Session 12 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

              50

              Lab Session 12 OBJECT

              Designing sequential circuit for the given state diagram using D flip-flop GIVEN STATE DIAGRAM

              00

              11

              Figure 121 State Diagram COMPONENTS AND APPARATUS REQUIRED 1 Following ICs and their Datasheets

              bull 7474 D Flip-Flop bull ICs of basic gates (AND OR NOT XOR etc) as required

              2 Digital Trainer DT-01 or the following components Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches

              THEORY

              Sequential Circuits In Sequential Circuits the output not only depends on the present inputs but also on previous states of the circuit These circuits use memory elements (latches flip-flops) and the binary information stored in the memory elements at any given time defines the state of the sequential circuit Analysis of a Sequential Circuit The behavior of a sequential circuit is determined from the inputs the outputs and the states of its flip-flops Both the outputs and next state are a function of the inputs and the

              10

              01

              00 11 10

              00

              00 11 10 00

              Logic Design amp Switching Theory 1 Lab Session 12 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

              51

              present state The analysis of a sequential circuit form a state diagram comprises of the following bull Selecting a particular flip-flop to design the circuit bull Obtaining state table from the state diagram bull Finding input equations for the selected flip-flop bull Finding state equations (not required for the construction of circuit) bull Implementing the circuit using selected flip-flops and their input equations ANALYZING THE GIVEN STATE DIAGRAM D Flip-Flop D flip-flop is also called transparent flip-flop as it simply transfers the input data to the output For our design we require the graphical symbol and excitation table of D flip-flop (see figure 122)

              Qt Qt+1 T 0 0 0 0 1 1 1 0 0 1 1 1

              (b) Excitation table of D Flip-Flop

              (a) Graphical Symbol

              Figure 122 Characteristic equation of D flip-flop is Q(t+1) = D State Table The given state diagram has four states so we will need two D flip-flops (FF-0 FF-1) Form state table form the given state diagram and record the results in the following table

              Present State Input Next State Output Input to FF-0 D0

              Input to FF-1 D1 Q1t Q0t x Q1(t+1) Q0(t+1) z

              Logic Design amp Switching Theory 1 Lab Session 12 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

              52

              Input Equations Using Karnaugh map the input equations D0 and D1 for the two flip-flops can be found

              D0 D1 Q0x

              Q1

              _ _ Q0x

              _ Q0x

              Q0x

              _ Q0x

              Q0x

              Q1

              _ _ Q0x

              _ Q0x

              Q0x

              _ Q0x

              _ Q1

              _ Q1

              Q1

              Q1

              D0 = _________________ D1 = _________________

              State Equations Using the characteristic equation of D flip-flop we can find the state equations Q0(t+1) and Q1(t+1) for the to flip flops Q0(t+1) = _______________________ Q1(t+1) = _______________________ _______________________ _______________________ _______________________ _______________________ Circuit Diagram

              Logic Design amp Switching Theory 1 Lab Session 12 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

              53

              Implementation Procedure and Observations

              1 Implement the circuit using digital ICs on a bread board (prepare the pin diagram (use appendix A) and refer to laboratory session 01 for procedure)

              2 Make the clear inputs of the flip-flops low (to clear the flip-flops) The flip-flops will remain in clear state as long as the clear inputs are connected to low level

              3 Connect output Q0 and the clock pulse to an oscilloscope 4 Apply 0 to the input x 5 Now make the clear inputs to high 6 Observe the waveform for the first 5 clock pulses and record it 7 Repeat steps 2 to 6 keeping x=1 in step 4 this time 8 Repeat steps 2 to 7 this time connecting Q1 instead of Q0 to the oscilloscope in step

              3 Record your observations (Keep frequency of the clock pulse low (eg1Hz) so that the output waveforms can be observed easily)

              1 2 3 4 5 Clock Pulse

              Output Waveform for Q0 when x=0

              Output Waveform for Q0 when x=1

              Output Waveform for Q1 when x=0

              Output Waveform for Q1 when x=1

              Logic Design amp Switching Theory 1 Lab Session 13 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

              Lab Session 13 OBJECT

              Designing a modulo-5 asynchronous up-counter using JK-FF COMPONENTS AND APPARATUS REQUIRED

              1 Following ICs and their Datasheets

              bull 7400 Quad 2-input or 7410 Triple 3-input NAND Gates bull 7476 7473 JK Flip-Flop

              2 Digital Trainer DT-01 or the following components Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches

              THEORY

              Digital Counters A digital counter is a set of flip-flops whose states change in response to pulses applied at the input to the counter The flip-flops are interconnected so that their combined state at any time is the binary equivalent of the total number of pulses that have occurred up to that time Every counter resets after a certain number of clock pulses Thus as it name implies a counter is used to count pulses An n stage counter can count up to a maximum of 2n states n is equal to the number of flip-flops required for the construction of counter

              Modulus Counters The number of input pulses that causes a counter to reset to its initial count is called the modulus of the counter Thus the modulus equals to total number of distinct states (counts) including zero that a counter can store A binary counter with n stages is a modulo-2n (or mod-2n) counter The largest count a mod-N counter can achieve is N-1 ie a mod-N counter never reaches the binary number equal to its modulus N is always equal to or less than 2n Counters can be classified as bull Synchronous Counters which are clock driven All the flip-flops are driven by a

              single clock bull Asynchronous Counters which are event driven Clock input is given to the first

              flip-flop only Rest of the flip-flops are driven by their preceding flip-flops

              DESIGN OF A MOD-5 ASYNCHRONOUS UP COUNTER The number of flip-flops required to construct a mod-5 counter is 3 because 5 should be less than or equal to 2n This counter will count from 0 to 4 a total of 5 distinct states Since a 3-stage counter can count up to 8 states at maximum a NAND gate is used to reset it after 5 clock pulses Figure 131 shows the logic diagram

              54

              Logic Design amp Switching Theory 1 Lab Session 13 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

              55

              Figure 131 A Mod-5 Asynchronous Up Counter

              Implementation and Observations

              Implement the mod-5 counter circuit (figure 131) on a bread board (prepare the pin diagram (use appendix A) and refer to laboratory session 01 for implementation procedure) and record the observations in the following table

              Clock Pulse Q2 Q1 Q0

              0 1 2 3 4 5 6 7

              ACTIVITY

              Draw the timing diagram for mod-5 counter designed in this laboratory session

              Logic Design amp Switching Theory 1 Lab Session 14 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

              Lab Session 14 OBJECT

              Experimenting with 74194 4-bit bidirectional universal shift register COMPONENTS AND APPARATUS REQUIRED

              1 Following ICs and their Datasheets

              bull 74194 4-bit bidirectional universal shift register 2 Digital Trainer DT-01 or the following components

              Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches

              THEORY

              Shift Registers

              A Register is a set of flip-flops used to store binary data A register which is capable of shifting its binary information either to the right or left is called a shift register The logical configuration of a register consists of a chain of flip-flops connected in cascade with the output of one flip-flop connected to the input of next flip-flop All flip-flops receive a common clock pulse which causes the shift from one stage to the next

              Bidirectional Shift Registers A bi-directional shift register is one whose bits can be shifted from left to right or from right to left

              Universal Shift Registers A universal shift register is a bi-directional register whose input can be in either serial or parallel form and whose output can be in either serial or parallel form

              74194 4-BIT BIDIRECTIONAL UNIVERSAL SHIFT REGISTER

              The 74194 register provides parallel as well as serial loading in both directions Function of various pins of this IC is described below

              bull A B C and D Active high inputs for parallel loading bull QA QB QC and QD Active high outputs bull S0 and S1 Active high mode control inputs The following table shows combinations

              of S1 and S0 to enable various modes

              S1 S0 Clock Action 0 0 x No change 0 1 uarr Shift right 1 0 uarr Shift left 1 1 uarr Parallel load

              uarr shows the rising edge of the clock pulse

              56

              Logic Design amp Switching Theory 1 Lab Session 14 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering bull SR Active high serial input for right shifting bull SL Active high serial input for left shifting bull CLR Active low input Clears all the flip-flops of the register if set to 0 should be

              kept high otherwise bull CLK Clock input bull VCC and GND Supply connections lines Thus A B C and D are inputs for parallel loading whereas SR and SL are inputs for serial loading with right or left shifting respectively S1 and S0 are used to select the loading mode Circuit Diagram

              Figure 141 Pin connections of 74194 Testing Procedure

              bull Make connections as shown in the circuit diagram bull Observe the output for the input combinations given in the following table

              57

              Logic Design amp Switching Theory 1 Lab Session 14 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

              58

              Observations

              S1 S0 SL SR A B C D QA QB QC QD 0 0 0 1 0 0 0 0 0 1 1 0 0 0 0 1 1 0 0 0 0 0 1 0 1 1 0 0 0 0 1 1 0 0 1 1 0 1 0 0 0 1 1 1 0 1 0 1 1 0 1 0 0 1 1 0 1 1 1 0 0 1 1 1 1 1 0 0 1 1 1 1

              ACTIVITY 1 Show connections of 74194 to convert it into a ring counter with right shifting

              Logic Design amp Switching Theory 1 Lab Session 15 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

              Lab Session 15

              OBJECT

              Experimenting with 74245 octal bus transceivers using parallel port PC interfacing COMPONENTS AND APPARATUS REQUIRED 1 Parallel Port Connectors (DB-25) with Cable 2 Personal Computer with Windows 98 and TurboC Compiler Installed 3 Following ICs and their Datasheets

              bull 74245 Octal Bus Transceivers with 3-State Outputs 4 Digital Trainer DT-01 or the following components

              Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches

              THEORY

              3-State Logic Sometimes it is necessary to isolate one part of circuit from the other part For this purpose some TTL ICs are designed with 3-state logic Such devices have three possible output states high low and high impedance The device can be put into high impedance state by a control signal applied to an appropriate pin When such a device is in high impedance state there is very high impedance at its output effectively isolating the device from whatever circuitry the output normally drives 74245 Octal Bus Transceivers A bus is any conducting path or set of paths having electrical connections to one or more devices 74245 octal bus transceivers are mainly used to control connectivity between two devices or circuits It also provides direction control for signal flow Function of various pin of this IC is given below

              bull A1 through A8 Bus A bull B1 through B8 Bus B bull G΄ Active low enable input When high sets all the bus pins to high impedance state bull DIR Direction control for signal flow When set to high logic level transfers bus A

              data to B bus When set to low logic level transfers bus B data to A bus bull VCC and GND Supply connections lines Serial and Parallel Port Connectors A Parallel Port can consist of only 25 pin port adapter called a DB-25 and a serial port can consist of either a 25 pin port adapter called a DB-25 or 9 pin adapter called a DB-9 port adapter Whether the port is a 9 pin or 25 pin it can accomplish all of the same tasks that serial port communications have been designed for

              59

              Logic Design amp Switching Theory 1 Lab Session 15 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

              60

              Each adapter can be a male type connector with pins or a female type adapter with tiny holes Generally a PRINTER port (called LPT1) on the back of a computer is female type adapter and we need to use MALE DB-25 pin cable on it for PRINTER connection or for parallel LAPLINK cable And a COM port on the back of a computer is male for the serial ports but it may not necessarily be Parallel Port Connector ndash DB-25 The DB-25 connector (named for its B-size D-shaped shell and 25 pins) is practically ubiquitous in the electronics industry The DB-25 connector is used for a variety of purposes Two common applications are RS-232EIA-232 (serial) connections and the parallel printer interface on the IBM PC The DB-25 connector is also used for SCSI connections Normally the parallel port is used for output to a printer or other device It sends data 8-bits or one byte at a time in parallel The other lines available on the DB-25 connector are a combination of status lines control lines and ground lines The status and control lines are used for handshaking commands and feedback when we are talking to a printer

              Figure 152 DB-25 Female Figure 151 DB-25 Male

              Figure 153 Pin Layout for DB-25 As can be seen form figure 153 there are four types of pins in this connector

              bull Data pins (8 pins - D0 to D7) Active high bidirectional lines

              Logic Design amp Switching Theory 1 Lab Session 15 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering bull Control pins (4 pins - C0 to C3) C0 C1 and C3 are active low whereas C2 is active

              high These lines also are bidirectional bull Status pins (5 pins ndash S3 to S7) Only S7 is active low rest are active high input lines bull Ground pins (8 pins) Used as a reference signal for the low (below 05 volts) charge

              Parallel Port Addresses A DB-25 connector at a parallel port has three address one for each kind of pins register data status and control The first or base address generally refers to data register Second address is for status register and the third one is for control register In Windows 98 the base address is usually found to be 278H 378H or 3BCH Now if 378H is the base address then it refers to the data register whereas addresses for status and control register are respectively 379H and 37AH For Windows 98 the base address can be found as follows 1 On your Desktop right-click on My Computer and select Properties 2 Click on the Device Manager tab and find LPT1 under Plug and Play BIOS 3 After selecting LPT1 click the Properties button 4 Next select the Resources tab and the address should then appear next to InputOutput

              Range Accessing parallel port through C Language Programming There are multiple functions in C Language for accessing external ports The most commonly used are listed below

              bull unsigned char inportb(int portid) inportb reads a byte from a hardware port

              bull int inport(int portid) reads a word from a hardware port

              bull void outportb(int portid unsigned char value) outputs a byte to a hardware port

              bull void outport(int portid int value) outputs a word to a hardware port

              portid refers to the port address whereas value refers to the data to be sent TESTING 74245 USING PARALLEL PORT PC INTERFACING At one end the parallel port connector will be connected to the PC via parallel port cable and another connector (to be plugged into the PC parallel port slot) At the other end it will be connected to the buffer IC 74245 Data lines of the connector will be used to transfer 8-bit data between the PC and the buffer Out of the 8-bits of 74245 4-bits will be used to enter data which will be displayed at the monitor through a C language

              61

              Logic Design amp Switching Theory 1 Lab Session 15 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering program The remaining 4-bits will receive data from PC as entered by the user via keyboard

              Circuit Diagram

              Figure 154 Interface of 74245 to PC via Parallel Port

              Procedure

              1 Connect the DB-25 connector to the PC at one end and solder it to the circuit board at the other end

              2 Connect various pins of the connector and 74245 according to the circuit diagram shown in figure 152

              3 Using the functions listed in the previous section write a program in C language to operate various pins of the buffer The user interface of the program should provide option to the user whether to send or receive data from the port

              4 Set DIR switch to 1 5 Try sending some data bits to the port The result should be displayed at the LEDs 6 Set DIR switch to 0 7 Set some binary 4-bit value through the switches Try reading it via parallel port

              C Language Program

              A program to access parallel port for data transfers

              use header file include ltstdiohgt main program void main() define variable

              62

              Logic Design amp Switching Theory 1 Lab Session 15 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering unsigned int data=0 char choice while(1) printing option menu clrscr() printf(This program will send or receive a BCD digit from the parallel portn) printf(nPress your choice numbern) printf(n1 Send Data) printf(n2 Receive Data) printf(n3 Exitn) choice = getch() sending entered digit to the port if(choice == 1) input BCD digit printf(nEnter BCD digit to be sent to the port) data = getche() masking the first four bits data = data amp 0x0f sending to the port outportb(0x378data) printf(nThe BCD digit c has been sent to the port data) printing on screen the data received from the port else if(choice == 2) receiving data from the port data = inportb(0x378) masking the last four bits data = data amp 0xf0 shifting first four bits to make them the last four bits datagtgt=4 printf(nThe BCD digit set at the port is c data) exit else if(choice == 3) break key pressed is not in the menu else printf(nEnter valid choice number) printf(nnPress any key to continue) getch()

              63

              Logic Design amp Switching Theory 1 Lab Session 15 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

              ACTIVITY 1 In the above circuit DIR and G΄ inputs are hardwired Connect them to status or

              control pins of the parallel port connector and control their function through your software program Circuit Diagram Program Code ______________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________

              ___________________________________________________________________________________________________________________________________________________

              64

              Logic Design amp Switching Theory 1 Lab Session 15 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

              65

              _____________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ _____________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ _______________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ _________________________________________________ _________________________________________________

              Logic Design amp Switching Theory 1 Appendix A NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

              Appendix A

              PIN DIAGRAMS OF THE ICS REQUIRED FOR THE LABORATORY SESSIONS Consult the TTLIC data book for internal diagrams and electrical characteristics of these ICs 7400 Quad 2-Input NAND 7402 Quad 2-Input NOR

              7404 Hex Inverter 7408 Quad 2-Input AND

              7410 Triple 3-Input NAND 7411 Triple 3-Input AND

              7421 Dual 4-Input AND 7432 Quad 2-Input OR

              66

              Logic Design amp Switching Theory 1 Appendix A NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

              BCD-to-Seven Segm 7448 BCD-to-Seven Segment 7447 ent

              Decoder (15V OC) Decoder (2kΩ pull-up output)

              7473 Dual JK Flip-Flop 7474 Dual D-Type Flip-Flop

              7476 Dual JK Flop-Flop -Bit Binary Full Adder 7483 4 with Fast Carry

              86 Quad 2-Inpu 74138 3-to-8 Line 74 t Exclusive OR Decoder Demultiplexer

              67

              Logic Design amp Switching Theory 1 Appendix A NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

              68

              74148 8-to-3 Line 16-to-1 Line Data

              Priority Encoder 74150 Selector Multiplexer

              74245 Oct nsceivers Universal Shift Register (PIPO) (3-State)

              74194 4-Bit Bidirectional al Bus Tra

              Logic Design amp Switching Theory 1 Appendix B NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

              Appendix B

              DEBOUNCING CIRCUITRY FOR MECHANICAL SWITCHES Mechanical switches form the interface between human beings and computers or other digital systems For example a keyboard is a matrix of switches used to supply alphanumeric data to a computer Whatever the switch design it is a potential source of problems due to contact bounce The contact bounce creates a sense of narrow pulses when a switch is opened or closed An example of device whose operation would be adversely affected by contact bounce is a digital counter used to count the number of times a switch is depressed Eliminating the effects of contact bounce is called debouncing When data is entered into a computer via a keyboard a software debounce is often used This type of debouncing is a program that causes the computer to sample the switch terminal (ie to input data from it) many times in succession during the interval of time that contact bounce occurs If the data is sensed to be 1s (or 0s) for a specific number of consecutive samples then it is assumed that contact bounce has ended and the last value sensed is valid Hardware debouncing is the use of electronic circuitry to eliminate the effects of contact bounce There are numerous versions of such circuitry including those that use monostable multivibrators (one-shots) but the most straightforward is simply an RS latch Figure B1 shows the circuit When the switch is in position 1 R = 0 and S = 1 so the latch is set and the output (Q) is 1 When the switch is in position 0 R = 1and S = 0 so the latch is reset and the output is 0 When the switch is moved form one position to the other the latch changes state and bouncing occurs at either the R or the S input The bouncing does not affect the latch after it has change state An RS latch will remain set for example when its R input is 0 and its S input is alternately changed form 1 to 0

              Figure B1 Use of RS latch to debounce a mechanical switch

              69

              • 01-ldst-Outer title
                • Practical Workbook
                • Logic Design amp Switching Theory I
                  • Dept of Computer amp Information Systems Engineering
                    • NED University of Engineering amp Technology
                    • Karachi ndash 75270 Pakistan
                      • 02-ldst-inner Title
                        • Practical Workbook
                        • Logic Design amp Switching Theory I
                          • Dept of Computer amp Information Systems Engineering
                            • NED University of Engineering amp Technology
                            • Karachi ndash 75270 Pakistan
                              • 03-ldst-general info
                              • 04-ldst-introduction
                              • 05-Table of Contents
                                • CONTENTS
                                  • Lab Session No Object Page No
                                  • 1
                                  • Also implementing and testing the given circuit on a bread board
                                    • Working with Electronics Workbench
                                      • Driving a seven segment display using 7447 7448 driver IC
                                        • Designing a modulus-5 asynchronous up-counter using JK-FF
                                          • Experimenting with 74194 4-bit bidirectional universal shift register
                                              • 13
                                                  • 06-ldst-Exp01
                                                    • Lab Session 01
                                                    • OBJECT
                                                      • 1 Bread board
                                                      • 2 5 V - power supply
                                                      • 3 Multimeter
                                                      • 4 Logic probe
                                                      • 5 LEDs with resistors
                                                      • 6 Connecting wires
                                                      • 8 Following ICs and their datasheets
                                                        • THEORY
                                                          • Logic Gates
                                                          • 1 The AND Gate ndash An AND gatersquos output is 1 if and only if all its inputs are 1 If A and B are two inputs to an AND gate then output F of the gate is given as F = AB
                                                          • 2 The OR Gate - An OR gatersquos output is 1 if at least one of its input is 1 If A and B are two inputs to an OR gate then output F of the gate is given as F = A+B
                                                          • 3 The NOT Gate (Inverter) ndash Its output is 1 when its input is 0 and its output is 0 when the input is 1 ie it complements a digital variable If A is the input to a NOT gate then output F of the gate is given as
                                                          • 4 The NAND Gate ndash Its output is 1 if at least one of its input is 0 This gate performs the same logic as an AND gate followed by an inverter If A and B are two inputs to a NAND gate then output F of the gate is given as
                                                            • 5 The NOR Gate - The output of a NOR gate is 1 if and only if all its inputs are 0 This gate performs the same logic function as an OR gate followed by an inverter If A and B are two inputs to a NAND gate then output F of the gate is given as
                                                                • DATA SHEETS
                                                                  • Logic expression for the given logic diagram __________________________________
                                                                      • 07-ldst-exp02
                                                                        • Working with Electronics Workbench
                                                                          • 08-ldst-exp03
                                                                            • Designing Half and Full Adder Circuits
                                                                              • COMPONENTS AND APPARATUS REQUIRED
                                                                                • 1 Following ICs and their Datasheets
                                                                                • 7408 Quad 2-input AND Gate
                                                                                • 2 Digital Trainer DT-01 or the following components
                                                                                  • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                  • Connecting wires Switches
                                                                                    • THEORY
                                                                                        • IMPLEMENTATION AND OBSERVATIONS
                                                                                          • 09-ldst-Exp04
                                                                                            • Lab Session 04
                                                                                            • 1 Digital ICs and their Datasheets
                                                                                            • 7408 Quad 2-input AND Gate
                                                                                            • 2 Digital Trainer DT-01 or the following components
                                                                                              • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                              • Connecting wires Switches
                                                                                              • PROCEDURE
                                                                                              • REDUCTION OF LOGIC EXPRESSION USING KARNAUGH MAP
                                                                                              • OBSERVATIONS
                                                                                              • RESULT
                                                                                                  • 10-ldst-Exp05
                                                                                                    • Lab Session 05
                                                                                                    • 1 Following ICs and their Datasheets
                                                                                                    • 7408 Quad 2-input AND Gate
                                                                                                    • 2 Digital Trainer DT-01 or the following components
                                                                                                      • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                      • (100 Ω) Connecting wires Switches
                                                                                                      • THEORY
                                                                                                        • IMPLEMENTATION AND OBSERVATIONS
                                                                                                          • 11-ldst-Exp06
                                                                                                            • OBJECT
                                                                                                            • 1 Following ICs and their Datasheets
                                                                                                            • 7408 Quad 2-input AND Gates or 7411 Triple 3-input AND Gates
                                                                                                            • 2 Digital Trainer DT-01 or the following components
                                                                                                              • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                              • Connecting wires Switches
                                                                                                                • Figure 62 Circuit Diagram for 4 x 1 Multiplexer
                                                                                                                • Implementation and Observations
                                                                                                                  • Circuit Diagram
                                                                                                                    • ACTIVITY
                                                                                                                      • 12-ldst-exp07
                                                                                                                        • 1 Following ICs and their Datasheets
                                                                                                                        • 7408 Quad 2-input or 7411 Triple 3-input AND Gates
                                                                                                                        • 2 Digital Trainer DT-01 or the following components
                                                                                                                          • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                          • Connecting wires Switches
                                                                                                                            • THEORY
                                                                                                                                • Figure 72 Circuit Diagram for 2 x 4 Decoder 1 x 4 Demultiplexer
                                                                                                                                • Implementation and Observations
                                                                                                                                  • Circuit Diagram
                                                                                                                                    • ACTIVITY
                                                                                                                                      • 13-ldst-Exp08
                                                                                                                                        • OBJECT
                                                                                                                                        • 1 Following ICs and their Datasheets
                                                                                                                                        • 7408 Quad 2-input or 7421 Dual 4-input AND Gates
                                                                                                                                        • 2 Digital Trainer DT-01 or the following components
                                                                                                                                          • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                          • Connecting wires Switches
                                                                                                                                            • THEORY
                                                                                                                                                • Figure 81 Circuit Diagram for 4 x 2 Priority Encoder
                                                                                                                                                • Implementation and Observations
                                                                                                                                                  • Therefore if GS A2 A1 and A0 are all low then it shows that line 0 is selected and if E0 A2 A1 and A0 are all low then it shows that none of the inputs selected E0 and GS cannot be in the same state provided that E1 is enabled
                                                                                                                                                  • Circuit Diagram
                                                                                                                                                    • ACTIVITY
                                                                                                                                                      • 14-ldst-exp09
                                                                                                                                                        • OBJECT
                                                                                                                                                        • 1 Following ICs and their Datasheets
                                                                                                                                                        • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                          • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                          • Connecting wires Switches
                                                                                                                                                            • THEORY
                                                                                                                                                              • Parity Generator
                                                                                                                                                                • Let x y and z be the three bits that constitute the message and are the input to the Odd Parity Generator Circuit Since it is an odd parity system the bit P is generated so as to make the total number of 1s odd (including P) The function P can be expressed as follows
                                                                                                                                                                • Figure 91 Circuit Diagram for a 3-bit Parity Generator
                                                                                                                                                                  • C = x Ο y Ο z Ο P
                                                                                                                                                                    • Implementation and Observations
                                                                                                                                                                      • ACTIVITY
                                                                                                                                                                          • 15-ldst-exp10
                                                                                                                                                                            • Driving a seven segment display using 7447 7448 driver IC
                                                                                                                                                                            • COMPONENTS AND APPARATUS REQUIRED
                                                                                                                                                                            • 1 Following ICs and their Datasheets
                                                                                                                                                                            • 7447 7448 BCD to Seven Segment Driver
                                                                                                                                                                            • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                              • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches
                                                                                                                                                                                • THEORY
                                                                                                                                                                                • Seven Segment Displays
                                                                                                                                                                                • CIRCUIT DIAGRAM
                                                                                                                                                                                • Figure 102 Circuit diagram for 7447driving a common-anode display
                                                                                                                                                                                    • IMPLEMENTATION AND OBSERVATIONS
                                                                                                                                                                                      • Decimal Digit
                                                                                                                                                                                      • BCD Inputs
                                                                                                                                                                                      • Seven Segment Outputs
                                                                                                                                                                                      • D
                                                                                                                                                                                      • C
                                                                                                                                                                                      • B
                                                                                                                                                                                      • A
                                                                                                                                                                                      • a
                                                                                                                                                                                      • b
                                                                                                                                                                                      • c
                                                                                                                                                                                      • d
                                                                                                                                                                                      • e
                                                                                                                                                                                      • f
                                                                                                                                                                                      • g
                                                                                                                                                                                      • 0
                                                                                                                                                                                      • 0
                                                                                                                                                                                      • 0
                                                                                                                                                                                      • 0
                                                                                                                                                                                      • 0
                                                                                                                                                                                      • 1
                                                                                                                                                                                      • 0
                                                                                                                                                                                      • 0
                                                                                                                                                                                      • 0
                                                                                                                                                                                      • 1
                                                                                                                                                                                      • 2
                                                                                                                                                                                      • 0
                                                                                                                                                                                      • 0
                                                                                                                                                                                      • 1
                                                                                                                                                                                      • 0
                                                                                                                                                                                      • 3
                                                                                                                                                                                      • 0
                                                                                                                                                                                      • 0
                                                                                                                                                                                      • 1
                                                                                                                                                                                      • 1
                                                                                                                                                                                      • 4
                                                                                                                                                                                      • 0
                                                                                                                                                                                      • 1
                                                                                                                                                                                      • 0
                                                                                                                                                                                      • 0
                                                                                                                                                                                      • 5
                                                                                                                                                                                      • 0
                                                                                                                                                                                      • 1
                                                                                                                                                                                      • 0
                                                                                                                                                                                      • 1
                                                                                                                                                                                      • 6
                                                                                                                                                                                      • 0
                                                                                                                                                                                      • 1
                                                                                                                                                                                      • 1
                                                                                                                                                                                      • 0
                                                                                                                                                                                      • 7
                                                                                                                                                                                      • 0
                                                                                                                                                                                      • 1
                                                                                                                                                                                      • 1
                                                                                                                                                                                      • 1
                                                                                                                                                                                      • 8
                                                                                                                                                                                      • 1
                                                                                                                                                                                      • 0
                                                                                                                                                                                      • 0
                                                                                                                                                                                      • 0
                                                                                                                                                                                      • 9
                                                                                                                                                                                      • 1
                                                                                                                                                                                      • 0
                                                                                                                                                                                      • 0
                                                                                                                                                                                      • 1
                                                                                                                                                                                        • ACTIVITY
                                                                                                                                                                                          • 16-ldst-exp11
                                                                                                                                                                                            • Lab Session 11
                                                                                                                                                                                              • OBJECT
                                                                                                                                                                                              • COMPONENTS AND APPARATUS REQUIRED
                                                                                                                                                                                                • 1 Following ICs and their Datasheets
                                                                                                                                                                                                • 7473 7476 JK Flip-Flop
                                                                                                                                                                                                • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                  • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                  • Connecting wires Switches
                                                                                                                                                                                                    • THEORY
                                                                                                                                                                                                        • Flip-Flop
                                                                                                                                                                                                        • JK Flip-Flop
                                                                                                                                                                                                          • Circuit Diagram
                                                                                                                                                                                                            • Observations
                                                                                                                                                                                                              • ACTIVITY
                                                                                                                                                                                                                  • 17-ldst-exp12
                                                                                                                                                                                                                    • Lab Session 12
                                                                                                                                                                                                                      • OBJECT
                                                                                                                                                                                                                      • GIVEN STATE DIAGRAM
                                                                                                                                                                                                                      • Figure 121 State Diagram
                                                                                                                                                                                                                      • COMPONENTS AND APPARATUS REQUIRED
                                                                                                                                                                                                                        • 1 Following ICs and their Datasheets
                                                                                                                                                                                                                        • 7474 D Flip-Flop
                                                                                                                                                                                                                        • ICs of basic gates (AND OR NOT XOR etc) as required
                                                                                                                                                                                                                        • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                          • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                                          • Connecting wires Switches
                                                                                                                                                                                                                            • THEORY
                                                                                                                                                                                                                                • Sequential Circuits
                                                                                                                                                                                                                                  • 18-ldst-exp13
                                                                                                                                                                                                                                    • Lab Session 13
                                                                                                                                                                                                                                      • Designing a modulo-5 asynchronous up-counter using JK-FF
                                                                                                                                                                                                                                        • 1 Following ICs and their Datasheets
                                                                                                                                                                                                                                        • 7400 Quad 2-input or 7410 Triple 3-input NAND Gates
                                                                                                                                                                                                                                        • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                                          • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                                                          • Connecting wires Switches
                                                                                                                                                                                                                                            • THEORY
                                                                                                                                                                                                                                                • Figure 131 A Mod-5 Asynchronous Up Counter
                                                                                                                                                                                                                                                • Implementation and Observations
                                                                                                                                                                                                                                                  • ACTIVITY
                                                                                                                                                                                                                                                      • 19-ldst-exp14
                                                                                                                                                                                                                                                        • Experimenting with 74194 4-bit bidirectional universal shift register
                                                                                                                                                                                                                                                        • 1 Following ICs and their Datasheets
                                                                                                                                                                                                                                                        • 74194 4-bit bidirectional universal shift register
                                                                                                                                                                                                                                                        • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                                                          • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                                                                          • Connecting wires Switches
                                                                                                                                                                                                                                                            • THEORY
                                                                                                                                                                                                                                                              • Shift Registers
                                                                                                                                                                                                                                                              • Bidirectional Shift Registers
                                                                                                                                                                                                                                                              • Universal Shift Registers
                                                                                                                                                                                                                                                                • S1
                                                                                                                                                                                                                                                                  • Circuit Diagram
                                                                                                                                                                                                                                                                  • ACTIVITY
                                                                                                                                                                                                                                                                      • 20-ldst-exp15
                                                                                                                                                                                                                                                                        • COMPONENTS AND APPARATUS REQUIRED
                                                                                                                                                                                                                                                                        • 1 Parallel Port Connectors (DB-25) with Cable
                                                                                                                                                                                                                                                                        • 2 Personal Computer with Windows 98 and TurboC Compiler Installed
                                                                                                                                                                                                                                                                        • 3 Following ICs and their Datasheets
                                                                                                                                                                                                                                                                        • 74245 Octal Bus Transceivers with 3-State Outputs
                                                                                                                                                                                                                                                                        • 4 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                                                                          • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                                                                                            • Connecting wires Switches
                                                                                                                                                                                                                                                                              • THEORY
                                                                                                                                                                                                                                                                              • 3-State Logic
                                                                                                                                                                                                                                                                                • Serial and Parallel Port Connectors
                                                                                                                                                                                                                                                                                • Parallel Port Connector ndash DB-25
                                                                                                                                                                                                                                                                                  • Accessing parallel port through C Language Programming
                                                                                                                                                                                                                                                                                      • 21-ldst-appendixA
                                                                                                                                                                                                                                                                                      • 22-ldst-appendixB
                                                                                                                                                                                                                                                                                        • DEBOUNCING CIRCUITRY FOR MECHANICAL SWITCHES

                RESISTOR COLOUR CODE Resistor values are given in ohms (shortened to Ω the Greek letter lsquoomegarsquo) They are marked on the resistor using a color code Three colored bands are painted round the resistor Each color stands for a number To read the color code start at the 1st band it is nearest the end Sometimes it is not clear which is the 1st band because there is a 4th band of gold or silver near the other end These two colors are not used for the 1st band they give the accuracy of the resistor (gold is plusmn 5 and silver plusmn 10) so you should not have too much trouble deciding where to start The 1st band gives the first number the 2nd band gives the second number and the 3rd band tells how many zeroes come after the first two numbers

                8

                INTRODUCTION

                Digital Logic Design is concerned with the interconnection among digital components and modules and the area of Switching Theory that can be identified between circuit design and system formulation Logic design is the base of any computer system as every digital system consists of different ICrsquoS and ICs contain a large number of interconnected digital circuits within a small package MSI devices provide digital function while LSI device cover a complete computer modules These circuitries are widely used in digital system like digital voltmeter frequency meter calculating machines telephone-switching system etc In this Practical Workbook laboratory sessions based on both combinational and sequential logic are covered First laboratory session gives an introduction to the basic logic gates and fundamentals of circuit building The second laboratory session covers a CAD software ndash Electronics Workbench (EWB) EWB is excellent simulation software where circuits can be designed and tested before physical implementation Various laboratory sessions of this workbook provide activities and exercises on EWB Next eight laboratory sessions are based on combinational logic Here various MSI circuits like adders converters multiplexers decoders encoders etc are designed Some of these laboratory sessions also include testing of MSI ICs Next four laboratory sessions help in exploring various designs based on sequential logic Here a variety of circuits are designed form the testing of basic flip-flop ICs to registers and different types of counters Last laboratory session demonstrates how digital hardware can be interfaced with a personal computer via parallel port and can be controlled by software All laboratory sessions of this workbook incorporate brief theoretical backgrounds as details may be covered in the respective theory classes Exercises activities are included with almost all the sessions for the students to practice Two appendices are also included in this workbook The first one provides pin diagrams for all the ICs required for the laboratory work provided in this workbook It will help the students in preparing the pin diagrams for the circuits Second appendix discusses a hardware debouncing circuit for mechanical switches as such switches are extensively used for input purpose in logic circuits

                9

                CONTENTS Lab Session No Object Page No

                1 2 3 4 5 6 7 8 9

                10

                11

                12

                13

                14

                15

                To study the logic gates in the following TTL ICs

                7400 Quad 2-input NAND gate 7402 Quad 2-input NOR gate

                7404 Hex inverter 7408 Quad 2-input AND gate 7432 Quad 2-input OR gate

                Also implementing and testing the given circuit on a bread board Working with Electronics Workbench Designing Half and Full Adder Circuits Use of Karnaugh Map (SOP-Expression) method Designing a BCD Adder Designing of a 4 x 1 Multiplexer Experimenting with 74150 IC Designing of a 2 x 4 Decoder 1 x 4 Demultiplexer Experimenting with 74138 IC Designing of a 4 x 2 Priority Encoder Experimenting with 74148 IC Designing an Odd Parity Generator and Checker for a 3-bit Data Driving a seven segment display using 7447 7448 driver IC Experimenting with different modes of JK-FF Designing sequential circuit for the given state diagram using D flip-flop Designing a modulus-5 asynchronous up-counter using JK-FF Experimenting with 74194 4-bit bidirectional universal shift register Experimenting with 74245 octal bus transceivers using parallel port PC interfacing Appendix A ndash Pin Diagrams of the ICs required for the laboratory sessions Appendix B ndash Debouncing circuitry for mechanical switches

                13

                17

                19

                22

                28

                30

                34

                38

                42

                45

                48

                50

                54

                56

                59

                66

                69

                11

                Logic Design amp Switching Theory 1 Lab Session 01 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                Lab Session 01 OBJECT

                bull To study the logic gates in the following TTL ICs

                i) 7400 Quad 2-input NAND gate ii) 7402 Quad 2-input NOR gate iii) 7404 Hex inverter iv) 7408 Quad 2-input AND gate v) 7432 Quad 2-input OR gate

                bull Implementing and testing the given circuit on a bread board

                COMPONENTS REQUIRED 1 Bread board 2 5 V - power supply 3 Multimeter 4 Logic probe 5 LEDs with resistors 6 Connecting wires 7 Switches (optional) 8 Following ICs and their datasheets

                bull 7408 quad 2 input AND gate bull 7432 quad 2 input OR gate bull 7404 hex inverter bull 7400 quad 2 input NAND gate bull 7402 quad 2 input NOR gate

                THEORY

                Logic Gates

                Logic gates are the fundamental building blocks of digital systems These devices are able to make decisions in the sense that they produce one output level when some combinations of input levels are present and a different output when other combinations are applied hence given the name Logic Gates The two levels produced by digital circuitry are referred to variously as HIGH and LOW TRUE and FALSE ON and OFF or simply 1 and 0 There are only three basic gates AND OR and NOT The other gates are merely combinations of these basic gates Logic gates can be interconnected to perform a variety of logical operations This interconnection of gates to achieve prescribed outcomes is called logic design

                1 The AND Gate ndash An AND gatersquos output is 1 if and only if all its inputs are 1 If A and B are two inputs to an AND gate then output F of the gate is given as F = AB

                2 The OR Gate - An OR gatersquos output is 1 if at least one of its input is 1 If A and B are two inputs to an OR gate then output F of the gate is given as F = A+B

                13

                Logic Design amp Switching Theory 1 Lab Session 01 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering 3 The NOT Gate (Inverter) ndash Its output is 1 when its input is 0 and its output is 0 when

                the input is 1 ie it complements a digital variable If A is the input to a NOT gate then output F of the gate is given as AF =

                4 The NAND Gate ndash Its output is 1 if at least one of its input is 0 This gate performs the same logic as an AND gate followed by an inverter If A and B are two inputs to a NAND gate then output F of the gate is given as BAF =

                5 The NOR Gate - The output of a NOR gate is 1 if and only if all its inputs are 0 This gate performs the same logic function as an OR gate followed by an inverter If A and B are two inputs to a NAND gate then output F of the gate is given as BAF +=

                All the above gates have one output and two or more inputs except the NOT gate which has only one input

                PROCEDURE FOR TESTING THE LOGIC GATES IN GIVEN ICs

                1 Set the power supply to 5V With the help of a multimeter check the voltage at the output knobs of the power supply

                2 Connect wires long enough to reach the breadboard with the two knobs of the power supply Again using multimeter check voltage at the non-connected end of the wires

                3 Insert the 7408 quad 2 input AND gate IC on to the bread board and make supply and ground connections by joining 5V wire to pin 14 and 0V wire to pin 7

                4 Consult ICrsquos internal connection diagram for input and output pins of the first AND gate Connect input pins to logic 0 (0V) and observe the output using LED or logic probe You can also connect switches at the input lines to facilitate toggling between 1 and 0

                5 Try different combinations of logic levels at the two inputs Again observe the output 6 Repeat the last two steps for all other gates of the same IC Record the observations 7 Repeat this procedure for all other ICs

                OBSERVATIONS

                Gate Input A Input B Expected Output Observed Output

                AND

                0 0 0 1 1 0 1 1

                OR

                0 0 0 1 1 0 1 1

                NOT 0 - 1 -

                NAND

                0 0 0 1 1 0 1 1

                14

                Logic Design amp Switching Theory 1 Lab Session 01 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                NOR

                0 0 0 1 1 0 1 1

                DATA SHEETS

                Figure 11

                15

                Logic Design amp Switching Theory 1 Lab Session 01 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                16

                GIVEN CIRCUIT

                Figure 12

                PROCEDURE FOR IMPLEMENTATION OF THE GIVEN CIRCUIT 1 Set the power supply 2 Insert ICs on the bread board and make their supply and ground connections 3 As given in the logic diagram make connections using wires and gates in the ICs 4 Apply different combinations at the three inputs and observe the output OBSERVATIONS Logic expression for the given logic diagram __________________________________

                A B C Expected Output Observed Output 0 0 0 0 0 1 0 1 0 0 1 1 1 0 0 1 0 1 1 1 0 1 1 1

                Logic Design amp Switching Theory 1 Lab Session 02 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                Lab Session 02

                OBJECT

                Working with Electronics Workbench

                ELECTRONICS WORKBENCH - EWB Electronics Workbench is a computer aided design tool that provides you with all the components and instruments necessary to create board-level designs It has complete mixed analog and digital simulation and graphical waveform analysis allowing you to design your circuit and then analyze it using different simulated instruments and analysis options It is fully integrated and interactive thus you can change your circuits quickly allowing fast and repeated what-if analysis Electronics Workbench provides the following kind of components bull Sources parts bin (AC voltage source Vcc source ground battery etc) bull Basic parts bin (resistors capacitors transformers switches etc) bull Diodes parts bin bull Transistors parts bin bull Analog ICs parts bin (op-amps etc) bull Mixed ICs parts bin (ADCs DACs 555 timers etc) bull Digital ICs parts bin (AND OR adders multiplexers etc) bull Indicators parts bin (voltmeter ammeter probe displays etc) bull Controls parts bin (voltage differentiator multiplier etc) bull Instruments parts bin (multimeter oscilloscope function generator etc) bull Miscellaneous parts bin (write data textbox etc)

                o Write data This component allows you to save simulation results as an ASCII file o Text Box Use this to add descriptive text anywhere in a circuit

                ACTIVITY

                Design circuit for the logic expression )( CBDCABAF ++=

                Procedure 1 From Logic Gates Parts Bin Drag and drop the required logic gates on the design

                area Use Component Properties dialog box to customize these gates 2 Connect the terminal of these gates according to the given expression Use additional

                connectors form the Basic Parts Bin if you want to connect more than wire at a single node

                3 Drag and drop a probe from Indicators Parts Bin Use Component Properties dialog box to customize the color and other properties of the probe Connect this probe at the output terminal of the circuit to indicate results

                4 Select four switches form Basic Parts Bin Specify the key that controls the switch by typing its name in the Value tab of the Component Properties dialog box For

                17

                Logic Design amp Switching Theory 1 Lab Session 02 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                18

                example if you want the switch to close or open when digit lsquo1rsquo is pressed type 1 in the Value tab then click OK Assign different keys to all the switches

                5 Connect the output terminals of these switches to each of the four inputs A B C and D of the circuit

                6 Drag and drop Vcc and Ground form the Sources Parts Bin 7 Connect Vcc terminal to one end and Ground terminal to the other end of all the

                switches 8 Label the circuit properly using text boxes found in the miscellaneous parts bin 9 Run the circuit using the Activate Simulation switch Use the keys you have assigned

                to the switches to toggle them between Vcc and Ground connections thus providing 1 or 0 respectively to the inputs Record the results as indicated by the probe for all possible combinations of 1s and 0s at the inputs

                EWB Circuit

                Figure 21

                Observations

                A B C D Expected Output Observed Output 0 0 0 0 0 0 0 1 0 0 1 0 0 0 1 1 0 1 0 0 0 1 0 1 0 1 1 0 0 1 1 1 1 0 0 0 1 0 0 1 1 0 1 0 1 0 1 1 1 1 0 0 1 1 0 1 1 1 1 0 1 1 1 1

                Logic Design amp Switching Theory 1 Lab Session 03 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                Lab Session 03

                OBJECT

                Designing Half and Full Adder Circuits COMPONENTS AND APPARATUS REQUIRED 1 Following ICs and their Datasheets

                bull 7408 Quad 2-input AND Gate bull 7432 Quad 2-input OR Gate bull 7486 Quad 2-input XOR Gate

                2 Digital Trainer DT-01 or the following components Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches

                THEORY Half Adder A combination circuit that performs the addition of two bits without accounting for the previous carry is called half adder It needs two binary inputs and two binary outputs The input variables designate the augend and addend bits The output variables produce the sum and carry The simplified sum of product expressions for a half adder are

                yxyxyxS oplus=+= yxC =

                Figure 31 Circuit diagram for Half Adder

                19

                Logic Design amp Switching Theory 1 Lab Session 03 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                bles produce the sum and carry The simplified sum of product expressions for a half adder are

                Full Adder

                A combinational circuit that performs the addition of three input bits It consist of three inputs and two outputs Two of the input variables represent the two significant bits to be added The third input represents the carry from the previous lower significant position The output varia

                zyxzyxzyxzyxzyxS oplusoplus=+++= yxzyxzyzxxyC )( +oplus=++=

                Figure 32 Circuit diagram for Full Adder

                efer to laboratory session 01 for procedure) and record the observations in the following ta

                alf Adde ull Adder Inputs u

                IMPLEMENTATION AND OBSERVATIONS

                Implement the half adder and full adder circuits on a bread board (prepare the pin diagram (use appendix A) and r

                bles H r F

                Inputs Outputs Outp ts x y Carry Su Carry Sum m x y z 0 0 0 0 0 0 1 0 0 1 1 0 0 1 0 1 1 0 1 1 1 0 0 1 0 1 1 1 0 1 1 1

                20

                Logic Design amp Switching Theory 1 Lab Session 03 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                at of your designed circuit Attach hardcopy of the output form electronic workbench

                at of your designed circuit Attach hardcopy of the output form lectronic workbench here

                ACTIVITY

                1 Simulate half adder circuit using Electronics Workbench Compare the results of simulation with thhere

                2 Design a full subtractor circuit and simulate it using Electronics Workbench Compare the results of simulation with the

                21

                Logic Design amp Switching Theory 1 Lab Session 04 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                Lab Session 04 OBJECT

                Use of Karnaugh Map (SOP-Expression) method GIVEN LOGIC EXPRESSION

                F (A B C D) = sum ( 0 1 2 4 5 6 8 9 12 13 14 ) COMPONENTS AND APPARATUS REQUIRED 1 Digital ICs and their Datasheets

                bull 7408 Quad 2-input AND Gate bull 7432 Quad 2-input OR Gate bull 7404 Hex Inverter

                2 Digital Trainer DT-01 or the following components Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches PROCEDURE 1 Use Karnaugh map to reduce the given function 2 Draw the circuit diagram for the obtained reduced function 3 Implement the reduced circuit using digital ICs on a bread board (prepare the pin

                diagram (use appendix A) and refer to laboratory session 01 for procedure) and record the observations

                REDUCTION OF LOGIC EXPRESSION USING KARNAUGH MAP F

                CD

                AB DC

                DC DC

                DC

                BA0 1 3 2

                BA4 5 7 6

                BA12 13 15 14

                BA8 9 11 10

                Reduced form of the given logic expression is __________________________________

                22

                Logic Design amp Switching Theory 1 Lab Session 04 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                LOGIC DIAGRAM (REDUCED FORM) OBSERVATIONS

                A B C D Output 0 0 0 0 0 0 0 1 0 0 1 0 0 0 1 1 0 1 0 0 0 1 0 1 0 1 1 0 0 1 1 1 1 0 0 0 1 0 0 1 1 0 1 0 1 0 1 1 1 1 0 0 1 1 0 1 1 1 1 0 1 1 1 1

                RESULT The reduced form (SOP Expression) of the given logic function is

                ____________________________________________________________

                The observation table reflects the given logic function

                23

                Logic Design amp Switching Theory 1 Lab Session 04 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                ACTIVITY 1 Using Electronics Workbench derive a truth table and logic circuit for the following logic expression

                BAAF +=

                Procedure 1 From the Instruments Parts Bin drag and drop Logic Converter on the design area 2 Double click the Logic Converter to reveal Logic Converter dialog box This dialog

                box shows various conversion options between truth table logic expression and logic circuit

                3 Enter the given logic expression in the edit box found at the end of the dialog box Use lsquo to represent invert of a variable For example A is written as Arsquo

                4 Click the Boolean Expression to Truth Table button The truth table appears in the logic converters display

                5 Now click the Boolean Expression to Circuit button This creates the logic circuit for the given expression in the design area Label the diagram if needed

                Resulting Logic Circuit For the given expression the final circuit will look like

                Figure 41

                24

                Logic Design amp Switching Theory 1 Lab Session 04 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                ACTIVITY 2

                Using Electronics Workbench find a simplified logic expression and circuit for the following truth table

                A B C Output 0 0 0 1 0 0 1 1 0 1 0 0 0 1 1 1 1 0 0 0 1 0 1 0 1 1 0 0 1 1 1 1

                Procedure 1 Click three input channels from A to H across the top of the logic converter The

                display area below the terminals fills up with the necessary combinations of ones and zeros to fulfill the input conditions The values in the output column on the right are initially set to 0

                2 Edit the output column to specify the desired output for each input condition To change an output value select it and type a new value 1 0 or x An x indicates a donrsquot care condition

                3 To convert this truth table to a Boolean expression click the Truth Table to Boolean Expression button The Boolean expression will be displayed at the bottom of the logic converter

                4 Simplify the expression by clicking the Simplify button 5 Now click the Boolean Expression to Circuit button This creates the logic circuit for

                the given expression in the design area Resulting Logic Circuit For the given truth table the final simplified circuit will look like

                Figure 42

                25

                Logic Design amp Switching Theory 1 Lab Session 04 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                ACTIVITY 3

                Using Electronics Workbench find the logic expression and truth table for the following logic circuit

                Figure 43

                Procedure 1 Attach the input terminals of the logic converter to up to four input points in the

                circuit 2 Connect the single output of the circuit to the output terminal on the logic converter

                icon 3 Click the Circuit to Truth Table button The truth table appears in the logic

                converters display 4 To convert this truth table to a Boolean expression click the Truth Table to Boolean

                Expression button The Boolean expression will be displayed at the bottom of the logic converter

                Resulting Logic Expression Logic Expression for the given circuit is found to be _____________________________

                26

                Logic Design amp Switching Theory 1 Lab Session 04 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                27

                For activities 1 2 and 3 attach hardcopy of the output (truth table logic expression and logic circuit) form electronic workbench here

                Logic Design amp Switching Theory 1 Lab Session 05 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                Lab Session 05 Lab Session 05 OBJECT OBJECT

                Designing a BCD Adder Designing a BCD Adder COMPONENTS AND APPARATUS REQUIRED COMPONENTS AND APPARATUS REQUIRED

                1 Following ICs and their Datasheets 1 Following ICs and their Datasheets bull 7408 Quad 2-input AND Gate bull 7408 Quad 2-input AND Gate bull 7432 Quad 2-input OR Gate bull 7432 Quad 2-input OR Gate bull 7483 4-bit Binary Adder bull 7483 4-bit Binary Adder

                2 Digital Trainer DT-01 or the following components 2 Digital Trainer DT-01 or the following components Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors (100 Ω) Connecting wires Switches (100 Ω) Connecting wires Switches

                THEORY THEORY

                A BCD Adder is a combinational circuit that adds two BCD digits in parallel and produces a sum digit also in BCD A BCD Adder is a combinational circuit that adds two BCD digits in parallel and produces a sum digit also in BCD

                A4 A3 A2 A1 B4 B3 B2 B1

                7483-BCD ADDER

                Cout (C4 ) Z4 Z3 Z2 Z1 Cin(C0)

                A4 A3 A2 A1 B4 B3 B2 B1

                7483-BCD ADDER

                Cout

                (C4 ) Z4 Z3 Z2 Z1 Cin(C0)

                Figure 51 BCD Adder Circuit

                28

                Logic Design amp Switching Theory 1 Lab Session 05 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                29

                A BCD adder must include the correction logic in its internal construction The two BCD digits together with the input carry are first added using a 4-bit binary adder to produce the binary sum If no output carry is generated and the binary sum is less than or equal to 9 then the corresponding BCD sum is identical and therefore no conversion is needed When the output carry is equal to 1 or the binary sum is greater than 9 then a binary 0110 is added to the binary sum through another 4-bit binary adder If Cout is the carry output and Z4Z3Z2Z1 is the binary sum form the first 4-bit binary adder then the following equation indicates the condition when a binary 0110 is to be added

                C = COUT + Z4Z2 + Z4Z3 IMPLEMENTATION AND OBSERVATIONS Implement the BCD adder circuit according to figure 51 on a bread board (prepare the pin diagram (use appendix A) and refer to laboratory session 01 for procedure) A BCD adder has nine input bits (two BCD digits and a carry bit) which can result in a total of 512 combinations of which 312 inputs are donrsquot care Since it is a very lengthy procedure to record results for 200 valid input combinations therefore for simplicity just record results for any eight combinations in the following table

                Input Carry

                BCD Digit 1 BCD Digit 2 Carry Output

                BCD Sum A4 A3 A2 A1 B4 B3 B2 B1 Z4 Z3 Z2 Z1

                Logic Design amp Switching Theory 1 lab Session 06 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                Lab Session 06

                OBJECT

                bull Designing of a 4 x 1 Multiplexer bull Experimenting with 74150 IC

                COMPONENTS AND APPARATUS REQUIRED 1 Following ICs and their Datasheets

                bull 7408 Quad 2-input AND Gates or 7411 Triple 3-input AND Gates bull 7432 Quad 2-input OR Gates bull 7404 Hex Inverter bull 74150 16 x 1 MUX

                2 Digital Trainer DT-01 or the following components Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches THEORY

                Multiplexers A digital data Multiplexer (MUX) is a combinational circuit having several data inputs and a single output A set of data-select inputs is used to control which of the data inputs is routed to the single output A multiplexer is also called a data selector because of this ability to select which data input is connected o the output Normally there are 2n input lines and n selection lines whose bit combination determine which input is selected DESIGN OF A 4 x 1 MULTIPLEXER A 4 x 1 multiplexer is capable of selecting one of four data inputs (see figure 61) The 2-bit binary number at the data select inputs S1 and S0 specifies which of the four data inputs is to be routed to the output Since there are two data select inputs therefore they can select 22 = 4 different data inputs lines

                S0 S1 D0 D1

                D2 D3

                Data-select Inputs Output

                Data Inputs

                Figure 61 Block Diagram of a 4 x1 Multiplexer

                30

                Logic Design amp Switching Theory 1 lab Session 06 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                Figure 62 Circuit Diagram for 4 x 1 Multiplexer

                Implementation and Observations

                Implement the 4 x 1 Multiplexer circuit (figure 62) on a bread board (prepare the pin diagram (use appendix A) and refer to laboratory session 01 for implementation procedure) and record the observations in the following table For each data select combination specify the switch number as well as the binary value present on that selected switch

                S1 S0 Output 0 0 0 1 1 0 1 1

                TESTING OF 74150 - 16 x 1 MUX

                The 74150 IC has sixteen data inputs and four data-selection lines Function of various pins of this IC is described below

                bull E0 through E15 Data input lines

                31

                Logic Design amp Switching Theory 1 lab Session 06 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering bull A B C D Data select lines with D being the MSB bull W Active low output line bull Grsquo Active low enable line bull VCC and GND Supply connections lines

                Circuit Diagram

                Figure 63 Pin connections of 74150 for selecting E0

                Testing Procedure

                bull Make connections as shown in the circuit diagram bull Apply different data (1 or 0) at data inputs that are labeled as E0 to E15 Only

                connection for E0 is shown is the figure for simplicity bull Select the data input E0 with the help of data selectors A B C and D bull Observe the output which shows the complement of the data from E0 bull Select all the sixteen data inputs one by one and record your observations in the

                following table

                32

                Logic Design amp Switching Theory 1 lab Session 06 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                33

                Observations

                Grsquo D C B A W Grsquo D C B A W 0 0 0 0 0 0 1 0 0 0 0 0 0 0 1 0 1 0 0 1 0 0 0 1 0 0 1 0 1 0 0 0 0 1 1 0 1 0 1 1 0 0 1 0 0 0 1 1 0 0 0 0 1 0 1 0 1 1 0 1 0 0 1 1 0 0 1 1 1 0 0 0 1 1 1 0 1 1 1 1

                ACTIVITY 1 Consider 4x1 Multiplexer Draw the output wave-form for the following data inputs

                (E0 E1 E2 E3) and select lines A B (B being the MSB) Output is W

                E3 E2 E1 E0 A B

                W

                2 Using the 4 x 1 MUX designed in this laboratory session implement the following logical function F (A B C) = Σ (0147)

                Show your working and input connections in the following block diagram according to the circuit you have implemented

                4 x 1 MUX

                S0 S1

                Output D0

                D1

                D2

                D3

                Logic Design amp Switching Theory 1 Lab Session 07 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                Lab Session 07

                OBJECT

                bull Designing of a 2 x 4 Decoder 1 x 4 Demultiplexer bull Experimenting with 74138 IC

                COMPONENTS AND APPARATUS REQUIRED 1 Following ICs and their Datasheets

                bull 7408 Quad 2-input or 7411 Triple 3-input AND Gates bull 7404 Hex Inverter bull 74138 3 x 8 Decoder

                2 Digital Trainer DT-01 or the following components Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches THEORY

                Decoder A Decoder is a combinational circuit that converts binary information form n input lines to a maximum of 2n unique output lines In practical applications decoders are often used for selecting one of several devices

                Demultiplexer A decoder with an enable input can function as a Demultiplexer A Demultiplexer (DMUX) id a circuit that receives information on a single line and transmits this information on one of 2n possible output lines The selection of a specific output line is controlled by the bit values of n selection lines DESIGN OF A 2 x 4 DECODER 1 x 4 DEMULTIPLEXER A 2 x 4 decoder is capable of selecting one of four output lines (see figure 71 (a)) The 2-bit binary number at the data inputs S1 and S0 specifies which of the four data inputs is to be selected If we add an enable pin and use it as an input line then this decoder can be converted to a 1 x 4 Demultiplexer where S1 and S0 will select a line to which data input is to be routed (see figure 71 (b))

                Select S0 S0 Inputs

                S1 D0 D1

                D2

                D3

                Enable (a) Block Diagram of a 2 x 4 Decoder

                Figure 71

                S1 D0 D1

                D2

                D3

                Inputs

                Data Input (b) Block Diagram of a 1 x 4 Demulptiplexer

                34

                Logic Design amp Switching Theory 1 Lab Session 07 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                Figure 72 Circuit Diagram for 2 x 4 Decoder 1 x 4 Demultiplexer

                Implementation and Observations Implement the 2 x 4 Decoder 1 x 4 Demultiplexer circuit (figure 72) on a bread board (prepare the pin diagram (use appendix A) and refer to laboratory session 01 for implementation procedure) and record the observations in the following table

                Enable Data Input S1 S0 D0 D1 D2 D3

                0 0 0 0 0 1 0 1 0 0 1 1 1 0 0 1 0 1 1 1 0 1 1 1

                TESTING OF 74138 3 x 8 Decoder The 74138 IC has three inputs and eight output lines It has three enable inputs and for the IC to function all three inputs need to be enabled Function of various pins of this IC is described below

                35

                Logic Design amp Switching Theory 1 Lab Session 07 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                bull Y0 through Y7 Active low data outputs bull A B C Input select lines with C being the MSB bull G1 Active high enable Input bull G2Arsquo and G2Brsquo Active low enable Inputs bull VCC and GND Supply connections lines Circuit Diagram

                Figure 73 Pin connections of 74138

                Testing Procedure

                bull Make connections as shown in the circuit diagram bull Apply different combinations of 1s and 0s at data inputs bull Observe the output and record your observations in the following table

                Observations

                C B A Y0 Y1 Y2 Y3 Y4 Y5 Y6 Y7 0 0 0 0 0 1 0 1 0 0 1 1 1 0 0 1 0 1 1 1 0 1 1 1

                36

                Logic Design amp Switching Theory 1 Lab Session 07 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                37

                ACTIVITY ACTIVITY 1 What will be the binary values at the outputs Y0 through Y7 of 74138 if 1 What will be the binary values at the outputs Y0 through Y7 of 74138 if

                bull All three enable pins are connected to ground bull All three enable pins are connected to ground __________________________________________________________________________________________________________________________________________ __________________________________________________________________________________________________________________________________________ _____________________________________________________________________ _____________________________________________________________________

                bull All three enable pins are connected to VCC bull All three enable pins are connected to VCC _______________________________________________________________________________________________________________________________________________________________________________________________________________

                _______________________________________________________________________________________________________________________________________________________________________________________________________________

                2 Show connections for 74138 in order to use it as a 1 x 8 Demultiplexer 2 Show connections for 74138 in order to use it as a 1 x 8 Demultiplexer

                3 Consider a 2 x 4 Decoder with two enable inputs (one active high - G and one active low ndash Grsquo) Draw the output wave-forms for D0 D1 D2 and D3 if the two select inputs are A and B (B being the MSB) All outputs are active low

                Grsquo

                G

                A B

                D0 D1 D2

                D3

                Logic Design amp Switching Theory 1 Lab Session 08 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                Lab Session 08 OBJECT

                bull Designing of a 4 x 2 Priority Encoder bull Experimenting with 74148 IC

                COMPONENTS AND APPARATUS REQUIRED

                1 Following ICs and their Datasheets

                bull 7408 Quad 2-input or 7421 Dual 4-input AND Gates bull 7432 Quad 2-input OR Gates bull 7404 Hex Inverter bull 74148 Encoder

                2 Digital Trainer DT-01 or the following components Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches

                THEORY

                Encoder An Encoder is a digital function that produces a reverse operation from that of a decoder An Encoder has 2n (or less) input lines and n output lines The output lines generate the binary code for the 2n input variables Priority Encoder

                A simple encoder may produce an erroneous output if more than one of its inputs is high A Priority Encoder is one that responds to just one input among those that may be simultaneously high in accordance with some priority system The most common priority system is based on the relative magnitudes of the inputs whichever decimal input is largest is the one that is encoded

                DESIGN OF A 4 x 2 Priority Encoder

                The following equations represent the outputs of a 4 x 2 priority encoder 32 DDA +=

                321 DDDB += As can be seen from the equations that input D0 which has a binary code 00 is not used in any equation A binary code 00 at the output indicates two conditions Either D0 is selected or no input is selected In order to differentiate these two conditions we will provide an additional output Z to indicate if at least one of the inputs is a 1 The equation for Z will be

                4321 DDDDZ = If Z is 0 then the binary code 00 at the output indicates that D0 is selected and if Z is 1 then it indicates that no input line is selected

                38

                Logic Design amp Switching Theory 1 Lab Session 08 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                Figure 81 Circuit Diagram for 4 x 2 Priority Encoder

                it (figure 81) on a bread board (prepare the to laboratory session 01 for implementation

                Implementation a Implement the 4 x 2 Priority Encoder circu

                ram (use appendix A) and refer

                nd Observations

                pin diagprocedure) and record the observations in the following table

                D3 D2 D1 D0 A B 0 0 0 1 0 0 1 x 0 1 x x 1 x x x

                TESTING OF 74148 8 x 3 Octal Priority Encoder

                imal digits There are nine of which three represents

                ing any of the inputs is high

                then it shows that line 0 is selected and if e inputs selected E0 and GS

                cannot be in the same state provided that E1 is enabled

                The 74148 is a priority encoder with active-Low input for dec

                input) and five output linesinputs lines (including an enablethe binary code for the octal digit Function of various pins of this IC is described below

                bull 0 through 7 Active low data inputs representing the octal digits A2 A1 A0 Active low output lines representing the binary code bullbull E1 Active low enable Input bull E0 Active low output indicating none of the inputs is high bull GS Active low output indicatbull VCC and GND Supply connections lines Therefore if GS A2 A1 and A0 are all low

                then it shows that none of thE0 A2 A1 and A0 are all low

                39

                Logic Design amp Switching Theory 1 Lab Session 08 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                Circuit Diagram

                Figure 82 Pin connections of 74148

                Testing Procedure bull Make connections as sho

                binations of 1s and 0s at data inputs d record your observations in the following table

                GS E0

                wn in the circuit diagram bull Apply different combull Observe the output an Observations

                0 1 2 3 4 5 6 7 A2 A1 A0 1 1 1 1 1 1 1 1 x x x x x x x 0 x x x x x x 0 1 x x x x x 0 1 1 x x x x 0 1 1 1 x x x 0 1 1 1 1 x x 0 1 1 1 1 1 x 0 1 1 1 1 1 1 0 1 1 1 1 1 1 1

                40

                Logic Design amp Switching Theory 1 Lab Session 08 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                41

                CTIVITY

                Cascade the following two 74148 8 x 3 Priority Encoders to form 16 x 4 Priority

                A 1

                Encoder

                Logic Design amp Switching Theory 1 Lab Session 09 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering `

                Lab Session 09 OBJECT

                Designing an Odd Parity Generator and Checker for a 3-bit Data COMPONENTS AND APPARATUS REQUIRED

                1 Following ICs and their Datasheets

                bull 7486 Quad 2-input Exclusive-OR Gates bull 7404 Hex Inverter

                2 Digital Trainer DT-01 or the following components Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches

                THEORY

                Parity Generator When binary data is transmitted and processed it is ndash as are all electrical signals ndash susceptible to noise that can either alter or distort its contents 1s may be effectively changed to 0s and 0s to 1s To overcome this problem one or more bits are often added to the data as an aid in detecting errors caused by noise The most common of these is a Parity bit that signifies whether the total number of 1s in a code group is odd or even In an Odd Parity system the parity bit is made 0 or 1 as necessary to make the total number 1s odd (counting the parity bit itself) In an Even Parity system the parity bit is chosen to make the total number of 1s even Table 91 shows how parity bits would be added to BCD code group in both systems

                Decimal BCD Value Parity Bit ABCD Odd Parity Even Parity

                0 0000 1 0 1 0001 0 1 2 0010 0 1 3 0011 1 0 4 0100 0 1 5 0101 1 0 6 0110 1 0 7 0111 0 1 8 1000 0 1 9 1001 1 0

                Table 91 Odd and Even Parity in BCD

                When digital data is received a parity checking circuit generates an error signal if the total number of 1s is odd in an even parity system or if it is even in an odd parity system Parity check always detects a single error (one bit change from 0 to 1 or 1 to 0) but may not detect

                42

                Logic Design amp Switching Theory 1 Lab Session 09 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering ` two or more errors Odd parity is used more often than even parity because even parity does not detect a situation where all 0s are created due to short circuit or other fault condition DESIGN OF A 3-BIT ODD PARITY GENERATOR AND CHECKER Let x y and z be the three bits that constitute the message and are the input to the Odd Parity Generator Circuit Since it is an odd parity system the bit P is generated so as to make the total number of 1s odd (including P) The function P can be expressed as follows P = x oplus y Ο z or P = x Ο y oplus z Since the IC available is 7486 which is quad 2input XOR IC therefore we will convert XNOR also to XOR

                P = x oplus y Ο z

                P = ( x oplus y ) Ο z Since for even number of variables ______

                XOR = XNOR Therefore ___________ _________

                P = ( x oplus y ) oplus z = x oplus y oplus z This logical expression can be implemented with two XOR gates and an inverter (see figure 91)

                Figure 91 Circuit Diagram for a 3-bit Parity Generator

                The 3-bit message and the parity bit are transmitted to their destination where they are applied to a Parity Checker Circuit An error occurs during transmission if the parity of the four bits received is even since the binary information transmitted was originally odd The output C of the parity checker should be a 1 when an error occurs ie when the number of 1s in the four inputs is even Therefore the function C can be expressed as

                C = x Ο y Ο z Ο P

                Using the same logic applied for the conversion of the equation of P

                PzyxC oplusoplusoplus= This logical expression can be implemented with three XOR gates and an inverter (see figure 92)

                43

                Logic Design amp Switching Theory 1 Lab Session 09 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering `

                44

                Figure 92 Circuit Diagram for a 3-bit Parity Checker Implementation and Observations Implement the 3-bit Parity Generator and Checker circuits (figure 91 and 92) on a bread board (prepare the pin diagram (use appendix A) and refer to laboratory session 01 for implementation procedure) and record the observations in the following table

                x y z P x y z P C x y z P C 0 0 0 0 0 0 0 1 0 0 0 0 0 1 0 0 0 1 1 0 0 1 0 1 0 0 0 1 0 1 0 1 0 0 1 1 0 0 1 1 1 0 1 1 1 0 0 0 1 0 0 1 1 0 0 1 0 1 0 1 0 1 1 1 0 1 1 1 0 0 1 1 0 1 1 1 0 1 1 1 0 1 1 1 1 1 1 1

                Odd Parity Generation Odd Parity Check ACTIVITY 1 Try using the parity checker of figure 92 as 3-bit parity generator Write the details here

                _____________________________________________________________________________________________________________________________________________________________________________________________________________________ ______________________________________________________________________________________________________________________________________________ _______________________________________________________________________ ______________________________________________________________________________________________________________________________________________

                Logic Design amp Switching Theory 1 Lab Session 10 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                Lab Session 10 OBJECT

                Driving a seven segment display using 7447 7448 driver IC COMPONENTS AND APPARATUS REQUIRED

                1 Following ICs and their Datasheets

                bull Seven Segment Displays (Common Anode Common Cathode) bull 7447 7448 BCD to Seven Segment Driver

                2 Digital Trainer DT-01 or the following components Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches

                THEORY Seven Segment Displays A Seven Segment Display consists of seven light-emitting segments The segments are designated by letters a through g (see figure 101) By illuminating various combinations of segments the numerals 0 through 9 can be displayed Seven Segment Displays are commonly constructed with light-emitting diodes (LEDs) and with liquid-crystal displays (LCDs) LEDs generally provide greater illumination levels but require much greater power than LCDs An LED display can be a common-anode type or common cathode type In common anode type a high voltage is applied at the common terminal of the display and low voltage is applied at a segmentrsquos terminal for illumination In the common-cathode type a low voltage is applied at the common terminal of the display and high voltage is applied at a segmentrsquos terminal for illumination

                Figure 101 Seven Segment Display

                a f b g

                e c d

                7447 7448 BCD to Seven Segment Driver 7447 7448 IC is particularly used to drive Seven Segment Its input is a BCD number and output drives a seven segment display 7447 is used to drive common-anode displays whereas 7448 is used to drive common cathode displays 7447 7448 is a 16 pin IC Function of various pins of these ICs is described below

                bull A B C D Inputs representing BCD digits (D being the MSB)

                45

                Logic Design amp Switching Theory 1 Lab Session 10 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering bull OA through OG Outputs to drive segments a through g of the display (Active low

                in 7447 and active high in 7448) bull RBI Ripple Blanking Input Turns off all the segments if kept low provided that LT

                is kept high and all other inputs (A B C D BI) are kept low Should be kept high otherwise

                bull BI RBO Wire-AND logic serving as a Blanking Input and or Ripple Blanking Output

                o BI Turns off all the segments if low o RBO Goes to a low level (response condition) along with other outputs when

                RBI and inputs A B C and D are low with LT input at high level bull LT Lamp Test input Tests whether all segments are working or not Illuminates all

                segments if kept low provided that BI is kept high Should be kept high otherwise bull VCC and GND Supply connections lines CIRCUIT DIAGRAM

                Figure 102 Circuit diagram for 7447driving a common-anode display

                IMPLEMENTATION AND OBSERVATIONS

                bull Make connections as shown in the circuit diagram (refer to laboratory session 01 for implementation procedure)

                bull Apply different combinations of 1s and 0s at data inputs bull Observe the output and record your observations in the following table

                46

                Logic Design amp Switching Theory 1 Lab Session 10 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                47

                Decimal Digit

                BCD Inputs Seven Segment Outputs D C B A a b c d e f g

                0 0 0 0 0 1 0 0 0 1 2 0 0 1 0 3 0 0 1 1 4 0 1 0 0 5 0 1 0 1 6 0 1 1 0 7 0 1 1 1 8 1 0 0 0 9 1 0 0 1

                ACTIVITY 1 Perform the Lamp Test for the designed circuit and write your observations

                ____________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________

                2 How can you use 7447 IC to drive a common-cathode display

                ____________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________

                3 What symbols appear in the seven segment display if inputs DCBA are

                DCBA Symbol

                1010

                1011

                1100

                1101

                1110

                1111

                Logic Design amp Switching Theory 1 Lab Session 11 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                48

                Lab Session 11 OBJECT

                Testing different modes of JK-FF COMPONENTS AND APPARATUS REQUIRED 1 Following ICs and their Datasheets

                bull 7473 7476 JK Flip-Flop 2 Digital Trainer DT-01 or the following components

                Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches

                THEORY

                Flip-Flop A flip-flop circuit can maintain a binary state indefinitely (as long as the power is delivered to the circuit) until directed by an input signal to switch states The major differences among various types of flip-flops are in the number of inputs they possess and in the manner in which the inputs affect the binary state

                JK Flip-Flop JK flip flop is an edge triggered device A typical JK flip flop has three inputs J K and a clock input The flip-flop can be either positive or negative edge triggered The output Q is available in complemented form as well Beside the usual inputs and output most of the flip-flop IC also possess two asynchronous inputs namely Preset and Clear These inputs are usually active low If used Preset and Clear inputs keep the flip-flop in set and reset state respectively irrespective of the other inputs Both of these inputs cannot be used simultaneously otherwise they will bring the flip-flop in unstable state

                Figure 111 Symbol for JK flip-flop

                (a) positive-edge triggering (b) active low Preset (PR) and Clear (CLR) with positive-edge triggering

                (c) active low Preset (PR) and Clear (CLR) with negative-edge triggering

                Logic Design amp Switching Theory 1 Lab Session 11 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                49

                TESTING OF 7473 7476 DUAL JK FLIP-FLOP

                Both the ICs 7473 and 7476 are similar in functionality except for one difference The flip-flops in 7473 have only one type of active low asynchronous input which is the Clear input whereas the flip-flops in 7476 have both Preset and Clear inputs Both these ICs have negative edge triggered flip-flops

                Circuit Diagram

                Figure 112 Pin connections of 7476

                Testing Procedure

                bull Make connections as shown in the circuit diagram (figure 112) bull Apply different combinations of 1s and 0s at J and K inputs bull Observe the output and record your observations in the following table

                Observations

                J

                K Q

                0 0 0 1 1 0 1 1

                ACTIVITY

                1 Observe the output Q of JK flip-flop if the clock input is connected to VCC or GND instead of a clock source Write your observations here __________________________________________________________________________________________________________________________________________ _______________________________________________________________________________________________________________________________________________________________________________________________________________

                Logic Design amp Switching Theory 1 Lab Session 12 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                50

                Lab Session 12 OBJECT

                Designing sequential circuit for the given state diagram using D flip-flop GIVEN STATE DIAGRAM

                00

                11

                Figure 121 State Diagram COMPONENTS AND APPARATUS REQUIRED 1 Following ICs and their Datasheets

                bull 7474 D Flip-Flop bull ICs of basic gates (AND OR NOT XOR etc) as required

                2 Digital Trainer DT-01 or the following components Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches

                THEORY

                Sequential Circuits In Sequential Circuits the output not only depends on the present inputs but also on previous states of the circuit These circuits use memory elements (latches flip-flops) and the binary information stored in the memory elements at any given time defines the state of the sequential circuit Analysis of a Sequential Circuit The behavior of a sequential circuit is determined from the inputs the outputs and the states of its flip-flops Both the outputs and next state are a function of the inputs and the

                10

                01

                00 11 10

                00

                00 11 10 00

                Logic Design amp Switching Theory 1 Lab Session 12 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                51

                present state The analysis of a sequential circuit form a state diagram comprises of the following bull Selecting a particular flip-flop to design the circuit bull Obtaining state table from the state diagram bull Finding input equations for the selected flip-flop bull Finding state equations (not required for the construction of circuit) bull Implementing the circuit using selected flip-flops and their input equations ANALYZING THE GIVEN STATE DIAGRAM D Flip-Flop D flip-flop is also called transparent flip-flop as it simply transfers the input data to the output For our design we require the graphical symbol and excitation table of D flip-flop (see figure 122)

                Qt Qt+1 T 0 0 0 0 1 1 1 0 0 1 1 1

                (b) Excitation table of D Flip-Flop

                (a) Graphical Symbol

                Figure 122 Characteristic equation of D flip-flop is Q(t+1) = D State Table The given state diagram has four states so we will need two D flip-flops (FF-0 FF-1) Form state table form the given state diagram and record the results in the following table

                Present State Input Next State Output Input to FF-0 D0

                Input to FF-1 D1 Q1t Q0t x Q1(t+1) Q0(t+1) z

                Logic Design amp Switching Theory 1 Lab Session 12 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                52

                Input Equations Using Karnaugh map the input equations D0 and D1 for the two flip-flops can be found

                D0 D1 Q0x

                Q1

                _ _ Q0x

                _ Q0x

                Q0x

                _ Q0x

                Q0x

                Q1

                _ _ Q0x

                _ Q0x

                Q0x

                _ Q0x

                _ Q1

                _ Q1

                Q1

                Q1

                D0 = _________________ D1 = _________________

                State Equations Using the characteristic equation of D flip-flop we can find the state equations Q0(t+1) and Q1(t+1) for the to flip flops Q0(t+1) = _______________________ Q1(t+1) = _______________________ _______________________ _______________________ _______________________ _______________________ Circuit Diagram

                Logic Design amp Switching Theory 1 Lab Session 12 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                53

                Implementation Procedure and Observations

                1 Implement the circuit using digital ICs on a bread board (prepare the pin diagram (use appendix A) and refer to laboratory session 01 for procedure)

                2 Make the clear inputs of the flip-flops low (to clear the flip-flops) The flip-flops will remain in clear state as long as the clear inputs are connected to low level

                3 Connect output Q0 and the clock pulse to an oscilloscope 4 Apply 0 to the input x 5 Now make the clear inputs to high 6 Observe the waveform for the first 5 clock pulses and record it 7 Repeat steps 2 to 6 keeping x=1 in step 4 this time 8 Repeat steps 2 to 7 this time connecting Q1 instead of Q0 to the oscilloscope in step

                3 Record your observations (Keep frequency of the clock pulse low (eg1Hz) so that the output waveforms can be observed easily)

                1 2 3 4 5 Clock Pulse

                Output Waveform for Q0 when x=0

                Output Waveform for Q0 when x=1

                Output Waveform for Q1 when x=0

                Output Waveform for Q1 when x=1

                Logic Design amp Switching Theory 1 Lab Session 13 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                Lab Session 13 OBJECT

                Designing a modulo-5 asynchronous up-counter using JK-FF COMPONENTS AND APPARATUS REQUIRED

                1 Following ICs and their Datasheets

                bull 7400 Quad 2-input or 7410 Triple 3-input NAND Gates bull 7476 7473 JK Flip-Flop

                2 Digital Trainer DT-01 or the following components Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches

                THEORY

                Digital Counters A digital counter is a set of flip-flops whose states change in response to pulses applied at the input to the counter The flip-flops are interconnected so that their combined state at any time is the binary equivalent of the total number of pulses that have occurred up to that time Every counter resets after a certain number of clock pulses Thus as it name implies a counter is used to count pulses An n stage counter can count up to a maximum of 2n states n is equal to the number of flip-flops required for the construction of counter

                Modulus Counters The number of input pulses that causes a counter to reset to its initial count is called the modulus of the counter Thus the modulus equals to total number of distinct states (counts) including zero that a counter can store A binary counter with n stages is a modulo-2n (or mod-2n) counter The largest count a mod-N counter can achieve is N-1 ie a mod-N counter never reaches the binary number equal to its modulus N is always equal to or less than 2n Counters can be classified as bull Synchronous Counters which are clock driven All the flip-flops are driven by a

                single clock bull Asynchronous Counters which are event driven Clock input is given to the first

                flip-flop only Rest of the flip-flops are driven by their preceding flip-flops

                DESIGN OF A MOD-5 ASYNCHRONOUS UP COUNTER The number of flip-flops required to construct a mod-5 counter is 3 because 5 should be less than or equal to 2n This counter will count from 0 to 4 a total of 5 distinct states Since a 3-stage counter can count up to 8 states at maximum a NAND gate is used to reset it after 5 clock pulses Figure 131 shows the logic diagram

                54

                Logic Design amp Switching Theory 1 Lab Session 13 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                55

                Figure 131 A Mod-5 Asynchronous Up Counter

                Implementation and Observations

                Implement the mod-5 counter circuit (figure 131) on a bread board (prepare the pin diagram (use appendix A) and refer to laboratory session 01 for implementation procedure) and record the observations in the following table

                Clock Pulse Q2 Q1 Q0

                0 1 2 3 4 5 6 7

                ACTIVITY

                Draw the timing diagram for mod-5 counter designed in this laboratory session

                Logic Design amp Switching Theory 1 Lab Session 14 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                Lab Session 14 OBJECT

                Experimenting with 74194 4-bit bidirectional universal shift register COMPONENTS AND APPARATUS REQUIRED

                1 Following ICs and their Datasheets

                bull 74194 4-bit bidirectional universal shift register 2 Digital Trainer DT-01 or the following components

                Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches

                THEORY

                Shift Registers

                A Register is a set of flip-flops used to store binary data A register which is capable of shifting its binary information either to the right or left is called a shift register The logical configuration of a register consists of a chain of flip-flops connected in cascade with the output of one flip-flop connected to the input of next flip-flop All flip-flops receive a common clock pulse which causes the shift from one stage to the next

                Bidirectional Shift Registers A bi-directional shift register is one whose bits can be shifted from left to right or from right to left

                Universal Shift Registers A universal shift register is a bi-directional register whose input can be in either serial or parallel form and whose output can be in either serial or parallel form

                74194 4-BIT BIDIRECTIONAL UNIVERSAL SHIFT REGISTER

                The 74194 register provides parallel as well as serial loading in both directions Function of various pins of this IC is described below

                bull A B C and D Active high inputs for parallel loading bull QA QB QC and QD Active high outputs bull S0 and S1 Active high mode control inputs The following table shows combinations

                of S1 and S0 to enable various modes

                S1 S0 Clock Action 0 0 x No change 0 1 uarr Shift right 1 0 uarr Shift left 1 1 uarr Parallel load

                uarr shows the rising edge of the clock pulse

                56

                Logic Design amp Switching Theory 1 Lab Session 14 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering bull SR Active high serial input for right shifting bull SL Active high serial input for left shifting bull CLR Active low input Clears all the flip-flops of the register if set to 0 should be

                kept high otherwise bull CLK Clock input bull VCC and GND Supply connections lines Thus A B C and D are inputs for parallel loading whereas SR and SL are inputs for serial loading with right or left shifting respectively S1 and S0 are used to select the loading mode Circuit Diagram

                Figure 141 Pin connections of 74194 Testing Procedure

                bull Make connections as shown in the circuit diagram bull Observe the output for the input combinations given in the following table

                57

                Logic Design amp Switching Theory 1 Lab Session 14 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                58

                Observations

                S1 S0 SL SR A B C D QA QB QC QD 0 0 0 1 0 0 0 0 0 1 1 0 0 0 0 1 1 0 0 0 0 0 1 0 1 1 0 0 0 0 1 1 0 0 1 1 0 1 0 0 0 1 1 1 0 1 0 1 1 0 1 0 0 1 1 0 1 1 1 0 0 1 1 1 1 1 0 0 1 1 1 1

                ACTIVITY 1 Show connections of 74194 to convert it into a ring counter with right shifting

                Logic Design amp Switching Theory 1 Lab Session 15 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                Lab Session 15

                OBJECT

                Experimenting with 74245 octal bus transceivers using parallel port PC interfacing COMPONENTS AND APPARATUS REQUIRED 1 Parallel Port Connectors (DB-25) with Cable 2 Personal Computer with Windows 98 and TurboC Compiler Installed 3 Following ICs and their Datasheets

                bull 74245 Octal Bus Transceivers with 3-State Outputs 4 Digital Trainer DT-01 or the following components

                Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches

                THEORY

                3-State Logic Sometimes it is necessary to isolate one part of circuit from the other part For this purpose some TTL ICs are designed with 3-state logic Such devices have three possible output states high low and high impedance The device can be put into high impedance state by a control signal applied to an appropriate pin When such a device is in high impedance state there is very high impedance at its output effectively isolating the device from whatever circuitry the output normally drives 74245 Octal Bus Transceivers A bus is any conducting path or set of paths having electrical connections to one or more devices 74245 octal bus transceivers are mainly used to control connectivity between two devices or circuits It also provides direction control for signal flow Function of various pin of this IC is given below

                bull A1 through A8 Bus A bull B1 through B8 Bus B bull G΄ Active low enable input When high sets all the bus pins to high impedance state bull DIR Direction control for signal flow When set to high logic level transfers bus A

                data to B bus When set to low logic level transfers bus B data to A bus bull VCC and GND Supply connections lines Serial and Parallel Port Connectors A Parallel Port can consist of only 25 pin port adapter called a DB-25 and a serial port can consist of either a 25 pin port adapter called a DB-25 or 9 pin adapter called a DB-9 port adapter Whether the port is a 9 pin or 25 pin it can accomplish all of the same tasks that serial port communications have been designed for

                59

                Logic Design amp Switching Theory 1 Lab Session 15 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                60

                Each adapter can be a male type connector with pins or a female type adapter with tiny holes Generally a PRINTER port (called LPT1) on the back of a computer is female type adapter and we need to use MALE DB-25 pin cable on it for PRINTER connection or for parallel LAPLINK cable And a COM port on the back of a computer is male for the serial ports but it may not necessarily be Parallel Port Connector ndash DB-25 The DB-25 connector (named for its B-size D-shaped shell and 25 pins) is practically ubiquitous in the electronics industry The DB-25 connector is used for a variety of purposes Two common applications are RS-232EIA-232 (serial) connections and the parallel printer interface on the IBM PC The DB-25 connector is also used for SCSI connections Normally the parallel port is used for output to a printer or other device It sends data 8-bits or one byte at a time in parallel The other lines available on the DB-25 connector are a combination of status lines control lines and ground lines The status and control lines are used for handshaking commands and feedback when we are talking to a printer

                Figure 152 DB-25 Female Figure 151 DB-25 Male

                Figure 153 Pin Layout for DB-25 As can be seen form figure 153 there are four types of pins in this connector

                bull Data pins (8 pins - D0 to D7) Active high bidirectional lines

                Logic Design amp Switching Theory 1 Lab Session 15 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering bull Control pins (4 pins - C0 to C3) C0 C1 and C3 are active low whereas C2 is active

                high These lines also are bidirectional bull Status pins (5 pins ndash S3 to S7) Only S7 is active low rest are active high input lines bull Ground pins (8 pins) Used as a reference signal for the low (below 05 volts) charge

                Parallel Port Addresses A DB-25 connector at a parallel port has three address one for each kind of pins register data status and control The first or base address generally refers to data register Second address is for status register and the third one is for control register In Windows 98 the base address is usually found to be 278H 378H or 3BCH Now if 378H is the base address then it refers to the data register whereas addresses for status and control register are respectively 379H and 37AH For Windows 98 the base address can be found as follows 1 On your Desktop right-click on My Computer and select Properties 2 Click on the Device Manager tab and find LPT1 under Plug and Play BIOS 3 After selecting LPT1 click the Properties button 4 Next select the Resources tab and the address should then appear next to InputOutput

                Range Accessing parallel port through C Language Programming There are multiple functions in C Language for accessing external ports The most commonly used are listed below

                bull unsigned char inportb(int portid) inportb reads a byte from a hardware port

                bull int inport(int portid) reads a word from a hardware port

                bull void outportb(int portid unsigned char value) outputs a byte to a hardware port

                bull void outport(int portid int value) outputs a word to a hardware port

                portid refers to the port address whereas value refers to the data to be sent TESTING 74245 USING PARALLEL PORT PC INTERFACING At one end the parallel port connector will be connected to the PC via parallel port cable and another connector (to be plugged into the PC parallel port slot) At the other end it will be connected to the buffer IC 74245 Data lines of the connector will be used to transfer 8-bit data between the PC and the buffer Out of the 8-bits of 74245 4-bits will be used to enter data which will be displayed at the monitor through a C language

                61

                Logic Design amp Switching Theory 1 Lab Session 15 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering program The remaining 4-bits will receive data from PC as entered by the user via keyboard

                Circuit Diagram

                Figure 154 Interface of 74245 to PC via Parallel Port

                Procedure

                1 Connect the DB-25 connector to the PC at one end and solder it to the circuit board at the other end

                2 Connect various pins of the connector and 74245 according to the circuit diagram shown in figure 152

                3 Using the functions listed in the previous section write a program in C language to operate various pins of the buffer The user interface of the program should provide option to the user whether to send or receive data from the port

                4 Set DIR switch to 1 5 Try sending some data bits to the port The result should be displayed at the LEDs 6 Set DIR switch to 0 7 Set some binary 4-bit value through the switches Try reading it via parallel port

                C Language Program

                A program to access parallel port for data transfers

                use header file include ltstdiohgt main program void main() define variable

                62

                Logic Design amp Switching Theory 1 Lab Session 15 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering unsigned int data=0 char choice while(1) printing option menu clrscr() printf(This program will send or receive a BCD digit from the parallel portn) printf(nPress your choice numbern) printf(n1 Send Data) printf(n2 Receive Data) printf(n3 Exitn) choice = getch() sending entered digit to the port if(choice == 1) input BCD digit printf(nEnter BCD digit to be sent to the port) data = getche() masking the first four bits data = data amp 0x0f sending to the port outportb(0x378data) printf(nThe BCD digit c has been sent to the port data) printing on screen the data received from the port else if(choice == 2) receiving data from the port data = inportb(0x378) masking the last four bits data = data amp 0xf0 shifting first four bits to make them the last four bits datagtgt=4 printf(nThe BCD digit set at the port is c data) exit else if(choice == 3) break key pressed is not in the menu else printf(nEnter valid choice number) printf(nnPress any key to continue) getch()

                63

                Logic Design amp Switching Theory 1 Lab Session 15 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                ACTIVITY 1 In the above circuit DIR and G΄ inputs are hardwired Connect them to status or

                control pins of the parallel port connector and control their function through your software program Circuit Diagram Program Code ______________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________

                ___________________________________________________________________________________________________________________________________________________

                64

                Logic Design amp Switching Theory 1 Lab Session 15 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                65

                _____________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ _____________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ _______________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ _________________________________________________ _________________________________________________

                Logic Design amp Switching Theory 1 Appendix A NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                Appendix A

                PIN DIAGRAMS OF THE ICS REQUIRED FOR THE LABORATORY SESSIONS Consult the TTLIC data book for internal diagrams and electrical characteristics of these ICs 7400 Quad 2-Input NAND 7402 Quad 2-Input NOR

                7404 Hex Inverter 7408 Quad 2-Input AND

                7410 Triple 3-Input NAND 7411 Triple 3-Input AND

                7421 Dual 4-Input AND 7432 Quad 2-Input OR

                66

                Logic Design amp Switching Theory 1 Appendix A NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                BCD-to-Seven Segm 7448 BCD-to-Seven Segment 7447 ent

                Decoder (15V OC) Decoder (2kΩ pull-up output)

                7473 Dual JK Flip-Flop 7474 Dual D-Type Flip-Flop

                7476 Dual JK Flop-Flop -Bit Binary Full Adder 7483 4 with Fast Carry

                86 Quad 2-Inpu 74138 3-to-8 Line 74 t Exclusive OR Decoder Demultiplexer

                67

                Logic Design amp Switching Theory 1 Appendix A NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                68

                74148 8-to-3 Line 16-to-1 Line Data

                Priority Encoder 74150 Selector Multiplexer

                74245 Oct nsceivers Universal Shift Register (PIPO) (3-State)

                74194 4-Bit Bidirectional al Bus Tra

                Logic Design amp Switching Theory 1 Appendix B NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                Appendix B

                DEBOUNCING CIRCUITRY FOR MECHANICAL SWITCHES Mechanical switches form the interface between human beings and computers or other digital systems For example a keyboard is a matrix of switches used to supply alphanumeric data to a computer Whatever the switch design it is a potential source of problems due to contact bounce The contact bounce creates a sense of narrow pulses when a switch is opened or closed An example of device whose operation would be adversely affected by contact bounce is a digital counter used to count the number of times a switch is depressed Eliminating the effects of contact bounce is called debouncing When data is entered into a computer via a keyboard a software debounce is often used This type of debouncing is a program that causes the computer to sample the switch terminal (ie to input data from it) many times in succession during the interval of time that contact bounce occurs If the data is sensed to be 1s (or 0s) for a specific number of consecutive samples then it is assumed that contact bounce has ended and the last value sensed is valid Hardware debouncing is the use of electronic circuitry to eliminate the effects of contact bounce There are numerous versions of such circuitry including those that use monostable multivibrators (one-shots) but the most straightforward is simply an RS latch Figure B1 shows the circuit When the switch is in position 1 R = 0 and S = 1 so the latch is set and the output (Q) is 1 When the switch is in position 0 R = 1and S = 0 so the latch is reset and the output is 0 When the switch is moved form one position to the other the latch changes state and bouncing occurs at either the R or the S input The bouncing does not affect the latch after it has change state An RS latch will remain set for example when its R input is 0 and its S input is alternately changed form 1 to 0

                Figure B1 Use of RS latch to debounce a mechanical switch

                69

                • 01-ldst-Outer title
                  • Practical Workbook
                  • Logic Design amp Switching Theory I
                    • Dept of Computer amp Information Systems Engineering
                      • NED University of Engineering amp Technology
                      • Karachi ndash 75270 Pakistan
                        • 02-ldst-inner Title
                          • Practical Workbook
                          • Logic Design amp Switching Theory I
                            • Dept of Computer amp Information Systems Engineering
                              • NED University of Engineering amp Technology
                              • Karachi ndash 75270 Pakistan
                                • 03-ldst-general info
                                • 04-ldst-introduction
                                • 05-Table of Contents
                                  • CONTENTS
                                    • Lab Session No Object Page No
                                    • 1
                                    • Also implementing and testing the given circuit on a bread board
                                      • Working with Electronics Workbench
                                        • Driving a seven segment display using 7447 7448 driver IC
                                          • Designing a modulus-5 asynchronous up-counter using JK-FF
                                            • Experimenting with 74194 4-bit bidirectional universal shift register
                                                • 13
                                                    • 06-ldst-Exp01
                                                      • Lab Session 01
                                                      • OBJECT
                                                        • 1 Bread board
                                                        • 2 5 V - power supply
                                                        • 3 Multimeter
                                                        • 4 Logic probe
                                                        • 5 LEDs with resistors
                                                        • 6 Connecting wires
                                                        • 8 Following ICs and their datasheets
                                                          • THEORY
                                                            • Logic Gates
                                                            • 1 The AND Gate ndash An AND gatersquos output is 1 if and only if all its inputs are 1 If A and B are two inputs to an AND gate then output F of the gate is given as F = AB
                                                            • 2 The OR Gate - An OR gatersquos output is 1 if at least one of its input is 1 If A and B are two inputs to an OR gate then output F of the gate is given as F = A+B
                                                            • 3 The NOT Gate (Inverter) ndash Its output is 1 when its input is 0 and its output is 0 when the input is 1 ie it complements a digital variable If A is the input to a NOT gate then output F of the gate is given as
                                                            • 4 The NAND Gate ndash Its output is 1 if at least one of its input is 0 This gate performs the same logic as an AND gate followed by an inverter If A and B are two inputs to a NAND gate then output F of the gate is given as
                                                              • 5 The NOR Gate - The output of a NOR gate is 1 if and only if all its inputs are 0 This gate performs the same logic function as an OR gate followed by an inverter If A and B are two inputs to a NAND gate then output F of the gate is given as
                                                                  • DATA SHEETS
                                                                    • Logic expression for the given logic diagram __________________________________
                                                                        • 07-ldst-exp02
                                                                          • Working with Electronics Workbench
                                                                            • 08-ldst-exp03
                                                                              • Designing Half and Full Adder Circuits
                                                                                • COMPONENTS AND APPARATUS REQUIRED
                                                                                  • 1 Following ICs and their Datasheets
                                                                                  • 7408 Quad 2-input AND Gate
                                                                                  • 2 Digital Trainer DT-01 or the following components
                                                                                    • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                    • Connecting wires Switches
                                                                                      • THEORY
                                                                                          • IMPLEMENTATION AND OBSERVATIONS
                                                                                            • 09-ldst-Exp04
                                                                                              • Lab Session 04
                                                                                              • 1 Digital ICs and their Datasheets
                                                                                              • 7408 Quad 2-input AND Gate
                                                                                              • 2 Digital Trainer DT-01 or the following components
                                                                                                • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                • Connecting wires Switches
                                                                                                • PROCEDURE
                                                                                                • REDUCTION OF LOGIC EXPRESSION USING KARNAUGH MAP
                                                                                                • OBSERVATIONS
                                                                                                • RESULT
                                                                                                    • 10-ldst-Exp05
                                                                                                      • Lab Session 05
                                                                                                      • 1 Following ICs and their Datasheets
                                                                                                      • 7408 Quad 2-input AND Gate
                                                                                                      • 2 Digital Trainer DT-01 or the following components
                                                                                                        • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                        • (100 Ω) Connecting wires Switches
                                                                                                        • THEORY
                                                                                                          • IMPLEMENTATION AND OBSERVATIONS
                                                                                                            • 11-ldst-Exp06
                                                                                                              • OBJECT
                                                                                                              • 1 Following ICs and their Datasheets
                                                                                                              • 7408 Quad 2-input AND Gates or 7411 Triple 3-input AND Gates
                                                                                                              • 2 Digital Trainer DT-01 or the following components
                                                                                                                • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                • Connecting wires Switches
                                                                                                                  • Figure 62 Circuit Diagram for 4 x 1 Multiplexer
                                                                                                                  • Implementation and Observations
                                                                                                                    • Circuit Diagram
                                                                                                                      • ACTIVITY
                                                                                                                        • 12-ldst-exp07
                                                                                                                          • 1 Following ICs and their Datasheets
                                                                                                                          • 7408 Quad 2-input or 7411 Triple 3-input AND Gates
                                                                                                                          • 2 Digital Trainer DT-01 or the following components
                                                                                                                            • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                            • Connecting wires Switches
                                                                                                                              • THEORY
                                                                                                                                  • Figure 72 Circuit Diagram for 2 x 4 Decoder 1 x 4 Demultiplexer
                                                                                                                                  • Implementation and Observations
                                                                                                                                    • Circuit Diagram
                                                                                                                                      • ACTIVITY
                                                                                                                                        • 13-ldst-Exp08
                                                                                                                                          • OBJECT
                                                                                                                                          • 1 Following ICs and their Datasheets
                                                                                                                                          • 7408 Quad 2-input or 7421 Dual 4-input AND Gates
                                                                                                                                          • 2 Digital Trainer DT-01 or the following components
                                                                                                                                            • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                            • Connecting wires Switches
                                                                                                                                              • THEORY
                                                                                                                                                  • Figure 81 Circuit Diagram for 4 x 2 Priority Encoder
                                                                                                                                                  • Implementation and Observations
                                                                                                                                                    • Therefore if GS A2 A1 and A0 are all low then it shows that line 0 is selected and if E0 A2 A1 and A0 are all low then it shows that none of the inputs selected E0 and GS cannot be in the same state provided that E1 is enabled
                                                                                                                                                    • Circuit Diagram
                                                                                                                                                      • ACTIVITY
                                                                                                                                                        • 14-ldst-exp09
                                                                                                                                                          • OBJECT
                                                                                                                                                          • 1 Following ICs and their Datasheets
                                                                                                                                                          • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                            • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                            • Connecting wires Switches
                                                                                                                                                              • THEORY
                                                                                                                                                                • Parity Generator
                                                                                                                                                                  • Let x y and z be the three bits that constitute the message and are the input to the Odd Parity Generator Circuit Since it is an odd parity system the bit P is generated so as to make the total number of 1s odd (including P) The function P can be expressed as follows
                                                                                                                                                                  • Figure 91 Circuit Diagram for a 3-bit Parity Generator
                                                                                                                                                                    • C = x Ο y Ο z Ο P
                                                                                                                                                                      • Implementation and Observations
                                                                                                                                                                        • ACTIVITY
                                                                                                                                                                            • 15-ldst-exp10
                                                                                                                                                                              • Driving a seven segment display using 7447 7448 driver IC
                                                                                                                                                                              • COMPONENTS AND APPARATUS REQUIRED
                                                                                                                                                                              • 1 Following ICs and their Datasheets
                                                                                                                                                                              • 7447 7448 BCD to Seven Segment Driver
                                                                                                                                                                              • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches
                                                                                                                                                                                  • THEORY
                                                                                                                                                                                  • Seven Segment Displays
                                                                                                                                                                                  • CIRCUIT DIAGRAM
                                                                                                                                                                                  • Figure 102 Circuit diagram for 7447driving a common-anode display
                                                                                                                                                                                      • IMPLEMENTATION AND OBSERVATIONS
                                                                                                                                                                                        • Decimal Digit
                                                                                                                                                                                        • BCD Inputs
                                                                                                                                                                                        • Seven Segment Outputs
                                                                                                                                                                                        • D
                                                                                                                                                                                        • C
                                                                                                                                                                                        • B
                                                                                                                                                                                        • A
                                                                                                                                                                                        • a
                                                                                                                                                                                        • b
                                                                                                                                                                                        • c
                                                                                                                                                                                        • d
                                                                                                                                                                                        • e
                                                                                                                                                                                        • f
                                                                                                                                                                                        • g
                                                                                                                                                                                        • 0
                                                                                                                                                                                        • 0
                                                                                                                                                                                        • 0
                                                                                                                                                                                        • 0
                                                                                                                                                                                        • 0
                                                                                                                                                                                        • 1
                                                                                                                                                                                        • 0
                                                                                                                                                                                        • 0
                                                                                                                                                                                        • 0
                                                                                                                                                                                        • 1
                                                                                                                                                                                        • 2
                                                                                                                                                                                        • 0
                                                                                                                                                                                        • 0
                                                                                                                                                                                        • 1
                                                                                                                                                                                        • 0
                                                                                                                                                                                        • 3
                                                                                                                                                                                        • 0
                                                                                                                                                                                        • 0
                                                                                                                                                                                        • 1
                                                                                                                                                                                        • 1
                                                                                                                                                                                        • 4
                                                                                                                                                                                        • 0
                                                                                                                                                                                        • 1
                                                                                                                                                                                        • 0
                                                                                                                                                                                        • 0
                                                                                                                                                                                        • 5
                                                                                                                                                                                        • 0
                                                                                                                                                                                        • 1
                                                                                                                                                                                        • 0
                                                                                                                                                                                        • 1
                                                                                                                                                                                        • 6
                                                                                                                                                                                        • 0
                                                                                                                                                                                        • 1
                                                                                                                                                                                        • 1
                                                                                                                                                                                        • 0
                                                                                                                                                                                        • 7
                                                                                                                                                                                        • 0
                                                                                                                                                                                        • 1
                                                                                                                                                                                        • 1
                                                                                                                                                                                        • 1
                                                                                                                                                                                        • 8
                                                                                                                                                                                        • 1
                                                                                                                                                                                        • 0
                                                                                                                                                                                        • 0
                                                                                                                                                                                        • 0
                                                                                                                                                                                        • 9
                                                                                                                                                                                        • 1
                                                                                                                                                                                        • 0
                                                                                                                                                                                        • 0
                                                                                                                                                                                        • 1
                                                                                                                                                                                          • ACTIVITY
                                                                                                                                                                                            • 16-ldst-exp11
                                                                                                                                                                                              • Lab Session 11
                                                                                                                                                                                                • OBJECT
                                                                                                                                                                                                • COMPONENTS AND APPARATUS REQUIRED
                                                                                                                                                                                                  • 1 Following ICs and their Datasheets
                                                                                                                                                                                                  • 7473 7476 JK Flip-Flop
                                                                                                                                                                                                  • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                    • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                    • Connecting wires Switches
                                                                                                                                                                                                      • THEORY
                                                                                                                                                                                                          • Flip-Flop
                                                                                                                                                                                                          • JK Flip-Flop
                                                                                                                                                                                                            • Circuit Diagram
                                                                                                                                                                                                              • Observations
                                                                                                                                                                                                                • ACTIVITY
                                                                                                                                                                                                                    • 17-ldst-exp12
                                                                                                                                                                                                                      • Lab Session 12
                                                                                                                                                                                                                        • OBJECT
                                                                                                                                                                                                                        • GIVEN STATE DIAGRAM
                                                                                                                                                                                                                        • Figure 121 State Diagram
                                                                                                                                                                                                                        • COMPONENTS AND APPARATUS REQUIRED
                                                                                                                                                                                                                          • 1 Following ICs and their Datasheets
                                                                                                                                                                                                                          • 7474 D Flip-Flop
                                                                                                                                                                                                                          • ICs of basic gates (AND OR NOT XOR etc) as required
                                                                                                                                                                                                                          • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                            • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                                            • Connecting wires Switches
                                                                                                                                                                                                                              • THEORY
                                                                                                                                                                                                                                  • Sequential Circuits
                                                                                                                                                                                                                                    • 18-ldst-exp13
                                                                                                                                                                                                                                      • Lab Session 13
                                                                                                                                                                                                                                        • Designing a modulo-5 asynchronous up-counter using JK-FF
                                                                                                                                                                                                                                          • 1 Following ICs and their Datasheets
                                                                                                                                                                                                                                          • 7400 Quad 2-input or 7410 Triple 3-input NAND Gates
                                                                                                                                                                                                                                          • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                                            • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                                                            • Connecting wires Switches
                                                                                                                                                                                                                                              • THEORY
                                                                                                                                                                                                                                                  • Figure 131 A Mod-5 Asynchronous Up Counter
                                                                                                                                                                                                                                                  • Implementation and Observations
                                                                                                                                                                                                                                                    • ACTIVITY
                                                                                                                                                                                                                                                        • 19-ldst-exp14
                                                                                                                                                                                                                                                          • Experimenting with 74194 4-bit bidirectional universal shift register
                                                                                                                                                                                                                                                          • 1 Following ICs and their Datasheets
                                                                                                                                                                                                                                                          • 74194 4-bit bidirectional universal shift register
                                                                                                                                                                                                                                                          • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                                                            • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                                                                            • Connecting wires Switches
                                                                                                                                                                                                                                                              • THEORY
                                                                                                                                                                                                                                                                • Shift Registers
                                                                                                                                                                                                                                                                • Bidirectional Shift Registers
                                                                                                                                                                                                                                                                • Universal Shift Registers
                                                                                                                                                                                                                                                                  • S1
                                                                                                                                                                                                                                                                    • Circuit Diagram
                                                                                                                                                                                                                                                                    • ACTIVITY
                                                                                                                                                                                                                                                                        • 20-ldst-exp15
                                                                                                                                                                                                                                                                          • COMPONENTS AND APPARATUS REQUIRED
                                                                                                                                                                                                                                                                          • 1 Parallel Port Connectors (DB-25) with Cable
                                                                                                                                                                                                                                                                          • 2 Personal Computer with Windows 98 and TurboC Compiler Installed
                                                                                                                                                                                                                                                                          • 3 Following ICs and their Datasheets
                                                                                                                                                                                                                                                                          • 74245 Octal Bus Transceivers with 3-State Outputs
                                                                                                                                                                                                                                                                          • 4 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                                                                            • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                                                                                              • Connecting wires Switches
                                                                                                                                                                                                                                                                                • THEORY
                                                                                                                                                                                                                                                                                • 3-State Logic
                                                                                                                                                                                                                                                                                  • Serial and Parallel Port Connectors
                                                                                                                                                                                                                                                                                  • Parallel Port Connector ndash DB-25
                                                                                                                                                                                                                                                                                    • Accessing parallel port through C Language Programming
                                                                                                                                                                                                                                                                                        • 21-ldst-appendixA
                                                                                                                                                                                                                                                                                        • 22-ldst-appendixB
                                                                                                                                                                                                                                                                                          • DEBOUNCING CIRCUITRY FOR MECHANICAL SWITCHES

                  INTRODUCTION

                  Digital Logic Design is concerned with the interconnection among digital components and modules and the area of Switching Theory that can be identified between circuit design and system formulation Logic design is the base of any computer system as every digital system consists of different ICrsquoS and ICs contain a large number of interconnected digital circuits within a small package MSI devices provide digital function while LSI device cover a complete computer modules These circuitries are widely used in digital system like digital voltmeter frequency meter calculating machines telephone-switching system etc In this Practical Workbook laboratory sessions based on both combinational and sequential logic are covered First laboratory session gives an introduction to the basic logic gates and fundamentals of circuit building The second laboratory session covers a CAD software ndash Electronics Workbench (EWB) EWB is excellent simulation software where circuits can be designed and tested before physical implementation Various laboratory sessions of this workbook provide activities and exercises on EWB Next eight laboratory sessions are based on combinational logic Here various MSI circuits like adders converters multiplexers decoders encoders etc are designed Some of these laboratory sessions also include testing of MSI ICs Next four laboratory sessions help in exploring various designs based on sequential logic Here a variety of circuits are designed form the testing of basic flip-flop ICs to registers and different types of counters Last laboratory session demonstrates how digital hardware can be interfaced with a personal computer via parallel port and can be controlled by software All laboratory sessions of this workbook incorporate brief theoretical backgrounds as details may be covered in the respective theory classes Exercises activities are included with almost all the sessions for the students to practice Two appendices are also included in this workbook The first one provides pin diagrams for all the ICs required for the laboratory work provided in this workbook It will help the students in preparing the pin diagrams for the circuits Second appendix discusses a hardware debouncing circuit for mechanical switches as such switches are extensively used for input purpose in logic circuits

                  9

                  CONTENTS Lab Session No Object Page No

                  1 2 3 4 5 6 7 8 9

                  10

                  11

                  12

                  13

                  14

                  15

                  To study the logic gates in the following TTL ICs

                  7400 Quad 2-input NAND gate 7402 Quad 2-input NOR gate

                  7404 Hex inverter 7408 Quad 2-input AND gate 7432 Quad 2-input OR gate

                  Also implementing and testing the given circuit on a bread board Working with Electronics Workbench Designing Half and Full Adder Circuits Use of Karnaugh Map (SOP-Expression) method Designing a BCD Adder Designing of a 4 x 1 Multiplexer Experimenting with 74150 IC Designing of a 2 x 4 Decoder 1 x 4 Demultiplexer Experimenting with 74138 IC Designing of a 4 x 2 Priority Encoder Experimenting with 74148 IC Designing an Odd Parity Generator and Checker for a 3-bit Data Driving a seven segment display using 7447 7448 driver IC Experimenting with different modes of JK-FF Designing sequential circuit for the given state diagram using D flip-flop Designing a modulus-5 asynchronous up-counter using JK-FF Experimenting with 74194 4-bit bidirectional universal shift register Experimenting with 74245 octal bus transceivers using parallel port PC interfacing Appendix A ndash Pin Diagrams of the ICs required for the laboratory sessions Appendix B ndash Debouncing circuitry for mechanical switches

                  13

                  17

                  19

                  22

                  28

                  30

                  34

                  38

                  42

                  45

                  48

                  50

                  54

                  56

                  59

                  66

                  69

                  11

                  Logic Design amp Switching Theory 1 Lab Session 01 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                  Lab Session 01 OBJECT

                  bull To study the logic gates in the following TTL ICs

                  i) 7400 Quad 2-input NAND gate ii) 7402 Quad 2-input NOR gate iii) 7404 Hex inverter iv) 7408 Quad 2-input AND gate v) 7432 Quad 2-input OR gate

                  bull Implementing and testing the given circuit on a bread board

                  COMPONENTS REQUIRED 1 Bread board 2 5 V - power supply 3 Multimeter 4 Logic probe 5 LEDs with resistors 6 Connecting wires 7 Switches (optional) 8 Following ICs and their datasheets

                  bull 7408 quad 2 input AND gate bull 7432 quad 2 input OR gate bull 7404 hex inverter bull 7400 quad 2 input NAND gate bull 7402 quad 2 input NOR gate

                  THEORY

                  Logic Gates

                  Logic gates are the fundamental building blocks of digital systems These devices are able to make decisions in the sense that they produce one output level when some combinations of input levels are present and a different output when other combinations are applied hence given the name Logic Gates The two levels produced by digital circuitry are referred to variously as HIGH and LOW TRUE and FALSE ON and OFF or simply 1 and 0 There are only three basic gates AND OR and NOT The other gates are merely combinations of these basic gates Logic gates can be interconnected to perform a variety of logical operations This interconnection of gates to achieve prescribed outcomes is called logic design

                  1 The AND Gate ndash An AND gatersquos output is 1 if and only if all its inputs are 1 If A and B are two inputs to an AND gate then output F of the gate is given as F = AB

                  2 The OR Gate - An OR gatersquos output is 1 if at least one of its input is 1 If A and B are two inputs to an OR gate then output F of the gate is given as F = A+B

                  13

                  Logic Design amp Switching Theory 1 Lab Session 01 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering 3 The NOT Gate (Inverter) ndash Its output is 1 when its input is 0 and its output is 0 when

                  the input is 1 ie it complements a digital variable If A is the input to a NOT gate then output F of the gate is given as AF =

                  4 The NAND Gate ndash Its output is 1 if at least one of its input is 0 This gate performs the same logic as an AND gate followed by an inverter If A and B are two inputs to a NAND gate then output F of the gate is given as BAF =

                  5 The NOR Gate - The output of a NOR gate is 1 if and only if all its inputs are 0 This gate performs the same logic function as an OR gate followed by an inverter If A and B are two inputs to a NAND gate then output F of the gate is given as BAF +=

                  All the above gates have one output and two or more inputs except the NOT gate which has only one input

                  PROCEDURE FOR TESTING THE LOGIC GATES IN GIVEN ICs

                  1 Set the power supply to 5V With the help of a multimeter check the voltage at the output knobs of the power supply

                  2 Connect wires long enough to reach the breadboard with the two knobs of the power supply Again using multimeter check voltage at the non-connected end of the wires

                  3 Insert the 7408 quad 2 input AND gate IC on to the bread board and make supply and ground connections by joining 5V wire to pin 14 and 0V wire to pin 7

                  4 Consult ICrsquos internal connection diagram for input and output pins of the first AND gate Connect input pins to logic 0 (0V) and observe the output using LED or logic probe You can also connect switches at the input lines to facilitate toggling between 1 and 0

                  5 Try different combinations of logic levels at the two inputs Again observe the output 6 Repeat the last two steps for all other gates of the same IC Record the observations 7 Repeat this procedure for all other ICs

                  OBSERVATIONS

                  Gate Input A Input B Expected Output Observed Output

                  AND

                  0 0 0 1 1 0 1 1

                  OR

                  0 0 0 1 1 0 1 1

                  NOT 0 - 1 -

                  NAND

                  0 0 0 1 1 0 1 1

                  14

                  Logic Design amp Switching Theory 1 Lab Session 01 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                  NOR

                  0 0 0 1 1 0 1 1

                  DATA SHEETS

                  Figure 11

                  15

                  Logic Design amp Switching Theory 1 Lab Session 01 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                  16

                  GIVEN CIRCUIT

                  Figure 12

                  PROCEDURE FOR IMPLEMENTATION OF THE GIVEN CIRCUIT 1 Set the power supply 2 Insert ICs on the bread board and make their supply and ground connections 3 As given in the logic diagram make connections using wires and gates in the ICs 4 Apply different combinations at the three inputs and observe the output OBSERVATIONS Logic expression for the given logic diagram __________________________________

                  A B C Expected Output Observed Output 0 0 0 0 0 1 0 1 0 0 1 1 1 0 0 1 0 1 1 1 0 1 1 1

                  Logic Design amp Switching Theory 1 Lab Session 02 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                  Lab Session 02

                  OBJECT

                  Working with Electronics Workbench

                  ELECTRONICS WORKBENCH - EWB Electronics Workbench is a computer aided design tool that provides you with all the components and instruments necessary to create board-level designs It has complete mixed analog and digital simulation and graphical waveform analysis allowing you to design your circuit and then analyze it using different simulated instruments and analysis options It is fully integrated and interactive thus you can change your circuits quickly allowing fast and repeated what-if analysis Electronics Workbench provides the following kind of components bull Sources parts bin (AC voltage source Vcc source ground battery etc) bull Basic parts bin (resistors capacitors transformers switches etc) bull Diodes parts bin bull Transistors parts bin bull Analog ICs parts bin (op-amps etc) bull Mixed ICs parts bin (ADCs DACs 555 timers etc) bull Digital ICs parts bin (AND OR adders multiplexers etc) bull Indicators parts bin (voltmeter ammeter probe displays etc) bull Controls parts bin (voltage differentiator multiplier etc) bull Instruments parts bin (multimeter oscilloscope function generator etc) bull Miscellaneous parts bin (write data textbox etc)

                  o Write data This component allows you to save simulation results as an ASCII file o Text Box Use this to add descriptive text anywhere in a circuit

                  ACTIVITY

                  Design circuit for the logic expression )( CBDCABAF ++=

                  Procedure 1 From Logic Gates Parts Bin Drag and drop the required logic gates on the design

                  area Use Component Properties dialog box to customize these gates 2 Connect the terminal of these gates according to the given expression Use additional

                  connectors form the Basic Parts Bin if you want to connect more than wire at a single node

                  3 Drag and drop a probe from Indicators Parts Bin Use Component Properties dialog box to customize the color and other properties of the probe Connect this probe at the output terminal of the circuit to indicate results

                  4 Select four switches form Basic Parts Bin Specify the key that controls the switch by typing its name in the Value tab of the Component Properties dialog box For

                  17

                  Logic Design amp Switching Theory 1 Lab Session 02 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                  18

                  example if you want the switch to close or open when digit lsquo1rsquo is pressed type 1 in the Value tab then click OK Assign different keys to all the switches

                  5 Connect the output terminals of these switches to each of the four inputs A B C and D of the circuit

                  6 Drag and drop Vcc and Ground form the Sources Parts Bin 7 Connect Vcc terminal to one end and Ground terminal to the other end of all the

                  switches 8 Label the circuit properly using text boxes found in the miscellaneous parts bin 9 Run the circuit using the Activate Simulation switch Use the keys you have assigned

                  to the switches to toggle them between Vcc and Ground connections thus providing 1 or 0 respectively to the inputs Record the results as indicated by the probe for all possible combinations of 1s and 0s at the inputs

                  EWB Circuit

                  Figure 21

                  Observations

                  A B C D Expected Output Observed Output 0 0 0 0 0 0 0 1 0 0 1 0 0 0 1 1 0 1 0 0 0 1 0 1 0 1 1 0 0 1 1 1 1 0 0 0 1 0 0 1 1 0 1 0 1 0 1 1 1 1 0 0 1 1 0 1 1 1 1 0 1 1 1 1

                  Logic Design amp Switching Theory 1 Lab Session 03 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                  Lab Session 03

                  OBJECT

                  Designing Half and Full Adder Circuits COMPONENTS AND APPARATUS REQUIRED 1 Following ICs and their Datasheets

                  bull 7408 Quad 2-input AND Gate bull 7432 Quad 2-input OR Gate bull 7486 Quad 2-input XOR Gate

                  2 Digital Trainer DT-01 or the following components Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches

                  THEORY Half Adder A combination circuit that performs the addition of two bits without accounting for the previous carry is called half adder It needs two binary inputs and two binary outputs The input variables designate the augend and addend bits The output variables produce the sum and carry The simplified sum of product expressions for a half adder are

                  yxyxyxS oplus=+= yxC =

                  Figure 31 Circuit diagram for Half Adder

                  19

                  Logic Design amp Switching Theory 1 Lab Session 03 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                  bles produce the sum and carry The simplified sum of product expressions for a half adder are

                  Full Adder

                  A combinational circuit that performs the addition of three input bits It consist of three inputs and two outputs Two of the input variables represent the two significant bits to be added The third input represents the carry from the previous lower significant position The output varia

                  zyxzyxzyxzyxzyxS oplusoplus=+++= yxzyxzyzxxyC )( +oplus=++=

                  Figure 32 Circuit diagram for Full Adder

                  efer to laboratory session 01 for procedure) and record the observations in the following ta

                  alf Adde ull Adder Inputs u

                  IMPLEMENTATION AND OBSERVATIONS

                  Implement the half adder and full adder circuits on a bread board (prepare the pin diagram (use appendix A) and r

                  bles H r F

                  Inputs Outputs Outp ts x y Carry Su Carry Sum m x y z 0 0 0 0 0 0 1 0 0 1 1 0 0 1 0 1 1 0 1 1 1 0 0 1 0 1 1 1 0 1 1 1

                  20

                  Logic Design amp Switching Theory 1 Lab Session 03 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                  at of your designed circuit Attach hardcopy of the output form electronic workbench

                  at of your designed circuit Attach hardcopy of the output form lectronic workbench here

                  ACTIVITY

                  1 Simulate half adder circuit using Electronics Workbench Compare the results of simulation with thhere

                  2 Design a full subtractor circuit and simulate it using Electronics Workbench Compare the results of simulation with the

                  21

                  Logic Design amp Switching Theory 1 Lab Session 04 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                  Lab Session 04 OBJECT

                  Use of Karnaugh Map (SOP-Expression) method GIVEN LOGIC EXPRESSION

                  F (A B C D) = sum ( 0 1 2 4 5 6 8 9 12 13 14 ) COMPONENTS AND APPARATUS REQUIRED 1 Digital ICs and their Datasheets

                  bull 7408 Quad 2-input AND Gate bull 7432 Quad 2-input OR Gate bull 7404 Hex Inverter

                  2 Digital Trainer DT-01 or the following components Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches PROCEDURE 1 Use Karnaugh map to reduce the given function 2 Draw the circuit diagram for the obtained reduced function 3 Implement the reduced circuit using digital ICs on a bread board (prepare the pin

                  diagram (use appendix A) and refer to laboratory session 01 for procedure) and record the observations

                  REDUCTION OF LOGIC EXPRESSION USING KARNAUGH MAP F

                  CD

                  AB DC

                  DC DC

                  DC

                  BA0 1 3 2

                  BA4 5 7 6

                  BA12 13 15 14

                  BA8 9 11 10

                  Reduced form of the given logic expression is __________________________________

                  22

                  Logic Design amp Switching Theory 1 Lab Session 04 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                  LOGIC DIAGRAM (REDUCED FORM) OBSERVATIONS

                  A B C D Output 0 0 0 0 0 0 0 1 0 0 1 0 0 0 1 1 0 1 0 0 0 1 0 1 0 1 1 0 0 1 1 1 1 0 0 0 1 0 0 1 1 0 1 0 1 0 1 1 1 1 0 0 1 1 0 1 1 1 1 0 1 1 1 1

                  RESULT The reduced form (SOP Expression) of the given logic function is

                  ____________________________________________________________

                  The observation table reflects the given logic function

                  23

                  Logic Design amp Switching Theory 1 Lab Session 04 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                  ACTIVITY 1 Using Electronics Workbench derive a truth table and logic circuit for the following logic expression

                  BAAF +=

                  Procedure 1 From the Instruments Parts Bin drag and drop Logic Converter on the design area 2 Double click the Logic Converter to reveal Logic Converter dialog box This dialog

                  box shows various conversion options between truth table logic expression and logic circuit

                  3 Enter the given logic expression in the edit box found at the end of the dialog box Use lsquo to represent invert of a variable For example A is written as Arsquo

                  4 Click the Boolean Expression to Truth Table button The truth table appears in the logic converters display

                  5 Now click the Boolean Expression to Circuit button This creates the logic circuit for the given expression in the design area Label the diagram if needed

                  Resulting Logic Circuit For the given expression the final circuit will look like

                  Figure 41

                  24

                  Logic Design amp Switching Theory 1 Lab Session 04 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                  ACTIVITY 2

                  Using Electronics Workbench find a simplified logic expression and circuit for the following truth table

                  A B C Output 0 0 0 1 0 0 1 1 0 1 0 0 0 1 1 1 1 0 0 0 1 0 1 0 1 1 0 0 1 1 1 1

                  Procedure 1 Click three input channels from A to H across the top of the logic converter The

                  display area below the terminals fills up with the necessary combinations of ones and zeros to fulfill the input conditions The values in the output column on the right are initially set to 0

                  2 Edit the output column to specify the desired output for each input condition To change an output value select it and type a new value 1 0 or x An x indicates a donrsquot care condition

                  3 To convert this truth table to a Boolean expression click the Truth Table to Boolean Expression button The Boolean expression will be displayed at the bottom of the logic converter

                  4 Simplify the expression by clicking the Simplify button 5 Now click the Boolean Expression to Circuit button This creates the logic circuit for

                  the given expression in the design area Resulting Logic Circuit For the given truth table the final simplified circuit will look like

                  Figure 42

                  25

                  Logic Design amp Switching Theory 1 Lab Session 04 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                  ACTIVITY 3

                  Using Electronics Workbench find the logic expression and truth table for the following logic circuit

                  Figure 43

                  Procedure 1 Attach the input terminals of the logic converter to up to four input points in the

                  circuit 2 Connect the single output of the circuit to the output terminal on the logic converter

                  icon 3 Click the Circuit to Truth Table button The truth table appears in the logic

                  converters display 4 To convert this truth table to a Boolean expression click the Truth Table to Boolean

                  Expression button The Boolean expression will be displayed at the bottom of the logic converter

                  Resulting Logic Expression Logic Expression for the given circuit is found to be _____________________________

                  26

                  Logic Design amp Switching Theory 1 Lab Session 04 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                  27

                  For activities 1 2 and 3 attach hardcopy of the output (truth table logic expression and logic circuit) form electronic workbench here

                  Logic Design amp Switching Theory 1 Lab Session 05 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                  Lab Session 05 Lab Session 05 OBJECT OBJECT

                  Designing a BCD Adder Designing a BCD Adder COMPONENTS AND APPARATUS REQUIRED COMPONENTS AND APPARATUS REQUIRED

                  1 Following ICs and their Datasheets 1 Following ICs and their Datasheets bull 7408 Quad 2-input AND Gate bull 7408 Quad 2-input AND Gate bull 7432 Quad 2-input OR Gate bull 7432 Quad 2-input OR Gate bull 7483 4-bit Binary Adder bull 7483 4-bit Binary Adder

                  2 Digital Trainer DT-01 or the following components 2 Digital Trainer DT-01 or the following components Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors (100 Ω) Connecting wires Switches (100 Ω) Connecting wires Switches

                  THEORY THEORY

                  A BCD Adder is a combinational circuit that adds two BCD digits in parallel and produces a sum digit also in BCD A BCD Adder is a combinational circuit that adds two BCD digits in parallel and produces a sum digit also in BCD

                  A4 A3 A2 A1 B4 B3 B2 B1

                  7483-BCD ADDER

                  Cout (C4 ) Z4 Z3 Z2 Z1 Cin(C0)

                  A4 A3 A2 A1 B4 B3 B2 B1

                  7483-BCD ADDER

                  Cout

                  (C4 ) Z4 Z3 Z2 Z1 Cin(C0)

                  Figure 51 BCD Adder Circuit

                  28

                  Logic Design amp Switching Theory 1 Lab Session 05 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                  29

                  A BCD adder must include the correction logic in its internal construction The two BCD digits together with the input carry are first added using a 4-bit binary adder to produce the binary sum If no output carry is generated and the binary sum is less than or equal to 9 then the corresponding BCD sum is identical and therefore no conversion is needed When the output carry is equal to 1 or the binary sum is greater than 9 then a binary 0110 is added to the binary sum through another 4-bit binary adder If Cout is the carry output and Z4Z3Z2Z1 is the binary sum form the first 4-bit binary adder then the following equation indicates the condition when a binary 0110 is to be added

                  C = COUT + Z4Z2 + Z4Z3 IMPLEMENTATION AND OBSERVATIONS Implement the BCD adder circuit according to figure 51 on a bread board (prepare the pin diagram (use appendix A) and refer to laboratory session 01 for procedure) A BCD adder has nine input bits (two BCD digits and a carry bit) which can result in a total of 512 combinations of which 312 inputs are donrsquot care Since it is a very lengthy procedure to record results for 200 valid input combinations therefore for simplicity just record results for any eight combinations in the following table

                  Input Carry

                  BCD Digit 1 BCD Digit 2 Carry Output

                  BCD Sum A4 A3 A2 A1 B4 B3 B2 B1 Z4 Z3 Z2 Z1

                  Logic Design amp Switching Theory 1 lab Session 06 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                  Lab Session 06

                  OBJECT

                  bull Designing of a 4 x 1 Multiplexer bull Experimenting with 74150 IC

                  COMPONENTS AND APPARATUS REQUIRED 1 Following ICs and their Datasheets

                  bull 7408 Quad 2-input AND Gates or 7411 Triple 3-input AND Gates bull 7432 Quad 2-input OR Gates bull 7404 Hex Inverter bull 74150 16 x 1 MUX

                  2 Digital Trainer DT-01 or the following components Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches THEORY

                  Multiplexers A digital data Multiplexer (MUX) is a combinational circuit having several data inputs and a single output A set of data-select inputs is used to control which of the data inputs is routed to the single output A multiplexer is also called a data selector because of this ability to select which data input is connected o the output Normally there are 2n input lines and n selection lines whose bit combination determine which input is selected DESIGN OF A 4 x 1 MULTIPLEXER A 4 x 1 multiplexer is capable of selecting one of four data inputs (see figure 61) The 2-bit binary number at the data select inputs S1 and S0 specifies which of the four data inputs is to be routed to the output Since there are two data select inputs therefore they can select 22 = 4 different data inputs lines

                  S0 S1 D0 D1

                  D2 D3

                  Data-select Inputs Output

                  Data Inputs

                  Figure 61 Block Diagram of a 4 x1 Multiplexer

                  30

                  Logic Design amp Switching Theory 1 lab Session 06 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                  Figure 62 Circuit Diagram for 4 x 1 Multiplexer

                  Implementation and Observations

                  Implement the 4 x 1 Multiplexer circuit (figure 62) on a bread board (prepare the pin diagram (use appendix A) and refer to laboratory session 01 for implementation procedure) and record the observations in the following table For each data select combination specify the switch number as well as the binary value present on that selected switch

                  S1 S0 Output 0 0 0 1 1 0 1 1

                  TESTING OF 74150 - 16 x 1 MUX

                  The 74150 IC has sixteen data inputs and four data-selection lines Function of various pins of this IC is described below

                  bull E0 through E15 Data input lines

                  31

                  Logic Design amp Switching Theory 1 lab Session 06 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering bull A B C D Data select lines with D being the MSB bull W Active low output line bull Grsquo Active low enable line bull VCC and GND Supply connections lines

                  Circuit Diagram

                  Figure 63 Pin connections of 74150 for selecting E0

                  Testing Procedure

                  bull Make connections as shown in the circuit diagram bull Apply different data (1 or 0) at data inputs that are labeled as E0 to E15 Only

                  connection for E0 is shown is the figure for simplicity bull Select the data input E0 with the help of data selectors A B C and D bull Observe the output which shows the complement of the data from E0 bull Select all the sixteen data inputs one by one and record your observations in the

                  following table

                  32

                  Logic Design amp Switching Theory 1 lab Session 06 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                  33

                  Observations

                  Grsquo D C B A W Grsquo D C B A W 0 0 0 0 0 0 1 0 0 0 0 0 0 0 1 0 1 0 0 1 0 0 0 1 0 0 1 0 1 0 0 0 0 1 1 0 1 0 1 1 0 0 1 0 0 0 1 1 0 0 0 0 1 0 1 0 1 1 0 1 0 0 1 1 0 0 1 1 1 0 0 0 1 1 1 0 1 1 1 1

                  ACTIVITY 1 Consider 4x1 Multiplexer Draw the output wave-form for the following data inputs

                  (E0 E1 E2 E3) and select lines A B (B being the MSB) Output is W

                  E3 E2 E1 E0 A B

                  W

                  2 Using the 4 x 1 MUX designed in this laboratory session implement the following logical function F (A B C) = Σ (0147)

                  Show your working and input connections in the following block diagram according to the circuit you have implemented

                  4 x 1 MUX

                  S0 S1

                  Output D0

                  D1

                  D2

                  D3

                  Logic Design amp Switching Theory 1 Lab Session 07 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                  Lab Session 07

                  OBJECT

                  bull Designing of a 2 x 4 Decoder 1 x 4 Demultiplexer bull Experimenting with 74138 IC

                  COMPONENTS AND APPARATUS REQUIRED 1 Following ICs and their Datasheets

                  bull 7408 Quad 2-input or 7411 Triple 3-input AND Gates bull 7404 Hex Inverter bull 74138 3 x 8 Decoder

                  2 Digital Trainer DT-01 or the following components Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches THEORY

                  Decoder A Decoder is a combinational circuit that converts binary information form n input lines to a maximum of 2n unique output lines In practical applications decoders are often used for selecting one of several devices

                  Demultiplexer A decoder with an enable input can function as a Demultiplexer A Demultiplexer (DMUX) id a circuit that receives information on a single line and transmits this information on one of 2n possible output lines The selection of a specific output line is controlled by the bit values of n selection lines DESIGN OF A 2 x 4 DECODER 1 x 4 DEMULTIPLEXER A 2 x 4 decoder is capable of selecting one of four output lines (see figure 71 (a)) The 2-bit binary number at the data inputs S1 and S0 specifies which of the four data inputs is to be selected If we add an enable pin and use it as an input line then this decoder can be converted to a 1 x 4 Demultiplexer where S1 and S0 will select a line to which data input is to be routed (see figure 71 (b))

                  Select S0 S0 Inputs

                  S1 D0 D1

                  D2

                  D3

                  Enable (a) Block Diagram of a 2 x 4 Decoder

                  Figure 71

                  S1 D0 D1

                  D2

                  D3

                  Inputs

                  Data Input (b) Block Diagram of a 1 x 4 Demulptiplexer

                  34

                  Logic Design amp Switching Theory 1 Lab Session 07 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                  Figure 72 Circuit Diagram for 2 x 4 Decoder 1 x 4 Demultiplexer

                  Implementation and Observations Implement the 2 x 4 Decoder 1 x 4 Demultiplexer circuit (figure 72) on a bread board (prepare the pin diagram (use appendix A) and refer to laboratory session 01 for implementation procedure) and record the observations in the following table

                  Enable Data Input S1 S0 D0 D1 D2 D3

                  0 0 0 0 0 1 0 1 0 0 1 1 1 0 0 1 0 1 1 1 0 1 1 1

                  TESTING OF 74138 3 x 8 Decoder The 74138 IC has three inputs and eight output lines It has three enable inputs and for the IC to function all three inputs need to be enabled Function of various pins of this IC is described below

                  35

                  Logic Design amp Switching Theory 1 Lab Session 07 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                  bull Y0 through Y7 Active low data outputs bull A B C Input select lines with C being the MSB bull G1 Active high enable Input bull G2Arsquo and G2Brsquo Active low enable Inputs bull VCC and GND Supply connections lines Circuit Diagram

                  Figure 73 Pin connections of 74138

                  Testing Procedure

                  bull Make connections as shown in the circuit diagram bull Apply different combinations of 1s and 0s at data inputs bull Observe the output and record your observations in the following table

                  Observations

                  C B A Y0 Y1 Y2 Y3 Y4 Y5 Y6 Y7 0 0 0 0 0 1 0 1 0 0 1 1 1 0 0 1 0 1 1 1 0 1 1 1

                  36

                  Logic Design amp Switching Theory 1 Lab Session 07 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                  37

                  ACTIVITY ACTIVITY 1 What will be the binary values at the outputs Y0 through Y7 of 74138 if 1 What will be the binary values at the outputs Y0 through Y7 of 74138 if

                  bull All three enable pins are connected to ground bull All three enable pins are connected to ground __________________________________________________________________________________________________________________________________________ __________________________________________________________________________________________________________________________________________ _____________________________________________________________________ _____________________________________________________________________

                  bull All three enable pins are connected to VCC bull All three enable pins are connected to VCC _______________________________________________________________________________________________________________________________________________________________________________________________________________

                  _______________________________________________________________________________________________________________________________________________________________________________________________________________

                  2 Show connections for 74138 in order to use it as a 1 x 8 Demultiplexer 2 Show connections for 74138 in order to use it as a 1 x 8 Demultiplexer

                  3 Consider a 2 x 4 Decoder with two enable inputs (one active high - G and one active low ndash Grsquo) Draw the output wave-forms for D0 D1 D2 and D3 if the two select inputs are A and B (B being the MSB) All outputs are active low

                  Grsquo

                  G

                  A B

                  D0 D1 D2

                  D3

                  Logic Design amp Switching Theory 1 Lab Session 08 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                  Lab Session 08 OBJECT

                  bull Designing of a 4 x 2 Priority Encoder bull Experimenting with 74148 IC

                  COMPONENTS AND APPARATUS REQUIRED

                  1 Following ICs and their Datasheets

                  bull 7408 Quad 2-input or 7421 Dual 4-input AND Gates bull 7432 Quad 2-input OR Gates bull 7404 Hex Inverter bull 74148 Encoder

                  2 Digital Trainer DT-01 or the following components Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches

                  THEORY

                  Encoder An Encoder is a digital function that produces a reverse operation from that of a decoder An Encoder has 2n (or less) input lines and n output lines The output lines generate the binary code for the 2n input variables Priority Encoder

                  A simple encoder may produce an erroneous output if more than one of its inputs is high A Priority Encoder is one that responds to just one input among those that may be simultaneously high in accordance with some priority system The most common priority system is based on the relative magnitudes of the inputs whichever decimal input is largest is the one that is encoded

                  DESIGN OF A 4 x 2 Priority Encoder

                  The following equations represent the outputs of a 4 x 2 priority encoder 32 DDA +=

                  321 DDDB += As can be seen from the equations that input D0 which has a binary code 00 is not used in any equation A binary code 00 at the output indicates two conditions Either D0 is selected or no input is selected In order to differentiate these two conditions we will provide an additional output Z to indicate if at least one of the inputs is a 1 The equation for Z will be

                  4321 DDDDZ = If Z is 0 then the binary code 00 at the output indicates that D0 is selected and if Z is 1 then it indicates that no input line is selected

                  38

                  Logic Design amp Switching Theory 1 Lab Session 08 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                  Figure 81 Circuit Diagram for 4 x 2 Priority Encoder

                  it (figure 81) on a bread board (prepare the to laboratory session 01 for implementation

                  Implementation a Implement the 4 x 2 Priority Encoder circu

                  ram (use appendix A) and refer

                  nd Observations

                  pin diagprocedure) and record the observations in the following table

                  D3 D2 D1 D0 A B 0 0 0 1 0 0 1 x 0 1 x x 1 x x x

                  TESTING OF 74148 8 x 3 Octal Priority Encoder

                  imal digits There are nine of which three represents

                  ing any of the inputs is high

                  then it shows that line 0 is selected and if e inputs selected E0 and GS

                  cannot be in the same state provided that E1 is enabled

                  The 74148 is a priority encoder with active-Low input for dec

                  input) and five output linesinputs lines (including an enablethe binary code for the octal digit Function of various pins of this IC is described below

                  bull 0 through 7 Active low data inputs representing the octal digits A2 A1 A0 Active low output lines representing the binary code bullbull E1 Active low enable Input bull E0 Active low output indicating none of the inputs is high bull GS Active low output indicatbull VCC and GND Supply connections lines Therefore if GS A2 A1 and A0 are all low

                  then it shows that none of thE0 A2 A1 and A0 are all low

                  39

                  Logic Design amp Switching Theory 1 Lab Session 08 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                  Circuit Diagram

                  Figure 82 Pin connections of 74148

                  Testing Procedure bull Make connections as sho

                  binations of 1s and 0s at data inputs d record your observations in the following table

                  GS E0

                  wn in the circuit diagram bull Apply different combull Observe the output an Observations

                  0 1 2 3 4 5 6 7 A2 A1 A0 1 1 1 1 1 1 1 1 x x x x x x x 0 x x x x x x 0 1 x x x x x 0 1 1 x x x x 0 1 1 1 x x x 0 1 1 1 1 x x 0 1 1 1 1 1 x 0 1 1 1 1 1 1 0 1 1 1 1 1 1 1

                  40

                  Logic Design amp Switching Theory 1 Lab Session 08 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                  41

                  CTIVITY

                  Cascade the following two 74148 8 x 3 Priority Encoders to form 16 x 4 Priority

                  A 1

                  Encoder

                  Logic Design amp Switching Theory 1 Lab Session 09 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering `

                  Lab Session 09 OBJECT

                  Designing an Odd Parity Generator and Checker for a 3-bit Data COMPONENTS AND APPARATUS REQUIRED

                  1 Following ICs and their Datasheets

                  bull 7486 Quad 2-input Exclusive-OR Gates bull 7404 Hex Inverter

                  2 Digital Trainer DT-01 or the following components Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches

                  THEORY

                  Parity Generator When binary data is transmitted and processed it is ndash as are all electrical signals ndash susceptible to noise that can either alter or distort its contents 1s may be effectively changed to 0s and 0s to 1s To overcome this problem one or more bits are often added to the data as an aid in detecting errors caused by noise The most common of these is a Parity bit that signifies whether the total number of 1s in a code group is odd or even In an Odd Parity system the parity bit is made 0 or 1 as necessary to make the total number 1s odd (counting the parity bit itself) In an Even Parity system the parity bit is chosen to make the total number of 1s even Table 91 shows how parity bits would be added to BCD code group in both systems

                  Decimal BCD Value Parity Bit ABCD Odd Parity Even Parity

                  0 0000 1 0 1 0001 0 1 2 0010 0 1 3 0011 1 0 4 0100 0 1 5 0101 1 0 6 0110 1 0 7 0111 0 1 8 1000 0 1 9 1001 1 0

                  Table 91 Odd and Even Parity in BCD

                  When digital data is received a parity checking circuit generates an error signal if the total number of 1s is odd in an even parity system or if it is even in an odd parity system Parity check always detects a single error (one bit change from 0 to 1 or 1 to 0) but may not detect

                  42

                  Logic Design amp Switching Theory 1 Lab Session 09 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering ` two or more errors Odd parity is used more often than even parity because even parity does not detect a situation where all 0s are created due to short circuit or other fault condition DESIGN OF A 3-BIT ODD PARITY GENERATOR AND CHECKER Let x y and z be the three bits that constitute the message and are the input to the Odd Parity Generator Circuit Since it is an odd parity system the bit P is generated so as to make the total number of 1s odd (including P) The function P can be expressed as follows P = x oplus y Ο z or P = x Ο y oplus z Since the IC available is 7486 which is quad 2input XOR IC therefore we will convert XNOR also to XOR

                  P = x oplus y Ο z

                  P = ( x oplus y ) Ο z Since for even number of variables ______

                  XOR = XNOR Therefore ___________ _________

                  P = ( x oplus y ) oplus z = x oplus y oplus z This logical expression can be implemented with two XOR gates and an inverter (see figure 91)

                  Figure 91 Circuit Diagram for a 3-bit Parity Generator

                  The 3-bit message and the parity bit are transmitted to their destination where they are applied to a Parity Checker Circuit An error occurs during transmission if the parity of the four bits received is even since the binary information transmitted was originally odd The output C of the parity checker should be a 1 when an error occurs ie when the number of 1s in the four inputs is even Therefore the function C can be expressed as

                  C = x Ο y Ο z Ο P

                  Using the same logic applied for the conversion of the equation of P

                  PzyxC oplusoplusoplus= This logical expression can be implemented with three XOR gates and an inverter (see figure 92)

                  43

                  Logic Design amp Switching Theory 1 Lab Session 09 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering `

                  44

                  Figure 92 Circuit Diagram for a 3-bit Parity Checker Implementation and Observations Implement the 3-bit Parity Generator and Checker circuits (figure 91 and 92) on a bread board (prepare the pin diagram (use appendix A) and refer to laboratory session 01 for implementation procedure) and record the observations in the following table

                  x y z P x y z P C x y z P C 0 0 0 0 0 0 0 1 0 0 0 0 0 1 0 0 0 1 1 0 0 1 0 1 0 0 0 1 0 1 0 1 0 0 1 1 0 0 1 1 1 0 1 1 1 0 0 0 1 0 0 1 1 0 0 1 0 1 0 1 0 1 1 1 0 1 1 1 0 0 1 1 0 1 1 1 0 1 1 1 0 1 1 1 1 1 1 1

                  Odd Parity Generation Odd Parity Check ACTIVITY 1 Try using the parity checker of figure 92 as 3-bit parity generator Write the details here

                  _____________________________________________________________________________________________________________________________________________________________________________________________________________________ ______________________________________________________________________________________________________________________________________________ _______________________________________________________________________ ______________________________________________________________________________________________________________________________________________

                  Logic Design amp Switching Theory 1 Lab Session 10 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                  Lab Session 10 OBJECT

                  Driving a seven segment display using 7447 7448 driver IC COMPONENTS AND APPARATUS REQUIRED

                  1 Following ICs and their Datasheets

                  bull Seven Segment Displays (Common Anode Common Cathode) bull 7447 7448 BCD to Seven Segment Driver

                  2 Digital Trainer DT-01 or the following components Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches

                  THEORY Seven Segment Displays A Seven Segment Display consists of seven light-emitting segments The segments are designated by letters a through g (see figure 101) By illuminating various combinations of segments the numerals 0 through 9 can be displayed Seven Segment Displays are commonly constructed with light-emitting diodes (LEDs) and with liquid-crystal displays (LCDs) LEDs generally provide greater illumination levels but require much greater power than LCDs An LED display can be a common-anode type or common cathode type In common anode type a high voltage is applied at the common terminal of the display and low voltage is applied at a segmentrsquos terminal for illumination In the common-cathode type a low voltage is applied at the common terminal of the display and high voltage is applied at a segmentrsquos terminal for illumination

                  Figure 101 Seven Segment Display

                  a f b g

                  e c d

                  7447 7448 BCD to Seven Segment Driver 7447 7448 IC is particularly used to drive Seven Segment Its input is a BCD number and output drives a seven segment display 7447 is used to drive common-anode displays whereas 7448 is used to drive common cathode displays 7447 7448 is a 16 pin IC Function of various pins of these ICs is described below

                  bull A B C D Inputs representing BCD digits (D being the MSB)

                  45

                  Logic Design amp Switching Theory 1 Lab Session 10 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering bull OA through OG Outputs to drive segments a through g of the display (Active low

                  in 7447 and active high in 7448) bull RBI Ripple Blanking Input Turns off all the segments if kept low provided that LT

                  is kept high and all other inputs (A B C D BI) are kept low Should be kept high otherwise

                  bull BI RBO Wire-AND logic serving as a Blanking Input and or Ripple Blanking Output

                  o BI Turns off all the segments if low o RBO Goes to a low level (response condition) along with other outputs when

                  RBI and inputs A B C and D are low with LT input at high level bull LT Lamp Test input Tests whether all segments are working or not Illuminates all

                  segments if kept low provided that BI is kept high Should be kept high otherwise bull VCC and GND Supply connections lines CIRCUIT DIAGRAM

                  Figure 102 Circuit diagram for 7447driving a common-anode display

                  IMPLEMENTATION AND OBSERVATIONS

                  bull Make connections as shown in the circuit diagram (refer to laboratory session 01 for implementation procedure)

                  bull Apply different combinations of 1s and 0s at data inputs bull Observe the output and record your observations in the following table

                  46

                  Logic Design amp Switching Theory 1 Lab Session 10 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                  47

                  Decimal Digit

                  BCD Inputs Seven Segment Outputs D C B A a b c d e f g

                  0 0 0 0 0 1 0 0 0 1 2 0 0 1 0 3 0 0 1 1 4 0 1 0 0 5 0 1 0 1 6 0 1 1 0 7 0 1 1 1 8 1 0 0 0 9 1 0 0 1

                  ACTIVITY 1 Perform the Lamp Test for the designed circuit and write your observations

                  ____________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________

                  2 How can you use 7447 IC to drive a common-cathode display

                  ____________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________

                  3 What symbols appear in the seven segment display if inputs DCBA are

                  DCBA Symbol

                  1010

                  1011

                  1100

                  1101

                  1110

                  1111

                  Logic Design amp Switching Theory 1 Lab Session 11 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                  48

                  Lab Session 11 OBJECT

                  Testing different modes of JK-FF COMPONENTS AND APPARATUS REQUIRED 1 Following ICs and their Datasheets

                  bull 7473 7476 JK Flip-Flop 2 Digital Trainer DT-01 or the following components

                  Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches

                  THEORY

                  Flip-Flop A flip-flop circuit can maintain a binary state indefinitely (as long as the power is delivered to the circuit) until directed by an input signal to switch states The major differences among various types of flip-flops are in the number of inputs they possess and in the manner in which the inputs affect the binary state

                  JK Flip-Flop JK flip flop is an edge triggered device A typical JK flip flop has three inputs J K and a clock input The flip-flop can be either positive or negative edge triggered The output Q is available in complemented form as well Beside the usual inputs and output most of the flip-flop IC also possess two asynchronous inputs namely Preset and Clear These inputs are usually active low If used Preset and Clear inputs keep the flip-flop in set and reset state respectively irrespective of the other inputs Both of these inputs cannot be used simultaneously otherwise they will bring the flip-flop in unstable state

                  Figure 111 Symbol for JK flip-flop

                  (a) positive-edge triggering (b) active low Preset (PR) and Clear (CLR) with positive-edge triggering

                  (c) active low Preset (PR) and Clear (CLR) with negative-edge triggering

                  Logic Design amp Switching Theory 1 Lab Session 11 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                  49

                  TESTING OF 7473 7476 DUAL JK FLIP-FLOP

                  Both the ICs 7473 and 7476 are similar in functionality except for one difference The flip-flops in 7473 have only one type of active low asynchronous input which is the Clear input whereas the flip-flops in 7476 have both Preset and Clear inputs Both these ICs have negative edge triggered flip-flops

                  Circuit Diagram

                  Figure 112 Pin connections of 7476

                  Testing Procedure

                  bull Make connections as shown in the circuit diagram (figure 112) bull Apply different combinations of 1s and 0s at J and K inputs bull Observe the output and record your observations in the following table

                  Observations

                  J

                  K Q

                  0 0 0 1 1 0 1 1

                  ACTIVITY

                  1 Observe the output Q of JK flip-flop if the clock input is connected to VCC or GND instead of a clock source Write your observations here __________________________________________________________________________________________________________________________________________ _______________________________________________________________________________________________________________________________________________________________________________________________________________

                  Logic Design amp Switching Theory 1 Lab Session 12 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                  50

                  Lab Session 12 OBJECT

                  Designing sequential circuit for the given state diagram using D flip-flop GIVEN STATE DIAGRAM

                  00

                  11

                  Figure 121 State Diagram COMPONENTS AND APPARATUS REQUIRED 1 Following ICs and their Datasheets

                  bull 7474 D Flip-Flop bull ICs of basic gates (AND OR NOT XOR etc) as required

                  2 Digital Trainer DT-01 or the following components Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches

                  THEORY

                  Sequential Circuits In Sequential Circuits the output not only depends on the present inputs but also on previous states of the circuit These circuits use memory elements (latches flip-flops) and the binary information stored in the memory elements at any given time defines the state of the sequential circuit Analysis of a Sequential Circuit The behavior of a sequential circuit is determined from the inputs the outputs and the states of its flip-flops Both the outputs and next state are a function of the inputs and the

                  10

                  01

                  00 11 10

                  00

                  00 11 10 00

                  Logic Design amp Switching Theory 1 Lab Session 12 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                  51

                  present state The analysis of a sequential circuit form a state diagram comprises of the following bull Selecting a particular flip-flop to design the circuit bull Obtaining state table from the state diagram bull Finding input equations for the selected flip-flop bull Finding state equations (not required for the construction of circuit) bull Implementing the circuit using selected flip-flops and their input equations ANALYZING THE GIVEN STATE DIAGRAM D Flip-Flop D flip-flop is also called transparent flip-flop as it simply transfers the input data to the output For our design we require the graphical symbol and excitation table of D flip-flop (see figure 122)

                  Qt Qt+1 T 0 0 0 0 1 1 1 0 0 1 1 1

                  (b) Excitation table of D Flip-Flop

                  (a) Graphical Symbol

                  Figure 122 Characteristic equation of D flip-flop is Q(t+1) = D State Table The given state diagram has four states so we will need two D flip-flops (FF-0 FF-1) Form state table form the given state diagram and record the results in the following table

                  Present State Input Next State Output Input to FF-0 D0

                  Input to FF-1 D1 Q1t Q0t x Q1(t+1) Q0(t+1) z

                  Logic Design amp Switching Theory 1 Lab Session 12 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                  52

                  Input Equations Using Karnaugh map the input equations D0 and D1 for the two flip-flops can be found

                  D0 D1 Q0x

                  Q1

                  _ _ Q0x

                  _ Q0x

                  Q0x

                  _ Q0x

                  Q0x

                  Q1

                  _ _ Q0x

                  _ Q0x

                  Q0x

                  _ Q0x

                  _ Q1

                  _ Q1

                  Q1

                  Q1

                  D0 = _________________ D1 = _________________

                  State Equations Using the characteristic equation of D flip-flop we can find the state equations Q0(t+1) and Q1(t+1) for the to flip flops Q0(t+1) = _______________________ Q1(t+1) = _______________________ _______________________ _______________________ _______________________ _______________________ Circuit Diagram

                  Logic Design amp Switching Theory 1 Lab Session 12 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                  53

                  Implementation Procedure and Observations

                  1 Implement the circuit using digital ICs on a bread board (prepare the pin diagram (use appendix A) and refer to laboratory session 01 for procedure)

                  2 Make the clear inputs of the flip-flops low (to clear the flip-flops) The flip-flops will remain in clear state as long as the clear inputs are connected to low level

                  3 Connect output Q0 and the clock pulse to an oscilloscope 4 Apply 0 to the input x 5 Now make the clear inputs to high 6 Observe the waveform for the first 5 clock pulses and record it 7 Repeat steps 2 to 6 keeping x=1 in step 4 this time 8 Repeat steps 2 to 7 this time connecting Q1 instead of Q0 to the oscilloscope in step

                  3 Record your observations (Keep frequency of the clock pulse low (eg1Hz) so that the output waveforms can be observed easily)

                  1 2 3 4 5 Clock Pulse

                  Output Waveform for Q0 when x=0

                  Output Waveform for Q0 when x=1

                  Output Waveform for Q1 when x=0

                  Output Waveform for Q1 when x=1

                  Logic Design amp Switching Theory 1 Lab Session 13 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                  Lab Session 13 OBJECT

                  Designing a modulo-5 asynchronous up-counter using JK-FF COMPONENTS AND APPARATUS REQUIRED

                  1 Following ICs and their Datasheets

                  bull 7400 Quad 2-input or 7410 Triple 3-input NAND Gates bull 7476 7473 JK Flip-Flop

                  2 Digital Trainer DT-01 or the following components Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches

                  THEORY

                  Digital Counters A digital counter is a set of flip-flops whose states change in response to pulses applied at the input to the counter The flip-flops are interconnected so that their combined state at any time is the binary equivalent of the total number of pulses that have occurred up to that time Every counter resets after a certain number of clock pulses Thus as it name implies a counter is used to count pulses An n stage counter can count up to a maximum of 2n states n is equal to the number of flip-flops required for the construction of counter

                  Modulus Counters The number of input pulses that causes a counter to reset to its initial count is called the modulus of the counter Thus the modulus equals to total number of distinct states (counts) including zero that a counter can store A binary counter with n stages is a modulo-2n (or mod-2n) counter The largest count a mod-N counter can achieve is N-1 ie a mod-N counter never reaches the binary number equal to its modulus N is always equal to or less than 2n Counters can be classified as bull Synchronous Counters which are clock driven All the flip-flops are driven by a

                  single clock bull Asynchronous Counters which are event driven Clock input is given to the first

                  flip-flop only Rest of the flip-flops are driven by their preceding flip-flops

                  DESIGN OF A MOD-5 ASYNCHRONOUS UP COUNTER The number of flip-flops required to construct a mod-5 counter is 3 because 5 should be less than or equal to 2n This counter will count from 0 to 4 a total of 5 distinct states Since a 3-stage counter can count up to 8 states at maximum a NAND gate is used to reset it after 5 clock pulses Figure 131 shows the logic diagram

                  54

                  Logic Design amp Switching Theory 1 Lab Session 13 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                  55

                  Figure 131 A Mod-5 Asynchronous Up Counter

                  Implementation and Observations

                  Implement the mod-5 counter circuit (figure 131) on a bread board (prepare the pin diagram (use appendix A) and refer to laboratory session 01 for implementation procedure) and record the observations in the following table

                  Clock Pulse Q2 Q1 Q0

                  0 1 2 3 4 5 6 7

                  ACTIVITY

                  Draw the timing diagram for mod-5 counter designed in this laboratory session

                  Logic Design amp Switching Theory 1 Lab Session 14 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                  Lab Session 14 OBJECT

                  Experimenting with 74194 4-bit bidirectional universal shift register COMPONENTS AND APPARATUS REQUIRED

                  1 Following ICs and their Datasheets

                  bull 74194 4-bit bidirectional universal shift register 2 Digital Trainer DT-01 or the following components

                  Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches

                  THEORY

                  Shift Registers

                  A Register is a set of flip-flops used to store binary data A register which is capable of shifting its binary information either to the right or left is called a shift register The logical configuration of a register consists of a chain of flip-flops connected in cascade with the output of one flip-flop connected to the input of next flip-flop All flip-flops receive a common clock pulse which causes the shift from one stage to the next

                  Bidirectional Shift Registers A bi-directional shift register is one whose bits can be shifted from left to right or from right to left

                  Universal Shift Registers A universal shift register is a bi-directional register whose input can be in either serial or parallel form and whose output can be in either serial or parallel form

                  74194 4-BIT BIDIRECTIONAL UNIVERSAL SHIFT REGISTER

                  The 74194 register provides parallel as well as serial loading in both directions Function of various pins of this IC is described below

                  bull A B C and D Active high inputs for parallel loading bull QA QB QC and QD Active high outputs bull S0 and S1 Active high mode control inputs The following table shows combinations

                  of S1 and S0 to enable various modes

                  S1 S0 Clock Action 0 0 x No change 0 1 uarr Shift right 1 0 uarr Shift left 1 1 uarr Parallel load

                  uarr shows the rising edge of the clock pulse

                  56

                  Logic Design amp Switching Theory 1 Lab Session 14 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering bull SR Active high serial input for right shifting bull SL Active high serial input for left shifting bull CLR Active low input Clears all the flip-flops of the register if set to 0 should be

                  kept high otherwise bull CLK Clock input bull VCC and GND Supply connections lines Thus A B C and D are inputs for parallel loading whereas SR and SL are inputs for serial loading with right or left shifting respectively S1 and S0 are used to select the loading mode Circuit Diagram

                  Figure 141 Pin connections of 74194 Testing Procedure

                  bull Make connections as shown in the circuit diagram bull Observe the output for the input combinations given in the following table

                  57

                  Logic Design amp Switching Theory 1 Lab Session 14 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                  58

                  Observations

                  S1 S0 SL SR A B C D QA QB QC QD 0 0 0 1 0 0 0 0 0 1 1 0 0 0 0 1 1 0 0 0 0 0 1 0 1 1 0 0 0 0 1 1 0 0 1 1 0 1 0 0 0 1 1 1 0 1 0 1 1 0 1 0 0 1 1 0 1 1 1 0 0 1 1 1 1 1 0 0 1 1 1 1

                  ACTIVITY 1 Show connections of 74194 to convert it into a ring counter with right shifting

                  Logic Design amp Switching Theory 1 Lab Session 15 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                  Lab Session 15

                  OBJECT

                  Experimenting with 74245 octal bus transceivers using parallel port PC interfacing COMPONENTS AND APPARATUS REQUIRED 1 Parallel Port Connectors (DB-25) with Cable 2 Personal Computer with Windows 98 and TurboC Compiler Installed 3 Following ICs and their Datasheets

                  bull 74245 Octal Bus Transceivers with 3-State Outputs 4 Digital Trainer DT-01 or the following components

                  Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches

                  THEORY

                  3-State Logic Sometimes it is necessary to isolate one part of circuit from the other part For this purpose some TTL ICs are designed with 3-state logic Such devices have three possible output states high low and high impedance The device can be put into high impedance state by a control signal applied to an appropriate pin When such a device is in high impedance state there is very high impedance at its output effectively isolating the device from whatever circuitry the output normally drives 74245 Octal Bus Transceivers A bus is any conducting path or set of paths having electrical connections to one or more devices 74245 octal bus transceivers are mainly used to control connectivity between two devices or circuits It also provides direction control for signal flow Function of various pin of this IC is given below

                  bull A1 through A8 Bus A bull B1 through B8 Bus B bull G΄ Active low enable input When high sets all the bus pins to high impedance state bull DIR Direction control for signal flow When set to high logic level transfers bus A

                  data to B bus When set to low logic level transfers bus B data to A bus bull VCC and GND Supply connections lines Serial and Parallel Port Connectors A Parallel Port can consist of only 25 pin port adapter called a DB-25 and a serial port can consist of either a 25 pin port adapter called a DB-25 or 9 pin adapter called a DB-9 port adapter Whether the port is a 9 pin or 25 pin it can accomplish all of the same tasks that serial port communications have been designed for

                  59

                  Logic Design amp Switching Theory 1 Lab Session 15 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                  60

                  Each adapter can be a male type connector with pins or a female type adapter with tiny holes Generally a PRINTER port (called LPT1) on the back of a computer is female type adapter and we need to use MALE DB-25 pin cable on it for PRINTER connection or for parallel LAPLINK cable And a COM port on the back of a computer is male for the serial ports but it may not necessarily be Parallel Port Connector ndash DB-25 The DB-25 connector (named for its B-size D-shaped shell and 25 pins) is practically ubiquitous in the electronics industry The DB-25 connector is used for a variety of purposes Two common applications are RS-232EIA-232 (serial) connections and the parallel printer interface on the IBM PC The DB-25 connector is also used for SCSI connections Normally the parallel port is used for output to a printer or other device It sends data 8-bits or one byte at a time in parallel The other lines available on the DB-25 connector are a combination of status lines control lines and ground lines The status and control lines are used for handshaking commands and feedback when we are talking to a printer

                  Figure 152 DB-25 Female Figure 151 DB-25 Male

                  Figure 153 Pin Layout for DB-25 As can be seen form figure 153 there are four types of pins in this connector

                  bull Data pins (8 pins - D0 to D7) Active high bidirectional lines

                  Logic Design amp Switching Theory 1 Lab Session 15 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering bull Control pins (4 pins - C0 to C3) C0 C1 and C3 are active low whereas C2 is active

                  high These lines also are bidirectional bull Status pins (5 pins ndash S3 to S7) Only S7 is active low rest are active high input lines bull Ground pins (8 pins) Used as a reference signal for the low (below 05 volts) charge

                  Parallel Port Addresses A DB-25 connector at a parallel port has three address one for each kind of pins register data status and control The first or base address generally refers to data register Second address is for status register and the third one is for control register In Windows 98 the base address is usually found to be 278H 378H or 3BCH Now if 378H is the base address then it refers to the data register whereas addresses for status and control register are respectively 379H and 37AH For Windows 98 the base address can be found as follows 1 On your Desktop right-click on My Computer and select Properties 2 Click on the Device Manager tab and find LPT1 under Plug and Play BIOS 3 After selecting LPT1 click the Properties button 4 Next select the Resources tab and the address should then appear next to InputOutput

                  Range Accessing parallel port through C Language Programming There are multiple functions in C Language for accessing external ports The most commonly used are listed below

                  bull unsigned char inportb(int portid) inportb reads a byte from a hardware port

                  bull int inport(int portid) reads a word from a hardware port

                  bull void outportb(int portid unsigned char value) outputs a byte to a hardware port

                  bull void outport(int portid int value) outputs a word to a hardware port

                  portid refers to the port address whereas value refers to the data to be sent TESTING 74245 USING PARALLEL PORT PC INTERFACING At one end the parallel port connector will be connected to the PC via parallel port cable and another connector (to be plugged into the PC parallel port slot) At the other end it will be connected to the buffer IC 74245 Data lines of the connector will be used to transfer 8-bit data between the PC and the buffer Out of the 8-bits of 74245 4-bits will be used to enter data which will be displayed at the monitor through a C language

                  61

                  Logic Design amp Switching Theory 1 Lab Session 15 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering program The remaining 4-bits will receive data from PC as entered by the user via keyboard

                  Circuit Diagram

                  Figure 154 Interface of 74245 to PC via Parallel Port

                  Procedure

                  1 Connect the DB-25 connector to the PC at one end and solder it to the circuit board at the other end

                  2 Connect various pins of the connector and 74245 according to the circuit diagram shown in figure 152

                  3 Using the functions listed in the previous section write a program in C language to operate various pins of the buffer The user interface of the program should provide option to the user whether to send or receive data from the port

                  4 Set DIR switch to 1 5 Try sending some data bits to the port The result should be displayed at the LEDs 6 Set DIR switch to 0 7 Set some binary 4-bit value through the switches Try reading it via parallel port

                  C Language Program

                  A program to access parallel port for data transfers

                  use header file include ltstdiohgt main program void main() define variable

                  62

                  Logic Design amp Switching Theory 1 Lab Session 15 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering unsigned int data=0 char choice while(1) printing option menu clrscr() printf(This program will send or receive a BCD digit from the parallel portn) printf(nPress your choice numbern) printf(n1 Send Data) printf(n2 Receive Data) printf(n3 Exitn) choice = getch() sending entered digit to the port if(choice == 1) input BCD digit printf(nEnter BCD digit to be sent to the port) data = getche() masking the first four bits data = data amp 0x0f sending to the port outportb(0x378data) printf(nThe BCD digit c has been sent to the port data) printing on screen the data received from the port else if(choice == 2) receiving data from the port data = inportb(0x378) masking the last four bits data = data amp 0xf0 shifting first four bits to make them the last four bits datagtgt=4 printf(nThe BCD digit set at the port is c data) exit else if(choice == 3) break key pressed is not in the menu else printf(nEnter valid choice number) printf(nnPress any key to continue) getch()

                  63

                  Logic Design amp Switching Theory 1 Lab Session 15 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                  ACTIVITY 1 In the above circuit DIR and G΄ inputs are hardwired Connect them to status or

                  control pins of the parallel port connector and control their function through your software program Circuit Diagram Program Code ______________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________

                  ___________________________________________________________________________________________________________________________________________________

                  64

                  Logic Design amp Switching Theory 1 Lab Session 15 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                  65

                  _____________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ _____________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ _______________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ _________________________________________________ _________________________________________________

                  Logic Design amp Switching Theory 1 Appendix A NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                  Appendix A

                  PIN DIAGRAMS OF THE ICS REQUIRED FOR THE LABORATORY SESSIONS Consult the TTLIC data book for internal diagrams and electrical characteristics of these ICs 7400 Quad 2-Input NAND 7402 Quad 2-Input NOR

                  7404 Hex Inverter 7408 Quad 2-Input AND

                  7410 Triple 3-Input NAND 7411 Triple 3-Input AND

                  7421 Dual 4-Input AND 7432 Quad 2-Input OR

                  66

                  Logic Design amp Switching Theory 1 Appendix A NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                  BCD-to-Seven Segm 7448 BCD-to-Seven Segment 7447 ent

                  Decoder (15V OC) Decoder (2kΩ pull-up output)

                  7473 Dual JK Flip-Flop 7474 Dual D-Type Flip-Flop

                  7476 Dual JK Flop-Flop -Bit Binary Full Adder 7483 4 with Fast Carry

                  86 Quad 2-Inpu 74138 3-to-8 Line 74 t Exclusive OR Decoder Demultiplexer

                  67

                  Logic Design amp Switching Theory 1 Appendix A NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                  68

                  74148 8-to-3 Line 16-to-1 Line Data

                  Priority Encoder 74150 Selector Multiplexer

                  74245 Oct nsceivers Universal Shift Register (PIPO) (3-State)

                  74194 4-Bit Bidirectional al Bus Tra

                  Logic Design amp Switching Theory 1 Appendix B NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                  Appendix B

                  DEBOUNCING CIRCUITRY FOR MECHANICAL SWITCHES Mechanical switches form the interface between human beings and computers or other digital systems For example a keyboard is a matrix of switches used to supply alphanumeric data to a computer Whatever the switch design it is a potential source of problems due to contact bounce The contact bounce creates a sense of narrow pulses when a switch is opened or closed An example of device whose operation would be adversely affected by contact bounce is a digital counter used to count the number of times a switch is depressed Eliminating the effects of contact bounce is called debouncing When data is entered into a computer via a keyboard a software debounce is often used This type of debouncing is a program that causes the computer to sample the switch terminal (ie to input data from it) many times in succession during the interval of time that contact bounce occurs If the data is sensed to be 1s (or 0s) for a specific number of consecutive samples then it is assumed that contact bounce has ended and the last value sensed is valid Hardware debouncing is the use of electronic circuitry to eliminate the effects of contact bounce There are numerous versions of such circuitry including those that use monostable multivibrators (one-shots) but the most straightforward is simply an RS latch Figure B1 shows the circuit When the switch is in position 1 R = 0 and S = 1 so the latch is set and the output (Q) is 1 When the switch is in position 0 R = 1and S = 0 so the latch is reset and the output is 0 When the switch is moved form one position to the other the latch changes state and bouncing occurs at either the R or the S input The bouncing does not affect the latch after it has change state An RS latch will remain set for example when its R input is 0 and its S input is alternately changed form 1 to 0

                  Figure B1 Use of RS latch to debounce a mechanical switch

                  69

                  • 01-ldst-Outer title
                    • Practical Workbook
                    • Logic Design amp Switching Theory I
                      • Dept of Computer amp Information Systems Engineering
                        • NED University of Engineering amp Technology
                        • Karachi ndash 75270 Pakistan
                          • 02-ldst-inner Title
                            • Practical Workbook
                            • Logic Design amp Switching Theory I
                              • Dept of Computer amp Information Systems Engineering
                                • NED University of Engineering amp Technology
                                • Karachi ndash 75270 Pakistan
                                  • 03-ldst-general info
                                  • 04-ldst-introduction
                                  • 05-Table of Contents
                                    • CONTENTS
                                      • Lab Session No Object Page No
                                      • 1
                                      • Also implementing and testing the given circuit on a bread board
                                        • Working with Electronics Workbench
                                          • Driving a seven segment display using 7447 7448 driver IC
                                            • Designing a modulus-5 asynchronous up-counter using JK-FF
                                              • Experimenting with 74194 4-bit bidirectional universal shift register
                                                  • 13
                                                      • 06-ldst-Exp01
                                                        • Lab Session 01
                                                        • OBJECT
                                                          • 1 Bread board
                                                          • 2 5 V - power supply
                                                          • 3 Multimeter
                                                          • 4 Logic probe
                                                          • 5 LEDs with resistors
                                                          • 6 Connecting wires
                                                          • 8 Following ICs and their datasheets
                                                            • THEORY
                                                              • Logic Gates
                                                              • 1 The AND Gate ndash An AND gatersquos output is 1 if and only if all its inputs are 1 If A and B are two inputs to an AND gate then output F of the gate is given as F = AB
                                                              • 2 The OR Gate - An OR gatersquos output is 1 if at least one of its input is 1 If A and B are two inputs to an OR gate then output F of the gate is given as F = A+B
                                                              • 3 The NOT Gate (Inverter) ndash Its output is 1 when its input is 0 and its output is 0 when the input is 1 ie it complements a digital variable If A is the input to a NOT gate then output F of the gate is given as
                                                              • 4 The NAND Gate ndash Its output is 1 if at least one of its input is 0 This gate performs the same logic as an AND gate followed by an inverter If A and B are two inputs to a NAND gate then output F of the gate is given as
                                                                • 5 The NOR Gate - The output of a NOR gate is 1 if and only if all its inputs are 0 This gate performs the same logic function as an OR gate followed by an inverter If A and B are two inputs to a NAND gate then output F of the gate is given as
                                                                    • DATA SHEETS
                                                                      • Logic expression for the given logic diagram __________________________________
                                                                          • 07-ldst-exp02
                                                                            • Working with Electronics Workbench
                                                                              • 08-ldst-exp03
                                                                                • Designing Half and Full Adder Circuits
                                                                                  • COMPONENTS AND APPARATUS REQUIRED
                                                                                    • 1 Following ICs and their Datasheets
                                                                                    • 7408 Quad 2-input AND Gate
                                                                                    • 2 Digital Trainer DT-01 or the following components
                                                                                      • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                      • Connecting wires Switches
                                                                                        • THEORY
                                                                                            • IMPLEMENTATION AND OBSERVATIONS
                                                                                              • 09-ldst-Exp04
                                                                                                • Lab Session 04
                                                                                                • 1 Digital ICs and their Datasheets
                                                                                                • 7408 Quad 2-input AND Gate
                                                                                                • 2 Digital Trainer DT-01 or the following components
                                                                                                  • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                  • Connecting wires Switches
                                                                                                  • PROCEDURE
                                                                                                  • REDUCTION OF LOGIC EXPRESSION USING KARNAUGH MAP
                                                                                                  • OBSERVATIONS
                                                                                                  • RESULT
                                                                                                      • 10-ldst-Exp05
                                                                                                        • Lab Session 05
                                                                                                        • 1 Following ICs and their Datasheets
                                                                                                        • 7408 Quad 2-input AND Gate
                                                                                                        • 2 Digital Trainer DT-01 or the following components
                                                                                                          • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                          • (100 Ω) Connecting wires Switches
                                                                                                          • THEORY
                                                                                                            • IMPLEMENTATION AND OBSERVATIONS
                                                                                                              • 11-ldst-Exp06
                                                                                                                • OBJECT
                                                                                                                • 1 Following ICs and their Datasheets
                                                                                                                • 7408 Quad 2-input AND Gates or 7411 Triple 3-input AND Gates
                                                                                                                • 2 Digital Trainer DT-01 or the following components
                                                                                                                  • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                  • Connecting wires Switches
                                                                                                                    • Figure 62 Circuit Diagram for 4 x 1 Multiplexer
                                                                                                                    • Implementation and Observations
                                                                                                                      • Circuit Diagram
                                                                                                                        • ACTIVITY
                                                                                                                          • 12-ldst-exp07
                                                                                                                            • 1 Following ICs and their Datasheets
                                                                                                                            • 7408 Quad 2-input or 7411 Triple 3-input AND Gates
                                                                                                                            • 2 Digital Trainer DT-01 or the following components
                                                                                                                              • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                              • Connecting wires Switches
                                                                                                                                • THEORY
                                                                                                                                    • Figure 72 Circuit Diagram for 2 x 4 Decoder 1 x 4 Demultiplexer
                                                                                                                                    • Implementation and Observations
                                                                                                                                      • Circuit Diagram
                                                                                                                                        • ACTIVITY
                                                                                                                                          • 13-ldst-Exp08
                                                                                                                                            • OBJECT
                                                                                                                                            • 1 Following ICs and their Datasheets
                                                                                                                                            • 7408 Quad 2-input or 7421 Dual 4-input AND Gates
                                                                                                                                            • 2 Digital Trainer DT-01 or the following components
                                                                                                                                              • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                              • Connecting wires Switches
                                                                                                                                                • THEORY
                                                                                                                                                    • Figure 81 Circuit Diagram for 4 x 2 Priority Encoder
                                                                                                                                                    • Implementation and Observations
                                                                                                                                                      • Therefore if GS A2 A1 and A0 are all low then it shows that line 0 is selected and if E0 A2 A1 and A0 are all low then it shows that none of the inputs selected E0 and GS cannot be in the same state provided that E1 is enabled
                                                                                                                                                      • Circuit Diagram
                                                                                                                                                        • ACTIVITY
                                                                                                                                                          • 14-ldst-exp09
                                                                                                                                                            • OBJECT
                                                                                                                                                            • 1 Following ICs and their Datasheets
                                                                                                                                                            • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                              • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                              • Connecting wires Switches
                                                                                                                                                                • THEORY
                                                                                                                                                                  • Parity Generator
                                                                                                                                                                    • Let x y and z be the three bits that constitute the message and are the input to the Odd Parity Generator Circuit Since it is an odd parity system the bit P is generated so as to make the total number of 1s odd (including P) The function P can be expressed as follows
                                                                                                                                                                    • Figure 91 Circuit Diagram for a 3-bit Parity Generator
                                                                                                                                                                      • C = x Ο y Ο z Ο P
                                                                                                                                                                        • Implementation and Observations
                                                                                                                                                                          • ACTIVITY
                                                                                                                                                                              • 15-ldst-exp10
                                                                                                                                                                                • Driving a seven segment display using 7447 7448 driver IC
                                                                                                                                                                                • COMPONENTS AND APPARATUS REQUIRED
                                                                                                                                                                                • 1 Following ICs and their Datasheets
                                                                                                                                                                                • 7447 7448 BCD to Seven Segment Driver
                                                                                                                                                                                • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                  • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches
                                                                                                                                                                                    • THEORY
                                                                                                                                                                                    • Seven Segment Displays
                                                                                                                                                                                    • CIRCUIT DIAGRAM
                                                                                                                                                                                    • Figure 102 Circuit diagram for 7447driving a common-anode display
                                                                                                                                                                                        • IMPLEMENTATION AND OBSERVATIONS
                                                                                                                                                                                          • Decimal Digit
                                                                                                                                                                                          • BCD Inputs
                                                                                                                                                                                          • Seven Segment Outputs
                                                                                                                                                                                          • D
                                                                                                                                                                                          • C
                                                                                                                                                                                          • B
                                                                                                                                                                                          • A
                                                                                                                                                                                          • a
                                                                                                                                                                                          • b
                                                                                                                                                                                          • c
                                                                                                                                                                                          • d
                                                                                                                                                                                          • e
                                                                                                                                                                                          • f
                                                                                                                                                                                          • g
                                                                                                                                                                                          • 0
                                                                                                                                                                                          • 0
                                                                                                                                                                                          • 0
                                                                                                                                                                                          • 0
                                                                                                                                                                                          • 0
                                                                                                                                                                                          • 1
                                                                                                                                                                                          • 0
                                                                                                                                                                                          • 0
                                                                                                                                                                                          • 0
                                                                                                                                                                                          • 1
                                                                                                                                                                                          • 2
                                                                                                                                                                                          • 0
                                                                                                                                                                                          • 0
                                                                                                                                                                                          • 1
                                                                                                                                                                                          • 0
                                                                                                                                                                                          • 3
                                                                                                                                                                                          • 0
                                                                                                                                                                                          • 0
                                                                                                                                                                                          • 1
                                                                                                                                                                                          • 1
                                                                                                                                                                                          • 4
                                                                                                                                                                                          • 0
                                                                                                                                                                                          • 1
                                                                                                                                                                                          • 0
                                                                                                                                                                                          • 0
                                                                                                                                                                                          • 5
                                                                                                                                                                                          • 0
                                                                                                                                                                                          • 1
                                                                                                                                                                                          • 0
                                                                                                                                                                                          • 1
                                                                                                                                                                                          • 6
                                                                                                                                                                                          • 0
                                                                                                                                                                                          • 1
                                                                                                                                                                                          • 1
                                                                                                                                                                                          • 0
                                                                                                                                                                                          • 7
                                                                                                                                                                                          • 0
                                                                                                                                                                                          • 1
                                                                                                                                                                                          • 1
                                                                                                                                                                                          • 1
                                                                                                                                                                                          • 8
                                                                                                                                                                                          • 1
                                                                                                                                                                                          • 0
                                                                                                                                                                                          • 0
                                                                                                                                                                                          • 0
                                                                                                                                                                                          • 9
                                                                                                                                                                                          • 1
                                                                                                                                                                                          • 0
                                                                                                                                                                                          • 0
                                                                                                                                                                                          • 1
                                                                                                                                                                                            • ACTIVITY
                                                                                                                                                                                              • 16-ldst-exp11
                                                                                                                                                                                                • Lab Session 11
                                                                                                                                                                                                  • OBJECT
                                                                                                                                                                                                  • COMPONENTS AND APPARATUS REQUIRED
                                                                                                                                                                                                    • 1 Following ICs and their Datasheets
                                                                                                                                                                                                    • 7473 7476 JK Flip-Flop
                                                                                                                                                                                                    • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                      • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                      • Connecting wires Switches
                                                                                                                                                                                                        • THEORY
                                                                                                                                                                                                            • Flip-Flop
                                                                                                                                                                                                            • JK Flip-Flop
                                                                                                                                                                                                              • Circuit Diagram
                                                                                                                                                                                                                • Observations
                                                                                                                                                                                                                  • ACTIVITY
                                                                                                                                                                                                                      • 17-ldst-exp12
                                                                                                                                                                                                                        • Lab Session 12
                                                                                                                                                                                                                          • OBJECT
                                                                                                                                                                                                                          • GIVEN STATE DIAGRAM
                                                                                                                                                                                                                          • Figure 121 State Diagram
                                                                                                                                                                                                                          • COMPONENTS AND APPARATUS REQUIRED
                                                                                                                                                                                                                            • 1 Following ICs and their Datasheets
                                                                                                                                                                                                                            • 7474 D Flip-Flop
                                                                                                                                                                                                                            • ICs of basic gates (AND OR NOT XOR etc) as required
                                                                                                                                                                                                                            • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                              • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                                              • Connecting wires Switches
                                                                                                                                                                                                                                • THEORY
                                                                                                                                                                                                                                    • Sequential Circuits
                                                                                                                                                                                                                                      • 18-ldst-exp13
                                                                                                                                                                                                                                        • Lab Session 13
                                                                                                                                                                                                                                          • Designing a modulo-5 asynchronous up-counter using JK-FF
                                                                                                                                                                                                                                            • 1 Following ICs and their Datasheets
                                                                                                                                                                                                                                            • 7400 Quad 2-input or 7410 Triple 3-input NAND Gates
                                                                                                                                                                                                                                            • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                                              • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                                                              • Connecting wires Switches
                                                                                                                                                                                                                                                • THEORY
                                                                                                                                                                                                                                                    • Figure 131 A Mod-5 Asynchronous Up Counter
                                                                                                                                                                                                                                                    • Implementation and Observations
                                                                                                                                                                                                                                                      • ACTIVITY
                                                                                                                                                                                                                                                          • 19-ldst-exp14
                                                                                                                                                                                                                                                            • Experimenting with 74194 4-bit bidirectional universal shift register
                                                                                                                                                                                                                                                            • 1 Following ICs and their Datasheets
                                                                                                                                                                                                                                                            • 74194 4-bit bidirectional universal shift register
                                                                                                                                                                                                                                                            • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                                                              • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                                                                              • Connecting wires Switches
                                                                                                                                                                                                                                                                • THEORY
                                                                                                                                                                                                                                                                  • Shift Registers
                                                                                                                                                                                                                                                                  • Bidirectional Shift Registers
                                                                                                                                                                                                                                                                  • Universal Shift Registers
                                                                                                                                                                                                                                                                    • S1
                                                                                                                                                                                                                                                                      • Circuit Diagram
                                                                                                                                                                                                                                                                      • ACTIVITY
                                                                                                                                                                                                                                                                          • 20-ldst-exp15
                                                                                                                                                                                                                                                                            • COMPONENTS AND APPARATUS REQUIRED
                                                                                                                                                                                                                                                                            • 1 Parallel Port Connectors (DB-25) with Cable
                                                                                                                                                                                                                                                                            • 2 Personal Computer with Windows 98 and TurboC Compiler Installed
                                                                                                                                                                                                                                                                            • 3 Following ICs and their Datasheets
                                                                                                                                                                                                                                                                            • 74245 Octal Bus Transceivers with 3-State Outputs
                                                                                                                                                                                                                                                                            • 4 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                                                                              • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                                                                                                • Connecting wires Switches
                                                                                                                                                                                                                                                                                  • THEORY
                                                                                                                                                                                                                                                                                  • 3-State Logic
                                                                                                                                                                                                                                                                                    • Serial and Parallel Port Connectors
                                                                                                                                                                                                                                                                                    • Parallel Port Connector ndash DB-25
                                                                                                                                                                                                                                                                                      • Accessing parallel port through C Language Programming
                                                                                                                                                                                                                                                                                          • 21-ldst-appendixA
                                                                                                                                                                                                                                                                                          • 22-ldst-appendixB
                                                                                                                                                                                                                                                                                            • DEBOUNCING CIRCUITRY FOR MECHANICAL SWITCHES

                    CONTENTS Lab Session No Object Page No

                    1 2 3 4 5 6 7 8 9

                    10

                    11

                    12

                    13

                    14

                    15

                    To study the logic gates in the following TTL ICs

                    7400 Quad 2-input NAND gate 7402 Quad 2-input NOR gate

                    7404 Hex inverter 7408 Quad 2-input AND gate 7432 Quad 2-input OR gate

                    Also implementing and testing the given circuit on a bread board Working with Electronics Workbench Designing Half and Full Adder Circuits Use of Karnaugh Map (SOP-Expression) method Designing a BCD Adder Designing of a 4 x 1 Multiplexer Experimenting with 74150 IC Designing of a 2 x 4 Decoder 1 x 4 Demultiplexer Experimenting with 74138 IC Designing of a 4 x 2 Priority Encoder Experimenting with 74148 IC Designing an Odd Parity Generator and Checker for a 3-bit Data Driving a seven segment display using 7447 7448 driver IC Experimenting with different modes of JK-FF Designing sequential circuit for the given state diagram using D flip-flop Designing a modulus-5 asynchronous up-counter using JK-FF Experimenting with 74194 4-bit bidirectional universal shift register Experimenting with 74245 octal bus transceivers using parallel port PC interfacing Appendix A ndash Pin Diagrams of the ICs required for the laboratory sessions Appendix B ndash Debouncing circuitry for mechanical switches

                    13

                    17

                    19

                    22

                    28

                    30

                    34

                    38

                    42

                    45

                    48

                    50

                    54

                    56

                    59

                    66

                    69

                    11

                    Logic Design amp Switching Theory 1 Lab Session 01 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                    Lab Session 01 OBJECT

                    bull To study the logic gates in the following TTL ICs

                    i) 7400 Quad 2-input NAND gate ii) 7402 Quad 2-input NOR gate iii) 7404 Hex inverter iv) 7408 Quad 2-input AND gate v) 7432 Quad 2-input OR gate

                    bull Implementing and testing the given circuit on a bread board

                    COMPONENTS REQUIRED 1 Bread board 2 5 V - power supply 3 Multimeter 4 Logic probe 5 LEDs with resistors 6 Connecting wires 7 Switches (optional) 8 Following ICs and their datasheets

                    bull 7408 quad 2 input AND gate bull 7432 quad 2 input OR gate bull 7404 hex inverter bull 7400 quad 2 input NAND gate bull 7402 quad 2 input NOR gate

                    THEORY

                    Logic Gates

                    Logic gates are the fundamental building blocks of digital systems These devices are able to make decisions in the sense that they produce one output level when some combinations of input levels are present and a different output when other combinations are applied hence given the name Logic Gates The two levels produced by digital circuitry are referred to variously as HIGH and LOW TRUE and FALSE ON and OFF or simply 1 and 0 There are only three basic gates AND OR and NOT The other gates are merely combinations of these basic gates Logic gates can be interconnected to perform a variety of logical operations This interconnection of gates to achieve prescribed outcomes is called logic design

                    1 The AND Gate ndash An AND gatersquos output is 1 if and only if all its inputs are 1 If A and B are two inputs to an AND gate then output F of the gate is given as F = AB

                    2 The OR Gate - An OR gatersquos output is 1 if at least one of its input is 1 If A and B are two inputs to an OR gate then output F of the gate is given as F = A+B

                    13

                    Logic Design amp Switching Theory 1 Lab Session 01 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering 3 The NOT Gate (Inverter) ndash Its output is 1 when its input is 0 and its output is 0 when

                    the input is 1 ie it complements a digital variable If A is the input to a NOT gate then output F of the gate is given as AF =

                    4 The NAND Gate ndash Its output is 1 if at least one of its input is 0 This gate performs the same logic as an AND gate followed by an inverter If A and B are two inputs to a NAND gate then output F of the gate is given as BAF =

                    5 The NOR Gate - The output of a NOR gate is 1 if and only if all its inputs are 0 This gate performs the same logic function as an OR gate followed by an inverter If A and B are two inputs to a NAND gate then output F of the gate is given as BAF +=

                    All the above gates have one output and two or more inputs except the NOT gate which has only one input

                    PROCEDURE FOR TESTING THE LOGIC GATES IN GIVEN ICs

                    1 Set the power supply to 5V With the help of a multimeter check the voltage at the output knobs of the power supply

                    2 Connect wires long enough to reach the breadboard with the two knobs of the power supply Again using multimeter check voltage at the non-connected end of the wires

                    3 Insert the 7408 quad 2 input AND gate IC on to the bread board and make supply and ground connections by joining 5V wire to pin 14 and 0V wire to pin 7

                    4 Consult ICrsquos internal connection diagram for input and output pins of the first AND gate Connect input pins to logic 0 (0V) and observe the output using LED or logic probe You can also connect switches at the input lines to facilitate toggling between 1 and 0

                    5 Try different combinations of logic levels at the two inputs Again observe the output 6 Repeat the last two steps for all other gates of the same IC Record the observations 7 Repeat this procedure for all other ICs

                    OBSERVATIONS

                    Gate Input A Input B Expected Output Observed Output

                    AND

                    0 0 0 1 1 0 1 1

                    OR

                    0 0 0 1 1 0 1 1

                    NOT 0 - 1 -

                    NAND

                    0 0 0 1 1 0 1 1

                    14

                    Logic Design amp Switching Theory 1 Lab Session 01 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                    NOR

                    0 0 0 1 1 0 1 1

                    DATA SHEETS

                    Figure 11

                    15

                    Logic Design amp Switching Theory 1 Lab Session 01 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                    16

                    GIVEN CIRCUIT

                    Figure 12

                    PROCEDURE FOR IMPLEMENTATION OF THE GIVEN CIRCUIT 1 Set the power supply 2 Insert ICs on the bread board and make their supply and ground connections 3 As given in the logic diagram make connections using wires and gates in the ICs 4 Apply different combinations at the three inputs and observe the output OBSERVATIONS Logic expression for the given logic diagram __________________________________

                    A B C Expected Output Observed Output 0 0 0 0 0 1 0 1 0 0 1 1 1 0 0 1 0 1 1 1 0 1 1 1

                    Logic Design amp Switching Theory 1 Lab Session 02 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                    Lab Session 02

                    OBJECT

                    Working with Electronics Workbench

                    ELECTRONICS WORKBENCH - EWB Electronics Workbench is a computer aided design tool that provides you with all the components and instruments necessary to create board-level designs It has complete mixed analog and digital simulation and graphical waveform analysis allowing you to design your circuit and then analyze it using different simulated instruments and analysis options It is fully integrated and interactive thus you can change your circuits quickly allowing fast and repeated what-if analysis Electronics Workbench provides the following kind of components bull Sources parts bin (AC voltage source Vcc source ground battery etc) bull Basic parts bin (resistors capacitors transformers switches etc) bull Diodes parts bin bull Transistors parts bin bull Analog ICs parts bin (op-amps etc) bull Mixed ICs parts bin (ADCs DACs 555 timers etc) bull Digital ICs parts bin (AND OR adders multiplexers etc) bull Indicators parts bin (voltmeter ammeter probe displays etc) bull Controls parts bin (voltage differentiator multiplier etc) bull Instruments parts bin (multimeter oscilloscope function generator etc) bull Miscellaneous parts bin (write data textbox etc)

                    o Write data This component allows you to save simulation results as an ASCII file o Text Box Use this to add descriptive text anywhere in a circuit

                    ACTIVITY

                    Design circuit for the logic expression )( CBDCABAF ++=

                    Procedure 1 From Logic Gates Parts Bin Drag and drop the required logic gates on the design

                    area Use Component Properties dialog box to customize these gates 2 Connect the terminal of these gates according to the given expression Use additional

                    connectors form the Basic Parts Bin if you want to connect more than wire at a single node

                    3 Drag and drop a probe from Indicators Parts Bin Use Component Properties dialog box to customize the color and other properties of the probe Connect this probe at the output terminal of the circuit to indicate results

                    4 Select four switches form Basic Parts Bin Specify the key that controls the switch by typing its name in the Value tab of the Component Properties dialog box For

                    17

                    Logic Design amp Switching Theory 1 Lab Session 02 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                    18

                    example if you want the switch to close or open when digit lsquo1rsquo is pressed type 1 in the Value tab then click OK Assign different keys to all the switches

                    5 Connect the output terminals of these switches to each of the four inputs A B C and D of the circuit

                    6 Drag and drop Vcc and Ground form the Sources Parts Bin 7 Connect Vcc terminal to one end and Ground terminal to the other end of all the

                    switches 8 Label the circuit properly using text boxes found in the miscellaneous parts bin 9 Run the circuit using the Activate Simulation switch Use the keys you have assigned

                    to the switches to toggle them between Vcc and Ground connections thus providing 1 or 0 respectively to the inputs Record the results as indicated by the probe for all possible combinations of 1s and 0s at the inputs

                    EWB Circuit

                    Figure 21

                    Observations

                    A B C D Expected Output Observed Output 0 0 0 0 0 0 0 1 0 0 1 0 0 0 1 1 0 1 0 0 0 1 0 1 0 1 1 0 0 1 1 1 1 0 0 0 1 0 0 1 1 0 1 0 1 0 1 1 1 1 0 0 1 1 0 1 1 1 1 0 1 1 1 1

                    Logic Design amp Switching Theory 1 Lab Session 03 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                    Lab Session 03

                    OBJECT

                    Designing Half and Full Adder Circuits COMPONENTS AND APPARATUS REQUIRED 1 Following ICs and their Datasheets

                    bull 7408 Quad 2-input AND Gate bull 7432 Quad 2-input OR Gate bull 7486 Quad 2-input XOR Gate

                    2 Digital Trainer DT-01 or the following components Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches

                    THEORY Half Adder A combination circuit that performs the addition of two bits without accounting for the previous carry is called half adder It needs two binary inputs and two binary outputs The input variables designate the augend and addend bits The output variables produce the sum and carry The simplified sum of product expressions for a half adder are

                    yxyxyxS oplus=+= yxC =

                    Figure 31 Circuit diagram for Half Adder

                    19

                    Logic Design amp Switching Theory 1 Lab Session 03 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                    bles produce the sum and carry The simplified sum of product expressions for a half adder are

                    Full Adder

                    A combinational circuit that performs the addition of three input bits It consist of three inputs and two outputs Two of the input variables represent the two significant bits to be added The third input represents the carry from the previous lower significant position The output varia

                    zyxzyxzyxzyxzyxS oplusoplus=+++= yxzyxzyzxxyC )( +oplus=++=

                    Figure 32 Circuit diagram for Full Adder

                    efer to laboratory session 01 for procedure) and record the observations in the following ta

                    alf Adde ull Adder Inputs u

                    IMPLEMENTATION AND OBSERVATIONS

                    Implement the half adder and full adder circuits on a bread board (prepare the pin diagram (use appendix A) and r

                    bles H r F

                    Inputs Outputs Outp ts x y Carry Su Carry Sum m x y z 0 0 0 0 0 0 1 0 0 1 1 0 0 1 0 1 1 0 1 1 1 0 0 1 0 1 1 1 0 1 1 1

                    20

                    Logic Design amp Switching Theory 1 Lab Session 03 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                    at of your designed circuit Attach hardcopy of the output form electronic workbench

                    at of your designed circuit Attach hardcopy of the output form lectronic workbench here

                    ACTIVITY

                    1 Simulate half adder circuit using Electronics Workbench Compare the results of simulation with thhere

                    2 Design a full subtractor circuit and simulate it using Electronics Workbench Compare the results of simulation with the

                    21

                    Logic Design amp Switching Theory 1 Lab Session 04 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                    Lab Session 04 OBJECT

                    Use of Karnaugh Map (SOP-Expression) method GIVEN LOGIC EXPRESSION

                    F (A B C D) = sum ( 0 1 2 4 5 6 8 9 12 13 14 ) COMPONENTS AND APPARATUS REQUIRED 1 Digital ICs and their Datasheets

                    bull 7408 Quad 2-input AND Gate bull 7432 Quad 2-input OR Gate bull 7404 Hex Inverter

                    2 Digital Trainer DT-01 or the following components Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches PROCEDURE 1 Use Karnaugh map to reduce the given function 2 Draw the circuit diagram for the obtained reduced function 3 Implement the reduced circuit using digital ICs on a bread board (prepare the pin

                    diagram (use appendix A) and refer to laboratory session 01 for procedure) and record the observations

                    REDUCTION OF LOGIC EXPRESSION USING KARNAUGH MAP F

                    CD

                    AB DC

                    DC DC

                    DC

                    BA0 1 3 2

                    BA4 5 7 6

                    BA12 13 15 14

                    BA8 9 11 10

                    Reduced form of the given logic expression is __________________________________

                    22

                    Logic Design amp Switching Theory 1 Lab Session 04 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                    LOGIC DIAGRAM (REDUCED FORM) OBSERVATIONS

                    A B C D Output 0 0 0 0 0 0 0 1 0 0 1 0 0 0 1 1 0 1 0 0 0 1 0 1 0 1 1 0 0 1 1 1 1 0 0 0 1 0 0 1 1 0 1 0 1 0 1 1 1 1 0 0 1 1 0 1 1 1 1 0 1 1 1 1

                    RESULT The reduced form (SOP Expression) of the given logic function is

                    ____________________________________________________________

                    The observation table reflects the given logic function

                    23

                    Logic Design amp Switching Theory 1 Lab Session 04 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                    ACTIVITY 1 Using Electronics Workbench derive a truth table and logic circuit for the following logic expression

                    BAAF +=

                    Procedure 1 From the Instruments Parts Bin drag and drop Logic Converter on the design area 2 Double click the Logic Converter to reveal Logic Converter dialog box This dialog

                    box shows various conversion options between truth table logic expression and logic circuit

                    3 Enter the given logic expression in the edit box found at the end of the dialog box Use lsquo to represent invert of a variable For example A is written as Arsquo

                    4 Click the Boolean Expression to Truth Table button The truth table appears in the logic converters display

                    5 Now click the Boolean Expression to Circuit button This creates the logic circuit for the given expression in the design area Label the diagram if needed

                    Resulting Logic Circuit For the given expression the final circuit will look like

                    Figure 41

                    24

                    Logic Design amp Switching Theory 1 Lab Session 04 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                    ACTIVITY 2

                    Using Electronics Workbench find a simplified logic expression and circuit for the following truth table

                    A B C Output 0 0 0 1 0 0 1 1 0 1 0 0 0 1 1 1 1 0 0 0 1 0 1 0 1 1 0 0 1 1 1 1

                    Procedure 1 Click three input channels from A to H across the top of the logic converter The

                    display area below the terminals fills up with the necessary combinations of ones and zeros to fulfill the input conditions The values in the output column on the right are initially set to 0

                    2 Edit the output column to specify the desired output for each input condition To change an output value select it and type a new value 1 0 or x An x indicates a donrsquot care condition

                    3 To convert this truth table to a Boolean expression click the Truth Table to Boolean Expression button The Boolean expression will be displayed at the bottom of the logic converter

                    4 Simplify the expression by clicking the Simplify button 5 Now click the Boolean Expression to Circuit button This creates the logic circuit for

                    the given expression in the design area Resulting Logic Circuit For the given truth table the final simplified circuit will look like

                    Figure 42

                    25

                    Logic Design amp Switching Theory 1 Lab Session 04 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                    ACTIVITY 3

                    Using Electronics Workbench find the logic expression and truth table for the following logic circuit

                    Figure 43

                    Procedure 1 Attach the input terminals of the logic converter to up to four input points in the

                    circuit 2 Connect the single output of the circuit to the output terminal on the logic converter

                    icon 3 Click the Circuit to Truth Table button The truth table appears in the logic

                    converters display 4 To convert this truth table to a Boolean expression click the Truth Table to Boolean

                    Expression button The Boolean expression will be displayed at the bottom of the logic converter

                    Resulting Logic Expression Logic Expression for the given circuit is found to be _____________________________

                    26

                    Logic Design amp Switching Theory 1 Lab Session 04 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                    27

                    For activities 1 2 and 3 attach hardcopy of the output (truth table logic expression and logic circuit) form electronic workbench here

                    Logic Design amp Switching Theory 1 Lab Session 05 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                    Lab Session 05 Lab Session 05 OBJECT OBJECT

                    Designing a BCD Adder Designing a BCD Adder COMPONENTS AND APPARATUS REQUIRED COMPONENTS AND APPARATUS REQUIRED

                    1 Following ICs and their Datasheets 1 Following ICs and their Datasheets bull 7408 Quad 2-input AND Gate bull 7408 Quad 2-input AND Gate bull 7432 Quad 2-input OR Gate bull 7432 Quad 2-input OR Gate bull 7483 4-bit Binary Adder bull 7483 4-bit Binary Adder

                    2 Digital Trainer DT-01 or the following components 2 Digital Trainer DT-01 or the following components Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors (100 Ω) Connecting wires Switches (100 Ω) Connecting wires Switches

                    THEORY THEORY

                    A BCD Adder is a combinational circuit that adds two BCD digits in parallel and produces a sum digit also in BCD A BCD Adder is a combinational circuit that adds two BCD digits in parallel and produces a sum digit also in BCD

                    A4 A3 A2 A1 B4 B3 B2 B1

                    7483-BCD ADDER

                    Cout (C4 ) Z4 Z3 Z2 Z1 Cin(C0)

                    A4 A3 A2 A1 B4 B3 B2 B1

                    7483-BCD ADDER

                    Cout

                    (C4 ) Z4 Z3 Z2 Z1 Cin(C0)

                    Figure 51 BCD Adder Circuit

                    28

                    Logic Design amp Switching Theory 1 Lab Session 05 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                    29

                    A BCD adder must include the correction logic in its internal construction The two BCD digits together with the input carry are first added using a 4-bit binary adder to produce the binary sum If no output carry is generated and the binary sum is less than or equal to 9 then the corresponding BCD sum is identical and therefore no conversion is needed When the output carry is equal to 1 or the binary sum is greater than 9 then a binary 0110 is added to the binary sum through another 4-bit binary adder If Cout is the carry output and Z4Z3Z2Z1 is the binary sum form the first 4-bit binary adder then the following equation indicates the condition when a binary 0110 is to be added

                    C = COUT + Z4Z2 + Z4Z3 IMPLEMENTATION AND OBSERVATIONS Implement the BCD adder circuit according to figure 51 on a bread board (prepare the pin diagram (use appendix A) and refer to laboratory session 01 for procedure) A BCD adder has nine input bits (two BCD digits and a carry bit) which can result in a total of 512 combinations of which 312 inputs are donrsquot care Since it is a very lengthy procedure to record results for 200 valid input combinations therefore for simplicity just record results for any eight combinations in the following table

                    Input Carry

                    BCD Digit 1 BCD Digit 2 Carry Output

                    BCD Sum A4 A3 A2 A1 B4 B3 B2 B1 Z4 Z3 Z2 Z1

                    Logic Design amp Switching Theory 1 lab Session 06 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                    Lab Session 06

                    OBJECT

                    bull Designing of a 4 x 1 Multiplexer bull Experimenting with 74150 IC

                    COMPONENTS AND APPARATUS REQUIRED 1 Following ICs and their Datasheets

                    bull 7408 Quad 2-input AND Gates or 7411 Triple 3-input AND Gates bull 7432 Quad 2-input OR Gates bull 7404 Hex Inverter bull 74150 16 x 1 MUX

                    2 Digital Trainer DT-01 or the following components Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches THEORY

                    Multiplexers A digital data Multiplexer (MUX) is a combinational circuit having several data inputs and a single output A set of data-select inputs is used to control which of the data inputs is routed to the single output A multiplexer is also called a data selector because of this ability to select which data input is connected o the output Normally there are 2n input lines and n selection lines whose bit combination determine which input is selected DESIGN OF A 4 x 1 MULTIPLEXER A 4 x 1 multiplexer is capable of selecting one of four data inputs (see figure 61) The 2-bit binary number at the data select inputs S1 and S0 specifies which of the four data inputs is to be routed to the output Since there are two data select inputs therefore they can select 22 = 4 different data inputs lines

                    S0 S1 D0 D1

                    D2 D3

                    Data-select Inputs Output

                    Data Inputs

                    Figure 61 Block Diagram of a 4 x1 Multiplexer

                    30

                    Logic Design amp Switching Theory 1 lab Session 06 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                    Figure 62 Circuit Diagram for 4 x 1 Multiplexer

                    Implementation and Observations

                    Implement the 4 x 1 Multiplexer circuit (figure 62) on a bread board (prepare the pin diagram (use appendix A) and refer to laboratory session 01 for implementation procedure) and record the observations in the following table For each data select combination specify the switch number as well as the binary value present on that selected switch

                    S1 S0 Output 0 0 0 1 1 0 1 1

                    TESTING OF 74150 - 16 x 1 MUX

                    The 74150 IC has sixteen data inputs and four data-selection lines Function of various pins of this IC is described below

                    bull E0 through E15 Data input lines

                    31

                    Logic Design amp Switching Theory 1 lab Session 06 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering bull A B C D Data select lines with D being the MSB bull W Active low output line bull Grsquo Active low enable line bull VCC and GND Supply connections lines

                    Circuit Diagram

                    Figure 63 Pin connections of 74150 for selecting E0

                    Testing Procedure

                    bull Make connections as shown in the circuit diagram bull Apply different data (1 or 0) at data inputs that are labeled as E0 to E15 Only

                    connection for E0 is shown is the figure for simplicity bull Select the data input E0 with the help of data selectors A B C and D bull Observe the output which shows the complement of the data from E0 bull Select all the sixteen data inputs one by one and record your observations in the

                    following table

                    32

                    Logic Design amp Switching Theory 1 lab Session 06 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                    33

                    Observations

                    Grsquo D C B A W Grsquo D C B A W 0 0 0 0 0 0 1 0 0 0 0 0 0 0 1 0 1 0 0 1 0 0 0 1 0 0 1 0 1 0 0 0 0 1 1 0 1 0 1 1 0 0 1 0 0 0 1 1 0 0 0 0 1 0 1 0 1 1 0 1 0 0 1 1 0 0 1 1 1 0 0 0 1 1 1 0 1 1 1 1

                    ACTIVITY 1 Consider 4x1 Multiplexer Draw the output wave-form for the following data inputs

                    (E0 E1 E2 E3) and select lines A B (B being the MSB) Output is W

                    E3 E2 E1 E0 A B

                    W

                    2 Using the 4 x 1 MUX designed in this laboratory session implement the following logical function F (A B C) = Σ (0147)

                    Show your working and input connections in the following block diagram according to the circuit you have implemented

                    4 x 1 MUX

                    S0 S1

                    Output D0

                    D1

                    D2

                    D3

                    Logic Design amp Switching Theory 1 Lab Session 07 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                    Lab Session 07

                    OBJECT

                    bull Designing of a 2 x 4 Decoder 1 x 4 Demultiplexer bull Experimenting with 74138 IC

                    COMPONENTS AND APPARATUS REQUIRED 1 Following ICs and their Datasheets

                    bull 7408 Quad 2-input or 7411 Triple 3-input AND Gates bull 7404 Hex Inverter bull 74138 3 x 8 Decoder

                    2 Digital Trainer DT-01 or the following components Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches THEORY

                    Decoder A Decoder is a combinational circuit that converts binary information form n input lines to a maximum of 2n unique output lines In practical applications decoders are often used for selecting one of several devices

                    Demultiplexer A decoder with an enable input can function as a Demultiplexer A Demultiplexer (DMUX) id a circuit that receives information on a single line and transmits this information on one of 2n possible output lines The selection of a specific output line is controlled by the bit values of n selection lines DESIGN OF A 2 x 4 DECODER 1 x 4 DEMULTIPLEXER A 2 x 4 decoder is capable of selecting one of four output lines (see figure 71 (a)) The 2-bit binary number at the data inputs S1 and S0 specifies which of the four data inputs is to be selected If we add an enable pin and use it as an input line then this decoder can be converted to a 1 x 4 Demultiplexer where S1 and S0 will select a line to which data input is to be routed (see figure 71 (b))

                    Select S0 S0 Inputs

                    S1 D0 D1

                    D2

                    D3

                    Enable (a) Block Diagram of a 2 x 4 Decoder

                    Figure 71

                    S1 D0 D1

                    D2

                    D3

                    Inputs

                    Data Input (b) Block Diagram of a 1 x 4 Demulptiplexer

                    34

                    Logic Design amp Switching Theory 1 Lab Session 07 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                    Figure 72 Circuit Diagram for 2 x 4 Decoder 1 x 4 Demultiplexer

                    Implementation and Observations Implement the 2 x 4 Decoder 1 x 4 Demultiplexer circuit (figure 72) on a bread board (prepare the pin diagram (use appendix A) and refer to laboratory session 01 for implementation procedure) and record the observations in the following table

                    Enable Data Input S1 S0 D0 D1 D2 D3

                    0 0 0 0 0 1 0 1 0 0 1 1 1 0 0 1 0 1 1 1 0 1 1 1

                    TESTING OF 74138 3 x 8 Decoder The 74138 IC has three inputs and eight output lines It has three enable inputs and for the IC to function all three inputs need to be enabled Function of various pins of this IC is described below

                    35

                    Logic Design amp Switching Theory 1 Lab Session 07 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                    bull Y0 through Y7 Active low data outputs bull A B C Input select lines with C being the MSB bull G1 Active high enable Input bull G2Arsquo and G2Brsquo Active low enable Inputs bull VCC and GND Supply connections lines Circuit Diagram

                    Figure 73 Pin connections of 74138

                    Testing Procedure

                    bull Make connections as shown in the circuit diagram bull Apply different combinations of 1s and 0s at data inputs bull Observe the output and record your observations in the following table

                    Observations

                    C B A Y0 Y1 Y2 Y3 Y4 Y5 Y6 Y7 0 0 0 0 0 1 0 1 0 0 1 1 1 0 0 1 0 1 1 1 0 1 1 1

                    36

                    Logic Design amp Switching Theory 1 Lab Session 07 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                    37

                    ACTIVITY ACTIVITY 1 What will be the binary values at the outputs Y0 through Y7 of 74138 if 1 What will be the binary values at the outputs Y0 through Y7 of 74138 if

                    bull All three enable pins are connected to ground bull All three enable pins are connected to ground __________________________________________________________________________________________________________________________________________ __________________________________________________________________________________________________________________________________________ _____________________________________________________________________ _____________________________________________________________________

                    bull All three enable pins are connected to VCC bull All three enable pins are connected to VCC _______________________________________________________________________________________________________________________________________________________________________________________________________________

                    _______________________________________________________________________________________________________________________________________________________________________________________________________________

                    2 Show connections for 74138 in order to use it as a 1 x 8 Demultiplexer 2 Show connections for 74138 in order to use it as a 1 x 8 Demultiplexer

                    3 Consider a 2 x 4 Decoder with two enable inputs (one active high - G and one active low ndash Grsquo) Draw the output wave-forms for D0 D1 D2 and D3 if the two select inputs are A and B (B being the MSB) All outputs are active low

                    Grsquo

                    G

                    A B

                    D0 D1 D2

                    D3

                    Logic Design amp Switching Theory 1 Lab Session 08 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                    Lab Session 08 OBJECT

                    bull Designing of a 4 x 2 Priority Encoder bull Experimenting with 74148 IC

                    COMPONENTS AND APPARATUS REQUIRED

                    1 Following ICs and their Datasheets

                    bull 7408 Quad 2-input or 7421 Dual 4-input AND Gates bull 7432 Quad 2-input OR Gates bull 7404 Hex Inverter bull 74148 Encoder

                    2 Digital Trainer DT-01 or the following components Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches

                    THEORY

                    Encoder An Encoder is a digital function that produces a reverse operation from that of a decoder An Encoder has 2n (or less) input lines and n output lines The output lines generate the binary code for the 2n input variables Priority Encoder

                    A simple encoder may produce an erroneous output if more than one of its inputs is high A Priority Encoder is one that responds to just one input among those that may be simultaneously high in accordance with some priority system The most common priority system is based on the relative magnitudes of the inputs whichever decimal input is largest is the one that is encoded

                    DESIGN OF A 4 x 2 Priority Encoder

                    The following equations represent the outputs of a 4 x 2 priority encoder 32 DDA +=

                    321 DDDB += As can be seen from the equations that input D0 which has a binary code 00 is not used in any equation A binary code 00 at the output indicates two conditions Either D0 is selected or no input is selected In order to differentiate these two conditions we will provide an additional output Z to indicate if at least one of the inputs is a 1 The equation for Z will be

                    4321 DDDDZ = If Z is 0 then the binary code 00 at the output indicates that D0 is selected and if Z is 1 then it indicates that no input line is selected

                    38

                    Logic Design amp Switching Theory 1 Lab Session 08 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                    Figure 81 Circuit Diagram for 4 x 2 Priority Encoder

                    it (figure 81) on a bread board (prepare the to laboratory session 01 for implementation

                    Implementation a Implement the 4 x 2 Priority Encoder circu

                    ram (use appendix A) and refer

                    nd Observations

                    pin diagprocedure) and record the observations in the following table

                    D3 D2 D1 D0 A B 0 0 0 1 0 0 1 x 0 1 x x 1 x x x

                    TESTING OF 74148 8 x 3 Octal Priority Encoder

                    imal digits There are nine of which three represents

                    ing any of the inputs is high

                    then it shows that line 0 is selected and if e inputs selected E0 and GS

                    cannot be in the same state provided that E1 is enabled

                    The 74148 is a priority encoder with active-Low input for dec

                    input) and five output linesinputs lines (including an enablethe binary code for the octal digit Function of various pins of this IC is described below

                    bull 0 through 7 Active low data inputs representing the octal digits A2 A1 A0 Active low output lines representing the binary code bullbull E1 Active low enable Input bull E0 Active low output indicating none of the inputs is high bull GS Active low output indicatbull VCC and GND Supply connections lines Therefore if GS A2 A1 and A0 are all low

                    then it shows that none of thE0 A2 A1 and A0 are all low

                    39

                    Logic Design amp Switching Theory 1 Lab Session 08 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                    Circuit Diagram

                    Figure 82 Pin connections of 74148

                    Testing Procedure bull Make connections as sho

                    binations of 1s and 0s at data inputs d record your observations in the following table

                    GS E0

                    wn in the circuit diagram bull Apply different combull Observe the output an Observations

                    0 1 2 3 4 5 6 7 A2 A1 A0 1 1 1 1 1 1 1 1 x x x x x x x 0 x x x x x x 0 1 x x x x x 0 1 1 x x x x 0 1 1 1 x x x 0 1 1 1 1 x x 0 1 1 1 1 1 x 0 1 1 1 1 1 1 0 1 1 1 1 1 1 1

                    40

                    Logic Design amp Switching Theory 1 Lab Session 08 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                    41

                    CTIVITY

                    Cascade the following two 74148 8 x 3 Priority Encoders to form 16 x 4 Priority

                    A 1

                    Encoder

                    Logic Design amp Switching Theory 1 Lab Session 09 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering `

                    Lab Session 09 OBJECT

                    Designing an Odd Parity Generator and Checker for a 3-bit Data COMPONENTS AND APPARATUS REQUIRED

                    1 Following ICs and their Datasheets

                    bull 7486 Quad 2-input Exclusive-OR Gates bull 7404 Hex Inverter

                    2 Digital Trainer DT-01 or the following components Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches

                    THEORY

                    Parity Generator When binary data is transmitted and processed it is ndash as are all electrical signals ndash susceptible to noise that can either alter or distort its contents 1s may be effectively changed to 0s and 0s to 1s To overcome this problem one or more bits are often added to the data as an aid in detecting errors caused by noise The most common of these is a Parity bit that signifies whether the total number of 1s in a code group is odd or even In an Odd Parity system the parity bit is made 0 or 1 as necessary to make the total number 1s odd (counting the parity bit itself) In an Even Parity system the parity bit is chosen to make the total number of 1s even Table 91 shows how parity bits would be added to BCD code group in both systems

                    Decimal BCD Value Parity Bit ABCD Odd Parity Even Parity

                    0 0000 1 0 1 0001 0 1 2 0010 0 1 3 0011 1 0 4 0100 0 1 5 0101 1 0 6 0110 1 0 7 0111 0 1 8 1000 0 1 9 1001 1 0

                    Table 91 Odd and Even Parity in BCD

                    When digital data is received a parity checking circuit generates an error signal if the total number of 1s is odd in an even parity system or if it is even in an odd parity system Parity check always detects a single error (one bit change from 0 to 1 or 1 to 0) but may not detect

                    42

                    Logic Design amp Switching Theory 1 Lab Session 09 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering ` two or more errors Odd parity is used more often than even parity because even parity does not detect a situation where all 0s are created due to short circuit or other fault condition DESIGN OF A 3-BIT ODD PARITY GENERATOR AND CHECKER Let x y and z be the three bits that constitute the message and are the input to the Odd Parity Generator Circuit Since it is an odd parity system the bit P is generated so as to make the total number of 1s odd (including P) The function P can be expressed as follows P = x oplus y Ο z or P = x Ο y oplus z Since the IC available is 7486 which is quad 2input XOR IC therefore we will convert XNOR also to XOR

                    P = x oplus y Ο z

                    P = ( x oplus y ) Ο z Since for even number of variables ______

                    XOR = XNOR Therefore ___________ _________

                    P = ( x oplus y ) oplus z = x oplus y oplus z This logical expression can be implemented with two XOR gates and an inverter (see figure 91)

                    Figure 91 Circuit Diagram for a 3-bit Parity Generator

                    The 3-bit message and the parity bit are transmitted to their destination where they are applied to a Parity Checker Circuit An error occurs during transmission if the parity of the four bits received is even since the binary information transmitted was originally odd The output C of the parity checker should be a 1 when an error occurs ie when the number of 1s in the four inputs is even Therefore the function C can be expressed as

                    C = x Ο y Ο z Ο P

                    Using the same logic applied for the conversion of the equation of P

                    PzyxC oplusoplusoplus= This logical expression can be implemented with three XOR gates and an inverter (see figure 92)

                    43

                    Logic Design amp Switching Theory 1 Lab Session 09 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering `

                    44

                    Figure 92 Circuit Diagram for a 3-bit Parity Checker Implementation and Observations Implement the 3-bit Parity Generator and Checker circuits (figure 91 and 92) on a bread board (prepare the pin diagram (use appendix A) and refer to laboratory session 01 for implementation procedure) and record the observations in the following table

                    x y z P x y z P C x y z P C 0 0 0 0 0 0 0 1 0 0 0 0 0 1 0 0 0 1 1 0 0 1 0 1 0 0 0 1 0 1 0 1 0 0 1 1 0 0 1 1 1 0 1 1 1 0 0 0 1 0 0 1 1 0 0 1 0 1 0 1 0 1 1 1 0 1 1 1 0 0 1 1 0 1 1 1 0 1 1 1 0 1 1 1 1 1 1 1

                    Odd Parity Generation Odd Parity Check ACTIVITY 1 Try using the parity checker of figure 92 as 3-bit parity generator Write the details here

                    _____________________________________________________________________________________________________________________________________________________________________________________________________________________ ______________________________________________________________________________________________________________________________________________ _______________________________________________________________________ ______________________________________________________________________________________________________________________________________________

                    Logic Design amp Switching Theory 1 Lab Session 10 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                    Lab Session 10 OBJECT

                    Driving a seven segment display using 7447 7448 driver IC COMPONENTS AND APPARATUS REQUIRED

                    1 Following ICs and their Datasheets

                    bull Seven Segment Displays (Common Anode Common Cathode) bull 7447 7448 BCD to Seven Segment Driver

                    2 Digital Trainer DT-01 or the following components Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches

                    THEORY Seven Segment Displays A Seven Segment Display consists of seven light-emitting segments The segments are designated by letters a through g (see figure 101) By illuminating various combinations of segments the numerals 0 through 9 can be displayed Seven Segment Displays are commonly constructed with light-emitting diodes (LEDs) and with liquid-crystal displays (LCDs) LEDs generally provide greater illumination levels but require much greater power than LCDs An LED display can be a common-anode type or common cathode type In common anode type a high voltage is applied at the common terminal of the display and low voltage is applied at a segmentrsquos terminal for illumination In the common-cathode type a low voltage is applied at the common terminal of the display and high voltage is applied at a segmentrsquos terminal for illumination

                    Figure 101 Seven Segment Display

                    a f b g

                    e c d

                    7447 7448 BCD to Seven Segment Driver 7447 7448 IC is particularly used to drive Seven Segment Its input is a BCD number and output drives a seven segment display 7447 is used to drive common-anode displays whereas 7448 is used to drive common cathode displays 7447 7448 is a 16 pin IC Function of various pins of these ICs is described below

                    bull A B C D Inputs representing BCD digits (D being the MSB)

                    45

                    Logic Design amp Switching Theory 1 Lab Session 10 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering bull OA through OG Outputs to drive segments a through g of the display (Active low

                    in 7447 and active high in 7448) bull RBI Ripple Blanking Input Turns off all the segments if kept low provided that LT

                    is kept high and all other inputs (A B C D BI) are kept low Should be kept high otherwise

                    bull BI RBO Wire-AND logic serving as a Blanking Input and or Ripple Blanking Output

                    o BI Turns off all the segments if low o RBO Goes to a low level (response condition) along with other outputs when

                    RBI and inputs A B C and D are low with LT input at high level bull LT Lamp Test input Tests whether all segments are working or not Illuminates all

                    segments if kept low provided that BI is kept high Should be kept high otherwise bull VCC and GND Supply connections lines CIRCUIT DIAGRAM

                    Figure 102 Circuit diagram for 7447driving a common-anode display

                    IMPLEMENTATION AND OBSERVATIONS

                    bull Make connections as shown in the circuit diagram (refer to laboratory session 01 for implementation procedure)

                    bull Apply different combinations of 1s and 0s at data inputs bull Observe the output and record your observations in the following table

                    46

                    Logic Design amp Switching Theory 1 Lab Session 10 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                    47

                    Decimal Digit

                    BCD Inputs Seven Segment Outputs D C B A a b c d e f g

                    0 0 0 0 0 1 0 0 0 1 2 0 0 1 0 3 0 0 1 1 4 0 1 0 0 5 0 1 0 1 6 0 1 1 0 7 0 1 1 1 8 1 0 0 0 9 1 0 0 1

                    ACTIVITY 1 Perform the Lamp Test for the designed circuit and write your observations

                    ____________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________

                    2 How can you use 7447 IC to drive a common-cathode display

                    ____________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________

                    3 What symbols appear in the seven segment display if inputs DCBA are

                    DCBA Symbol

                    1010

                    1011

                    1100

                    1101

                    1110

                    1111

                    Logic Design amp Switching Theory 1 Lab Session 11 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                    48

                    Lab Session 11 OBJECT

                    Testing different modes of JK-FF COMPONENTS AND APPARATUS REQUIRED 1 Following ICs and their Datasheets

                    bull 7473 7476 JK Flip-Flop 2 Digital Trainer DT-01 or the following components

                    Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches

                    THEORY

                    Flip-Flop A flip-flop circuit can maintain a binary state indefinitely (as long as the power is delivered to the circuit) until directed by an input signal to switch states The major differences among various types of flip-flops are in the number of inputs they possess and in the manner in which the inputs affect the binary state

                    JK Flip-Flop JK flip flop is an edge triggered device A typical JK flip flop has three inputs J K and a clock input The flip-flop can be either positive or negative edge triggered The output Q is available in complemented form as well Beside the usual inputs and output most of the flip-flop IC also possess two asynchronous inputs namely Preset and Clear These inputs are usually active low If used Preset and Clear inputs keep the flip-flop in set and reset state respectively irrespective of the other inputs Both of these inputs cannot be used simultaneously otherwise they will bring the flip-flop in unstable state

                    Figure 111 Symbol for JK flip-flop

                    (a) positive-edge triggering (b) active low Preset (PR) and Clear (CLR) with positive-edge triggering

                    (c) active low Preset (PR) and Clear (CLR) with negative-edge triggering

                    Logic Design amp Switching Theory 1 Lab Session 11 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                    49

                    TESTING OF 7473 7476 DUAL JK FLIP-FLOP

                    Both the ICs 7473 and 7476 are similar in functionality except for one difference The flip-flops in 7473 have only one type of active low asynchronous input which is the Clear input whereas the flip-flops in 7476 have both Preset and Clear inputs Both these ICs have negative edge triggered flip-flops

                    Circuit Diagram

                    Figure 112 Pin connections of 7476

                    Testing Procedure

                    bull Make connections as shown in the circuit diagram (figure 112) bull Apply different combinations of 1s and 0s at J and K inputs bull Observe the output and record your observations in the following table

                    Observations

                    J

                    K Q

                    0 0 0 1 1 0 1 1

                    ACTIVITY

                    1 Observe the output Q of JK flip-flop if the clock input is connected to VCC or GND instead of a clock source Write your observations here __________________________________________________________________________________________________________________________________________ _______________________________________________________________________________________________________________________________________________________________________________________________________________

                    Logic Design amp Switching Theory 1 Lab Session 12 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                    50

                    Lab Session 12 OBJECT

                    Designing sequential circuit for the given state diagram using D flip-flop GIVEN STATE DIAGRAM

                    00

                    11

                    Figure 121 State Diagram COMPONENTS AND APPARATUS REQUIRED 1 Following ICs and their Datasheets

                    bull 7474 D Flip-Flop bull ICs of basic gates (AND OR NOT XOR etc) as required

                    2 Digital Trainer DT-01 or the following components Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches

                    THEORY

                    Sequential Circuits In Sequential Circuits the output not only depends on the present inputs but also on previous states of the circuit These circuits use memory elements (latches flip-flops) and the binary information stored in the memory elements at any given time defines the state of the sequential circuit Analysis of a Sequential Circuit The behavior of a sequential circuit is determined from the inputs the outputs and the states of its flip-flops Both the outputs and next state are a function of the inputs and the

                    10

                    01

                    00 11 10

                    00

                    00 11 10 00

                    Logic Design amp Switching Theory 1 Lab Session 12 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                    51

                    present state The analysis of a sequential circuit form a state diagram comprises of the following bull Selecting a particular flip-flop to design the circuit bull Obtaining state table from the state diagram bull Finding input equations for the selected flip-flop bull Finding state equations (not required for the construction of circuit) bull Implementing the circuit using selected flip-flops and their input equations ANALYZING THE GIVEN STATE DIAGRAM D Flip-Flop D flip-flop is also called transparent flip-flop as it simply transfers the input data to the output For our design we require the graphical symbol and excitation table of D flip-flop (see figure 122)

                    Qt Qt+1 T 0 0 0 0 1 1 1 0 0 1 1 1

                    (b) Excitation table of D Flip-Flop

                    (a) Graphical Symbol

                    Figure 122 Characteristic equation of D flip-flop is Q(t+1) = D State Table The given state diagram has four states so we will need two D flip-flops (FF-0 FF-1) Form state table form the given state diagram and record the results in the following table

                    Present State Input Next State Output Input to FF-0 D0

                    Input to FF-1 D1 Q1t Q0t x Q1(t+1) Q0(t+1) z

                    Logic Design amp Switching Theory 1 Lab Session 12 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                    52

                    Input Equations Using Karnaugh map the input equations D0 and D1 for the two flip-flops can be found

                    D0 D1 Q0x

                    Q1

                    _ _ Q0x

                    _ Q0x

                    Q0x

                    _ Q0x

                    Q0x

                    Q1

                    _ _ Q0x

                    _ Q0x

                    Q0x

                    _ Q0x

                    _ Q1

                    _ Q1

                    Q1

                    Q1

                    D0 = _________________ D1 = _________________

                    State Equations Using the characteristic equation of D flip-flop we can find the state equations Q0(t+1) and Q1(t+1) for the to flip flops Q0(t+1) = _______________________ Q1(t+1) = _______________________ _______________________ _______________________ _______________________ _______________________ Circuit Diagram

                    Logic Design amp Switching Theory 1 Lab Session 12 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                    53

                    Implementation Procedure and Observations

                    1 Implement the circuit using digital ICs on a bread board (prepare the pin diagram (use appendix A) and refer to laboratory session 01 for procedure)

                    2 Make the clear inputs of the flip-flops low (to clear the flip-flops) The flip-flops will remain in clear state as long as the clear inputs are connected to low level

                    3 Connect output Q0 and the clock pulse to an oscilloscope 4 Apply 0 to the input x 5 Now make the clear inputs to high 6 Observe the waveform for the first 5 clock pulses and record it 7 Repeat steps 2 to 6 keeping x=1 in step 4 this time 8 Repeat steps 2 to 7 this time connecting Q1 instead of Q0 to the oscilloscope in step

                    3 Record your observations (Keep frequency of the clock pulse low (eg1Hz) so that the output waveforms can be observed easily)

                    1 2 3 4 5 Clock Pulse

                    Output Waveform for Q0 when x=0

                    Output Waveform for Q0 when x=1

                    Output Waveform for Q1 when x=0

                    Output Waveform for Q1 when x=1

                    Logic Design amp Switching Theory 1 Lab Session 13 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                    Lab Session 13 OBJECT

                    Designing a modulo-5 asynchronous up-counter using JK-FF COMPONENTS AND APPARATUS REQUIRED

                    1 Following ICs and their Datasheets

                    bull 7400 Quad 2-input or 7410 Triple 3-input NAND Gates bull 7476 7473 JK Flip-Flop

                    2 Digital Trainer DT-01 or the following components Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches

                    THEORY

                    Digital Counters A digital counter is a set of flip-flops whose states change in response to pulses applied at the input to the counter The flip-flops are interconnected so that their combined state at any time is the binary equivalent of the total number of pulses that have occurred up to that time Every counter resets after a certain number of clock pulses Thus as it name implies a counter is used to count pulses An n stage counter can count up to a maximum of 2n states n is equal to the number of flip-flops required for the construction of counter

                    Modulus Counters The number of input pulses that causes a counter to reset to its initial count is called the modulus of the counter Thus the modulus equals to total number of distinct states (counts) including zero that a counter can store A binary counter with n stages is a modulo-2n (or mod-2n) counter The largest count a mod-N counter can achieve is N-1 ie a mod-N counter never reaches the binary number equal to its modulus N is always equal to or less than 2n Counters can be classified as bull Synchronous Counters which are clock driven All the flip-flops are driven by a

                    single clock bull Asynchronous Counters which are event driven Clock input is given to the first

                    flip-flop only Rest of the flip-flops are driven by their preceding flip-flops

                    DESIGN OF A MOD-5 ASYNCHRONOUS UP COUNTER The number of flip-flops required to construct a mod-5 counter is 3 because 5 should be less than or equal to 2n This counter will count from 0 to 4 a total of 5 distinct states Since a 3-stage counter can count up to 8 states at maximum a NAND gate is used to reset it after 5 clock pulses Figure 131 shows the logic diagram

                    54

                    Logic Design amp Switching Theory 1 Lab Session 13 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                    55

                    Figure 131 A Mod-5 Asynchronous Up Counter

                    Implementation and Observations

                    Implement the mod-5 counter circuit (figure 131) on a bread board (prepare the pin diagram (use appendix A) and refer to laboratory session 01 for implementation procedure) and record the observations in the following table

                    Clock Pulse Q2 Q1 Q0

                    0 1 2 3 4 5 6 7

                    ACTIVITY

                    Draw the timing diagram for mod-5 counter designed in this laboratory session

                    Logic Design amp Switching Theory 1 Lab Session 14 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                    Lab Session 14 OBJECT

                    Experimenting with 74194 4-bit bidirectional universal shift register COMPONENTS AND APPARATUS REQUIRED

                    1 Following ICs and their Datasheets

                    bull 74194 4-bit bidirectional universal shift register 2 Digital Trainer DT-01 or the following components

                    Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches

                    THEORY

                    Shift Registers

                    A Register is a set of flip-flops used to store binary data A register which is capable of shifting its binary information either to the right or left is called a shift register The logical configuration of a register consists of a chain of flip-flops connected in cascade with the output of one flip-flop connected to the input of next flip-flop All flip-flops receive a common clock pulse which causes the shift from one stage to the next

                    Bidirectional Shift Registers A bi-directional shift register is one whose bits can be shifted from left to right or from right to left

                    Universal Shift Registers A universal shift register is a bi-directional register whose input can be in either serial or parallel form and whose output can be in either serial or parallel form

                    74194 4-BIT BIDIRECTIONAL UNIVERSAL SHIFT REGISTER

                    The 74194 register provides parallel as well as serial loading in both directions Function of various pins of this IC is described below

                    bull A B C and D Active high inputs for parallel loading bull QA QB QC and QD Active high outputs bull S0 and S1 Active high mode control inputs The following table shows combinations

                    of S1 and S0 to enable various modes

                    S1 S0 Clock Action 0 0 x No change 0 1 uarr Shift right 1 0 uarr Shift left 1 1 uarr Parallel load

                    uarr shows the rising edge of the clock pulse

                    56

                    Logic Design amp Switching Theory 1 Lab Session 14 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering bull SR Active high serial input for right shifting bull SL Active high serial input for left shifting bull CLR Active low input Clears all the flip-flops of the register if set to 0 should be

                    kept high otherwise bull CLK Clock input bull VCC and GND Supply connections lines Thus A B C and D are inputs for parallel loading whereas SR and SL are inputs for serial loading with right or left shifting respectively S1 and S0 are used to select the loading mode Circuit Diagram

                    Figure 141 Pin connections of 74194 Testing Procedure

                    bull Make connections as shown in the circuit diagram bull Observe the output for the input combinations given in the following table

                    57

                    Logic Design amp Switching Theory 1 Lab Session 14 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                    58

                    Observations

                    S1 S0 SL SR A B C D QA QB QC QD 0 0 0 1 0 0 0 0 0 1 1 0 0 0 0 1 1 0 0 0 0 0 1 0 1 1 0 0 0 0 1 1 0 0 1 1 0 1 0 0 0 1 1 1 0 1 0 1 1 0 1 0 0 1 1 0 1 1 1 0 0 1 1 1 1 1 0 0 1 1 1 1

                    ACTIVITY 1 Show connections of 74194 to convert it into a ring counter with right shifting

                    Logic Design amp Switching Theory 1 Lab Session 15 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                    Lab Session 15

                    OBJECT

                    Experimenting with 74245 octal bus transceivers using parallel port PC interfacing COMPONENTS AND APPARATUS REQUIRED 1 Parallel Port Connectors (DB-25) with Cable 2 Personal Computer with Windows 98 and TurboC Compiler Installed 3 Following ICs and their Datasheets

                    bull 74245 Octal Bus Transceivers with 3-State Outputs 4 Digital Trainer DT-01 or the following components

                    Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches

                    THEORY

                    3-State Logic Sometimes it is necessary to isolate one part of circuit from the other part For this purpose some TTL ICs are designed with 3-state logic Such devices have three possible output states high low and high impedance The device can be put into high impedance state by a control signal applied to an appropriate pin When such a device is in high impedance state there is very high impedance at its output effectively isolating the device from whatever circuitry the output normally drives 74245 Octal Bus Transceivers A bus is any conducting path or set of paths having electrical connections to one or more devices 74245 octal bus transceivers are mainly used to control connectivity between two devices or circuits It also provides direction control for signal flow Function of various pin of this IC is given below

                    bull A1 through A8 Bus A bull B1 through B8 Bus B bull G΄ Active low enable input When high sets all the bus pins to high impedance state bull DIR Direction control for signal flow When set to high logic level transfers bus A

                    data to B bus When set to low logic level transfers bus B data to A bus bull VCC and GND Supply connections lines Serial and Parallel Port Connectors A Parallel Port can consist of only 25 pin port adapter called a DB-25 and a serial port can consist of either a 25 pin port adapter called a DB-25 or 9 pin adapter called a DB-9 port adapter Whether the port is a 9 pin or 25 pin it can accomplish all of the same tasks that serial port communications have been designed for

                    59

                    Logic Design amp Switching Theory 1 Lab Session 15 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                    60

                    Each adapter can be a male type connector with pins or a female type adapter with tiny holes Generally a PRINTER port (called LPT1) on the back of a computer is female type adapter and we need to use MALE DB-25 pin cable on it for PRINTER connection or for parallel LAPLINK cable And a COM port on the back of a computer is male for the serial ports but it may not necessarily be Parallel Port Connector ndash DB-25 The DB-25 connector (named for its B-size D-shaped shell and 25 pins) is practically ubiquitous in the electronics industry The DB-25 connector is used for a variety of purposes Two common applications are RS-232EIA-232 (serial) connections and the parallel printer interface on the IBM PC The DB-25 connector is also used for SCSI connections Normally the parallel port is used for output to a printer or other device It sends data 8-bits or one byte at a time in parallel The other lines available on the DB-25 connector are a combination of status lines control lines and ground lines The status and control lines are used for handshaking commands and feedback when we are talking to a printer

                    Figure 152 DB-25 Female Figure 151 DB-25 Male

                    Figure 153 Pin Layout for DB-25 As can be seen form figure 153 there are four types of pins in this connector

                    bull Data pins (8 pins - D0 to D7) Active high bidirectional lines

                    Logic Design amp Switching Theory 1 Lab Session 15 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering bull Control pins (4 pins - C0 to C3) C0 C1 and C3 are active low whereas C2 is active

                    high These lines also are bidirectional bull Status pins (5 pins ndash S3 to S7) Only S7 is active low rest are active high input lines bull Ground pins (8 pins) Used as a reference signal for the low (below 05 volts) charge

                    Parallel Port Addresses A DB-25 connector at a parallel port has three address one for each kind of pins register data status and control The first or base address generally refers to data register Second address is for status register and the third one is for control register In Windows 98 the base address is usually found to be 278H 378H or 3BCH Now if 378H is the base address then it refers to the data register whereas addresses for status and control register are respectively 379H and 37AH For Windows 98 the base address can be found as follows 1 On your Desktop right-click on My Computer and select Properties 2 Click on the Device Manager tab and find LPT1 under Plug and Play BIOS 3 After selecting LPT1 click the Properties button 4 Next select the Resources tab and the address should then appear next to InputOutput

                    Range Accessing parallel port through C Language Programming There are multiple functions in C Language for accessing external ports The most commonly used are listed below

                    bull unsigned char inportb(int portid) inportb reads a byte from a hardware port

                    bull int inport(int portid) reads a word from a hardware port

                    bull void outportb(int portid unsigned char value) outputs a byte to a hardware port

                    bull void outport(int portid int value) outputs a word to a hardware port

                    portid refers to the port address whereas value refers to the data to be sent TESTING 74245 USING PARALLEL PORT PC INTERFACING At one end the parallel port connector will be connected to the PC via parallel port cable and another connector (to be plugged into the PC parallel port slot) At the other end it will be connected to the buffer IC 74245 Data lines of the connector will be used to transfer 8-bit data between the PC and the buffer Out of the 8-bits of 74245 4-bits will be used to enter data which will be displayed at the monitor through a C language

                    61

                    Logic Design amp Switching Theory 1 Lab Session 15 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering program The remaining 4-bits will receive data from PC as entered by the user via keyboard

                    Circuit Diagram

                    Figure 154 Interface of 74245 to PC via Parallel Port

                    Procedure

                    1 Connect the DB-25 connector to the PC at one end and solder it to the circuit board at the other end

                    2 Connect various pins of the connector and 74245 according to the circuit diagram shown in figure 152

                    3 Using the functions listed in the previous section write a program in C language to operate various pins of the buffer The user interface of the program should provide option to the user whether to send or receive data from the port

                    4 Set DIR switch to 1 5 Try sending some data bits to the port The result should be displayed at the LEDs 6 Set DIR switch to 0 7 Set some binary 4-bit value through the switches Try reading it via parallel port

                    C Language Program

                    A program to access parallel port for data transfers

                    use header file include ltstdiohgt main program void main() define variable

                    62

                    Logic Design amp Switching Theory 1 Lab Session 15 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering unsigned int data=0 char choice while(1) printing option menu clrscr() printf(This program will send or receive a BCD digit from the parallel portn) printf(nPress your choice numbern) printf(n1 Send Data) printf(n2 Receive Data) printf(n3 Exitn) choice = getch() sending entered digit to the port if(choice == 1) input BCD digit printf(nEnter BCD digit to be sent to the port) data = getche() masking the first four bits data = data amp 0x0f sending to the port outportb(0x378data) printf(nThe BCD digit c has been sent to the port data) printing on screen the data received from the port else if(choice == 2) receiving data from the port data = inportb(0x378) masking the last four bits data = data amp 0xf0 shifting first four bits to make them the last four bits datagtgt=4 printf(nThe BCD digit set at the port is c data) exit else if(choice == 3) break key pressed is not in the menu else printf(nEnter valid choice number) printf(nnPress any key to continue) getch()

                    63

                    Logic Design amp Switching Theory 1 Lab Session 15 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                    ACTIVITY 1 In the above circuit DIR and G΄ inputs are hardwired Connect them to status or

                    control pins of the parallel port connector and control their function through your software program Circuit Diagram Program Code ______________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________

                    ___________________________________________________________________________________________________________________________________________________

                    64

                    Logic Design amp Switching Theory 1 Lab Session 15 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                    65

                    _____________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ _____________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ _______________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ _________________________________________________ _________________________________________________

                    Logic Design amp Switching Theory 1 Appendix A NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                    Appendix A

                    PIN DIAGRAMS OF THE ICS REQUIRED FOR THE LABORATORY SESSIONS Consult the TTLIC data book for internal diagrams and electrical characteristics of these ICs 7400 Quad 2-Input NAND 7402 Quad 2-Input NOR

                    7404 Hex Inverter 7408 Quad 2-Input AND

                    7410 Triple 3-Input NAND 7411 Triple 3-Input AND

                    7421 Dual 4-Input AND 7432 Quad 2-Input OR

                    66

                    Logic Design amp Switching Theory 1 Appendix A NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                    BCD-to-Seven Segm 7448 BCD-to-Seven Segment 7447 ent

                    Decoder (15V OC) Decoder (2kΩ pull-up output)

                    7473 Dual JK Flip-Flop 7474 Dual D-Type Flip-Flop

                    7476 Dual JK Flop-Flop -Bit Binary Full Adder 7483 4 with Fast Carry

                    86 Quad 2-Inpu 74138 3-to-8 Line 74 t Exclusive OR Decoder Demultiplexer

                    67

                    Logic Design amp Switching Theory 1 Appendix A NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                    68

                    74148 8-to-3 Line 16-to-1 Line Data

                    Priority Encoder 74150 Selector Multiplexer

                    74245 Oct nsceivers Universal Shift Register (PIPO) (3-State)

                    74194 4-Bit Bidirectional al Bus Tra

                    Logic Design amp Switching Theory 1 Appendix B NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                    Appendix B

                    DEBOUNCING CIRCUITRY FOR MECHANICAL SWITCHES Mechanical switches form the interface between human beings and computers or other digital systems For example a keyboard is a matrix of switches used to supply alphanumeric data to a computer Whatever the switch design it is a potential source of problems due to contact bounce The contact bounce creates a sense of narrow pulses when a switch is opened or closed An example of device whose operation would be adversely affected by contact bounce is a digital counter used to count the number of times a switch is depressed Eliminating the effects of contact bounce is called debouncing When data is entered into a computer via a keyboard a software debounce is often used This type of debouncing is a program that causes the computer to sample the switch terminal (ie to input data from it) many times in succession during the interval of time that contact bounce occurs If the data is sensed to be 1s (or 0s) for a specific number of consecutive samples then it is assumed that contact bounce has ended and the last value sensed is valid Hardware debouncing is the use of electronic circuitry to eliminate the effects of contact bounce There are numerous versions of such circuitry including those that use monostable multivibrators (one-shots) but the most straightforward is simply an RS latch Figure B1 shows the circuit When the switch is in position 1 R = 0 and S = 1 so the latch is set and the output (Q) is 1 When the switch is in position 0 R = 1and S = 0 so the latch is reset and the output is 0 When the switch is moved form one position to the other the latch changes state and bouncing occurs at either the R or the S input The bouncing does not affect the latch after it has change state An RS latch will remain set for example when its R input is 0 and its S input is alternately changed form 1 to 0

                    Figure B1 Use of RS latch to debounce a mechanical switch

                    69

                    • 01-ldst-Outer title
                      • Practical Workbook
                      • Logic Design amp Switching Theory I
                        • Dept of Computer amp Information Systems Engineering
                          • NED University of Engineering amp Technology
                          • Karachi ndash 75270 Pakistan
                            • 02-ldst-inner Title
                              • Practical Workbook
                              • Logic Design amp Switching Theory I
                                • Dept of Computer amp Information Systems Engineering
                                  • NED University of Engineering amp Technology
                                  • Karachi ndash 75270 Pakistan
                                    • 03-ldst-general info
                                    • 04-ldst-introduction
                                    • 05-Table of Contents
                                      • CONTENTS
                                        • Lab Session No Object Page No
                                        • 1
                                        • Also implementing and testing the given circuit on a bread board
                                          • Working with Electronics Workbench
                                            • Driving a seven segment display using 7447 7448 driver IC
                                              • Designing a modulus-5 asynchronous up-counter using JK-FF
                                                • Experimenting with 74194 4-bit bidirectional universal shift register
                                                    • 13
                                                        • 06-ldst-Exp01
                                                          • Lab Session 01
                                                          • OBJECT
                                                            • 1 Bread board
                                                            • 2 5 V - power supply
                                                            • 3 Multimeter
                                                            • 4 Logic probe
                                                            • 5 LEDs with resistors
                                                            • 6 Connecting wires
                                                            • 8 Following ICs and their datasheets
                                                              • THEORY
                                                                • Logic Gates
                                                                • 1 The AND Gate ndash An AND gatersquos output is 1 if and only if all its inputs are 1 If A and B are two inputs to an AND gate then output F of the gate is given as F = AB
                                                                • 2 The OR Gate - An OR gatersquos output is 1 if at least one of its input is 1 If A and B are two inputs to an OR gate then output F of the gate is given as F = A+B
                                                                • 3 The NOT Gate (Inverter) ndash Its output is 1 when its input is 0 and its output is 0 when the input is 1 ie it complements a digital variable If A is the input to a NOT gate then output F of the gate is given as
                                                                • 4 The NAND Gate ndash Its output is 1 if at least one of its input is 0 This gate performs the same logic as an AND gate followed by an inverter If A and B are two inputs to a NAND gate then output F of the gate is given as
                                                                  • 5 The NOR Gate - The output of a NOR gate is 1 if and only if all its inputs are 0 This gate performs the same logic function as an OR gate followed by an inverter If A and B are two inputs to a NAND gate then output F of the gate is given as
                                                                      • DATA SHEETS
                                                                        • Logic expression for the given logic diagram __________________________________
                                                                            • 07-ldst-exp02
                                                                              • Working with Electronics Workbench
                                                                                • 08-ldst-exp03
                                                                                  • Designing Half and Full Adder Circuits
                                                                                    • COMPONENTS AND APPARATUS REQUIRED
                                                                                      • 1 Following ICs and their Datasheets
                                                                                      • 7408 Quad 2-input AND Gate
                                                                                      • 2 Digital Trainer DT-01 or the following components
                                                                                        • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                        • Connecting wires Switches
                                                                                          • THEORY
                                                                                              • IMPLEMENTATION AND OBSERVATIONS
                                                                                                • 09-ldst-Exp04
                                                                                                  • Lab Session 04
                                                                                                  • 1 Digital ICs and their Datasheets
                                                                                                  • 7408 Quad 2-input AND Gate
                                                                                                  • 2 Digital Trainer DT-01 or the following components
                                                                                                    • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                    • Connecting wires Switches
                                                                                                    • PROCEDURE
                                                                                                    • REDUCTION OF LOGIC EXPRESSION USING KARNAUGH MAP
                                                                                                    • OBSERVATIONS
                                                                                                    • RESULT
                                                                                                        • 10-ldst-Exp05
                                                                                                          • Lab Session 05
                                                                                                          • 1 Following ICs and their Datasheets
                                                                                                          • 7408 Quad 2-input AND Gate
                                                                                                          • 2 Digital Trainer DT-01 or the following components
                                                                                                            • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                            • (100 Ω) Connecting wires Switches
                                                                                                            • THEORY
                                                                                                              • IMPLEMENTATION AND OBSERVATIONS
                                                                                                                • 11-ldst-Exp06
                                                                                                                  • OBJECT
                                                                                                                  • 1 Following ICs and their Datasheets
                                                                                                                  • 7408 Quad 2-input AND Gates or 7411 Triple 3-input AND Gates
                                                                                                                  • 2 Digital Trainer DT-01 or the following components
                                                                                                                    • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                    • Connecting wires Switches
                                                                                                                      • Figure 62 Circuit Diagram for 4 x 1 Multiplexer
                                                                                                                      • Implementation and Observations
                                                                                                                        • Circuit Diagram
                                                                                                                          • ACTIVITY
                                                                                                                            • 12-ldst-exp07
                                                                                                                              • 1 Following ICs and their Datasheets
                                                                                                                              • 7408 Quad 2-input or 7411 Triple 3-input AND Gates
                                                                                                                              • 2 Digital Trainer DT-01 or the following components
                                                                                                                                • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                • Connecting wires Switches
                                                                                                                                  • THEORY
                                                                                                                                      • Figure 72 Circuit Diagram for 2 x 4 Decoder 1 x 4 Demultiplexer
                                                                                                                                      • Implementation and Observations
                                                                                                                                        • Circuit Diagram
                                                                                                                                          • ACTIVITY
                                                                                                                                            • 13-ldst-Exp08
                                                                                                                                              • OBJECT
                                                                                                                                              • 1 Following ICs and their Datasheets
                                                                                                                                              • 7408 Quad 2-input or 7421 Dual 4-input AND Gates
                                                                                                                                              • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                • Connecting wires Switches
                                                                                                                                                  • THEORY
                                                                                                                                                      • Figure 81 Circuit Diagram for 4 x 2 Priority Encoder
                                                                                                                                                      • Implementation and Observations
                                                                                                                                                        • Therefore if GS A2 A1 and A0 are all low then it shows that line 0 is selected and if E0 A2 A1 and A0 are all low then it shows that none of the inputs selected E0 and GS cannot be in the same state provided that E1 is enabled
                                                                                                                                                        • Circuit Diagram
                                                                                                                                                          • ACTIVITY
                                                                                                                                                            • 14-ldst-exp09
                                                                                                                                                              • OBJECT
                                                                                                                                                              • 1 Following ICs and their Datasheets
                                                                                                                                                              • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                • Connecting wires Switches
                                                                                                                                                                  • THEORY
                                                                                                                                                                    • Parity Generator
                                                                                                                                                                      • Let x y and z be the three bits that constitute the message and are the input to the Odd Parity Generator Circuit Since it is an odd parity system the bit P is generated so as to make the total number of 1s odd (including P) The function P can be expressed as follows
                                                                                                                                                                      • Figure 91 Circuit Diagram for a 3-bit Parity Generator
                                                                                                                                                                        • C = x Ο y Ο z Ο P
                                                                                                                                                                          • Implementation and Observations
                                                                                                                                                                            • ACTIVITY
                                                                                                                                                                                • 15-ldst-exp10
                                                                                                                                                                                  • Driving a seven segment display using 7447 7448 driver IC
                                                                                                                                                                                  • COMPONENTS AND APPARATUS REQUIRED
                                                                                                                                                                                  • 1 Following ICs and their Datasheets
                                                                                                                                                                                  • 7447 7448 BCD to Seven Segment Driver
                                                                                                                                                                                  • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                    • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches
                                                                                                                                                                                      • THEORY
                                                                                                                                                                                      • Seven Segment Displays
                                                                                                                                                                                      • CIRCUIT DIAGRAM
                                                                                                                                                                                      • Figure 102 Circuit diagram for 7447driving a common-anode display
                                                                                                                                                                                          • IMPLEMENTATION AND OBSERVATIONS
                                                                                                                                                                                            • Decimal Digit
                                                                                                                                                                                            • BCD Inputs
                                                                                                                                                                                            • Seven Segment Outputs
                                                                                                                                                                                            • D
                                                                                                                                                                                            • C
                                                                                                                                                                                            • B
                                                                                                                                                                                            • A
                                                                                                                                                                                            • a
                                                                                                                                                                                            • b
                                                                                                                                                                                            • c
                                                                                                                                                                                            • d
                                                                                                                                                                                            • e
                                                                                                                                                                                            • f
                                                                                                                                                                                            • g
                                                                                                                                                                                            • 0
                                                                                                                                                                                            • 0
                                                                                                                                                                                            • 0
                                                                                                                                                                                            • 0
                                                                                                                                                                                            • 0
                                                                                                                                                                                            • 1
                                                                                                                                                                                            • 0
                                                                                                                                                                                            • 0
                                                                                                                                                                                            • 0
                                                                                                                                                                                            • 1
                                                                                                                                                                                            • 2
                                                                                                                                                                                            • 0
                                                                                                                                                                                            • 0
                                                                                                                                                                                            • 1
                                                                                                                                                                                            • 0
                                                                                                                                                                                            • 3
                                                                                                                                                                                            • 0
                                                                                                                                                                                            • 0
                                                                                                                                                                                            • 1
                                                                                                                                                                                            • 1
                                                                                                                                                                                            • 4
                                                                                                                                                                                            • 0
                                                                                                                                                                                            • 1
                                                                                                                                                                                            • 0
                                                                                                                                                                                            • 0
                                                                                                                                                                                            • 5
                                                                                                                                                                                            • 0
                                                                                                                                                                                            • 1
                                                                                                                                                                                            • 0
                                                                                                                                                                                            • 1
                                                                                                                                                                                            • 6
                                                                                                                                                                                            • 0
                                                                                                                                                                                            • 1
                                                                                                                                                                                            • 1
                                                                                                                                                                                            • 0
                                                                                                                                                                                            • 7
                                                                                                                                                                                            • 0
                                                                                                                                                                                            • 1
                                                                                                                                                                                            • 1
                                                                                                                                                                                            • 1
                                                                                                                                                                                            • 8
                                                                                                                                                                                            • 1
                                                                                                                                                                                            • 0
                                                                                                                                                                                            • 0
                                                                                                                                                                                            • 0
                                                                                                                                                                                            • 9
                                                                                                                                                                                            • 1
                                                                                                                                                                                            • 0
                                                                                                                                                                                            • 0
                                                                                                                                                                                            • 1
                                                                                                                                                                                              • ACTIVITY
                                                                                                                                                                                                • 16-ldst-exp11
                                                                                                                                                                                                  • Lab Session 11
                                                                                                                                                                                                    • OBJECT
                                                                                                                                                                                                    • COMPONENTS AND APPARATUS REQUIRED
                                                                                                                                                                                                      • 1 Following ICs and their Datasheets
                                                                                                                                                                                                      • 7473 7476 JK Flip-Flop
                                                                                                                                                                                                      • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                        • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                        • Connecting wires Switches
                                                                                                                                                                                                          • THEORY
                                                                                                                                                                                                              • Flip-Flop
                                                                                                                                                                                                              • JK Flip-Flop
                                                                                                                                                                                                                • Circuit Diagram
                                                                                                                                                                                                                  • Observations
                                                                                                                                                                                                                    • ACTIVITY
                                                                                                                                                                                                                        • 17-ldst-exp12
                                                                                                                                                                                                                          • Lab Session 12
                                                                                                                                                                                                                            • OBJECT
                                                                                                                                                                                                                            • GIVEN STATE DIAGRAM
                                                                                                                                                                                                                            • Figure 121 State Diagram
                                                                                                                                                                                                                            • COMPONENTS AND APPARATUS REQUIRED
                                                                                                                                                                                                                              • 1 Following ICs and their Datasheets
                                                                                                                                                                                                                              • 7474 D Flip-Flop
                                                                                                                                                                                                                              • ICs of basic gates (AND OR NOT XOR etc) as required
                                                                                                                                                                                                                              • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                                • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                                                • Connecting wires Switches
                                                                                                                                                                                                                                  • THEORY
                                                                                                                                                                                                                                      • Sequential Circuits
                                                                                                                                                                                                                                        • 18-ldst-exp13
                                                                                                                                                                                                                                          • Lab Session 13
                                                                                                                                                                                                                                            • Designing a modulo-5 asynchronous up-counter using JK-FF
                                                                                                                                                                                                                                              • 1 Following ICs and their Datasheets
                                                                                                                                                                                                                                              • 7400 Quad 2-input or 7410 Triple 3-input NAND Gates
                                                                                                                                                                                                                                              • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                                                • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                                                                • Connecting wires Switches
                                                                                                                                                                                                                                                  • THEORY
                                                                                                                                                                                                                                                      • Figure 131 A Mod-5 Asynchronous Up Counter
                                                                                                                                                                                                                                                      • Implementation and Observations
                                                                                                                                                                                                                                                        • ACTIVITY
                                                                                                                                                                                                                                                            • 19-ldst-exp14
                                                                                                                                                                                                                                                              • Experimenting with 74194 4-bit bidirectional universal shift register
                                                                                                                                                                                                                                                              • 1 Following ICs and their Datasheets
                                                                                                                                                                                                                                                              • 74194 4-bit bidirectional universal shift register
                                                                                                                                                                                                                                                              • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                                                                • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                                                                                • Connecting wires Switches
                                                                                                                                                                                                                                                                  • THEORY
                                                                                                                                                                                                                                                                    • Shift Registers
                                                                                                                                                                                                                                                                    • Bidirectional Shift Registers
                                                                                                                                                                                                                                                                    • Universal Shift Registers
                                                                                                                                                                                                                                                                      • S1
                                                                                                                                                                                                                                                                        • Circuit Diagram
                                                                                                                                                                                                                                                                        • ACTIVITY
                                                                                                                                                                                                                                                                            • 20-ldst-exp15
                                                                                                                                                                                                                                                                              • COMPONENTS AND APPARATUS REQUIRED
                                                                                                                                                                                                                                                                              • 1 Parallel Port Connectors (DB-25) with Cable
                                                                                                                                                                                                                                                                              • 2 Personal Computer with Windows 98 and TurboC Compiler Installed
                                                                                                                                                                                                                                                                              • 3 Following ICs and their Datasheets
                                                                                                                                                                                                                                                                              • 74245 Octal Bus Transceivers with 3-State Outputs
                                                                                                                                                                                                                                                                              • 4 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                                                                                • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                                                                                                  • Connecting wires Switches
                                                                                                                                                                                                                                                                                    • THEORY
                                                                                                                                                                                                                                                                                    • 3-State Logic
                                                                                                                                                                                                                                                                                      • Serial and Parallel Port Connectors
                                                                                                                                                                                                                                                                                      • Parallel Port Connector ndash DB-25
                                                                                                                                                                                                                                                                                        • Accessing parallel port through C Language Programming
                                                                                                                                                                                                                                                                                            • 21-ldst-appendixA
                                                                                                                                                                                                                                                                                            • 22-ldst-appendixB
                                                                                                                                                                                                                                                                                              • DEBOUNCING CIRCUITRY FOR MECHANICAL SWITCHES

                      Logic Design amp Switching Theory 1 Lab Session 01 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                      Lab Session 01 OBJECT

                      bull To study the logic gates in the following TTL ICs

                      i) 7400 Quad 2-input NAND gate ii) 7402 Quad 2-input NOR gate iii) 7404 Hex inverter iv) 7408 Quad 2-input AND gate v) 7432 Quad 2-input OR gate

                      bull Implementing and testing the given circuit on a bread board

                      COMPONENTS REQUIRED 1 Bread board 2 5 V - power supply 3 Multimeter 4 Logic probe 5 LEDs with resistors 6 Connecting wires 7 Switches (optional) 8 Following ICs and their datasheets

                      bull 7408 quad 2 input AND gate bull 7432 quad 2 input OR gate bull 7404 hex inverter bull 7400 quad 2 input NAND gate bull 7402 quad 2 input NOR gate

                      THEORY

                      Logic Gates

                      Logic gates are the fundamental building blocks of digital systems These devices are able to make decisions in the sense that they produce one output level when some combinations of input levels are present and a different output when other combinations are applied hence given the name Logic Gates The two levels produced by digital circuitry are referred to variously as HIGH and LOW TRUE and FALSE ON and OFF or simply 1 and 0 There are only three basic gates AND OR and NOT The other gates are merely combinations of these basic gates Logic gates can be interconnected to perform a variety of logical operations This interconnection of gates to achieve prescribed outcomes is called logic design

                      1 The AND Gate ndash An AND gatersquos output is 1 if and only if all its inputs are 1 If A and B are two inputs to an AND gate then output F of the gate is given as F = AB

                      2 The OR Gate - An OR gatersquos output is 1 if at least one of its input is 1 If A and B are two inputs to an OR gate then output F of the gate is given as F = A+B

                      13

                      Logic Design amp Switching Theory 1 Lab Session 01 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering 3 The NOT Gate (Inverter) ndash Its output is 1 when its input is 0 and its output is 0 when

                      the input is 1 ie it complements a digital variable If A is the input to a NOT gate then output F of the gate is given as AF =

                      4 The NAND Gate ndash Its output is 1 if at least one of its input is 0 This gate performs the same logic as an AND gate followed by an inverter If A and B are two inputs to a NAND gate then output F of the gate is given as BAF =

                      5 The NOR Gate - The output of a NOR gate is 1 if and only if all its inputs are 0 This gate performs the same logic function as an OR gate followed by an inverter If A and B are two inputs to a NAND gate then output F of the gate is given as BAF +=

                      All the above gates have one output and two or more inputs except the NOT gate which has only one input

                      PROCEDURE FOR TESTING THE LOGIC GATES IN GIVEN ICs

                      1 Set the power supply to 5V With the help of a multimeter check the voltage at the output knobs of the power supply

                      2 Connect wires long enough to reach the breadboard with the two knobs of the power supply Again using multimeter check voltage at the non-connected end of the wires

                      3 Insert the 7408 quad 2 input AND gate IC on to the bread board and make supply and ground connections by joining 5V wire to pin 14 and 0V wire to pin 7

                      4 Consult ICrsquos internal connection diagram for input and output pins of the first AND gate Connect input pins to logic 0 (0V) and observe the output using LED or logic probe You can also connect switches at the input lines to facilitate toggling between 1 and 0

                      5 Try different combinations of logic levels at the two inputs Again observe the output 6 Repeat the last two steps for all other gates of the same IC Record the observations 7 Repeat this procedure for all other ICs

                      OBSERVATIONS

                      Gate Input A Input B Expected Output Observed Output

                      AND

                      0 0 0 1 1 0 1 1

                      OR

                      0 0 0 1 1 0 1 1

                      NOT 0 - 1 -

                      NAND

                      0 0 0 1 1 0 1 1

                      14

                      Logic Design amp Switching Theory 1 Lab Session 01 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                      NOR

                      0 0 0 1 1 0 1 1

                      DATA SHEETS

                      Figure 11

                      15

                      Logic Design amp Switching Theory 1 Lab Session 01 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                      16

                      GIVEN CIRCUIT

                      Figure 12

                      PROCEDURE FOR IMPLEMENTATION OF THE GIVEN CIRCUIT 1 Set the power supply 2 Insert ICs on the bread board and make their supply and ground connections 3 As given in the logic diagram make connections using wires and gates in the ICs 4 Apply different combinations at the three inputs and observe the output OBSERVATIONS Logic expression for the given logic diagram __________________________________

                      A B C Expected Output Observed Output 0 0 0 0 0 1 0 1 0 0 1 1 1 0 0 1 0 1 1 1 0 1 1 1

                      Logic Design amp Switching Theory 1 Lab Session 02 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                      Lab Session 02

                      OBJECT

                      Working with Electronics Workbench

                      ELECTRONICS WORKBENCH - EWB Electronics Workbench is a computer aided design tool that provides you with all the components and instruments necessary to create board-level designs It has complete mixed analog and digital simulation and graphical waveform analysis allowing you to design your circuit and then analyze it using different simulated instruments and analysis options It is fully integrated and interactive thus you can change your circuits quickly allowing fast and repeated what-if analysis Electronics Workbench provides the following kind of components bull Sources parts bin (AC voltage source Vcc source ground battery etc) bull Basic parts bin (resistors capacitors transformers switches etc) bull Diodes parts bin bull Transistors parts bin bull Analog ICs parts bin (op-amps etc) bull Mixed ICs parts bin (ADCs DACs 555 timers etc) bull Digital ICs parts bin (AND OR adders multiplexers etc) bull Indicators parts bin (voltmeter ammeter probe displays etc) bull Controls parts bin (voltage differentiator multiplier etc) bull Instruments parts bin (multimeter oscilloscope function generator etc) bull Miscellaneous parts bin (write data textbox etc)

                      o Write data This component allows you to save simulation results as an ASCII file o Text Box Use this to add descriptive text anywhere in a circuit

                      ACTIVITY

                      Design circuit for the logic expression )( CBDCABAF ++=

                      Procedure 1 From Logic Gates Parts Bin Drag and drop the required logic gates on the design

                      area Use Component Properties dialog box to customize these gates 2 Connect the terminal of these gates according to the given expression Use additional

                      connectors form the Basic Parts Bin if you want to connect more than wire at a single node

                      3 Drag and drop a probe from Indicators Parts Bin Use Component Properties dialog box to customize the color and other properties of the probe Connect this probe at the output terminal of the circuit to indicate results

                      4 Select four switches form Basic Parts Bin Specify the key that controls the switch by typing its name in the Value tab of the Component Properties dialog box For

                      17

                      Logic Design amp Switching Theory 1 Lab Session 02 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                      18

                      example if you want the switch to close or open when digit lsquo1rsquo is pressed type 1 in the Value tab then click OK Assign different keys to all the switches

                      5 Connect the output terminals of these switches to each of the four inputs A B C and D of the circuit

                      6 Drag and drop Vcc and Ground form the Sources Parts Bin 7 Connect Vcc terminal to one end and Ground terminal to the other end of all the

                      switches 8 Label the circuit properly using text boxes found in the miscellaneous parts bin 9 Run the circuit using the Activate Simulation switch Use the keys you have assigned

                      to the switches to toggle them between Vcc and Ground connections thus providing 1 or 0 respectively to the inputs Record the results as indicated by the probe for all possible combinations of 1s and 0s at the inputs

                      EWB Circuit

                      Figure 21

                      Observations

                      A B C D Expected Output Observed Output 0 0 0 0 0 0 0 1 0 0 1 0 0 0 1 1 0 1 0 0 0 1 0 1 0 1 1 0 0 1 1 1 1 0 0 0 1 0 0 1 1 0 1 0 1 0 1 1 1 1 0 0 1 1 0 1 1 1 1 0 1 1 1 1

                      Logic Design amp Switching Theory 1 Lab Session 03 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                      Lab Session 03

                      OBJECT

                      Designing Half and Full Adder Circuits COMPONENTS AND APPARATUS REQUIRED 1 Following ICs and their Datasheets

                      bull 7408 Quad 2-input AND Gate bull 7432 Quad 2-input OR Gate bull 7486 Quad 2-input XOR Gate

                      2 Digital Trainer DT-01 or the following components Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches

                      THEORY Half Adder A combination circuit that performs the addition of two bits without accounting for the previous carry is called half adder It needs two binary inputs and two binary outputs The input variables designate the augend and addend bits The output variables produce the sum and carry The simplified sum of product expressions for a half adder are

                      yxyxyxS oplus=+= yxC =

                      Figure 31 Circuit diagram for Half Adder

                      19

                      Logic Design amp Switching Theory 1 Lab Session 03 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                      bles produce the sum and carry The simplified sum of product expressions for a half adder are

                      Full Adder

                      A combinational circuit that performs the addition of three input bits It consist of three inputs and two outputs Two of the input variables represent the two significant bits to be added The third input represents the carry from the previous lower significant position The output varia

                      zyxzyxzyxzyxzyxS oplusoplus=+++= yxzyxzyzxxyC )( +oplus=++=

                      Figure 32 Circuit diagram for Full Adder

                      efer to laboratory session 01 for procedure) and record the observations in the following ta

                      alf Adde ull Adder Inputs u

                      IMPLEMENTATION AND OBSERVATIONS

                      Implement the half adder and full adder circuits on a bread board (prepare the pin diagram (use appendix A) and r

                      bles H r F

                      Inputs Outputs Outp ts x y Carry Su Carry Sum m x y z 0 0 0 0 0 0 1 0 0 1 1 0 0 1 0 1 1 0 1 1 1 0 0 1 0 1 1 1 0 1 1 1

                      20

                      Logic Design amp Switching Theory 1 Lab Session 03 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                      at of your designed circuit Attach hardcopy of the output form electronic workbench

                      at of your designed circuit Attach hardcopy of the output form lectronic workbench here

                      ACTIVITY

                      1 Simulate half adder circuit using Electronics Workbench Compare the results of simulation with thhere

                      2 Design a full subtractor circuit and simulate it using Electronics Workbench Compare the results of simulation with the

                      21

                      Logic Design amp Switching Theory 1 Lab Session 04 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                      Lab Session 04 OBJECT

                      Use of Karnaugh Map (SOP-Expression) method GIVEN LOGIC EXPRESSION

                      F (A B C D) = sum ( 0 1 2 4 5 6 8 9 12 13 14 ) COMPONENTS AND APPARATUS REQUIRED 1 Digital ICs and their Datasheets

                      bull 7408 Quad 2-input AND Gate bull 7432 Quad 2-input OR Gate bull 7404 Hex Inverter

                      2 Digital Trainer DT-01 or the following components Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches PROCEDURE 1 Use Karnaugh map to reduce the given function 2 Draw the circuit diagram for the obtained reduced function 3 Implement the reduced circuit using digital ICs on a bread board (prepare the pin

                      diagram (use appendix A) and refer to laboratory session 01 for procedure) and record the observations

                      REDUCTION OF LOGIC EXPRESSION USING KARNAUGH MAP F

                      CD

                      AB DC

                      DC DC

                      DC

                      BA0 1 3 2

                      BA4 5 7 6

                      BA12 13 15 14

                      BA8 9 11 10

                      Reduced form of the given logic expression is __________________________________

                      22

                      Logic Design amp Switching Theory 1 Lab Session 04 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                      LOGIC DIAGRAM (REDUCED FORM) OBSERVATIONS

                      A B C D Output 0 0 0 0 0 0 0 1 0 0 1 0 0 0 1 1 0 1 0 0 0 1 0 1 0 1 1 0 0 1 1 1 1 0 0 0 1 0 0 1 1 0 1 0 1 0 1 1 1 1 0 0 1 1 0 1 1 1 1 0 1 1 1 1

                      RESULT The reduced form (SOP Expression) of the given logic function is

                      ____________________________________________________________

                      The observation table reflects the given logic function

                      23

                      Logic Design amp Switching Theory 1 Lab Session 04 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                      ACTIVITY 1 Using Electronics Workbench derive a truth table and logic circuit for the following logic expression

                      BAAF +=

                      Procedure 1 From the Instruments Parts Bin drag and drop Logic Converter on the design area 2 Double click the Logic Converter to reveal Logic Converter dialog box This dialog

                      box shows various conversion options between truth table logic expression and logic circuit

                      3 Enter the given logic expression in the edit box found at the end of the dialog box Use lsquo to represent invert of a variable For example A is written as Arsquo

                      4 Click the Boolean Expression to Truth Table button The truth table appears in the logic converters display

                      5 Now click the Boolean Expression to Circuit button This creates the logic circuit for the given expression in the design area Label the diagram if needed

                      Resulting Logic Circuit For the given expression the final circuit will look like

                      Figure 41

                      24

                      Logic Design amp Switching Theory 1 Lab Session 04 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                      ACTIVITY 2

                      Using Electronics Workbench find a simplified logic expression and circuit for the following truth table

                      A B C Output 0 0 0 1 0 0 1 1 0 1 0 0 0 1 1 1 1 0 0 0 1 0 1 0 1 1 0 0 1 1 1 1

                      Procedure 1 Click three input channels from A to H across the top of the logic converter The

                      display area below the terminals fills up with the necessary combinations of ones and zeros to fulfill the input conditions The values in the output column on the right are initially set to 0

                      2 Edit the output column to specify the desired output for each input condition To change an output value select it and type a new value 1 0 or x An x indicates a donrsquot care condition

                      3 To convert this truth table to a Boolean expression click the Truth Table to Boolean Expression button The Boolean expression will be displayed at the bottom of the logic converter

                      4 Simplify the expression by clicking the Simplify button 5 Now click the Boolean Expression to Circuit button This creates the logic circuit for

                      the given expression in the design area Resulting Logic Circuit For the given truth table the final simplified circuit will look like

                      Figure 42

                      25

                      Logic Design amp Switching Theory 1 Lab Session 04 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                      ACTIVITY 3

                      Using Electronics Workbench find the logic expression and truth table for the following logic circuit

                      Figure 43

                      Procedure 1 Attach the input terminals of the logic converter to up to four input points in the

                      circuit 2 Connect the single output of the circuit to the output terminal on the logic converter

                      icon 3 Click the Circuit to Truth Table button The truth table appears in the logic

                      converters display 4 To convert this truth table to a Boolean expression click the Truth Table to Boolean

                      Expression button The Boolean expression will be displayed at the bottom of the logic converter

                      Resulting Logic Expression Logic Expression for the given circuit is found to be _____________________________

                      26

                      Logic Design amp Switching Theory 1 Lab Session 04 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                      27

                      For activities 1 2 and 3 attach hardcopy of the output (truth table logic expression and logic circuit) form electronic workbench here

                      Logic Design amp Switching Theory 1 Lab Session 05 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                      Lab Session 05 Lab Session 05 OBJECT OBJECT

                      Designing a BCD Adder Designing a BCD Adder COMPONENTS AND APPARATUS REQUIRED COMPONENTS AND APPARATUS REQUIRED

                      1 Following ICs and their Datasheets 1 Following ICs and their Datasheets bull 7408 Quad 2-input AND Gate bull 7408 Quad 2-input AND Gate bull 7432 Quad 2-input OR Gate bull 7432 Quad 2-input OR Gate bull 7483 4-bit Binary Adder bull 7483 4-bit Binary Adder

                      2 Digital Trainer DT-01 or the following components 2 Digital Trainer DT-01 or the following components Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors (100 Ω) Connecting wires Switches (100 Ω) Connecting wires Switches

                      THEORY THEORY

                      A BCD Adder is a combinational circuit that adds two BCD digits in parallel and produces a sum digit also in BCD A BCD Adder is a combinational circuit that adds two BCD digits in parallel and produces a sum digit also in BCD

                      A4 A3 A2 A1 B4 B3 B2 B1

                      7483-BCD ADDER

                      Cout (C4 ) Z4 Z3 Z2 Z1 Cin(C0)

                      A4 A3 A2 A1 B4 B3 B2 B1

                      7483-BCD ADDER

                      Cout

                      (C4 ) Z4 Z3 Z2 Z1 Cin(C0)

                      Figure 51 BCD Adder Circuit

                      28

                      Logic Design amp Switching Theory 1 Lab Session 05 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                      29

                      A BCD adder must include the correction logic in its internal construction The two BCD digits together with the input carry are first added using a 4-bit binary adder to produce the binary sum If no output carry is generated and the binary sum is less than or equal to 9 then the corresponding BCD sum is identical and therefore no conversion is needed When the output carry is equal to 1 or the binary sum is greater than 9 then a binary 0110 is added to the binary sum through another 4-bit binary adder If Cout is the carry output and Z4Z3Z2Z1 is the binary sum form the first 4-bit binary adder then the following equation indicates the condition when a binary 0110 is to be added

                      C = COUT + Z4Z2 + Z4Z3 IMPLEMENTATION AND OBSERVATIONS Implement the BCD adder circuit according to figure 51 on a bread board (prepare the pin diagram (use appendix A) and refer to laboratory session 01 for procedure) A BCD adder has nine input bits (two BCD digits and a carry bit) which can result in a total of 512 combinations of which 312 inputs are donrsquot care Since it is a very lengthy procedure to record results for 200 valid input combinations therefore for simplicity just record results for any eight combinations in the following table

                      Input Carry

                      BCD Digit 1 BCD Digit 2 Carry Output

                      BCD Sum A4 A3 A2 A1 B4 B3 B2 B1 Z4 Z3 Z2 Z1

                      Logic Design amp Switching Theory 1 lab Session 06 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                      Lab Session 06

                      OBJECT

                      bull Designing of a 4 x 1 Multiplexer bull Experimenting with 74150 IC

                      COMPONENTS AND APPARATUS REQUIRED 1 Following ICs and their Datasheets

                      bull 7408 Quad 2-input AND Gates or 7411 Triple 3-input AND Gates bull 7432 Quad 2-input OR Gates bull 7404 Hex Inverter bull 74150 16 x 1 MUX

                      2 Digital Trainer DT-01 or the following components Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches THEORY

                      Multiplexers A digital data Multiplexer (MUX) is a combinational circuit having several data inputs and a single output A set of data-select inputs is used to control which of the data inputs is routed to the single output A multiplexer is also called a data selector because of this ability to select which data input is connected o the output Normally there are 2n input lines and n selection lines whose bit combination determine which input is selected DESIGN OF A 4 x 1 MULTIPLEXER A 4 x 1 multiplexer is capable of selecting one of four data inputs (see figure 61) The 2-bit binary number at the data select inputs S1 and S0 specifies which of the four data inputs is to be routed to the output Since there are two data select inputs therefore they can select 22 = 4 different data inputs lines

                      S0 S1 D0 D1

                      D2 D3

                      Data-select Inputs Output

                      Data Inputs

                      Figure 61 Block Diagram of a 4 x1 Multiplexer

                      30

                      Logic Design amp Switching Theory 1 lab Session 06 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                      Figure 62 Circuit Diagram for 4 x 1 Multiplexer

                      Implementation and Observations

                      Implement the 4 x 1 Multiplexer circuit (figure 62) on a bread board (prepare the pin diagram (use appendix A) and refer to laboratory session 01 for implementation procedure) and record the observations in the following table For each data select combination specify the switch number as well as the binary value present on that selected switch

                      S1 S0 Output 0 0 0 1 1 0 1 1

                      TESTING OF 74150 - 16 x 1 MUX

                      The 74150 IC has sixteen data inputs and four data-selection lines Function of various pins of this IC is described below

                      bull E0 through E15 Data input lines

                      31

                      Logic Design amp Switching Theory 1 lab Session 06 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering bull A B C D Data select lines with D being the MSB bull W Active low output line bull Grsquo Active low enable line bull VCC and GND Supply connections lines

                      Circuit Diagram

                      Figure 63 Pin connections of 74150 for selecting E0

                      Testing Procedure

                      bull Make connections as shown in the circuit diagram bull Apply different data (1 or 0) at data inputs that are labeled as E0 to E15 Only

                      connection for E0 is shown is the figure for simplicity bull Select the data input E0 with the help of data selectors A B C and D bull Observe the output which shows the complement of the data from E0 bull Select all the sixteen data inputs one by one and record your observations in the

                      following table

                      32

                      Logic Design amp Switching Theory 1 lab Session 06 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                      33

                      Observations

                      Grsquo D C B A W Grsquo D C B A W 0 0 0 0 0 0 1 0 0 0 0 0 0 0 1 0 1 0 0 1 0 0 0 1 0 0 1 0 1 0 0 0 0 1 1 0 1 0 1 1 0 0 1 0 0 0 1 1 0 0 0 0 1 0 1 0 1 1 0 1 0 0 1 1 0 0 1 1 1 0 0 0 1 1 1 0 1 1 1 1

                      ACTIVITY 1 Consider 4x1 Multiplexer Draw the output wave-form for the following data inputs

                      (E0 E1 E2 E3) and select lines A B (B being the MSB) Output is W

                      E3 E2 E1 E0 A B

                      W

                      2 Using the 4 x 1 MUX designed in this laboratory session implement the following logical function F (A B C) = Σ (0147)

                      Show your working and input connections in the following block diagram according to the circuit you have implemented

                      4 x 1 MUX

                      S0 S1

                      Output D0

                      D1

                      D2

                      D3

                      Logic Design amp Switching Theory 1 Lab Session 07 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                      Lab Session 07

                      OBJECT

                      bull Designing of a 2 x 4 Decoder 1 x 4 Demultiplexer bull Experimenting with 74138 IC

                      COMPONENTS AND APPARATUS REQUIRED 1 Following ICs and their Datasheets

                      bull 7408 Quad 2-input or 7411 Triple 3-input AND Gates bull 7404 Hex Inverter bull 74138 3 x 8 Decoder

                      2 Digital Trainer DT-01 or the following components Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches THEORY

                      Decoder A Decoder is a combinational circuit that converts binary information form n input lines to a maximum of 2n unique output lines In practical applications decoders are often used for selecting one of several devices

                      Demultiplexer A decoder with an enable input can function as a Demultiplexer A Demultiplexer (DMUX) id a circuit that receives information on a single line and transmits this information on one of 2n possible output lines The selection of a specific output line is controlled by the bit values of n selection lines DESIGN OF A 2 x 4 DECODER 1 x 4 DEMULTIPLEXER A 2 x 4 decoder is capable of selecting one of four output lines (see figure 71 (a)) The 2-bit binary number at the data inputs S1 and S0 specifies which of the four data inputs is to be selected If we add an enable pin and use it as an input line then this decoder can be converted to a 1 x 4 Demultiplexer where S1 and S0 will select a line to which data input is to be routed (see figure 71 (b))

                      Select S0 S0 Inputs

                      S1 D0 D1

                      D2

                      D3

                      Enable (a) Block Diagram of a 2 x 4 Decoder

                      Figure 71

                      S1 D0 D1

                      D2

                      D3

                      Inputs

                      Data Input (b) Block Diagram of a 1 x 4 Demulptiplexer

                      34

                      Logic Design amp Switching Theory 1 Lab Session 07 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                      Figure 72 Circuit Diagram for 2 x 4 Decoder 1 x 4 Demultiplexer

                      Implementation and Observations Implement the 2 x 4 Decoder 1 x 4 Demultiplexer circuit (figure 72) on a bread board (prepare the pin diagram (use appendix A) and refer to laboratory session 01 for implementation procedure) and record the observations in the following table

                      Enable Data Input S1 S0 D0 D1 D2 D3

                      0 0 0 0 0 1 0 1 0 0 1 1 1 0 0 1 0 1 1 1 0 1 1 1

                      TESTING OF 74138 3 x 8 Decoder The 74138 IC has three inputs and eight output lines It has three enable inputs and for the IC to function all three inputs need to be enabled Function of various pins of this IC is described below

                      35

                      Logic Design amp Switching Theory 1 Lab Session 07 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                      bull Y0 through Y7 Active low data outputs bull A B C Input select lines with C being the MSB bull G1 Active high enable Input bull G2Arsquo and G2Brsquo Active low enable Inputs bull VCC and GND Supply connections lines Circuit Diagram

                      Figure 73 Pin connections of 74138

                      Testing Procedure

                      bull Make connections as shown in the circuit diagram bull Apply different combinations of 1s and 0s at data inputs bull Observe the output and record your observations in the following table

                      Observations

                      C B A Y0 Y1 Y2 Y3 Y4 Y5 Y6 Y7 0 0 0 0 0 1 0 1 0 0 1 1 1 0 0 1 0 1 1 1 0 1 1 1

                      36

                      Logic Design amp Switching Theory 1 Lab Session 07 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                      37

                      ACTIVITY ACTIVITY 1 What will be the binary values at the outputs Y0 through Y7 of 74138 if 1 What will be the binary values at the outputs Y0 through Y7 of 74138 if

                      bull All three enable pins are connected to ground bull All three enable pins are connected to ground __________________________________________________________________________________________________________________________________________ __________________________________________________________________________________________________________________________________________ _____________________________________________________________________ _____________________________________________________________________

                      bull All three enable pins are connected to VCC bull All three enable pins are connected to VCC _______________________________________________________________________________________________________________________________________________________________________________________________________________

                      _______________________________________________________________________________________________________________________________________________________________________________________________________________

                      2 Show connections for 74138 in order to use it as a 1 x 8 Demultiplexer 2 Show connections for 74138 in order to use it as a 1 x 8 Demultiplexer

                      3 Consider a 2 x 4 Decoder with two enable inputs (one active high - G and one active low ndash Grsquo) Draw the output wave-forms for D0 D1 D2 and D3 if the two select inputs are A and B (B being the MSB) All outputs are active low

                      Grsquo

                      G

                      A B

                      D0 D1 D2

                      D3

                      Logic Design amp Switching Theory 1 Lab Session 08 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                      Lab Session 08 OBJECT

                      bull Designing of a 4 x 2 Priority Encoder bull Experimenting with 74148 IC

                      COMPONENTS AND APPARATUS REQUIRED

                      1 Following ICs and their Datasheets

                      bull 7408 Quad 2-input or 7421 Dual 4-input AND Gates bull 7432 Quad 2-input OR Gates bull 7404 Hex Inverter bull 74148 Encoder

                      2 Digital Trainer DT-01 or the following components Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches

                      THEORY

                      Encoder An Encoder is a digital function that produces a reverse operation from that of a decoder An Encoder has 2n (or less) input lines and n output lines The output lines generate the binary code for the 2n input variables Priority Encoder

                      A simple encoder may produce an erroneous output if more than one of its inputs is high A Priority Encoder is one that responds to just one input among those that may be simultaneously high in accordance with some priority system The most common priority system is based on the relative magnitudes of the inputs whichever decimal input is largest is the one that is encoded

                      DESIGN OF A 4 x 2 Priority Encoder

                      The following equations represent the outputs of a 4 x 2 priority encoder 32 DDA +=

                      321 DDDB += As can be seen from the equations that input D0 which has a binary code 00 is not used in any equation A binary code 00 at the output indicates two conditions Either D0 is selected or no input is selected In order to differentiate these two conditions we will provide an additional output Z to indicate if at least one of the inputs is a 1 The equation for Z will be

                      4321 DDDDZ = If Z is 0 then the binary code 00 at the output indicates that D0 is selected and if Z is 1 then it indicates that no input line is selected

                      38

                      Logic Design amp Switching Theory 1 Lab Session 08 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                      Figure 81 Circuit Diagram for 4 x 2 Priority Encoder

                      it (figure 81) on a bread board (prepare the to laboratory session 01 for implementation

                      Implementation a Implement the 4 x 2 Priority Encoder circu

                      ram (use appendix A) and refer

                      nd Observations

                      pin diagprocedure) and record the observations in the following table

                      D3 D2 D1 D0 A B 0 0 0 1 0 0 1 x 0 1 x x 1 x x x

                      TESTING OF 74148 8 x 3 Octal Priority Encoder

                      imal digits There are nine of which three represents

                      ing any of the inputs is high

                      then it shows that line 0 is selected and if e inputs selected E0 and GS

                      cannot be in the same state provided that E1 is enabled

                      The 74148 is a priority encoder with active-Low input for dec

                      input) and five output linesinputs lines (including an enablethe binary code for the octal digit Function of various pins of this IC is described below

                      bull 0 through 7 Active low data inputs representing the octal digits A2 A1 A0 Active low output lines representing the binary code bullbull E1 Active low enable Input bull E0 Active low output indicating none of the inputs is high bull GS Active low output indicatbull VCC and GND Supply connections lines Therefore if GS A2 A1 and A0 are all low

                      then it shows that none of thE0 A2 A1 and A0 are all low

                      39

                      Logic Design amp Switching Theory 1 Lab Session 08 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                      Circuit Diagram

                      Figure 82 Pin connections of 74148

                      Testing Procedure bull Make connections as sho

                      binations of 1s and 0s at data inputs d record your observations in the following table

                      GS E0

                      wn in the circuit diagram bull Apply different combull Observe the output an Observations

                      0 1 2 3 4 5 6 7 A2 A1 A0 1 1 1 1 1 1 1 1 x x x x x x x 0 x x x x x x 0 1 x x x x x 0 1 1 x x x x 0 1 1 1 x x x 0 1 1 1 1 x x 0 1 1 1 1 1 x 0 1 1 1 1 1 1 0 1 1 1 1 1 1 1

                      40

                      Logic Design amp Switching Theory 1 Lab Session 08 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                      41

                      CTIVITY

                      Cascade the following two 74148 8 x 3 Priority Encoders to form 16 x 4 Priority

                      A 1

                      Encoder

                      Logic Design amp Switching Theory 1 Lab Session 09 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering `

                      Lab Session 09 OBJECT

                      Designing an Odd Parity Generator and Checker for a 3-bit Data COMPONENTS AND APPARATUS REQUIRED

                      1 Following ICs and their Datasheets

                      bull 7486 Quad 2-input Exclusive-OR Gates bull 7404 Hex Inverter

                      2 Digital Trainer DT-01 or the following components Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches

                      THEORY

                      Parity Generator When binary data is transmitted and processed it is ndash as are all electrical signals ndash susceptible to noise that can either alter or distort its contents 1s may be effectively changed to 0s and 0s to 1s To overcome this problem one or more bits are often added to the data as an aid in detecting errors caused by noise The most common of these is a Parity bit that signifies whether the total number of 1s in a code group is odd or even In an Odd Parity system the parity bit is made 0 or 1 as necessary to make the total number 1s odd (counting the parity bit itself) In an Even Parity system the parity bit is chosen to make the total number of 1s even Table 91 shows how parity bits would be added to BCD code group in both systems

                      Decimal BCD Value Parity Bit ABCD Odd Parity Even Parity

                      0 0000 1 0 1 0001 0 1 2 0010 0 1 3 0011 1 0 4 0100 0 1 5 0101 1 0 6 0110 1 0 7 0111 0 1 8 1000 0 1 9 1001 1 0

                      Table 91 Odd and Even Parity in BCD

                      When digital data is received a parity checking circuit generates an error signal if the total number of 1s is odd in an even parity system or if it is even in an odd parity system Parity check always detects a single error (one bit change from 0 to 1 or 1 to 0) but may not detect

                      42

                      Logic Design amp Switching Theory 1 Lab Session 09 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering ` two or more errors Odd parity is used more often than even parity because even parity does not detect a situation where all 0s are created due to short circuit or other fault condition DESIGN OF A 3-BIT ODD PARITY GENERATOR AND CHECKER Let x y and z be the three bits that constitute the message and are the input to the Odd Parity Generator Circuit Since it is an odd parity system the bit P is generated so as to make the total number of 1s odd (including P) The function P can be expressed as follows P = x oplus y Ο z or P = x Ο y oplus z Since the IC available is 7486 which is quad 2input XOR IC therefore we will convert XNOR also to XOR

                      P = x oplus y Ο z

                      P = ( x oplus y ) Ο z Since for even number of variables ______

                      XOR = XNOR Therefore ___________ _________

                      P = ( x oplus y ) oplus z = x oplus y oplus z This logical expression can be implemented with two XOR gates and an inverter (see figure 91)

                      Figure 91 Circuit Diagram for a 3-bit Parity Generator

                      The 3-bit message and the parity bit are transmitted to their destination where they are applied to a Parity Checker Circuit An error occurs during transmission if the parity of the four bits received is even since the binary information transmitted was originally odd The output C of the parity checker should be a 1 when an error occurs ie when the number of 1s in the four inputs is even Therefore the function C can be expressed as

                      C = x Ο y Ο z Ο P

                      Using the same logic applied for the conversion of the equation of P

                      PzyxC oplusoplusoplus= This logical expression can be implemented with three XOR gates and an inverter (see figure 92)

                      43

                      Logic Design amp Switching Theory 1 Lab Session 09 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering `

                      44

                      Figure 92 Circuit Diagram for a 3-bit Parity Checker Implementation and Observations Implement the 3-bit Parity Generator and Checker circuits (figure 91 and 92) on a bread board (prepare the pin diagram (use appendix A) and refer to laboratory session 01 for implementation procedure) and record the observations in the following table

                      x y z P x y z P C x y z P C 0 0 0 0 0 0 0 1 0 0 0 0 0 1 0 0 0 1 1 0 0 1 0 1 0 0 0 1 0 1 0 1 0 0 1 1 0 0 1 1 1 0 1 1 1 0 0 0 1 0 0 1 1 0 0 1 0 1 0 1 0 1 1 1 0 1 1 1 0 0 1 1 0 1 1 1 0 1 1 1 0 1 1 1 1 1 1 1

                      Odd Parity Generation Odd Parity Check ACTIVITY 1 Try using the parity checker of figure 92 as 3-bit parity generator Write the details here

                      _____________________________________________________________________________________________________________________________________________________________________________________________________________________ ______________________________________________________________________________________________________________________________________________ _______________________________________________________________________ ______________________________________________________________________________________________________________________________________________

                      Logic Design amp Switching Theory 1 Lab Session 10 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                      Lab Session 10 OBJECT

                      Driving a seven segment display using 7447 7448 driver IC COMPONENTS AND APPARATUS REQUIRED

                      1 Following ICs and their Datasheets

                      bull Seven Segment Displays (Common Anode Common Cathode) bull 7447 7448 BCD to Seven Segment Driver

                      2 Digital Trainer DT-01 or the following components Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches

                      THEORY Seven Segment Displays A Seven Segment Display consists of seven light-emitting segments The segments are designated by letters a through g (see figure 101) By illuminating various combinations of segments the numerals 0 through 9 can be displayed Seven Segment Displays are commonly constructed with light-emitting diodes (LEDs) and with liquid-crystal displays (LCDs) LEDs generally provide greater illumination levels but require much greater power than LCDs An LED display can be a common-anode type or common cathode type In common anode type a high voltage is applied at the common terminal of the display and low voltage is applied at a segmentrsquos terminal for illumination In the common-cathode type a low voltage is applied at the common terminal of the display and high voltage is applied at a segmentrsquos terminal for illumination

                      Figure 101 Seven Segment Display

                      a f b g

                      e c d

                      7447 7448 BCD to Seven Segment Driver 7447 7448 IC is particularly used to drive Seven Segment Its input is a BCD number and output drives a seven segment display 7447 is used to drive common-anode displays whereas 7448 is used to drive common cathode displays 7447 7448 is a 16 pin IC Function of various pins of these ICs is described below

                      bull A B C D Inputs representing BCD digits (D being the MSB)

                      45

                      Logic Design amp Switching Theory 1 Lab Session 10 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering bull OA through OG Outputs to drive segments a through g of the display (Active low

                      in 7447 and active high in 7448) bull RBI Ripple Blanking Input Turns off all the segments if kept low provided that LT

                      is kept high and all other inputs (A B C D BI) are kept low Should be kept high otherwise

                      bull BI RBO Wire-AND logic serving as a Blanking Input and or Ripple Blanking Output

                      o BI Turns off all the segments if low o RBO Goes to a low level (response condition) along with other outputs when

                      RBI and inputs A B C and D are low with LT input at high level bull LT Lamp Test input Tests whether all segments are working or not Illuminates all

                      segments if kept low provided that BI is kept high Should be kept high otherwise bull VCC and GND Supply connections lines CIRCUIT DIAGRAM

                      Figure 102 Circuit diagram for 7447driving a common-anode display

                      IMPLEMENTATION AND OBSERVATIONS

                      bull Make connections as shown in the circuit diagram (refer to laboratory session 01 for implementation procedure)

                      bull Apply different combinations of 1s and 0s at data inputs bull Observe the output and record your observations in the following table

                      46

                      Logic Design amp Switching Theory 1 Lab Session 10 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                      47

                      Decimal Digit

                      BCD Inputs Seven Segment Outputs D C B A a b c d e f g

                      0 0 0 0 0 1 0 0 0 1 2 0 0 1 0 3 0 0 1 1 4 0 1 0 0 5 0 1 0 1 6 0 1 1 0 7 0 1 1 1 8 1 0 0 0 9 1 0 0 1

                      ACTIVITY 1 Perform the Lamp Test for the designed circuit and write your observations

                      ____________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________

                      2 How can you use 7447 IC to drive a common-cathode display

                      ____________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________

                      3 What symbols appear in the seven segment display if inputs DCBA are

                      DCBA Symbol

                      1010

                      1011

                      1100

                      1101

                      1110

                      1111

                      Logic Design amp Switching Theory 1 Lab Session 11 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                      48

                      Lab Session 11 OBJECT

                      Testing different modes of JK-FF COMPONENTS AND APPARATUS REQUIRED 1 Following ICs and their Datasheets

                      bull 7473 7476 JK Flip-Flop 2 Digital Trainer DT-01 or the following components

                      Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches

                      THEORY

                      Flip-Flop A flip-flop circuit can maintain a binary state indefinitely (as long as the power is delivered to the circuit) until directed by an input signal to switch states The major differences among various types of flip-flops are in the number of inputs they possess and in the manner in which the inputs affect the binary state

                      JK Flip-Flop JK flip flop is an edge triggered device A typical JK flip flop has three inputs J K and a clock input The flip-flop can be either positive or negative edge triggered The output Q is available in complemented form as well Beside the usual inputs and output most of the flip-flop IC also possess two asynchronous inputs namely Preset and Clear These inputs are usually active low If used Preset and Clear inputs keep the flip-flop in set and reset state respectively irrespective of the other inputs Both of these inputs cannot be used simultaneously otherwise they will bring the flip-flop in unstable state

                      Figure 111 Symbol for JK flip-flop

                      (a) positive-edge triggering (b) active low Preset (PR) and Clear (CLR) with positive-edge triggering

                      (c) active low Preset (PR) and Clear (CLR) with negative-edge triggering

                      Logic Design amp Switching Theory 1 Lab Session 11 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                      49

                      TESTING OF 7473 7476 DUAL JK FLIP-FLOP

                      Both the ICs 7473 and 7476 are similar in functionality except for one difference The flip-flops in 7473 have only one type of active low asynchronous input which is the Clear input whereas the flip-flops in 7476 have both Preset and Clear inputs Both these ICs have negative edge triggered flip-flops

                      Circuit Diagram

                      Figure 112 Pin connections of 7476

                      Testing Procedure

                      bull Make connections as shown in the circuit diagram (figure 112) bull Apply different combinations of 1s and 0s at J and K inputs bull Observe the output and record your observations in the following table

                      Observations

                      J

                      K Q

                      0 0 0 1 1 0 1 1

                      ACTIVITY

                      1 Observe the output Q of JK flip-flop if the clock input is connected to VCC or GND instead of a clock source Write your observations here __________________________________________________________________________________________________________________________________________ _______________________________________________________________________________________________________________________________________________________________________________________________________________

                      Logic Design amp Switching Theory 1 Lab Session 12 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                      50

                      Lab Session 12 OBJECT

                      Designing sequential circuit for the given state diagram using D flip-flop GIVEN STATE DIAGRAM

                      00

                      11

                      Figure 121 State Diagram COMPONENTS AND APPARATUS REQUIRED 1 Following ICs and their Datasheets

                      bull 7474 D Flip-Flop bull ICs of basic gates (AND OR NOT XOR etc) as required

                      2 Digital Trainer DT-01 or the following components Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches

                      THEORY

                      Sequential Circuits In Sequential Circuits the output not only depends on the present inputs but also on previous states of the circuit These circuits use memory elements (latches flip-flops) and the binary information stored in the memory elements at any given time defines the state of the sequential circuit Analysis of a Sequential Circuit The behavior of a sequential circuit is determined from the inputs the outputs and the states of its flip-flops Both the outputs and next state are a function of the inputs and the

                      10

                      01

                      00 11 10

                      00

                      00 11 10 00

                      Logic Design amp Switching Theory 1 Lab Session 12 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                      51

                      present state The analysis of a sequential circuit form a state diagram comprises of the following bull Selecting a particular flip-flop to design the circuit bull Obtaining state table from the state diagram bull Finding input equations for the selected flip-flop bull Finding state equations (not required for the construction of circuit) bull Implementing the circuit using selected flip-flops and their input equations ANALYZING THE GIVEN STATE DIAGRAM D Flip-Flop D flip-flop is also called transparent flip-flop as it simply transfers the input data to the output For our design we require the graphical symbol and excitation table of D flip-flop (see figure 122)

                      Qt Qt+1 T 0 0 0 0 1 1 1 0 0 1 1 1

                      (b) Excitation table of D Flip-Flop

                      (a) Graphical Symbol

                      Figure 122 Characteristic equation of D flip-flop is Q(t+1) = D State Table The given state diagram has four states so we will need two D flip-flops (FF-0 FF-1) Form state table form the given state diagram and record the results in the following table

                      Present State Input Next State Output Input to FF-0 D0

                      Input to FF-1 D1 Q1t Q0t x Q1(t+1) Q0(t+1) z

                      Logic Design amp Switching Theory 1 Lab Session 12 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                      52

                      Input Equations Using Karnaugh map the input equations D0 and D1 for the two flip-flops can be found

                      D0 D1 Q0x

                      Q1

                      _ _ Q0x

                      _ Q0x

                      Q0x

                      _ Q0x

                      Q0x

                      Q1

                      _ _ Q0x

                      _ Q0x

                      Q0x

                      _ Q0x

                      _ Q1

                      _ Q1

                      Q1

                      Q1

                      D0 = _________________ D1 = _________________

                      State Equations Using the characteristic equation of D flip-flop we can find the state equations Q0(t+1) and Q1(t+1) for the to flip flops Q0(t+1) = _______________________ Q1(t+1) = _______________________ _______________________ _______________________ _______________________ _______________________ Circuit Diagram

                      Logic Design amp Switching Theory 1 Lab Session 12 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                      53

                      Implementation Procedure and Observations

                      1 Implement the circuit using digital ICs on a bread board (prepare the pin diagram (use appendix A) and refer to laboratory session 01 for procedure)

                      2 Make the clear inputs of the flip-flops low (to clear the flip-flops) The flip-flops will remain in clear state as long as the clear inputs are connected to low level

                      3 Connect output Q0 and the clock pulse to an oscilloscope 4 Apply 0 to the input x 5 Now make the clear inputs to high 6 Observe the waveform for the first 5 clock pulses and record it 7 Repeat steps 2 to 6 keeping x=1 in step 4 this time 8 Repeat steps 2 to 7 this time connecting Q1 instead of Q0 to the oscilloscope in step

                      3 Record your observations (Keep frequency of the clock pulse low (eg1Hz) so that the output waveforms can be observed easily)

                      1 2 3 4 5 Clock Pulse

                      Output Waveform for Q0 when x=0

                      Output Waveform for Q0 when x=1

                      Output Waveform for Q1 when x=0

                      Output Waveform for Q1 when x=1

                      Logic Design amp Switching Theory 1 Lab Session 13 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                      Lab Session 13 OBJECT

                      Designing a modulo-5 asynchronous up-counter using JK-FF COMPONENTS AND APPARATUS REQUIRED

                      1 Following ICs and their Datasheets

                      bull 7400 Quad 2-input or 7410 Triple 3-input NAND Gates bull 7476 7473 JK Flip-Flop

                      2 Digital Trainer DT-01 or the following components Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches

                      THEORY

                      Digital Counters A digital counter is a set of flip-flops whose states change in response to pulses applied at the input to the counter The flip-flops are interconnected so that their combined state at any time is the binary equivalent of the total number of pulses that have occurred up to that time Every counter resets after a certain number of clock pulses Thus as it name implies a counter is used to count pulses An n stage counter can count up to a maximum of 2n states n is equal to the number of flip-flops required for the construction of counter

                      Modulus Counters The number of input pulses that causes a counter to reset to its initial count is called the modulus of the counter Thus the modulus equals to total number of distinct states (counts) including zero that a counter can store A binary counter with n stages is a modulo-2n (or mod-2n) counter The largest count a mod-N counter can achieve is N-1 ie a mod-N counter never reaches the binary number equal to its modulus N is always equal to or less than 2n Counters can be classified as bull Synchronous Counters which are clock driven All the flip-flops are driven by a

                      single clock bull Asynchronous Counters which are event driven Clock input is given to the first

                      flip-flop only Rest of the flip-flops are driven by their preceding flip-flops

                      DESIGN OF A MOD-5 ASYNCHRONOUS UP COUNTER The number of flip-flops required to construct a mod-5 counter is 3 because 5 should be less than or equal to 2n This counter will count from 0 to 4 a total of 5 distinct states Since a 3-stage counter can count up to 8 states at maximum a NAND gate is used to reset it after 5 clock pulses Figure 131 shows the logic diagram

                      54

                      Logic Design amp Switching Theory 1 Lab Session 13 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                      55

                      Figure 131 A Mod-5 Asynchronous Up Counter

                      Implementation and Observations

                      Implement the mod-5 counter circuit (figure 131) on a bread board (prepare the pin diagram (use appendix A) and refer to laboratory session 01 for implementation procedure) and record the observations in the following table

                      Clock Pulse Q2 Q1 Q0

                      0 1 2 3 4 5 6 7

                      ACTIVITY

                      Draw the timing diagram for mod-5 counter designed in this laboratory session

                      Logic Design amp Switching Theory 1 Lab Session 14 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                      Lab Session 14 OBJECT

                      Experimenting with 74194 4-bit bidirectional universal shift register COMPONENTS AND APPARATUS REQUIRED

                      1 Following ICs and their Datasheets

                      bull 74194 4-bit bidirectional universal shift register 2 Digital Trainer DT-01 or the following components

                      Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches

                      THEORY

                      Shift Registers

                      A Register is a set of flip-flops used to store binary data A register which is capable of shifting its binary information either to the right or left is called a shift register The logical configuration of a register consists of a chain of flip-flops connected in cascade with the output of one flip-flop connected to the input of next flip-flop All flip-flops receive a common clock pulse which causes the shift from one stage to the next

                      Bidirectional Shift Registers A bi-directional shift register is one whose bits can be shifted from left to right or from right to left

                      Universal Shift Registers A universal shift register is a bi-directional register whose input can be in either serial or parallel form and whose output can be in either serial or parallel form

                      74194 4-BIT BIDIRECTIONAL UNIVERSAL SHIFT REGISTER

                      The 74194 register provides parallel as well as serial loading in both directions Function of various pins of this IC is described below

                      bull A B C and D Active high inputs for parallel loading bull QA QB QC and QD Active high outputs bull S0 and S1 Active high mode control inputs The following table shows combinations

                      of S1 and S0 to enable various modes

                      S1 S0 Clock Action 0 0 x No change 0 1 uarr Shift right 1 0 uarr Shift left 1 1 uarr Parallel load

                      uarr shows the rising edge of the clock pulse

                      56

                      Logic Design amp Switching Theory 1 Lab Session 14 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering bull SR Active high serial input for right shifting bull SL Active high serial input for left shifting bull CLR Active low input Clears all the flip-flops of the register if set to 0 should be

                      kept high otherwise bull CLK Clock input bull VCC and GND Supply connections lines Thus A B C and D are inputs for parallel loading whereas SR and SL are inputs for serial loading with right or left shifting respectively S1 and S0 are used to select the loading mode Circuit Diagram

                      Figure 141 Pin connections of 74194 Testing Procedure

                      bull Make connections as shown in the circuit diagram bull Observe the output for the input combinations given in the following table

                      57

                      Logic Design amp Switching Theory 1 Lab Session 14 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                      58

                      Observations

                      S1 S0 SL SR A B C D QA QB QC QD 0 0 0 1 0 0 0 0 0 1 1 0 0 0 0 1 1 0 0 0 0 0 1 0 1 1 0 0 0 0 1 1 0 0 1 1 0 1 0 0 0 1 1 1 0 1 0 1 1 0 1 0 0 1 1 0 1 1 1 0 0 1 1 1 1 1 0 0 1 1 1 1

                      ACTIVITY 1 Show connections of 74194 to convert it into a ring counter with right shifting

                      Logic Design amp Switching Theory 1 Lab Session 15 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                      Lab Session 15

                      OBJECT

                      Experimenting with 74245 octal bus transceivers using parallel port PC interfacing COMPONENTS AND APPARATUS REQUIRED 1 Parallel Port Connectors (DB-25) with Cable 2 Personal Computer with Windows 98 and TurboC Compiler Installed 3 Following ICs and their Datasheets

                      bull 74245 Octal Bus Transceivers with 3-State Outputs 4 Digital Trainer DT-01 or the following components

                      Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches

                      THEORY

                      3-State Logic Sometimes it is necessary to isolate one part of circuit from the other part For this purpose some TTL ICs are designed with 3-state logic Such devices have three possible output states high low and high impedance The device can be put into high impedance state by a control signal applied to an appropriate pin When such a device is in high impedance state there is very high impedance at its output effectively isolating the device from whatever circuitry the output normally drives 74245 Octal Bus Transceivers A bus is any conducting path or set of paths having electrical connections to one or more devices 74245 octal bus transceivers are mainly used to control connectivity between two devices or circuits It also provides direction control for signal flow Function of various pin of this IC is given below

                      bull A1 through A8 Bus A bull B1 through B8 Bus B bull G΄ Active low enable input When high sets all the bus pins to high impedance state bull DIR Direction control for signal flow When set to high logic level transfers bus A

                      data to B bus When set to low logic level transfers bus B data to A bus bull VCC and GND Supply connections lines Serial and Parallel Port Connectors A Parallel Port can consist of only 25 pin port adapter called a DB-25 and a serial port can consist of either a 25 pin port adapter called a DB-25 or 9 pin adapter called a DB-9 port adapter Whether the port is a 9 pin or 25 pin it can accomplish all of the same tasks that serial port communications have been designed for

                      59

                      Logic Design amp Switching Theory 1 Lab Session 15 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                      60

                      Each adapter can be a male type connector with pins or a female type adapter with tiny holes Generally a PRINTER port (called LPT1) on the back of a computer is female type adapter and we need to use MALE DB-25 pin cable on it for PRINTER connection or for parallel LAPLINK cable And a COM port on the back of a computer is male for the serial ports but it may not necessarily be Parallel Port Connector ndash DB-25 The DB-25 connector (named for its B-size D-shaped shell and 25 pins) is practically ubiquitous in the electronics industry The DB-25 connector is used for a variety of purposes Two common applications are RS-232EIA-232 (serial) connections and the parallel printer interface on the IBM PC The DB-25 connector is also used for SCSI connections Normally the parallel port is used for output to a printer or other device It sends data 8-bits or one byte at a time in parallel The other lines available on the DB-25 connector are a combination of status lines control lines and ground lines The status and control lines are used for handshaking commands and feedback when we are talking to a printer

                      Figure 152 DB-25 Female Figure 151 DB-25 Male

                      Figure 153 Pin Layout for DB-25 As can be seen form figure 153 there are four types of pins in this connector

                      bull Data pins (8 pins - D0 to D7) Active high bidirectional lines

                      Logic Design amp Switching Theory 1 Lab Session 15 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering bull Control pins (4 pins - C0 to C3) C0 C1 and C3 are active low whereas C2 is active

                      high These lines also are bidirectional bull Status pins (5 pins ndash S3 to S7) Only S7 is active low rest are active high input lines bull Ground pins (8 pins) Used as a reference signal for the low (below 05 volts) charge

                      Parallel Port Addresses A DB-25 connector at a parallel port has three address one for each kind of pins register data status and control The first or base address generally refers to data register Second address is for status register and the third one is for control register In Windows 98 the base address is usually found to be 278H 378H or 3BCH Now if 378H is the base address then it refers to the data register whereas addresses for status and control register are respectively 379H and 37AH For Windows 98 the base address can be found as follows 1 On your Desktop right-click on My Computer and select Properties 2 Click on the Device Manager tab and find LPT1 under Plug and Play BIOS 3 After selecting LPT1 click the Properties button 4 Next select the Resources tab and the address should then appear next to InputOutput

                      Range Accessing parallel port through C Language Programming There are multiple functions in C Language for accessing external ports The most commonly used are listed below

                      bull unsigned char inportb(int portid) inportb reads a byte from a hardware port

                      bull int inport(int portid) reads a word from a hardware port

                      bull void outportb(int portid unsigned char value) outputs a byte to a hardware port

                      bull void outport(int portid int value) outputs a word to a hardware port

                      portid refers to the port address whereas value refers to the data to be sent TESTING 74245 USING PARALLEL PORT PC INTERFACING At one end the parallel port connector will be connected to the PC via parallel port cable and another connector (to be plugged into the PC parallel port slot) At the other end it will be connected to the buffer IC 74245 Data lines of the connector will be used to transfer 8-bit data between the PC and the buffer Out of the 8-bits of 74245 4-bits will be used to enter data which will be displayed at the monitor through a C language

                      61

                      Logic Design amp Switching Theory 1 Lab Session 15 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering program The remaining 4-bits will receive data from PC as entered by the user via keyboard

                      Circuit Diagram

                      Figure 154 Interface of 74245 to PC via Parallel Port

                      Procedure

                      1 Connect the DB-25 connector to the PC at one end and solder it to the circuit board at the other end

                      2 Connect various pins of the connector and 74245 according to the circuit diagram shown in figure 152

                      3 Using the functions listed in the previous section write a program in C language to operate various pins of the buffer The user interface of the program should provide option to the user whether to send or receive data from the port

                      4 Set DIR switch to 1 5 Try sending some data bits to the port The result should be displayed at the LEDs 6 Set DIR switch to 0 7 Set some binary 4-bit value through the switches Try reading it via parallel port

                      C Language Program

                      A program to access parallel port for data transfers

                      use header file include ltstdiohgt main program void main() define variable

                      62

                      Logic Design amp Switching Theory 1 Lab Session 15 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering unsigned int data=0 char choice while(1) printing option menu clrscr() printf(This program will send or receive a BCD digit from the parallel portn) printf(nPress your choice numbern) printf(n1 Send Data) printf(n2 Receive Data) printf(n3 Exitn) choice = getch() sending entered digit to the port if(choice == 1) input BCD digit printf(nEnter BCD digit to be sent to the port) data = getche() masking the first four bits data = data amp 0x0f sending to the port outportb(0x378data) printf(nThe BCD digit c has been sent to the port data) printing on screen the data received from the port else if(choice == 2) receiving data from the port data = inportb(0x378) masking the last four bits data = data amp 0xf0 shifting first four bits to make them the last four bits datagtgt=4 printf(nThe BCD digit set at the port is c data) exit else if(choice == 3) break key pressed is not in the menu else printf(nEnter valid choice number) printf(nnPress any key to continue) getch()

                      63

                      Logic Design amp Switching Theory 1 Lab Session 15 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                      ACTIVITY 1 In the above circuit DIR and G΄ inputs are hardwired Connect them to status or

                      control pins of the parallel port connector and control their function through your software program Circuit Diagram Program Code ______________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________

                      ___________________________________________________________________________________________________________________________________________________

                      64

                      Logic Design amp Switching Theory 1 Lab Session 15 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                      65

                      _____________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ _____________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ _______________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ _________________________________________________ _________________________________________________

                      Logic Design amp Switching Theory 1 Appendix A NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                      Appendix A

                      PIN DIAGRAMS OF THE ICS REQUIRED FOR THE LABORATORY SESSIONS Consult the TTLIC data book for internal diagrams and electrical characteristics of these ICs 7400 Quad 2-Input NAND 7402 Quad 2-Input NOR

                      7404 Hex Inverter 7408 Quad 2-Input AND

                      7410 Triple 3-Input NAND 7411 Triple 3-Input AND

                      7421 Dual 4-Input AND 7432 Quad 2-Input OR

                      66

                      Logic Design amp Switching Theory 1 Appendix A NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                      BCD-to-Seven Segm 7448 BCD-to-Seven Segment 7447 ent

                      Decoder (15V OC) Decoder (2kΩ pull-up output)

                      7473 Dual JK Flip-Flop 7474 Dual D-Type Flip-Flop

                      7476 Dual JK Flop-Flop -Bit Binary Full Adder 7483 4 with Fast Carry

                      86 Quad 2-Inpu 74138 3-to-8 Line 74 t Exclusive OR Decoder Demultiplexer

                      67

                      Logic Design amp Switching Theory 1 Appendix A NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                      68

                      74148 8-to-3 Line 16-to-1 Line Data

                      Priority Encoder 74150 Selector Multiplexer

                      74245 Oct nsceivers Universal Shift Register (PIPO) (3-State)

                      74194 4-Bit Bidirectional al Bus Tra

                      Logic Design amp Switching Theory 1 Appendix B NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                      Appendix B

                      DEBOUNCING CIRCUITRY FOR MECHANICAL SWITCHES Mechanical switches form the interface between human beings and computers or other digital systems For example a keyboard is a matrix of switches used to supply alphanumeric data to a computer Whatever the switch design it is a potential source of problems due to contact bounce The contact bounce creates a sense of narrow pulses when a switch is opened or closed An example of device whose operation would be adversely affected by contact bounce is a digital counter used to count the number of times a switch is depressed Eliminating the effects of contact bounce is called debouncing When data is entered into a computer via a keyboard a software debounce is often used This type of debouncing is a program that causes the computer to sample the switch terminal (ie to input data from it) many times in succession during the interval of time that contact bounce occurs If the data is sensed to be 1s (or 0s) for a specific number of consecutive samples then it is assumed that contact bounce has ended and the last value sensed is valid Hardware debouncing is the use of electronic circuitry to eliminate the effects of contact bounce There are numerous versions of such circuitry including those that use monostable multivibrators (one-shots) but the most straightforward is simply an RS latch Figure B1 shows the circuit When the switch is in position 1 R = 0 and S = 1 so the latch is set and the output (Q) is 1 When the switch is in position 0 R = 1and S = 0 so the latch is reset and the output is 0 When the switch is moved form one position to the other the latch changes state and bouncing occurs at either the R or the S input The bouncing does not affect the latch after it has change state An RS latch will remain set for example when its R input is 0 and its S input is alternately changed form 1 to 0

                      Figure B1 Use of RS latch to debounce a mechanical switch

                      69

                      • 01-ldst-Outer title
                        • Practical Workbook
                        • Logic Design amp Switching Theory I
                          • Dept of Computer amp Information Systems Engineering
                            • NED University of Engineering amp Technology
                            • Karachi ndash 75270 Pakistan
                              • 02-ldst-inner Title
                                • Practical Workbook
                                • Logic Design amp Switching Theory I
                                  • Dept of Computer amp Information Systems Engineering
                                    • NED University of Engineering amp Technology
                                    • Karachi ndash 75270 Pakistan
                                      • 03-ldst-general info
                                      • 04-ldst-introduction
                                      • 05-Table of Contents
                                        • CONTENTS
                                          • Lab Session No Object Page No
                                          • 1
                                          • Also implementing and testing the given circuit on a bread board
                                            • Working with Electronics Workbench
                                              • Driving a seven segment display using 7447 7448 driver IC
                                                • Designing a modulus-5 asynchronous up-counter using JK-FF
                                                  • Experimenting with 74194 4-bit bidirectional universal shift register
                                                      • 13
                                                          • 06-ldst-Exp01
                                                            • Lab Session 01
                                                            • OBJECT
                                                              • 1 Bread board
                                                              • 2 5 V - power supply
                                                              • 3 Multimeter
                                                              • 4 Logic probe
                                                              • 5 LEDs with resistors
                                                              • 6 Connecting wires
                                                              • 8 Following ICs and their datasheets
                                                                • THEORY
                                                                  • Logic Gates
                                                                  • 1 The AND Gate ndash An AND gatersquos output is 1 if and only if all its inputs are 1 If A and B are two inputs to an AND gate then output F of the gate is given as F = AB
                                                                  • 2 The OR Gate - An OR gatersquos output is 1 if at least one of its input is 1 If A and B are two inputs to an OR gate then output F of the gate is given as F = A+B
                                                                  • 3 The NOT Gate (Inverter) ndash Its output is 1 when its input is 0 and its output is 0 when the input is 1 ie it complements a digital variable If A is the input to a NOT gate then output F of the gate is given as
                                                                  • 4 The NAND Gate ndash Its output is 1 if at least one of its input is 0 This gate performs the same logic as an AND gate followed by an inverter If A and B are two inputs to a NAND gate then output F of the gate is given as
                                                                    • 5 The NOR Gate - The output of a NOR gate is 1 if and only if all its inputs are 0 This gate performs the same logic function as an OR gate followed by an inverter If A and B are two inputs to a NAND gate then output F of the gate is given as
                                                                        • DATA SHEETS
                                                                          • Logic expression for the given logic diagram __________________________________
                                                                              • 07-ldst-exp02
                                                                                • Working with Electronics Workbench
                                                                                  • 08-ldst-exp03
                                                                                    • Designing Half and Full Adder Circuits
                                                                                      • COMPONENTS AND APPARATUS REQUIRED
                                                                                        • 1 Following ICs and their Datasheets
                                                                                        • 7408 Quad 2-input AND Gate
                                                                                        • 2 Digital Trainer DT-01 or the following components
                                                                                          • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                          • Connecting wires Switches
                                                                                            • THEORY
                                                                                                • IMPLEMENTATION AND OBSERVATIONS
                                                                                                  • 09-ldst-Exp04
                                                                                                    • Lab Session 04
                                                                                                    • 1 Digital ICs and their Datasheets
                                                                                                    • 7408 Quad 2-input AND Gate
                                                                                                    • 2 Digital Trainer DT-01 or the following components
                                                                                                      • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                      • Connecting wires Switches
                                                                                                      • PROCEDURE
                                                                                                      • REDUCTION OF LOGIC EXPRESSION USING KARNAUGH MAP
                                                                                                      • OBSERVATIONS
                                                                                                      • RESULT
                                                                                                          • 10-ldst-Exp05
                                                                                                            • Lab Session 05
                                                                                                            • 1 Following ICs and their Datasheets
                                                                                                            • 7408 Quad 2-input AND Gate
                                                                                                            • 2 Digital Trainer DT-01 or the following components
                                                                                                              • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                              • (100 Ω) Connecting wires Switches
                                                                                                              • THEORY
                                                                                                                • IMPLEMENTATION AND OBSERVATIONS
                                                                                                                  • 11-ldst-Exp06
                                                                                                                    • OBJECT
                                                                                                                    • 1 Following ICs and their Datasheets
                                                                                                                    • 7408 Quad 2-input AND Gates or 7411 Triple 3-input AND Gates
                                                                                                                    • 2 Digital Trainer DT-01 or the following components
                                                                                                                      • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                      • Connecting wires Switches
                                                                                                                        • Figure 62 Circuit Diagram for 4 x 1 Multiplexer
                                                                                                                        • Implementation and Observations
                                                                                                                          • Circuit Diagram
                                                                                                                            • ACTIVITY
                                                                                                                              • 12-ldst-exp07
                                                                                                                                • 1 Following ICs and their Datasheets
                                                                                                                                • 7408 Quad 2-input or 7411 Triple 3-input AND Gates
                                                                                                                                • 2 Digital Trainer DT-01 or the following components
                                                                                                                                  • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                  • Connecting wires Switches
                                                                                                                                    • THEORY
                                                                                                                                        • Figure 72 Circuit Diagram for 2 x 4 Decoder 1 x 4 Demultiplexer
                                                                                                                                        • Implementation and Observations
                                                                                                                                          • Circuit Diagram
                                                                                                                                            • ACTIVITY
                                                                                                                                              • 13-ldst-Exp08
                                                                                                                                                • OBJECT
                                                                                                                                                • 1 Following ICs and their Datasheets
                                                                                                                                                • 7408 Quad 2-input or 7421 Dual 4-input AND Gates
                                                                                                                                                • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                  • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                  • Connecting wires Switches
                                                                                                                                                    • THEORY
                                                                                                                                                        • Figure 81 Circuit Diagram for 4 x 2 Priority Encoder
                                                                                                                                                        • Implementation and Observations
                                                                                                                                                          • Therefore if GS A2 A1 and A0 are all low then it shows that line 0 is selected and if E0 A2 A1 and A0 are all low then it shows that none of the inputs selected E0 and GS cannot be in the same state provided that E1 is enabled
                                                                                                                                                          • Circuit Diagram
                                                                                                                                                            • ACTIVITY
                                                                                                                                                              • 14-ldst-exp09
                                                                                                                                                                • OBJECT
                                                                                                                                                                • 1 Following ICs and their Datasheets
                                                                                                                                                                • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                  • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                  • Connecting wires Switches
                                                                                                                                                                    • THEORY
                                                                                                                                                                      • Parity Generator
                                                                                                                                                                        • Let x y and z be the three bits that constitute the message and are the input to the Odd Parity Generator Circuit Since it is an odd parity system the bit P is generated so as to make the total number of 1s odd (including P) The function P can be expressed as follows
                                                                                                                                                                        • Figure 91 Circuit Diagram for a 3-bit Parity Generator
                                                                                                                                                                          • C = x Ο y Ο z Ο P
                                                                                                                                                                            • Implementation and Observations
                                                                                                                                                                              • ACTIVITY
                                                                                                                                                                                  • 15-ldst-exp10
                                                                                                                                                                                    • Driving a seven segment display using 7447 7448 driver IC
                                                                                                                                                                                    • COMPONENTS AND APPARATUS REQUIRED
                                                                                                                                                                                    • 1 Following ICs and their Datasheets
                                                                                                                                                                                    • 7447 7448 BCD to Seven Segment Driver
                                                                                                                                                                                    • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                      • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches
                                                                                                                                                                                        • THEORY
                                                                                                                                                                                        • Seven Segment Displays
                                                                                                                                                                                        • CIRCUIT DIAGRAM
                                                                                                                                                                                        • Figure 102 Circuit diagram for 7447driving a common-anode display
                                                                                                                                                                                            • IMPLEMENTATION AND OBSERVATIONS
                                                                                                                                                                                              • Decimal Digit
                                                                                                                                                                                              • BCD Inputs
                                                                                                                                                                                              • Seven Segment Outputs
                                                                                                                                                                                              • D
                                                                                                                                                                                              • C
                                                                                                                                                                                              • B
                                                                                                                                                                                              • A
                                                                                                                                                                                              • a
                                                                                                                                                                                              • b
                                                                                                                                                                                              • c
                                                                                                                                                                                              • d
                                                                                                                                                                                              • e
                                                                                                                                                                                              • f
                                                                                                                                                                                              • g
                                                                                                                                                                                              • 0
                                                                                                                                                                                              • 0
                                                                                                                                                                                              • 0
                                                                                                                                                                                              • 0
                                                                                                                                                                                              • 0
                                                                                                                                                                                              • 1
                                                                                                                                                                                              • 0
                                                                                                                                                                                              • 0
                                                                                                                                                                                              • 0
                                                                                                                                                                                              • 1
                                                                                                                                                                                              • 2
                                                                                                                                                                                              • 0
                                                                                                                                                                                              • 0
                                                                                                                                                                                              • 1
                                                                                                                                                                                              • 0
                                                                                                                                                                                              • 3
                                                                                                                                                                                              • 0
                                                                                                                                                                                              • 0
                                                                                                                                                                                              • 1
                                                                                                                                                                                              • 1
                                                                                                                                                                                              • 4
                                                                                                                                                                                              • 0
                                                                                                                                                                                              • 1
                                                                                                                                                                                              • 0
                                                                                                                                                                                              • 0
                                                                                                                                                                                              • 5
                                                                                                                                                                                              • 0
                                                                                                                                                                                              • 1
                                                                                                                                                                                              • 0
                                                                                                                                                                                              • 1
                                                                                                                                                                                              • 6
                                                                                                                                                                                              • 0
                                                                                                                                                                                              • 1
                                                                                                                                                                                              • 1
                                                                                                                                                                                              • 0
                                                                                                                                                                                              • 7
                                                                                                                                                                                              • 0
                                                                                                                                                                                              • 1
                                                                                                                                                                                              • 1
                                                                                                                                                                                              • 1
                                                                                                                                                                                              • 8
                                                                                                                                                                                              • 1
                                                                                                                                                                                              • 0
                                                                                                                                                                                              • 0
                                                                                                                                                                                              • 0
                                                                                                                                                                                              • 9
                                                                                                                                                                                              • 1
                                                                                                                                                                                              • 0
                                                                                                                                                                                              • 0
                                                                                                                                                                                              • 1
                                                                                                                                                                                                • ACTIVITY
                                                                                                                                                                                                  • 16-ldst-exp11
                                                                                                                                                                                                    • Lab Session 11
                                                                                                                                                                                                      • OBJECT
                                                                                                                                                                                                      • COMPONENTS AND APPARATUS REQUIRED
                                                                                                                                                                                                        • 1 Following ICs and their Datasheets
                                                                                                                                                                                                        • 7473 7476 JK Flip-Flop
                                                                                                                                                                                                        • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                          • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                          • Connecting wires Switches
                                                                                                                                                                                                            • THEORY
                                                                                                                                                                                                                • Flip-Flop
                                                                                                                                                                                                                • JK Flip-Flop
                                                                                                                                                                                                                  • Circuit Diagram
                                                                                                                                                                                                                    • Observations
                                                                                                                                                                                                                      • ACTIVITY
                                                                                                                                                                                                                          • 17-ldst-exp12
                                                                                                                                                                                                                            • Lab Session 12
                                                                                                                                                                                                                              • OBJECT
                                                                                                                                                                                                                              • GIVEN STATE DIAGRAM
                                                                                                                                                                                                                              • Figure 121 State Diagram
                                                                                                                                                                                                                              • COMPONENTS AND APPARATUS REQUIRED
                                                                                                                                                                                                                                • 1 Following ICs and their Datasheets
                                                                                                                                                                                                                                • 7474 D Flip-Flop
                                                                                                                                                                                                                                • ICs of basic gates (AND OR NOT XOR etc) as required
                                                                                                                                                                                                                                • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                                  • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                                                  • Connecting wires Switches
                                                                                                                                                                                                                                    • THEORY
                                                                                                                                                                                                                                        • Sequential Circuits
                                                                                                                                                                                                                                          • 18-ldst-exp13
                                                                                                                                                                                                                                            • Lab Session 13
                                                                                                                                                                                                                                              • Designing a modulo-5 asynchronous up-counter using JK-FF
                                                                                                                                                                                                                                                • 1 Following ICs and their Datasheets
                                                                                                                                                                                                                                                • 7400 Quad 2-input or 7410 Triple 3-input NAND Gates
                                                                                                                                                                                                                                                • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                                                  • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                                                                  • Connecting wires Switches
                                                                                                                                                                                                                                                    • THEORY
                                                                                                                                                                                                                                                        • Figure 131 A Mod-5 Asynchronous Up Counter
                                                                                                                                                                                                                                                        • Implementation and Observations
                                                                                                                                                                                                                                                          • ACTIVITY
                                                                                                                                                                                                                                                              • 19-ldst-exp14
                                                                                                                                                                                                                                                                • Experimenting with 74194 4-bit bidirectional universal shift register
                                                                                                                                                                                                                                                                • 1 Following ICs and their Datasheets
                                                                                                                                                                                                                                                                • 74194 4-bit bidirectional universal shift register
                                                                                                                                                                                                                                                                • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                                                                  • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                                                                                  • Connecting wires Switches
                                                                                                                                                                                                                                                                    • THEORY
                                                                                                                                                                                                                                                                      • Shift Registers
                                                                                                                                                                                                                                                                      • Bidirectional Shift Registers
                                                                                                                                                                                                                                                                      • Universal Shift Registers
                                                                                                                                                                                                                                                                        • S1
                                                                                                                                                                                                                                                                          • Circuit Diagram
                                                                                                                                                                                                                                                                          • ACTIVITY
                                                                                                                                                                                                                                                                              • 20-ldst-exp15
                                                                                                                                                                                                                                                                                • COMPONENTS AND APPARATUS REQUIRED
                                                                                                                                                                                                                                                                                • 1 Parallel Port Connectors (DB-25) with Cable
                                                                                                                                                                                                                                                                                • 2 Personal Computer with Windows 98 and TurboC Compiler Installed
                                                                                                                                                                                                                                                                                • 3 Following ICs and their Datasheets
                                                                                                                                                                                                                                                                                • 74245 Octal Bus Transceivers with 3-State Outputs
                                                                                                                                                                                                                                                                                • 4 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                                                                                  • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                                                                                                    • Connecting wires Switches
                                                                                                                                                                                                                                                                                      • THEORY
                                                                                                                                                                                                                                                                                      • 3-State Logic
                                                                                                                                                                                                                                                                                        • Serial and Parallel Port Connectors
                                                                                                                                                                                                                                                                                        • Parallel Port Connector ndash DB-25
                                                                                                                                                                                                                                                                                          • Accessing parallel port through C Language Programming
                                                                                                                                                                                                                                                                                              • 21-ldst-appendixA
                                                                                                                                                                                                                                                                                              • 22-ldst-appendixB
                                                                                                                                                                                                                                                                                                • DEBOUNCING CIRCUITRY FOR MECHANICAL SWITCHES

                        Logic Design amp Switching Theory 1 Lab Session 01 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering 3 The NOT Gate (Inverter) ndash Its output is 1 when its input is 0 and its output is 0 when

                        the input is 1 ie it complements a digital variable If A is the input to a NOT gate then output F of the gate is given as AF =

                        4 The NAND Gate ndash Its output is 1 if at least one of its input is 0 This gate performs the same logic as an AND gate followed by an inverter If A and B are two inputs to a NAND gate then output F of the gate is given as BAF =

                        5 The NOR Gate - The output of a NOR gate is 1 if and only if all its inputs are 0 This gate performs the same logic function as an OR gate followed by an inverter If A and B are two inputs to a NAND gate then output F of the gate is given as BAF +=

                        All the above gates have one output and two or more inputs except the NOT gate which has only one input

                        PROCEDURE FOR TESTING THE LOGIC GATES IN GIVEN ICs

                        1 Set the power supply to 5V With the help of a multimeter check the voltage at the output knobs of the power supply

                        2 Connect wires long enough to reach the breadboard with the two knobs of the power supply Again using multimeter check voltage at the non-connected end of the wires

                        3 Insert the 7408 quad 2 input AND gate IC on to the bread board and make supply and ground connections by joining 5V wire to pin 14 and 0V wire to pin 7

                        4 Consult ICrsquos internal connection diagram for input and output pins of the first AND gate Connect input pins to logic 0 (0V) and observe the output using LED or logic probe You can also connect switches at the input lines to facilitate toggling between 1 and 0

                        5 Try different combinations of logic levels at the two inputs Again observe the output 6 Repeat the last two steps for all other gates of the same IC Record the observations 7 Repeat this procedure for all other ICs

                        OBSERVATIONS

                        Gate Input A Input B Expected Output Observed Output

                        AND

                        0 0 0 1 1 0 1 1

                        OR

                        0 0 0 1 1 0 1 1

                        NOT 0 - 1 -

                        NAND

                        0 0 0 1 1 0 1 1

                        14

                        Logic Design amp Switching Theory 1 Lab Session 01 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                        NOR

                        0 0 0 1 1 0 1 1

                        DATA SHEETS

                        Figure 11

                        15

                        Logic Design amp Switching Theory 1 Lab Session 01 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                        16

                        GIVEN CIRCUIT

                        Figure 12

                        PROCEDURE FOR IMPLEMENTATION OF THE GIVEN CIRCUIT 1 Set the power supply 2 Insert ICs on the bread board and make their supply and ground connections 3 As given in the logic diagram make connections using wires and gates in the ICs 4 Apply different combinations at the three inputs and observe the output OBSERVATIONS Logic expression for the given logic diagram __________________________________

                        A B C Expected Output Observed Output 0 0 0 0 0 1 0 1 0 0 1 1 1 0 0 1 0 1 1 1 0 1 1 1

                        Logic Design amp Switching Theory 1 Lab Session 02 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                        Lab Session 02

                        OBJECT

                        Working with Electronics Workbench

                        ELECTRONICS WORKBENCH - EWB Electronics Workbench is a computer aided design tool that provides you with all the components and instruments necessary to create board-level designs It has complete mixed analog and digital simulation and graphical waveform analysis allowing you to design your circuit and then analyze it using different simulated instruments and analysis options It is fully integrated and interactive thus you can change your circuits quickly allowing fast and repeated what-if analysis Electronics Workbench provides the following kind of components bull Sources parts bin (AC voltage source Vcc source ground battery etc) bull Basic parts bin (resistors capacitors transformers switches etc) bull Diodes parts bin bull Transistors parts bin bull Analog ICs parts bin (op-amps etc) bull Mixed ICs parts bin (ADCs DACs 555 timers etc) bull Digital ICs parts bin (AND OR adders multiplexers etc) bull Indicators parts bin (voltmeter ammeter probe displays etc) bull Controls parts bin (voltage differentiator multiplier etc) bull Instruments parts bin (multimeter oscilloscope function generator etc) bull Miscellaneous parts bin (write data textbox etc)

                        o Write data This component allows you to save simulation results as an ASCII file o Text Box Use this to add descriptive text anywhere in a circuit

                        ACTIVITY

                        Design circuit for the logic expression )( CBDCABAF ++=

                        Procedure 1 From Logic Gates Parts Bin Drag and drop the required logic gates on the design

                        area Use Component Properties dialog box to customize these gates 2 Connect the terminal of these gates according to the given expression Use additional

                        connectors form the Basic Parts Bin if you want to connect more than wire at a single node

                        3 Drag and drop a probe from Indicators Parts Bin Use Component Properties dialog box to customize the color and other properties of the probe Connect this probe at the output terminal of the circuit to indicate results

                        4 Select four switches form Basic Parts Bin Specify the key that controls the switch by typing its name in the Value tab of the Component Properties dialog box For

                        17

                        Logic Design amp Switching Theory 1 Lab Session 02 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                        18

                        example if you want the switch to close or open when digit lsquo1rsquo is pressed type 1 in the Value tab then click OK Assign different keys to all the switches

                        5 Connect the output terminals of these switches to each of the four inputs A B C and D of the circuit

                        6 Drag and drop Vcc and Ground form the Sources Parts Bin 7 Connect Vcc terminal to one end and Ground terminal to the other end of all the

                        switches 8 Label the circuit properly using text boxes found in the miscellaneous parts bin 9 Run the circuit using the Activate Simulation switch Use the keys you have assigned

                        to the switches to toggle them between Vcc and Ground connections thus providing 1 or 0 respectively to the inputs Record the results as indicated by the probe for all possible combinations of 1s and 0s at the inputs

                        EWB Circuit

                        Figure 21

                        Observations

                        A B C D Expected Output Observed Output 0 0 0 0 0 0 0 1 0 0 1 0 0 0 1 1 0 1 0 0 0 1 0 1 0 1 1 0 0 1 1 1 1 0 0 0 1 0 0 1 1 0 1 0 1 0 1 1 1 1 0 0 1 1 0 1 1 1 1 0 1 1 1 1

                        Logic Design amp Switching Theory 1 Lab Session 03 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                        Lab Session 03

                        OBJECT

                        Designing Half and Full Adder Circuits COMPONENTS AND APPARATUS REQUIRED 1 Following ICs and their Datasheets

                        bull 7408 Quad 2-input AND Gate bull 7432 Quad 2-input OR Gate bull 7486 Quad 2-input XOR Gate

                        2 Digital Trainer DT-01 or the following components Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches

                        THEORY Half Adder A combination circuit that performs the addition of two bits without accounting for the previous carry is called half adder It needs two binary inputs and two binary outputs The input variables designate the augend and addend bits The output variables produce the sum and carry The simplified sum of product expressions for a half adder are

                        yxyxyxS oplus=+= yxC =

                        Figure 31 Circuit diagram for Half Adder

                        19

                        Logic Design amp Switching Theory 1 Lab Session 03 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                        bles produce the sum and carry The simplified sum of product expressions for a half adder are

                        Full Adder

                        A combinational circuit that performs the addition of three input bits It consist of three inputs and two outputs Two of the input variables represent the two significant bits to be added The third input represents the carry from the previous lower significant position The output varia

                        zyxzyxzyxzyxzyxS oplusoplus=+++= yxzyxzyzxxyC )( +oplus=++=

                        Figure 32 Circuit diagram for Full Adder

                        efer to laboratory session 01 for procedure) and record the observations in the following ta

                        alf Adde ull Adder Inputs u

                        IMPLEMENTATION AND OBSERVATIONS

                        Implement the half adder and full adder circuits on a bread board (prepare the pin diagram (use appendix A) and r

                        bles H r F

                        Inputs Outputs Outp ts x y Carry Su Carry Sum m x y z 0 0 0 0 0 0 1 0 0 1 1 0 0 1 0 1 1 0 1 1 1 0 0 1 0 1 1 1 0 1 1 1

                        20

                        Logic Design amp Switching Theory 1 Lab Session 03 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                        at of your designed circuit Attach hardcopy of the output form electronic workbench

                        at of your designed circuit Attach hardcopy of the output form lectronic workbench here

                        ACTIVITY

                        1 Simulate half adder circuit using Electronics Workbench Compare the results of simulation with thhere

                        2 Design a full subtractor circuit and simulate it using Electronics Workbench Compare the results of simulation with the

                        21

                        Logic Design amp Switching Theory 1 Lab Session 04 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                        Lab Session 04 OBJECT

                        Use of Karnaugh Map (SOP-Expression) method GIVEN LOGIC EXPRESSION

                        F (A B C D) = sum ( 0 1 2 4 5 6 8 9 12 13 14 ) COMPONENTS AND APPARATUS REQUIRED 1 Digital ICs and their Datasheets

                        bull 7408 Quad 2-input AND Gate bull 7432 Quad 2-input OR Gate bull 7404 Hex Inverter

                        2 Digital Trainer DT-01 or the following components Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches PROCEDURE 1 Use Karnaugh map to reduce the given function 2 Draw the circuit diagram for the obtained reduced function 3 Implement the reduced circuit using digital ICs on a bread board (prepare the pin

                        diagram (use appendix A) and refer to laboratory session 01 for procedure) and record the observations

                        REDUCTION OF LOGIC EXPRESSION USING KARNAUGH MAP F

                        CD

                        AB DC

                        DC DC

                        DC

                        BA0 1 3 2

                        BA4 5 7 6

                        BA12 13 15 14

                        BA8 9 11 10

                        Reduced form of the given logic expression is __________________________________

                        22

                        Logic Design amp Switching Theory 1 Lab Session 04 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                        LOGIC DIAGRAM (REDUCED FORM) OBSERVATIONS

                        A B C D Output 0 0 0 0 0 0 0 1 0 0 1 0 0 0 1 1 0 1 0 0 0 1 0 1 0 1 1 0 0 1 1 1 1 0 0 0 1 0 0 1 1 0 1 0 1 0 1 1 1 1 0 0 1 1 0 1 1 1 1 0 1 1 1 1

                        RESULT The reduced form (SOP Expression) of the given logic function is

                        ____________________________________________________________

                        The observation table reflects the given logic function

                        23

                        Logic Design amp Switching Theory 1 Lab Session 04 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                        ACTIVITY 1 Using Electronics Workbench derive a truth table and logic circuit for the following logic expression

                        BAAF +=

                        Procedure 1 From the Instruments Parts Bin drag and drop Logic Converter on the design area 2 Double click the Logic Converter to reveal Logic Converter dialog box This dialog

                        box shows various conversion options between truth table logic expression and logic circuit

                        3 Enter the given logic expression in the edit box found at the end of the dialog box Use lsquo to represent invert of a variable For example A is written as Arsquo

                        4 Click the Boolean Expression to Truth Table button The truth table appears in the logic converters display

                        5 Now click the Boolean Expression to Circuit button This creates the logic circuit for the given expression in the design area Label the diagram if needed

                        Resulting Logic Circuit For the given expression the final circuit will look like

                        Figure 41

                        24

                        Logic Design amp Switching Theory 1 Lab Session 04 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                        ACTIVITY 2

                        Using Electronics Workbench find a simplified logic expression and circuit for the following truth table

                        A B C Output 0 0 0 1 0 0 1 1 0 1 0 0 0 1 1 1 1 0 0 0 1 0 1 0 1 1 0 0 1 1 1 1

                        Procedure 1 Click three input channels from A to H across the top of the logic converter The

                        display area below the terminals fills up with the necessary combinations of ones and zeros to fulfill the input conditions The values in the output column on the right are initially set to 0

                        2 Edit the output column to specify the desired output for each input condition To change an output value select it and type a new value 1 0 or x An x indicates a donrsquot care condition

                        3 To convert this truth table to a Boolean expression click the Truth Table to Boolean Expression button The Boolean expression will be displayed at the bottom of the logic converter

                        4 Simplify the expression by clicking the Simplify button 5 Now click the Boolean Expression to Circuit button This creates the logic circuit for

                        the given expression in the design area Resulting Logic Circuit For the given truth table the final simplified circuit will look like

                        Figure 42

                        25

                        Logic Design amp Switching Theory 1 Lab Session 04 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                        ACTIVITY 3

                        Using Electronics Workbench find the logic expression and truth table for the following logic circuit

                        Figure 43

                        Procedure 1 Attach the input terminals of the logic converter to up to four input points in the

                        circuit 2 Connect the single output of the circuit to the output terminal on the logic converter

                        icon 3 Click the Circuit to Truth Table button The truth table appears in the logic

                        converters display 4 To convert this truth table to a Boolean expression click the Truth Table to Boolean

                        Expression button The Boolean expression will be displayed at the bottom of the logic converter

                        Resulting Logic Expression Logic Expression for the given circuit is found to be _____________________________

                        26

                        Logic Design amp Switching Theory 1 Lab Session 04 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                        27

                        For activities 1 2 and 3 attach hardcopy of the output (truth table logic expression and logic circuit) form electronic workbench here

                        Logic Design amp Switching Theory 1 Lab Session 05 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                        Lab Session 05 Lab Session 05 OBJECT OBJECT

                        Designing a BCD Adder Designing a BCD Adder COMPONENTS AND APPARATUS REQUIRED COMPONENTS AND APPARATUS REQUIRED

                        1 Following ICs and their Datasheets 1 Following ICs and their Datasheets bull 7408 Quad 2-input AND Gate bull 7408 Quad 2-input AND Gate bull 7432 Quad 2-input OR Gate bull 7432 Quad 2-input OR Gate bull 7483 4-bit Binary Adder bull 7483 4-bit Binary Adder

                        2 Digital Trainer DT-01 or the following components 2 Digital Trainer DT-01 or the following components Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors (100 Ω) Connecting wires Switches (100 Ω) Connecting wires Switches

                        THEORY THEORY

                        A BCD Adder is a combinational circuit that adds two BCD digits in parallel and produces a sum digit also in BCD A BCD Adder is a combinational circuit that adds two BCD digits in parallel and produces a sum digit also in BCD

                        A4 A3 A2 A1 B4 B3 B2 B1

                        7483-BCD ADDER

                        Cout (C4 ) Z4 Z3 Z2 Z1 Cin(C0)

                        A4 A3 A2 A1 B4 B3 B2 B1

                        7483-BCD ADDER

                        Cout

                        (C4 ) Z4 Z3 Z2 Z1 Cin(C0)

                        Figure 51 BCD Adder Circuit

                        28

                        Logic Design amp Switching Theory 1 Lab Session 05 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                        29

                        A BCD adder must include the correction logic in its internal construction The two BCD digits together with the input carry are first added using a 4-bit binary adder to produce the binary sum If no output carry is generated and the binary sum is less than or equal to 9 then the corresponding BCD sum is identical and therefore no conversion is needed When the output carry is equal to 1 or the binary sum is greater than 9 then a binary 0110 is added to the binary sum through another 4-bit binary adder If Cout is the carry output and Z4Z3Z2Z1 is the binary sum form the first 4-bit binary adder then the following equation indicates the condition when a binary 0110 is to be added

                        C = COUT + Z4Z2 + Z4Z3 IMPLEMENTATION AND OBSERVATIONS Implement the BCD adder circuit according to figure 51 on a bread board (prepare the pin diagram (use appendix A) and refer to laboratory session 01 for procedure) A BCD adder has nine input bits (two BCD digits and a carry bit) which can result in a total of 512 combinations of which 312 inputs are donrsquot care Since it is a very lengthy procedure to record results for 200 valid input combinations therefore for simplicity just record results for any eight combinations in the following table

                        Input Carry

                        BCD Digit 1 BCD Digit 2 Carry Output

                        BCD Sum A4 A3 A2 A1 B4 B3 B2 B1 Z4 Z3 Z2 Z1

                        Logic Design amp Switching Theory 1 lab Session 06 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                        Lab Session 06

                        OBJECT

                        bull Designing of a 4 x 1 Multiplexer bull Experimenting with 74150 IC

                        COMPONENTS AND APPARATUS REQUIRED 1 Following ICs and their Datasheets

                        bull 7408 Quad 2-input AND Gates or 7411 Triple 3-input AND Gates bull 7432 Quad 2-input OR Gates bull 7404 Hex Inverter bull 74150 16 x 1 MUX

                        2 Digital Trainer DT-01 or the following components Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches THEORY

                        Multiplexers A digital data Multiplexer (MUX) is a combinational circuit having several data inputs and a single output A set of data-select inputs is used to control which of the data inputs is routed to the single output A multiplexer is also called a data selector because of this ability to select which data input is connected o the output Normally there are 2n input lines and n selection lines whose bit combination determine which input is selected DESIGN OF A 4 x 1 MULTIPLEXER A 4 x 1 multiplexer is capable of selecting one of four data inputs (see figure 61) The 2-bit binary number at the data select inputs S1 and S0 specifies which of the four data inputs is to be routed to the output Since there are two data select inputs therefore they can select 22 = 4 different data inputs lines

                        S0 S1 D0 D1

                        D2 D3

                        Data-select Inputs Output

                        Data Inputs

                        Figure 61 Block Diagram of a 4 x1 Multiplexer

                        30

                        Logic Design amp Switching Theory 1 lab Session 06 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                        Figure 62 Circuit Diagram for 4 x 1 Multiplexer

                        Implementation and Observations

                        Implement the 4 x 1 Multiplexer circuit (figure 62) on a bread board (prepare the pin diagram (use appendix A) and refer to laboratory session 01 for implementation procedure) and record the observations in the following table For each data select combination specify the switch number as well as the binary value present on that selected switch

                        S1 S0 Output 0 0 0 1 1 0 1 1

                        TESTING OF 74150 - 16 x 1 MUX

                        The 74150 IC has sixteen data inputs and four data-selection lines Function of various pins of this IC is described below

                        bull E0 through E15 Data input lines

                        31

                        Logic Design amp Switching Theory 1 lab Session 06 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering bull A B C D Data select lines with D being the MSB bull W Active low output line bull Grsquo Active low enable line bull VCC and GND Supply connections lines

                        Circuit Diagram

                        Figure 63 Pin connections of 74150 for selecting E0

                        Testing Procedure

                        bull Make connections as shown in the circuit diagram bull Apply different data (1 or 0) at data inputs that are labeled as E0 to E15 Only

                        connection for E0 is shown is the figure for simplicity bull Select the data input E0 with the help of data selectors A B C and D bull Observe the output which shows the complement of the data from E0 bull Select all the sixteen data inputs one by one and record your observations in the

                        following table

                        32

                        Logic Design amp Switching Theory 1 lab Session 06 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                        33

                        Observations

                        Grsquo D C B A W Grsquo D C B A W 0 0 0 0 0 0 1 0 0 0 0 0 0 0 1 0 1 0 0 1 0 0 0 1 0 0 1 0 1 0 0 0 0 1 1 0 1 0 1 1 0 0 1 0 0 0 1 1 0 0 0 0 1 0 1 0 1 1 0 1 0 0 1 1 0 0 1 1 1 0 0 0 1 1 1 0 1 1 1 1

                        ACTIVITY 1 Consider 4x1 Multiplexer Draw the output wave-form for the following data inputs

                        (E0 E1 E2 E3) and select lines A B (B being the MSB) Output is W

                        E3 E2 E1 E0 A B

                        W

                        2 Using the 4 x 1 MUX designed in this laboratory session implement the following logical function F (A B C) = Σ (0147)

                        Show your working and input connections in the following block diagram according to the circuit you have implemented

                        4 x 1 MUX

                        S0 S1

                        Output D0

                        D1

                        D2

                        D3

                        Logic Design amp Switching Theory 1 Lab Session 07 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                        Lab Session 07

                        OBJECT

                        bull Designing of a 2 x 4 Decoder 1 x 4 Demultiplexer bull Experimenting with 74138 IC

                        COMPONENTS AND APPARATUS REQUIRED 1 Following ICs and their Datasheets

                        bull 7408 Quad 2-input or 7411 Triple 3-input AND Gates bull 7404 Hex Inverter bull 74138 3 x 8 Decoder

                        2 Digital Trainer DT-01 or the following components Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches THEORY

                        Decoder A Decoder is a combinational circuit that converts binary information form n input lines to a maximum of 2n unique output lines In practical applications decoders are often used for selecting one of several devices

                        Demultiplexer A decoder with an enable input can function as a Demultiplexer A Demultiplexer (DMUX) id a circuit that receives information on a single line and transmits this information on one of 2n possible output lines The selection of a specific output line is controlled by the bit values of n selection lines DESIGN OF A 2 x 4 DECODER 1 x 4 DEMULTIPLEXER A 2 x 4 decoder is capable of selecting one of four output lines (see figure 71 (a)) The 2-bit binary number at the data inputs S1 and S0 specifies which of the four data inputs is to be selected If we add an enable pin and use it as an input line then this decoder can be converted to a 1 x 4 Demultiplexer where S1 and S0 will select a line to which data input is to be routed (see figure 71 (b))

                        Select S0 S0 Inputs

                        S1 D0 D1

                        D2

                        D3

                        Enable (a) Block Diagram of a 2 x 4 Decoder

                        Figure 71

                        S1 D0 D1

                        D2

                        D3

                        Inputs

                        Data Input (b) Block Diagram of a 1 x 4 Demulptiplexer

                        34

                        Logic Design amp Switching Theory 1 Lab Session 07 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                        Figure 72 Circuit Diagram for 2 x 4 Decoder 1 x 4 Demultiplexer

                        Implementation and Observations Implement the 2 x 4 Decoder 1 x 4 Demultiplexer circuit (figure 72) on a bread board (prepare the pin diagram (use appendix A) and refer to laboratory session 01 for implementation procedure) and record the observations in the following table

                        Enable Data Input S1 S0 D0 D1 D2 D3

                        0 0 0 0 0 1 0 1 0 0 1 1 1 0 0 1 0 1 1 1 0 1 1 1

                        TESTING OF 74138 3 x 8 Decoder The 74138 IC has three inputs and eight output lines It has three enable inputs and for the IC to function all three inputs need to be enabled Function of various pins of this IC is described below

                        35

                        Logic Design amp Switching Theory 1 Lab Session 07 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                        bull Y0 through Y7 Active low data outputs bull A B C Input select lines with C being the MSB bull G1 Active high enable Input bull G2Arsquo and G2Brsquo Active low enable Inputs bull VCC and GND Supply connections lines Circuit Diagram

                        Figure 73 Pin connections of 74138

                        Testing Procedure

                        bull Make connections as shown in the circuit diagram bull Apply different combinations of 1s and 0s at data inputs bull Observe the output and record your observations in the following table

                        Observations

                        C B A Y0 Y1 Y2 Y3 Y4 Y5 Y6 Y7 0 0 0 0 0 1 0 1 0 0 1 1 1 0 0 1 0 1 1 1 0 1 1 1

                        36

                        Logic Design amp Switching Theory 1 Lab Session 07 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                        37

                        ACTIVITY ACTIVITY 1 What will be the binary values at the outputs Y0 through Y7 of 74138 if 1 What will be the binary values at the outputs Y0 through Y7 of 74138 if

                        bull All three enable pins are connected to ground bull All three enable pins are connected to ground __________________________________________________________________________________________________________________________________________ __________________________________________________________________________________________________________________________________________ _____________________________________________________________________ _____________________________________________________________________

                        bull All three enable pins are connected to VCC bull All three enable pins are connected to VCC _______________________________________________________________________________________________________________________________________________________________________________________________________________

                        _______________________________________________________________________________________________________________________________________________________________________________________________________________

                        2 Show connections for 74138 in order to use it as a 1 x 8 Demultiplexer 2 Show connections for 74138 in order to use it as a 1 x 8 Demultiplexer

                        3 Consider a 2 x 4 Decoder with two enable inputs (one active high - G and one active low ndash Grsquo) Draw the output wave-forms for D0 D1 D2 and D3 if the two select inputs are A and B (B being the MSB) All outputs are active low

                        Grsquo

                        G

                        A B

                        D0 D1 D2

                        D3

                        Logic Design amp Switching Theory 1 Lab Session 08 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                        Lab Session 08 OBJECT

                        bull Designing of a 4 x 2 Priority Encoder bull Experimenting with 74148 IC

                        COMPONENTS AND APPARATUS REQUIRED

                        1 Following ICs and their Datasheets

                        bull 7408 Quad 2-input or 7421 Dual 4-input AND Gates bull 7432 Quad 2-input OR Gates bull 7404 Hex Inverter bull 74148 Encoder

                        2 Digital Trainer DT-01 or the following components Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches

                        THEORY

                        Encoder An Encoder is a digital function that produces a reverse operation from that of a decoder An Encoder has 2n (or less) input lines and n output lines The output lines generate the binary code for the 2n input variables Priority Encoder

                        A simple encoder may produce an erroneous output if more than one of its inputs is high A Priority Encoder is one that responds to just one input among those that may be simultaneously high in accordance with some priority system The most common priority system is based on the relative magnitudes of the inputs whichever decimal input is largest is the one that is encoded

                        DESIGN OF A 4 x 2 Priority Encoder

                        The following equations represent the outputs of a 4 x 2 priority encoder 32 DDA +=

                        321 DDDB += As can be seen from the equations that input D0 which has a binary code 00 is not used in any equation A binary code 00 at the output indicates two conditions Either D0 is selected or no input is selected In order to differentiate these two conditions we will provide an additional output Z to indicate if at least one of the inputs is a 1 The equation for Z will be

                        4321 DDDDZ = If Z is 0 then the binary code 00 at the output indicates that D0 is selected and if Z is 1 then it indicates that no input line is selected

                        38

                        Logic Design amp Switching Theory 1 Lab Session 08 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                        Figure 81 Circuit Diagram for 4 x 2 Priority Encoder

                        it (figure 81) on a bread board (prepare the to laboratory session 01 for implementation

                        Implementation a Implement the 4 x 2 Priority Encoder circu

                        ram (use appendix A) and refer

                        nd Observations

                        pin diagprocedure) and record the observations in the following table

                        D3 D2 D1 D0 A B 0 0 0 1 0 0 1 x 0 1 x x 1 x x x

                        TESTING OF 74148 8 x 3 Octal Priority Encoder

                        imal digits There are nine of which three represents

                        ing any of the inputs is high

                        then it shows that line 0 is selected and if e inputs selected E0 and GS

                        cannot be in the same state provided that E1 is enabled

                        The 74148 is a priority encoder with active-Low input for dec

                        input) and five output linesinputs lines (including an enablethe binary code for the octal digit Function of various pins of this IC is described below

                        bull 0 through 7 Active low data inputs representing the octal digits A2 A1 A0 Active low output lines representing the binary code bullbull E1 Active low enable Input bull E0 Active low output indicating none of the inputs is high bull GS Active low output indicatbull VCC and GND Supply connections lines Therefore if GS A2 A1 and A0 are all low

                        then it shows that none of thE0 A2 A1 and A0 are all low

                        39

                        Logic Design amp Switching Theory 1 Lab Session 08 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                        Circuit Diagram

                        Figure 82 Pin connections of 74148

                        Testing Procedure bull Make connections as sho

                        binations of 1s and 0s at data inputs d record your observations in the following table

                        GS E0

                        wn in the circuit diagram bull Apply different combull Observe the output an Observations

                        0 1 2 3 4 5 6 7 A2 A1 A0 1 1 1 1 1 1 1 1 x x x x x x x 0 x x x x x x 0 1 x x x x x 0 1 1 x x x x 0 1 1 1 x x x 0 1 1 1 1 x x 0 1 1 1 1 1 x 0 1 1 1 1 1 1 0 1 1 1 1 1 1 1

                        40

                        Logic Design amp Switching Theory 1 Lab Session 08 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                        41

                        CTIVITY

                        Cascade the following two 74148 8 x 3 Priority Encoders to form 16 x 4 Priority

                        A 1

                        Encoder

                        Logic Design amp Switching Theory 1 Lab Session 09 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering `

                        Lab Session 09 OBJECT

                        Designing an Odd Parity Generator and Checker for a 3-bit Data COMPONENTS AND APPARATUS REQUIRED

                        1 Following ICs and their Datasheets

                        bull 7486 Quad 2-input Exclusive-OR Gates bull 7404 Hex Inverter

                        2 Digital Trainer DT-01 or the following components Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches

                        THEORY

                        Parity Generator When binary data is transmitted and processed it is ndash as are all electrical signals ndash susceptible to noise that can either alter or distort its contents 1s may be effectively changed to 0s and 0s to 1s To overcome this problem one or more bits are often added to the data as an aid in detecting errors caused by noise The most common of these is a Parity bit that signifies whether the total number of 1s in a code group is odd or even In an Odd Parity system the parity bit is made 0 or 1 as necessary to make the total number 1s odd (counting the parity bit itself) In an Even Parity system the parity bit is chosen to make the total number of 1s even Table 91 shows how parity bits would be added to BCD code group in both systems

                        Decimal BCD Value Parity Bit ABCD Odd Parity Even Parity

                        0 0000 1 0 1 0001 0 1 2 0010 0 1 3 0011 1 0 4 0100 0 1 5 0101 1 0 6 0110 1 0 7 0111 0 1 8 1000 0 1 9 1001 1 0

                        Table 91 Odd and Even Parity in BCD

                        When digital data is received a parity checking circuit generates an error signal if the total number of 1s is odd in an even parity system or if it is even in an odd parity system Parity check always detects a single error (one bit change from 0 to 1 or 1 to 0) but may not detect

                        42

                        Logic Design amp Switching Theory 1 Lab Session 09 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering ` two or more errors Odd parity is used more often than even parity because even parity does not detect a situation where all 0s are created due to short circuit or other fault condition DESIGN OF A 3-BIT ODD PARITY GENERATOR AND CHECKER Let x y and z be the three bits that constitute the message and are the input to the Odd Parity Generator Circuit Since it is an odd parity system the bit P is generated so as to make the total number of 1s odd (including P) The function P can be expressed as follows P = x oplus y Ο z or P = x Ο y oplus z Since the IC available is 7486 which is quad 2input XOR IC therefore we will convert XNOR also to XOR

                        P = x oplus y Ο z

                        P = ( x oplus y ) Ο z Since for even number of variables ______

                        XOR = XNOR Therefore ___________ _________

                        P = ( x oplus y ) oplus z = x oplus y oplus z This logical expression can be implemented with two XOR gates and an inverter (see figure 91)

                        Figure 91 Circuit Diagram for a 3-bit Parity Generator

                        The 3-bit message and the parity bit are transmitted to their destination where they are applied to a Parity Checker Circuit An error occurs during transmission if the parity of the four bits received is even since the binary information transmitted was originally odd The output C of the parity checker should be a 1 when an error occurs ie when the number of 1s in the four inputs is even Therefore the function C can be expressed as

                        C = x Ο y Ο z Ο P

                        Using the same logic applied for the conversion of the equation of P

                        PzyxC oplusoplusoplus= This logical expression can be implemented with three XOR gates and an inverter (see figure 92)

                        43

                        Logic Design amp Switching Theory 1 Lab Session 09 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering `

                        44

                        Figure 92 Circuit Diagram for a 3-bit Parity Checker Implementation and Observations Implement the 3-bit Parity Generator and Checker circuits (figure 91 and 92) on a bread board (prepare the pin diagram (use appendix A) and refer to laboratory session 01 for implementation procedure) and record the observations in the following table

                        x y z P x y z P C x y z P C 0 0 0 0 0 0 0 1 0 0 0 0 0 1 0 0 0 1 1 0 0 1 0 1 0 0 0 1 0 1 0 1 0 0 1 1 0 0 1 1 1 0 1 1 1 0 0 0 1 0 0 1 1 0 0 1 0 1 0 1 0 1 1 1 0 1 1 1 0 0 1 1 0 1 1 1 0 1 1 1 0 1 1 1 1 1 1 1

                        Odd Parity Generation Odd Parity Check ACTIVITY 1 Try using the parity checker of figure 92 as 3-bit parity generator Write the details here

                        _____________________________________________________________________________________________________________________________________________________________________________________________________________________ ______________________________________________________________________________________________________________________________________________ _______________________________________________________________________ ______________________________________________________________________________________________________________________________________________

                        Logic Design amp Switching Theory 1 Lab Session 10 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                        Lab Session 10 OBJECT

                        Driving a seven segment display using 7447 7448 driver IC COMPONENTS AND APPARATUS REQUIRED

                        1 Following ICs and their Datasheets

                        bull Seven Segment Displays (Common Anode Common Cathode) bull 7447 7448 BCD to Seven Segment Driver

                        2 Digital Trainer DT-01 or the following components Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches

                        THEORY Seven Segment Displays A Seven Segment Display consists of seven light-emitting segments The segments are designated by letters a through g (see figure 101) By illuminating various combinations of segments the numerals 0 through 9 can be displayed Seven Segment Displays are commonly constructed with light-emitting diodes (LEDs) and with liquid-crystal displays (LCDs) LEDs generally provide greater illumination levels but require much greater power than LCDs An LED display can be a common-anode type or common cathode type In common anode type a high voltage is applied at the common terminal of the display and low voltage is applied at a segmentrsquos terminal for illumination In the common-cathode type a low voltage is applied at the common terminal of the display and high voltage is applied at a segmentrsquos terminal for illumination

                        Figure 101 Seven Segment Display

                        a f b g

                        e c d

                        7447 7448 BCD to Seven Segment Driver 7447 7448 IC is particularly used to drive Seven Segment Its input is a BCD number and output drives a seven segment display 7447 is used to drive common-anode displays whereas 7448 is used to drive common cathode displays 7447 7448 is a 16 pin IC Function of various pins of these ICs is described below

                        bull A B C D Inputs representing BCD digits (D being the MSB)

                        45

                        Logic Design amp Switching Theory 1 Lab Session 10 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering bull OA through OG Outputs to drive segments a through g of the display (Active low

                        in 7447 and active high in 7448) bull RBI Ripple Blanking Input Turns off all the segments if kept low provided that LT

                        is kept high and all other inputs (A B C D BI) are kept low Should be kept high otherwise

                        bull BI RBO Wire-AND logic serving as a Blanking Input and or Ripple Blanking Output

                        o BI Turns off all the segments if low o RBO Goes to a low level (response condition) along with other outputs when

                        RBI and inputs A B C and D are low with LT input at high level bull LT Lamp Test input Tests whether all segments are working or not Illuminates all

                        segments if kept low provided that BI is kept high Should be kept high otherwise bull VCC and GND Supply connections lines CIRCUIT DIAGRAM

                        Figure 102 Circuit diagram for 7447driving a common-anode display

                        IMPLEMENTATION AND OBSERVATIONS

                        bull Make connections as shown in the circuit diagram (refer to laboratory session 01 for implementation procedure)

                        bull Apply different combinations of 1s and 0s at data inputs bull Observe the output and record your observations in the following table

                        46

                        Logic Design amp Switching Theory 1 Lab Session 10 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                        47

                        Decimal Digit

                        BCD Inputs Seven Segment Outputs D C B A a b c d e f g

                        0 0 0 0 0 1 0 0 0 1 2 0 0 1 0 3 0 0 1 1 4 0 1 0 0 5 0 1 0 1 6 0 1 1 0 7 0 1 1 1 8 1 0 0 0 9 1 0 0 1

                        ACTIVITY 1 Perform the Lamp Test for the designed circuit and write your observations

                        ____________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________

                        2 How can you use 7447 IC to drive a common-cathode display

                        ____________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________

                        3 What symbols appear in the seven segment display if inputs DCBA are

                        DCBA Symbol

                        1010

                        1011

                        1100

                        1101

                        1110

                        1111

                        Logic Design amp Switching Theory 1 Lab Session 11 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                        48

                        Lab Session 11 OBJECT

                        Testing different modes of JK-FF COMPONENTS AND APPARATUS REQUIRED 1 Following ICs and their Datasheets

                        bull 7473 7476 JK Flip-Flop 2 Digital Trainer DT-01 or the following components

                        Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches

                        THEORY

                        Flip-Flop A flip-flop circuit can maintain a binary state indefinitely (as long as the power is delivered to the circuit) until directed by an input signal to switch states The major differences among various types of flip-flops are in the number of inputs they possess and in the manner in which the inputs affect the binary state

                        JK Flip-Flop JK flip flop is an edge triggered device A typical JK flip flop has three inputs J K and a clock input The flip-flop can be either positive or negative edge triggered The output Q is available in complemented form as well Beside the usual inputs and output most of the flip-flop IC also possess two asynchronous inputs namely Preset and Clear These inputs are usually active low If used Preset and Clear inputs keep the flip-flop in set and reset state respectively irrespective of the other inputs Both of these inputs cannot be used simultaneously otherwise they will bring the flip-flop in unstable state

                        Figure 111 Symbol for JK flip-flop

                        (a) positive-edge triggering (b) active low Preset (PR) and Clear (CLR) with positive-edge triggering

                        (c) active low Preset (PR) and Clear (CLR) with negative-edge triggering

                        Logic Design amp Switching Theory 1 Lab Session 11 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                        49

                        TESTING OF 7473 7476 DUAL JK FLIP-FLOP

                        Both the ICs 7473 and 7476 are similar in functionality except for one difference The flip-flops in 7473 have only one type of active low asynchronous input which is the Clear input whereas the flip-flops in 7476 have both Preset and Clear inputs Both these ICs have negative edge triggered flip-flops

                        Circuit Diagram

                        Figure 112 Pin connections of 7476

                        Testing Procedure

                        bull Make connections as shown in the circuit diagram (figure 112) bull Apply different combinations of 1s and 0s at J and K inputs bull Observe the output and record your observations in the following table

                        Observations

                        J

                        K Q

                        0 0 0 1 1 0 1 1

                        ACTIVITY

                        1 Observe the output Q of JK flip-flop if the clock input is connected to VCC or GND instead of a clock source Write your observations here __________________________________________________________________________________________________________________________________________ _______________________________________________________________________________________________________________________________________________________________________________________________________________

                        Logic Design amp Switching Theory 1 Lab Session 12 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                        50

                        Lab Session 12 OBJECT

                        Designing sequential circuit for the given state diagram using D flip-flop GIVEN STATE DIAGRAM

                        00

                        11

                        Figure 121 State Diagram COMPONENTS AND APPARATUS REQUIRED 1 Following ICs and their Datasheets

                        bull 7474 D Flip-Flop bull ICs of basic gates (AND OR NOT XOR etc) as required

                        2 Digital Trainer DT-01 or the following components Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches

                        THEORY

                        Sequential Circuits In Sequential Circuits the output not only depends on the present inputs but also on previous states of the circuit These circuits use memory elements (latches flip-flops) and the binary information stored in the memory elements at any given time defines the state of the sequential circuit Analysis of a Sequential Circuit The behavior of a sequential circuit is determined from the inputs the outputs and the states of its flip-flops Both the outputs and next state are a function of the inputs and the

                        10

                        01

                        00 11 10

                        00

                        00 11 10 00

                        Logic Design amp Switching Theory 1 Lab Session 12 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                        51

                        present state The analysis of a sequential circuit form a state diagram comprises of the following bull Selecting a particular flip-flop to design the circuit bull Obtaining state table from the state diagram bull Finding input equations for the selected flip-flop bull Finding state equations (not required for the construction of circuit) bull Implementing the circuit using selected flip-flops and their input equations ANALYZING THE GIVEN STATE DIAGRAM D Flip-Flop D flip-flop is also called transparent flip-flop as it simply transfers the input data to the output For our design we require the graphical symbol and excitation table of D flip-flop (see figure 122)

                        Qt Qt+1 T 0 0 0 0 1 1 1 0 0 1 1 1

                        (b) Excitation table of D Flip-Flop

                        (a) Graphical Symbol

                        Figure 122 Characteristic equation of D flip-flop is Q(t+1) = D State Table The given state diagram has four states so we will need two D flip-flops (FF-0 FF-1) Form state table form the given state diagram and record the results in the following table

                        Present State Input Next State Output Input to FF-0 D0

                        Input to FF-1 D1 Q1t Q0t x Q1(t+1) Q0(t+1) z

                        Logic Design amp Switching Theory 1 Lab Session 12 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                        52

                        Input Equations Using Karnaugh map the input equations D0 and D1 for the two flip-flops can be found

                        D0 D1 Q0x

                        Q1

                        _ _ Q0x

                        _ Q0x

                        Q0x

                        _ Q0x

                        Q0x

                        Q1

                        _ _ Q0x

                        _ Q0x

                        Q0x

                        _ Q0x

                        _ Q1

                        _ Q1

                        Q1

                        Q1

                        D0 = _________________ D1 = _________________

                        State Equations Using the characteristic equation of D flip-flop we can find the state equations Q0(t+1) and Q1(t+1) for the to flip flops Q0(t+1) = _______________________ Q1(t+1) = _______________________ _______________________ _______________________ _______________________ _______________________ Circuit Diagram

                        Logic Design amp Switching Theory 1 Lab Session 12 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                        53

                        Implementation Procedure and Observations

                        1 Implement the circuit using digital ICs on a bread board (prepare the pin diagram (use appendix A) and refer to laboratory session 01 for procedure)

                        2 Make the clear inputs of the flip-flops low (to clear the flip-flops) The flip-flops will remain in clear state as long as the clear inputs are connected to low level

                        3 Connect output Q0 and the clock pulse to an oscilloscope 4 Apply 0 to the input x 5 Now make the clear inputs to high 6 Observe the waveform for the first 5 clock pulses and record it 7 Repeat steps 2 to 6 keeping x=1 in step 4 this time 8 Repeat steps 2 to 7 this time connecting Q1 instead of Q0 to the oscilloscope in step

                        3 Record your observations (Keep frequency of the clock pulse low (eg1Hz) so that the output waveforms can be observed easily)

                        1 2 3 4 5 Clock Pulse

                        Output Waveform for Q0 when x=0

                        Output Waveform for Q0 when x=1

                        Output Waveform for Q1 when x=0

                        Output Waveform for Q1 when x=1

                        Logic Design amp Switching Theory 1 Lab Session 13 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                        Lab Session 13 OBJECT

                        Designing a modulo-5 asynchronous up-counter using JK-FF COMPONENTS AND APPARATUS REQUIRED

                        1 Following ICs and their Datasheets

                        bull 7400 Quad 2-input or 7410 Triple 3-input NAND Gates bull 7476 7473 JK Flip-Flop

                        2 Digital Trainer DT-01 or the following components Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches

                        THEORY

                        Digital Counters A digital counter is a set of flip-flops whose states change in response to pulses applied at the input to the counter The flip-flops are interconnected so that their combined state at any time is the binary equivalent of the total number of pulses that have occurred up to that time Every counter resets after a certain number of clock pulses Thus as it name implies a counter is used to count pulses An n stage counter can count up to a maximum of 2n states n is equal to the number of flip-flops required for the construction of counter

                        Modulus Counters The number of input pulses that causes a counter to reset to its initial count is called the modulus of the counter Thus the modulus equals to total number of distinct states (counts) including zero that a counter can store A binary counter with n stages is a modulo-2n (or mod-2n) counter The largest count a mod-N counter can achieve is N-1 ie a mod-N counter never reaches the binary number equal to its modulus N is always equal to or less than 2n Counters can be classified as bull Synchronous Counters which are clock driven All the flip-flops are driven by a

                        single clock bull Asynchronous Counters which are event driven Clock input is given to the first

                        flip-flop only Rest of the flip-flops are driven by their preceding flip-flops

                        DESIGN OF A MOD-5 ASYNCHRONOUS UP COUNTER The number of flip-flops required to construct a mod-5 counter is 3 because 5 should be less than or equal to 2n This counter will count from 0 to 4 a total of 5 distinct states Since a 3-stage counter can count up to 8 states at maximum a NAND gate is used to reset it after 5 clock pulses Figure 131 shows the logic diagram

                        54

                        Logic Design amp Switching Theory 1 Lab Session 13 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                        55

                        Figure 131 A Mod-5 Asynchronous Up Counter

                        Implementation and Observations

                        Implement the mod-5 counter circuit (figure 131) on a bread board (prepare the pin diagram (use appendix A) and refer to laboratory session 01 for implementation procedure) and record the observations in the following table

                        Clock Pulse Q2 Q1 Q0

                        0 1 2 3 4 5 6 7

                        ACTIVITY

                        Draw the timing diagram for mod-5 counter designed in this laboratory session

                        Logic Design amp Switching Theory 1 Lab Session 14 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                        Lab Session 14 OBJECT

                        Experimenting with 74194 4-bit bidirectional universal shift register COMPONENTS AND APPARATUS REQUIRED

                        1 Following ICs and their Datasheets

                        bull 74194 4-bit bidirectional universal shift register 2 Digital Trainer DT-01 or the following components

                        Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches

                        THEORY

                        Shift Registers

                        A Register is a set of flip-flops used to store binary data A register which is capable of shifting its binary information either to the right or left is called a shift register The logical configuration of a register consists of a chain of flip-flops connected in cascade with the output of one flip-flop connected to the input of next flip-flop All flip-flops receive a common clock pulse which causes the shift from one stage to the next

                        Bidirectional Shift Registers A bi-directional shift register is one whose bits can be shifted from left to right or from right to left

                        Universal Shift Registers A universal shift register is a bi-directional register whose input can be in either serial or parallel form and whose output can be in either serial or parallel form

                        74194 4-BIT BIDIRECTIONAL UNIVERSAL SHIFT REGISTER

                        The 74194 register provides parallel as well as serial loading in both directions Function of various pins of this IC is described below

                        bull A B C and D Active high inputs for parallel loading bull QA QB QC and QD Active high outputs bull S0 and S1 Active high mode control inputs The following table shows combinations

                        of S1 and S0 to enable various modes

                        S1 S0 Clock Action 0 0 x No change 0 1 uarr Shift right 1 0 uarr Shift left 1 1 uarr Parallel load

                        uarr shows the rising edge of the clock pulse

                        56

                        Logic Design amp Switching Theory 1 Lab Session 14 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering bull SR Active high serial input for right shifting bull SL Active high serial input for left shifting bull CLR Active low input Clears all the flip-flops of the register if set to 0 should be

                        kept high otherwise bull CLK Clock input bull VCC and GND Supply connections lines Thus A B C and D are inputs for parallel loading whereas SR and SL are inputs for serial loading with right or left shifting respectively S1 and S0 are used to select the loading mode Circuit Diagram

                        Figure 141 Pin connections of 74194 Testing Procedure

                        bull Make connections as shown in the circuit diagram bull Observe the output for the input combinations given in the following table

                        57

                        Logic Design amp Switching Theory 1 Lab Session 14 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                        58

                        Observations

                        S1 S0 SL SR A B C D QA QB QC QD 0 0 0 1 0 0 0 0 0 1 1 0 0 0 0 1 1 0 0 0 0 0 1 0 1 1 0 0 0 0 1 1 0 0 1 1 0 1 0 0 0 1 1 1 0 1 0 1 1 0 1 0 0 1 1 0 1 1 1 0 0 1 1 1 1 1 0 0 1 1 1 1

                        ACTIVITY 1 Show connections of 74194 to convert it into a ring counter with right shifting

                        Logic Design amp Switching Theory 1 Lab Session 15 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                        Lab Session 15

                        OBJECT

                        Experimenting with 74245 octal bus transceivers using parallel port PC interfacing COMPONENTS AND APPARATUS REQUIRED 1 Parallel Port Connectors (DB-25) with Cable 2 Personal Computer with Windows 98 and TurboC Compiler Installed 3 Following ICs and their Datasheets

                        bull 74245 Octal Bus Transceivers with 3-State Outputs 4 Digital Trainer DT-01 or the following components

                        Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches

                        THEORY

                        3-State Logic Sometimes it is necessary to isolate one part of circuit from the other part For this purpose some TTL ICs are designed with 3-state logic Such devices have three possible output states high low and high impedance The device can be put into high impedance state by a control signal applied to an appropriate pin When such a device is in high impedance state there is very high impedance at its output effectively isolating the device from whatever circuitry the output normally drives 74245 Octal Bus Transceivers A bus is any conducting path or set of paths having electrical connections to one or more devices 74245 octal bus transceivers are mainly used to control connectivity between two devices or circuits It also provides direction control for signal flow Function of various pin of this IC is given below

                        bull A1 through A8 Bus A bull B1 through B8 Bus B bull G΄ Active low enable input When high sets all the bus pins to high impedance state bull DIR Direction control for signal flow When set to high logic level transfers bus A

                        data to B bus When set to low logic level transfers bus B data to A bus bull VCC and GND Supply connections lines Serial and Parallel Port Connectors A Parallel Port can consist of only 25 pin port adapter called a DB-25 and a serial port can consist of either a 25 pin port adapter called a DB-25 or 9 pin adapter called a DB-9 port adapter Whether the port is a 9 pin or 25 pin it can accomplish all of the same tasks that serial port communications have been designed for

                        59

                        Logic Design amp Switching Theory 1 Lab Session 15 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                        60

                        Each adapter can be a male type connector with pins or a female type adapter with tiny holes Generally a PRINTER port (called LPT1) on the back of a computer is female type adapter and we need to use MALE DB-25 pin cable on it for PRINTER connection or for parallel LAPLINK cable And a COM port on the back of a computer is male for the serial ports but it may not necessarily be Parallel Port Connector ndash DB-25 The DB-25 connector (named for its B-size D-shaped shell and 25 pins) is practically ubiquitous in the electronics industry The DB-25 connector is used for a variety of purposes Two common applications are RS-232EIA-232 (serial) connections and the parallel printer interface on the IBM PC The DB-25 connector is also used for SCSI connections Normally the parallel port is used for output to a printer or other device It sends data 8-bits or one byte at a time in parallel The other lines available on the DB-25 connector are a combination of status lines control lines and ground lines The status and control lines are used for handshaking commands and feedback when we are talking to a printer

                        Figure 152 DB-25 Female Figure 151 DB-25 Male

                        Figure 153 Pin Layout for DB-25 As can be seen form figure 153 there are four types of pins in this connector

                        bull Data pins (8 pins - D0 to D7) Active high bidirectional lines

                        Logic Design amp Switching Theory 1 Lab Session 15 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering bull Control pins (4 pins - C0 to C3) C0 C1 and C3 are active low whereas C2 is active

                        high These lines also are bidirectional bull Status pins (5 pins ndash S3 to S7) Only S7 is active low rest are active high input lines bull Ground pins (8 pins) Used as a reference signal for the low (below 05 volts) charge

                        Parallel Port Addresses A DB-25 connector at a parallel port has three address one for each kind of pins register data status and control The first or base address generally refers to data register Second address is for status register and the third one is for control register In Windows 98 the base address is usually found to be 278H 378H or 3BCH Now if 378H is the base address then it refers to the data register whereas addresses for status and control register are respectively 379H and 37AH For Windows 98 the base address can be found as follows 1 On your Desktop right-click on My Computer and select Properties 2 Click on the Device Manager tab and find LPT1 under Plug and Play BIOS 3 After selecting LPT1 click the Properties button 4 Next select the Resources tab and the address should then appear next to InputOutput

                        Range Accessing parallel port through C Language Programming There are multiple functions in C Language for accessing external ports The most commonly used are listed below

                        bull unsigned char inportb(int portid) inportb reads a byte from a hardware port

                        bull int inport(int portid) reads a word from a hardware port

                        bull void outportb(int portid unsigned char value) outputs a byte to a hardware port

                        bull void outport(int portid int value) outputs a word to a hardware port

                        portid refers to the port address whereas value refers to the data to be sent TESTING 74245 USING PARALLEL PORT PC INTERFACING At one end the parallel port connector will be connected to the PC via parallel port cable and another connector (to be plugged into the PC parallel port slot) At the other end it will be connected to the buffer IC 74245 Data lines of the connector will be used to transfer 8-bit data between the PC and the buffer Out of the 8-bits of 74245 4-bits will be used to enter data which will be displayed at the monitor through a C language

                        61

                        Logic Design amp Switching Theory 1 Lab Session 15 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering program The remaining 4-bits will receive data from PC as entered by the user via keyboard

                        Circuit Diagram

                        Figure 154 Interface of 74245 to PC via Parallel Port

                        Procedure

                        1 Connect the DB-25 connector to the PC at one end and solder it to the circuit board at the other end

                        2 Connect various pins of the connector and 74245 according to the circuit diagram shown in figure 152

                        3 Using the functions listed in the previous section write a program in C language to operate various pins of the buffer The user interface of the program should provide option to the user whether to send or receive data from the port

                        4 Set DIR switch to 1 5 Try sending some data bits to the port The result should be displayed at the LEDs 6 Set DIR switch to 0 7 Set some binary 4-bit value through the switches Try reading it via parallel port

                        C Language Program

                        A program to access parallel port for data transfers

                        use header file include ltstdiohgt main program void main() define variable

                        62

                        Logic Design amp Switching Theory 1 Lab Session 15 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering unsigned int data=0 char choice while(1) printing option menu clrscr() printf(This program will send or receive a BCD digit from the parallel portn) printf(nPress your choice numbern) printf(n1 Send Data) printf(n2 Receive Data) printf(n3 Exitn) choice = getch() sending entered digit to the port if(choice == 1) input BCD digit printf(nEnter BCD digit to be sent to the port) data = getche() masking the first four bits data = data amp 0x0f sending to the port outportb(0x378data) printf(nThe BCD digit c has been sent to the port data) printing on screen the data received from the port else if(choice == 2) receiving data from the port data = inportb(0x378) masking the last four bits data = data amp 0xf0 shifting first four bits to make them the last four bits datagtgt=4 printf(nThe BCD digit set at the port is c data) exit else if(choice == 3) break key pressed is not in the menu else printf(nEnter valid choice number) printf(nnPress any key to continue) getch()

                        63

                        Logic Design amp Switching Theory 1 Lab Session 15 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                        ACTIVITY 1 In the above circuit DIR and G΄ inputs are hardwired Connect them to status or

                        control pins of the parallel port connector and control their function through your software program Circuit Diagram Program Code ______________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________

                        ___________________________________________________________________________________________________________________________________________________

                        64

                        Logic Design amp Switching Theory 1 Lab Session 15 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                        65

                        _____________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ _____________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ _______________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ _________________________________________________ _________________________________________________

                        Logic Design amp Switching Theory 1 Appendix A NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                        Appendix A

                        PIN DIAGRAMS OF THE ICS REQUIRED FOR THE LABORATORY SESSIONS Consult the TTLIC data book for internal diagrams and electrical characteristics of these ICs 7400 Quad 2-Input NAND 7402 Quad 2-Input NOR

                        7404 Hex Inverter 7408 Quad 2-Input AND

                        7410 Triple 3-Input NAND 7411 Triple 3-Input AND

                        7421 Dual 4-Input AND 7432 Quad 2-Input OR

                        66

                        Logic Design amp Switching Theory 1 Appendix A NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                        BCD-to-Seven Segm 7448 BCD-to-Seven Segment 7447 ent

                        Decoder (15V OC) Decoder (2kΩ pull-up output)

                        7473 Dual JK Flip-Flop 7474 Dual D-Type Flip-Flop

                        7476 Dual JK Flop-Flop -Bit Binary Full Adder 7483 4 with Fast Carry

                        86 Quad 2-Inpu 74138 3-to-8 Line 74 t Exclusive OR Decoder Demultiplexer

                        67

                        Logic Design amp Switching Theory 1 Appendix A NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                        68

                        74148 8-to-3 Line 16-to-1 Line Data

                        Priority Encoder 74150 Selector Multiplexer

                        74245 Oct nsceivers Universal Shift Register (PIPO) (3-State)

                        74194 4-Bit Bidirectional al Bus Tra

                        Logic Design amp Switching Theory 1 Appendix B NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                        Appendix B

                        DEBOUNCING CIRCUITRY FOR MECHANICAL SWITCHES Mechanical switches form the interface between human beings and computers or other digital systems For example a keyboard is a matrix of switches used to supply alphanumeric data to a computer Whatever the switch design it is a potential source of problems due to contact bounce The contact bounce creates a sense of narrow pulses when a switch is opened or closed An example of device whose operation would be adversely affected by contact bounce is a digital counter used to count the number of times a switch is depressed Eliminating the effects of contact bounce is called debouncing When data is entered into a computer via a keyboard a software debounce is often used This type of debouncing is a program that causes the computer to sample the switch terminal (ie to input data from it) many times in succession during the interval of time that contact bounce occurs If the data is sensed to be 1s (or 0s) for a specific number of consecutive samples then it is assumed that contact bounce has ended and the last value sensed is valid Hardware debouncing is the use of electronic circuitry to eliminate the effects of contact bounce There are numerous versions of such circuitry including those that use monostable multivibrators (one-shots) but the most straightforward is simply an RS latch Figure B1 shows the circuit When the switch is in position 1 R = 0 and S = 1 so the latch is set and the output (Q) is 1 When the switch is in position 0 R = 1and S = 0 so the latch is reset and the output is 0 When the switch is moved form one position to the other the latch changes state and bouncing occurs at either the R or the S input The bouncing does not affect the latch after it has change state An RS latch will remain set for example when its R input is 0 and its S input is alternately changed form 1 to 0

                        Figure B1 Use of RS latch to debounce a mechanical switch

                        69

                        • 01-ldst-Outer title
                          • Practical Workbook
                          • Logic Design amp Switching Theory I
                            • Dept of Computer amp Information Systems Engineering
                              • NED University of Engineering amp Technology
                              • Karachi ndash 75270 Pakistan
                                • 02-ldst-inner Title
                                  • Practical Workbook
                                  • Logic Design amp Switching Theory I
                                    • Dept of Computer amp Information Systems Engineering
                                      • NED University of Engineering amp Technology
                                      • Karachi ndash 75270 Pakistan
                                        • 03-ldst-general info
                                        • 04-ldst-introduction
                                        • 05-Table of Contents
                                          • CONTENTS
                                            • Lab Session No Object Page No
                                            • 1
                                            • Also implementing and testing the given circuit on a bread board
                                              • Working with Electronics Workbench
                                                • Driving a seven segment display using 7447 7448 driver IC
                                                  • Designing a modulus-5 asynchronous up-counter using JK-FF
                                                    • Experimenting with 74194 4-bit bidirectional universal shift register
                                                        • 13
                                                            • 06-ldst-Exp01
                                                              • Lab Session 01
                                                              • OBJECT
                                                                • 1 Bread board
                                                                • 2 5 V - power supply
                                                                • 3 Multimeter
                                                                • 4 Logic probe
                                                                • 5 LEDs with resistors
                                                                • 6 Connecting wires
                                                                • 8 Following ICs and their datasheets
                                                                  • THEORY
                                                                    • Logic Gates
                                                                    • 1 The AND Gate ndash An AND gatersquos output is 1 if and only if all its inputs are 1 If A and B are two inputs to an AND gate then output F of the gate is given as F = AB
                                                                    • 2 The OR Gate - An OR gatersquos output is 1 if at least one of its input is 1 If A and B are two inputs to an OR gate then output F of the gate is given as F = A+B
                                                                    • 3 The NOT Gate (Inverter) ndash Its output is 1 when its input is 0 and its output is 0 when the input is 1 ie it complements a digital variable If A is the input to a NOT gate then output F of the gate is given as
                                                                    • 4 The NAND Gate ndash Its output is 1 if at least one of its input is 0 This gate performs the same logic as an AND gate followed by an inverter If A and B are two inputs to a NAND gate then output F of the gate is given as
                                                                      • 5 The NOR Gate - The output of a NOR gate is 1 if and only if all its inputs are 0 This gate performs the same logic function as an OR gate followed by an inverter If A and B are two inputs to a NAND gate then output F of the gate is given as
                                                                          • DATA SHEETS
                                                                            • Logic expression for the given logic diagram __________________________________
                                                                                • 07-ldst-exp02
                                                                                  • Working with Electronics Workbench
                                                                                    • 08-ldst-exp03
                                                                                      • Designing Half and Full Adder Circuits
                                                                                        • COMPONENTS AND APPARATUS REQUIRED
                                                                                          • 1 Following ICs and their Datasheets
                                                                                          • 7408 Quad 2-input AND Gate
                                                                                          • 2 Digital Trainer DT-01 or the following components
                                                                                            • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                            • Connecting wires Switches
                                                                                              • THEORY
                                                                                                  • IMPLEMENTATION AND OBSERVATIONS
                                                                                                    • 09-ldst-Exp04
                                                                                                      • Lab Session 04
                                                                                                      • 1 Digital ICs and their Datasheets
                                                                                                      • 7408 Quad 2-input AND Gate
                                                                                                      • 2 Digital Trainer DT-01 or the following components
                                                                                                        • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                        • Connecting wires Switches
                                                                                                        • PROCEDURE
                                                                                                        • REDUCTION OF LOGIC EXPRESSION USING KARNAUGH MAP
                                                                                                        • OBSERVATIONS
                                                                                                        • RESULT
                                                                                                            • 10-ldst-Exp05
                                                                                                              • Lab Session 05
                                                                                                              • 1 Following ICs and their Datasheets
                                                                                                              • 7408 Quad 2-input AND Gate
                                                                                                              • 2 Digital Trainer DT-01 or the following components
                                                                                                                • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                • (100 Ω) Connecting wires Switches
                                                                                                                • THEORY
                                                                                                                  • IMPLEMENTATION AND OBSERVATIONS
                                                                                                                    • 11-ldst-Exp06
                                                                                                                      • OBJECT
                                                                                                                      • 1 Following ICs and their Datasheets
                                                                                                                      • 7408 Quad 2-input AND Gates or 7411 Triple 3-input AND Gates
                                                                                                                      • 2 Digital Trainer DT-01 or the following components
                                                                                                                        • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                        • Connecting wires Switches
                                                                                                                          • Figure 62 Circuit Diagram for 4 x 1 Multiplexer
                                                                                                                          • Implementation and Observations
                                                                                                                            • Circuit Diagram
                                                                                                                              • ACTIVITY
                                                                                                                                • 12-ldst-exp07
                                                                                                                                  • 1 Following ICs and their Datasheets
                                                                                                                                  • 7408 Quad 2-input or 7411 Triple 3-input AND Gates
                                                                                                                                  • 2 Digital Trainer DT-01 or the following components
                                                                                                                                    • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                    • Connecting wires Switches
                                                                                                                                      • THEORY
                                                                                                                                          • Figure 72 Circuit Diagram for 2 x 4 Decoder 1 x 4 Demultiplexer
                                                                                                                                          • Implementation and Observations
                                                                                                                                            • Circuit Diagram
                                                                                                                                              • ACTIVITY
                                                                                                                                                • 13-ldst-Exp08
                                                                                                                                                  • OBJECT
                                                                                                                                                  • 1 Following ICs and their Datasheets
                                                                                                                                                  • 7408 Quad 2-input or 7421 Dual 4-input AND Gates
                                                                                                                                                  • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                    • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                    • Connecting wires Switches
                                                                                                                                                      • THEORY
                                                                                                                                                          • Figure 81 Circuit Diagram for 4 x 2 Priority Encoder
                                                                                                                                                          • Implementation and Observations
                                                                                                                                                            • Therefore if GS A2 A1 and A0 are all low then it shows that line 0 is selected and if E0 A2 A1 and A0 are all low then it shows that none of the inputs selected E0 and GS cannot be in the same state provided that E1 is enabled
                                                                                                                                                            • Circuit Diagram
                                                                                                                                                              • ACTIVITY
                                                                                                                                                                • 14-ldst-exp09
                                                                                                                                                                  • OBJECT
                                                                                                                                                                  • 1 Following ICs and their Datasheets
                                                                                                                                                                  • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                    • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                    • Connecting wires Switches
                                                                                                                                                                      • THEORY
                                                                                                                                                                        • Parity Generator
                                                                                                                                                                          • Let x y and z be the three bits that constitute the message and are the input to the Odd Parity Generator Circuit Since it is an odd parity system the bit P is generated so as to make the total number of 1s odd (including P) The function P can be expressed as follows
                                                                                                                                                                          • Figure 91 Circuit Diagram for a 3-bit Parity Generator
                                                                                                                                                                            • C = x Ο y Ο z Ο P
                                                                                                                                                                              • Implementation and Observations
                                                                                                                                                                                • ACTIVITY
                                                                                                                                                                                    • 15-ldst-exp10
                                                                                                                                                                                      • Driving a seven segment display using 7447 7448 driver IC
                                                                                                                                                                                      • COMPONENTS AND APPARATUS REQUIRED
                                                                                                                                                                                      • 1 Following ICs and their Datasheets
                                                                                                                                                                                      • 7447 7448 BCD to Seven Segment Driver
                                                                                                                                                                                      • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                        • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches
                                                                                                                                                                                          • THEORY
                                                                                                                                                                                          • Seven Segment Displays
                                                                                                                                                                                          • CIRCUIT DIAGRAM
                                                                                                                                                                                          • Figure 102 Circuit diagram for 7447driving a common-anode display
                                                                                                                                                                                              • IMPLEMENTATION AND OBSERVATIONS
                                                                                                                                                                                                • Decimal Digit
                                                                                                                                                                                                • BCD Inputs
                                                                                                                                                                                                • Seven Segment Outputs
                                                                                                                                                                                                • D
                                                                                                                                                                                                • C
                                                                                                                                                                                                • B
                                                                                                                                                                                                • A
                                                                                                                                                                                                • a
                                                                                                                                                                                                • b
                                                                                                                                                                                                • c
                                                                                                                                                                                                • d
                                                                                                                                                                                                • e
                                                                                                                                                                                                • f
                                                                                                                                                                                                • g
                                                                                                                                                                                                • 0
                                                                                                                                                                                                • 0
                                                                                                                                                                                                • 0
                                                                                                                                                                                                • 0
                                                                                                                                                                                                • 0
                                                                                                                                                                                                • 1
                                                                                                                                                                                                • 0
                                                                                                                                                                                                • 0
                                                                                                                                                                                                • 0
                                                                                                                                                                                                • 1
                                                                                                                                                                                                • 2
                                                                                                                                                                                                • 0
                                                                                                                                                                                                • 0
                                                                                                                                                                                                • 1
                                                                                                                                                                                                • 0
                                                                                                                                                                                                • 3
                                                                                                                                                                                                • 0
                                                                                                                                                                                                • 0
                                                                                                                                                                                                • 1
                                                                                                                                                                                                • 1
                                                                                                                                                                                                • 4
                                                                                                                                                                                                • 0
                                                                                                                                                                                                • 1
                                                                                                                                                                                                • 0
                                                                                                                                                                                                • 0
                                                                                                                                                                                                • 5
                                                                                                                                                                                                • 0
                                                                                                                                                                                                • 1
                                                                                                                                                                                                • 0
                                                                                                                                                                                                • 1
                                                                                                                                                                                                • 6
                                                                                                                                                                                                • 0
                                                                                                                                                                                                • 1
                                                                                                                                                                                                • 1
                                                                                                                                                                                                • 0
                                                                                                                                                                                                • 7
                                                                                                                                                                                                • 0
                                                                                                                                                                                                • 1
                                                                                                                                                                                                • 1
                                                                                                                                                                                                • 1
                                                                                                                                                                                                • 8
                                                                                                                                                                                                • 1
                                                                                                                                                                                                • 0
                                                                                                                                                                                                • 0
                                                                                                                                                                                                • 0
                                                                                                                                                                                                • 9
                                                                                                                                                                                                • 1
                                                                                                                                                                                                • 0
                                                                                                                                                                                                • 0
                                                                                                                                                                                                • 1
                                                                                                                                                                                                  • ACTIVITY
                                                                                                                                                                                                    • 16-ldst-exp11
                                                                                                                                                                                                      • Lab Session 11
                                                                                                                                                                                                        • OBJECT
                                                                                                                                                                                                        • COMPONENTS AND APPARATUS REQUIRED
                                                                                                                                                                                                          • 1 Following ICs and their Datasheets
                                                                                                                                                                                                          • 7473 7476 JK Flip-Flop
                                                                                                                                                                                                          • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                            • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                            • Connecting wires Switches
                                                                                                                                                                                                              • THEORY
                                                                                                                                                                                                                  • Flip-Flop
                                                                                                                                                                                                                  • JK Flip-Flop
                                                                                                                                                                                                                    • Circuit Diagram
                                                                                                                                                                                                                      • Observations
                                                                                                                                                                                                                        • ACTIVITY
                                                                                                                                                                                                                            • 17-ldst-exp12
                                                                                                                                                                                                                              • Lab Session 12
                                                                                                                                                                                                                                • OBJECT
                                                                                                                                                                                                                                • GIVEN STATE DIAGRAM
                                                                                                                                                                                                                                • Figure 121 State Diagram
                                                                                                                                                                                                                                • COMPONENTS AND APPARATUS REQUIRED
                                                                                                                                                                                                                                  • 1 Following ICs and their Datasheets
                                                                                                                                                                                                                                  • 7474 D Flip-Flop
                                                                                                                                                                                                                                  • ICs of basic gates (AND OR NOT XOR etc) as required
                                                                                                                                                                                                                                  • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                                    • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                                                    • Connecting wires Switches
                                                                                                                                                                                                                                      • THEORY
                                                                                                                                                                                                                                          • Sequential Circuits
                                                                                                                                                                                                                                            • 18-ldst-exp13
                                                                                                                                                                                                                                              • Lab Session 13
                                                                                                                                                                                                                                                • Designing a modulo-5 asynchronous up-counter using JK-FF
                                                                                                                                                                                                                                                  • 1 Following ICs and their Datasheets
                                                                                                                                                                                                                                                  • 7400 Quad 2-input or 7410 Triple 3-input NAND Gates
                                                                                                                                                                                                                                                  • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                                                    • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                                                                    • Connecting wires Switches
                                                                                                                                                                                                                                                      • THEORY
                                                                                                                                                                                                                                                          • Figure 131 A Mod-5 Asynchronous Up Counter
                                                                                                                                                                                                                                                          • Implementation and Observations
                                                                                                                                                                                                                                                            • ACTIVITY
                                                                                                                                                                                                                                                                • 19-ldst-exp14
                                                                                                                                                                                                                                                                  • Experimenting with 74194 4-bit bidirectional universal shift register
                                                                                                                                                                                                                                                                  • 1 Following ICs and their Datasheets
                                                                                                                                                                                                                                                                  • 74194 4-bit bidirectional universal shift register
                                                                                                                                                                                                                                                                  • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                                                                    • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                                                                                    • Connecting wires Switches
                                                                                                                                                                                                                                                                      • THEORY
                                                                                                                                                                                                                                                                        • Shift Registers
                                                                                                                                                                                                                                                                        • Bidirectional Shift Registers
                                                                                                                                                                                                                                                                        • Universal Shift Registers
                                                                                                                                                                                                                                                                          • S1
                                                                                                                                                                                                                                                                            • Circuit Diagram
                                                                                                                                                                                                                                                                            • ACTIVITY
                                                                                                                                                                                                                                                                                • 20-ldst-exp15
                                                                                                                                                                                                                                                                                  • COMPONENTS AND APPARATUS REQUIRED
                                                                                                                                                                                                                                                                                  • 1 Parallel Port Connectors (DB-25) with Cable
                                                                                                                                                                                                                                                                                  • 2 Personal Computer with Windows 98 and TurboC Compiler Installed
                                                                                                                                                                                                                                                                                  • 3 Following ICs and their Datasheets
                                                                                                                                                                                                                                                                                  • 74245 Octal Bus Transceivers with 3-State Outputs
                                                                                                                                                                                                                                                                                  • 4 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                                                                                    • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                                                                                                      • Connecting wires Switches
                                                                                                                                                                                                                                                                                        • THEORY
                                                                                                                                                                                                                                                                                        • 3-State Logic
                                                                                                                                                                                                                                                                                          • Serial and Parallel Port Connectors
                                                                                                                                                                                                                                                                                          • Parallel Port Connector ndash DB-25
                                                                                                                                                                                                                                                                                            • Accessing parallel port through C Language Programming
                                                                                                                                                                                                                                                                                                • 21-ldst-appendixA
                                                                                                                                                                                                                                                                                                • 22-ldst-appendixB
                                                                                                                                                                                                                                                                                                  • DEBOUNCING CIRCUITRY FOR MECHANICAL SWITCHES

                          Logic Design amp Switching Theory 1 Lab Session 01 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                          NOR

                          0 0 0 1 1 0 1 1

                          DATA SHEETS

                          Figure 11

                          15

                          Logic Design amp Switching Theory 1 Lab Session 01 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                          16

                          GIVEN CIRCUIT

                          Figure 12

                          PROCEDURE FOR IMPLEMENTATION OF THE GIVEN CIRCUIT 1 Set the power supply 2 Insert ICs on the bread board and make their supply and ground connections 3 As given in the logic diagram make connections using wires and gates in the ICs 4 Apply different combinations at the three inputs and observe the output OBSERVATIONS Logic expression for the given logic diagram __________________________________

                          A B C Expected Output Observed Output 0 0 0 0 0 1 0 1 0 0 1 1 1 0 0 1 0 1 1 1 0 1 1 1

                          Logic Design amp Switching Theory 1 Lab Session 02 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                          Lab Session 02

                          OBJECT

                          Working with Electronics Workbench

                          ELECTRONICS WORKBENCH - EWB Electronics Workbench is a computer aided design tool that provides you with all the components and instruments necessary to create board-level designs It has complete mixed analog and digital simulation and graphical waveform analysis allowing you to design your circuit and then analyze it using different simulated instruments and analysis options It is fully integrated and interactive thus you can change your circuits quickly allowing fast and repeated what-if analysis Electronics Workbench provides the following kind of components bull Sources parts bin (AC voltage source Vcc source ground battery etc) bull Basic parts bin (resistors capacitors transformers switches etc) bull Diodes parts bin bull Transistors parts bin bull Analog ICs parts bin (op-amps etc) bull Mixed ICs parts bin (ADCs DACs 555 timers etc) bull Digital ICs parts bin (AND OR adders multiplexers etc) bull Indicators parts bin (voltmeter ammeter probe displays etc) bull Controls parts bin (voltage differentiator multiplier etc) bull Instruments parts bin (multimeter oscilloscope function generator etc) bull Miscellaneous parts bin (write data textbox etc)

                          o Write data This component allows you to save simulation results as an ASCII file o Text Box Use this to add descriptive text anywhere in a circuit

                          ACTIVITY

                          Design circuit for the logic expression )( CBDCABAF ++=

                          Procedure 1 From Logic Gates Parts Bin Drag and drop the required logic gates on the design

                          area Use Component Properties dialog box to customize these gates 2 Connect the terminal of these gates according to the given expression Use additional

                          connectors form the Basic Parts Bin if you want to connect more than wire at a single node

                          3 Drag and drop a probe from Indicators Parts Bin Use Component Properties dialog box to customize the color and other properties of the probe Connect this probe at the output terminal of the circuit to indicate results

                          4 Select four switches form Basic Parts Bin Specify the key that controls the switch by typing its name in the Value tab of the Component Properties dialog box For

                          17

                          Logic Design amp Switching Theory 1 Lab Session 02 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                          18

                          example if you want the switch to close or open when digit lsquo1rsquo is pressed type 1 in the Value tab then click OK Assign different keys to all the switches

                          5 Connect the output terminals of these switches to each of the four inputs A B C and D of the circuit

                          6 Drag and drop Vcc and Ground form the Sources Parts Bin 7 Connect Vcc terminal to one end and Ground terminal to the other end of all the

                          switches 8 Label the circuit properly using text boxes found in the miscellaneous parts bin 9 Run the circuit using the Activate Simulation switch Use the keys you have assigned

                          to the switches to toggle them between Vcc and Ground connections thus providing 1 or 0 respectively to the inputs Record the results as indicated by the probe for all possible combinations of 1s and 0s at the inputs

                          EWB Circuit

                          Figure 21

                          Observations

                          A B C D Expected Output Observed Output 0 0 0 0 0 0 0 1 0 0 1 0 0 0 1 1 0 1 0 0 0 1 0 1 0 1 1 0 0 1 1 1 1 0 0 0 1 0 0 1 1 0 1 0 1 0 1 1 1 1 0 0 1 1 0 1 1 1 1 0 1 1 1 1

                          Logic Design amp Switching Theory 1 Lab Session 03 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                          Lab Session 03

                          OBJECT

                          Designing Half and Full Adder Circuits COMPONENTS AND APPARATUS REQUIRED 1 Following ICs and their Datasheets

                          bull 7408 Quad 2-input AND Gate bull 7432 Quad 2-input OR Gate bull 7486 Quad 2-input XOR Gate

                          2 Digital Trainer DT-01 or the following components Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches

                          THEORY Half Adder A combination circuit that performs the addition of two bits without accounting for the previous carry is called half adder It needs two binary inputs and two binary outputs The input variables designate the augend and addend bits The output variables produce the sum and carry The simplified sum of product expressions for a half adder are

                          yxyxyxS oplus=+= yxC =

                          Figure 31 Circuit diagram for Half Adder

                          19

                          Logic Design amp Switching Theory 1 Lab Session 03 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                          bles produce the sum and carry The simplified sum of product expressions for a half adder are

                          Full Adder

                          A combinational circuit that performs the addition of three input bits It consist of three inputs and two outputs Two of the input variables represent the two significant bits to be added The third input represents the carry from the previous lower significant position The output varia

                          zyxzyxzyxzyxzyxS oplusoplus=+++= yxzyxzyzxxyC )( +oplus=++=

                          Figure 32 Circuit diagram for Full Adder

                          efer to laboratory session 01 for procedure) and record the observations in the following ta

                          alf Adde ull Adder Inputs u

                          IMPLEMENTATION AND OBSERVATIONS

                          Implement the half adder and full adder circuits on a bread board (prepare the pin diagram (use appendix A) and r

                          bles H r F

                          Inputs Outputs Outp ts x y Carry Su Carry Sum m x y z 0 0 0 0 0 0 1 0 0 1 1 0 0 1 0 1 1 0 1 1 1 0 0 1 0 1 1 1 0 1 1 1

                          20

                          Logic Design amp Switching Theory 1 Lab Session 03 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                          at of your designed circuit Attach hardcopy of the output form electronic workbench

                          at of your designed circuit Attach hardcopy of the output form lectronic workbench here

                          ACTIVITY

                          1 Simulate half adder circuit using Electronics Workbench Compare the results of simulation with thhere

                          2 Design a full subtractor circuit and simulate it using Electronics Workbench Compare the results of simulation with the

                          21

                          Logic Design amp Switching Theory 1 Lab Session 04 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                          Lab Session 04 OBJECT

                          Use of Karnaugh Map (SOP-Expression) method GIVEN LOGIC EXPRESSION

                          F (A B C D) = sum ( 0 1 2 4 5 6 8 9 12 13 14 ) COMPONENTS AND APPARATUS REQUIRED 1 Digital ICs and their Datasheets

                          bull 7408 Quad 2-input AND Gate bull 7432 Quad 2-input OR Gate bull 7404 Hex Inverter

                          2 Digital Trainer DT-01 or the following components Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches PROCEDURE 1 Use Karnaugh map to reduce the given function 2 Draw the circuit diagram for the obtained reduced function 3 Implement the reduced circuit using digital ICs on a bread board (prepare the pin

                          diagram (use appendix A) and refer to laboratory session 01 for procedure) and record the observations

                          REDUCTION OF LOGIC EXPRESSION USING KARNAUGH MAP F

                          CD

                          AB DC

                          DC DC

                          DC

                          BA0 1 3 2

                          BA4 5 7 6

                          BA12 13 15 14

                          BA8 9 11 10

                          Reduced form of the given logic expression is __________________________________

                          22

                          Logic Design amp Switching Theory 1 Lab Session 04 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                          LOGIC DIAGRAM (REDUCED FORM) OBSERVATIONS

                          A B C D Output 0 0 0 0 0 0 0 1 0 0 1 0 0 0 1 1 0 1 0 0 0 1 0 1 0 1 1 0 0 1 1 1 1 0 0 0 1 0 0 1 1 0 1 0 1 0 1 1 1 1 0 0 1 1 0 1 1 1 1 0 1 1 1 1

                          RESULT The reduced form (SOP Expression) of the given logic function is

                          ____________________________________________________________

                          The observation table reflects the given logic function

                          23

                          Logic Design amp Switching Theory 1 Lab Session 04 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                          ACTIVITY 1 Using Electronics Workbench derive a truth table and logic circuit for the following logic expression

                          BAAF +=

                          Procedure 1 From the Instruments Parts Bin drag and drop Logic Converter on the design area 2 Double click the Logic Converter to reveal Logic Converter dialog box This dialog

                          box shows various conversion options between truth table logic expression and logic circuit

                          3 Enter the given logic expression in the edit box found at the end of the dialog box Use lsquo to represent invert of a variable For example A is written as Arsquo

                          4 Click the Boolean Expression to Truth Table button The truth table appears in the logic converters display

                          5 Now click the Boolean Expression to Circuit button This creates the logic circuit for the given expression in the design area Label the diagram if needed

                          Resulting Logic Circuit For the given expression the final circuit will look like

                          Figure 41

                          24

                          Logic Design amp Switching Theory 1 Lab Session 04 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                          ACTIVITY 2

                          Using Electronics Workbench find a simplified logic expression and circuit for the following truth table

                          A B C Output 0 0 0 1 0 0 1 1 0 1 0 0 0 1 1 1 1 0 0 0 1 0 1 0 1 1 0 0 1 1 1 1

                          Procedure 1 Click three input channels from A to H across the top of the logic converter The

                          display area below the terminals fills up with the necessary combinations of ones and zeros to fulfill the input conditions The values in the output column on the right are initially set to 0

                          2 Edit the output column to specify the desired output for each input condition To change an output value select it and type a new value 1 0 or x An x indicates a donrsquot care condition

                          3 To convert this truth table to a Boolean expression click the Truth Table to Boolean Expression button The Boolean expression will be displayed at the bottom of the logic converter

                          4 Simplify the expression by clicking the Simplify button 5 Now click the Boolean Expression to Circuit button This creates the logic circuit for

                          the given expression in the design area Resulting Logic Circuit For the given truth table the final simplified circuit will look like

                          Figure 42

                          25

                          Logic Design amp Switching Theory 1 Lab Session 04 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                          ACTIVITY 3

                          Using Electronics Workbench find the logic expression and truth table for the following logic circuit

                          Figure 43

                          Procedure 1 Attach the input terminals of the logic converter to up to four input points in the

                          circuit 2 Connect the single output of the circuit to the output terminal on the logic converter

                          icon 3 Click the Circuit to Truth Table button The truth table appears in the logic

                          converters display 4 To convert this truth table to a Boolean expression click the Truth Table to Boolean

                          Expression button The Boolean expression will be displayed at the bottom of the logic converter

                          Resulting Logic Expression Logic Expression for the given circuit is found to be _____________________________

                          26

                          Logic Design amp Switching Theory 1 Lab Session 04 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                          27

                          For activities 1 2 and 3 attach hardcopy of the output (truth table logic expression and logic circuit) form electronic workbench here

                          Logic Design amp Switching Theory 1 Lab Session 05 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                          Lab Session 05 Lab Session 05 OBJECT OBJECT

                          Designing a BCD Adder Designing a BCD Adder COMPONENTS AND APPARATUS REQUIRED COMPONENTS AND APPARATUS REQUIRED

                          1 Following ICs and their Datasheets 1 Following ICs and their Datasheets bull 7408 Quad 2-input AND Gate bull 7408 Quad 2-input AND Gate bull 7432 Quad 2-input OR Gate bull 7432 Quad 2-input OR Gate bull 7483 4-bit Binary Adder bull 7483 4-bit Binary Adder

                          2 Digital Trainer DT-01 or the following components 2 Digital Trainer DT-01 or the following components Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors (100 Ω) Connecting wires Switches (100 Ω) Connecting wires Switches

                          THEORY THEORY

                          A BCD Adder is a combinational circuit that adds two BCD digits in parallel and produces a sum digit also in BCD A BCD Adder is a combinational circuit that adds two BCD digits in parallel and produces a sum digit also in BCD

                          A4 A3 A2 A1 B4 B3 B2 B1

                          7483-BCD ADDER

                          Cout (C4 ) Z4 Z3 Z2 Z1 Cin(C0)

                          A4 A3 A2 A1 B4 B3 B2 B1

                          7483-BCD ADDER

                          Cout

                          (C4 ) Z4 Z3 Z2 Z1 Cin(C0)

                          Figure 51 BCD Adder Circuit

                          28

                          Logic Design amp Switching Theory 1 Lab Session 05 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                          29

                          A BCD adder must include the correction logic in its internal construction The two BCD digits together with the input carry are first added using a 4-bit binary adder to produce the binary sum If no output carry is generated and the binary sum is less than or equal to 9 then the corresponding BCD sum is identical and therefore no conversion is needed When the output carry is equal to 1 or the binary sum is greater than 9 then a binary 0110 is added to the binary sum through another 4-bit binary adder If Cout is the carry output and Z4Z3Z2Z1 is the binary sum form the first 4-bit binary adder then the following equation indicates the condition when a binary 0110 is to be added

                          C = COUT + Z4Z2 + Z4Z3 IMPLEMENTATION AND OBSERVATIONS Implement the BCD adder circuit according to figure 51 on a bread board (prepare the pin diagram (use appendix A) and refer to laboratory session 01 for procedure) A BCD adder has nine input bits (two BCD digits and a carry bit) which can result in a total of 512 combinations of which 312 inputs are donrsquot care Since it is a very lengthy procedure to record results for 200 valid input combinations therefore for simplicity just record results for any eight combinations in the following table

                          Input Carry

                          BCD Digit 1 BCD Digit 2 Carry Output

                          BCD Sum A4 A3 A2 A1 B4 B3 B2 B1 Z4 Z3 Z2 Z1

                          Logic Design amp Switching Theory 1 lab Session 06 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                          Lab Session 06

                          OBJECT

                          bull Designing of a 4 x 1 Multiplexer bull Experimenting with 74150 IC

                          COMPONENTS AND APPARATUS REQUIRED 1 Following ICs and their Datasheets

                          bull 7408 Quad 2-input AND Gates or 7411 Triple 3-input AND Gates bull 7432 Quad 2-input OR Gates bull 7404 Hex Inverter bull 74150 16 x 1 MUX

                          2 Digital Trainer DT-01 or the following components Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches THEORY

                          Multiplexers A digital data Multiplexer (MUX) is a combinational circuit having several data inputs and a single output A set of data-select inputs is used to control which of the data inputs is routed to the single output A multiplexer is also called a data selector because of this ability to select which data input is connected o the output Normally there are 2n input lines and n selection lines whose bit combination determine which input is selected DESIGN OF A 4 x 1 MULTIPLEXER A 4 x 1 multiplexer is capable of selecting one of four data inputs (see figure 61) The 2-bit binary number at the data select inputs S1 and S0 specifies which of the four data inputs is to be routed to the output Since there are two data select inputs therefore they can select 22 = 4 different data inputs lines

                          S0 S1 D0 D1

                          D2 D3

                          Data-select Inputs Output

                          Data Inputs

                          Figure 61 Block Diagram of a 4 x1 Multiplexer

                          30

                          Logic Design amp Switching Theory 1 lab Session 06 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                          Figure 62 Circuit Diagram for 4 x 1 Multiplexer

                          Implementation and Observations

                          Implement the 4 x 1 Multiplexer circuit (figure 62) on a bread board (prepare the pin diagram (use appendix A) and refer to laboratory session 01 for implementation procedure) and record the observations in the following table For each data select combination specify the switch number as well as the binary value present on that selected switch

                          S1 S0 Output 0 0 0 1 1 0 1 1

                          TESTING OF 74150 - 16 x 1 MUX

                          The 74150 IC has sixteen data inputs and four data-selection lines Function of various pins of this IC is described below

                          bull E0 through E15 Data input lines

                          31

                          Logic Design amp Switching Theory 1 lab Session 06 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering bull A B C D Data select lines with D being the MSB bull W Active low output line bull Grsquo Active low enable line bull VCC and GND Supply connections lines

                          Circuit Diagram

                          Figure 63 Pin connections of 74150 for selecting E0

                          Testing Procedure

                          bull Make connections as shown in the circuit diagram bull Apply different data (1 or 0) at data inputs that are labeled as E0 to E15 Only

                          connection for E0 is shown is the figure for simplicity bull Select the data input E0 with the help of data selectors A B C and D bull Observe the output which shows the complement of the data from E0 bull Select all the sixteen data inputs one by one and record your observations in the

                          following table

                          32

                          Logic Design amp Switching Theory 1 lab Session 06 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                          33

                          Observations

                          Grsquo D C B A W Grsquo D C B A W 0 0 0 0 0 0 1 0 0 0 0 0 0 0 1 0 1 0 0 1 0 0 0 1 0 0 1 0 1 0 0 0 0 1 1 0 1 0 1 1 0 0 1 0 0 0 1 1 0 0 0 0 1 0 1 0 1 1 0 1 0 0 1 1 0 0 1 1 1 0 0 0 1 1 1 0 1 1 1 1

                          ACTIVITY 1 Consider 4x1 Multiplexer Draw the output wave-form for the following data inputs

                          (E0 E1 E2 E3) and select lines A B (B being the MSB) Output is W

                          E3 E2 E1 E0 A B

                          W

                          2 Using the 4 x 1 MUX designed in this laboratory session implement the following logical function F (A B C) = Σ (0147)

                          Show your working and input connections in the following block diagram according to the circuit you have implemented

                          4 x 1 MUX

                          S0 S1

                          Output D0

                          D1

                          D2

                          D3

                          Logic Design amp Switching Theory 1 Lab Session 07 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                          Lab Session 07

                          OBJECT

                          bull Designing of a 2 x 4 Decoder 1 x 4 Demultiplexer bull Experimenting with 74138 IC

                          COMPONENTS AND APPARATUS REQUIRED 1 Following ICs and their Datasheets

                          bull 7408 Quad 2-input or 7411 Triple 3-input AND Gates bull 7404 Hex Inverter bull 74138 3 x 8 Decoder

                          2 Digital Trainer DT-01 or the following components Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches THEORY

                          Decoder A Decoder is a combinational circuit that converts binary information form n input lines to a maximum of 2n unique output lines In practical applications decoders are often used for selecting one of several devices

                          Demultiplexer A decoder with an enable input can function as a Demultiplexer A Demultiplexer (DMUX) id a circuit that receives information on a single line and transmits this information on one of 2n possible output lines The selection of a specific output line is controlled by the bit values of n selection lines DESIGN OF A 2 x 4 DECODER 1 x 4 DEMULTIPLEXER A 2 x 4 decoder is capable of selecting one of four output lines (see figure 71 (a)) The 2-bit binary number at the data inputs S1 and S0 specifies which of the four data inputs is to be selected If we add an enable pin and use it as an input line then this decoder can be converted to a 1 x 4 Demultiplexer where S1 and S0 will select a line to which data input is to be routed (see figure 71 (b))

                          Select S0 S0 Inputs

                          S1 D0 D1

                          D2

                          D3

                          Enable (a) Block Diagram of a 2 x 4 Decoder

                          Figure 71

                          S1 D0 D1

                          D2

                          D3

                          Inputs

                          Data Input (b) Block Diagram of a 1 x 4 Demulptiplexer

                          34

                          Logic Design amp Switching Theory 1 Lab Session 07 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                          Figure 72 Circuit Diagram for 2 x 4 Decoder 1 x 4 Demultiplexer

                          Implementation and Observations Implement the 2 x 4 Decoder 1 x 4 Demultiplexer circuit (figure 72) on a bread board (prepare the pin diagram (use appendix A) and refer to laboratory session 01 for implementation procedure) and record the observations in the following table

                          Enable Data Input S1 S0 D0 D1 D2 D3

                          0 0 0 0 0 1 0 1 0 0 1 1 1 0 0 1 0 1 1 1 0 1 1 1

                          TESTING OF 74138 3 x 8 Decoder The 74138 IC has three inputs and eight output lines It has three enable inputs and for the IC to function all three inputs need to be enabled Function of various pins of this IC is described below

                          35

                          Logic Design amp Switching Theory 1 Lab Session 07 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                          bull Y0 through Y7 Active low data outputs bull A B C Input select lines with C being the MSB bull G1 Active high enable Input bull G2Arsquo and G2Brsquo Active low enable Inputs bull VCC and GND Supply connections lines Circuit Diagram

                          Figure 73 Pin connections of 74138

                          Testing Procedure

                          bull Make connections as shown in the circuit diagram bull Apply different combinations of 1s and 0s at data inputs bull Observe the output and record your observations in the following table

                          Observations

                          C B A Y0 Y1 Y2 Y3 Y4 Y5 Y6 Y7 0 0 0 0 0 1 0 1 0 0 1 1 1 0 0 1 0 1 1 1 0 1 1 1

                          36

                          Logic Design amp Switching Theory 1 Lab Session 07 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                          37

                          ACTIVITY ACTIVITY 1 What will be the binary values at the outputs Y0 through Y7 of 74138 if 1 What will be the binary values at the outputs Y0 through Y7 of 74138 if

                          bull All three enable pins are connected to ground bull All three enable pins are connected to ground __________________________________________________________________________________________________________________________________________ __________________________________________________________________________________________________________________________________________ _____________________________________________________________________ _____________________________________________________________________

                          bull All three enable pins are connected to VCC bull All three enable pins are connected to VCC _______________________________________________________________________________________________________________________________________________________________________________________________________________

                          _______________________________________________________________________________________________________________________________________________________________________________________________________________

                          2 Show connections for 74138 in order to use it as a 1 x 8 Demultiplexer 2 Show connections for 74138 in order to use it as a 1 x 8 Demultiplexer

                          3 Consider a 2 x 4 Decoder with two enable inputs (one active high - G and one active low ndash Grsquo) Draw the output wave-forms for D0 D1 D2 and D3 if the two select inputs are A and B (B being the MSB) All outputs are active low

                          Grsquo

                          G

                          A B

                          D0 D1 D2

                          D3

                          Logic Design amp Switching Theory 1 Lab Session 08 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                          Lab Session 08 OBJECT

                          bull Designing of a 4 x 2 Priority Encoder bull Experimenting with 74148 IC

                          COMPONENTS AND APPARATUS REQUIRED

                          1 Following ICs and their Datasheets

                          bull 7408 Quad 2-input or 7421 Dual 4-input AND Gates bull 7432 Quad 2-input OR Gates bull 7404 Hex Inverter bull 74148 Encoder

                          2 Digital Trainer DT-01 or the following components Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches

                          THEORY

                          Encoder An Encoder is a digital function that produces a reverse operation from that of a decoder An Encoder has 2n (or less) input lines and n output lines The output lines generate the binary code for the 2n input variables Priority Encoder

                          A simple encoder may produce an erroneous output if more than one of its inputs is high A Priority Encoder is one that responds to just one input among those that may be simultaneously high in accordance with some priority system The most common priority system is based on the relative magnitudes of the inputs whichever decimal input is largest is the one that is encoded

                          DESIGN OF A 4 x 2 Priority Encoder

                          The following equations represent the outputs of a 4 x 2 priority encoder 32 DDA +=

                          321 DDDB += As can be seen from the equations that input D0 which has a binary code 00 is not used in any equation A binary code 00 at the output indicates two conditions Either D0 is selected or no input is selected In order to differentiate these two conditions we will provide an additional output Z to indicate if at least one of the inputs is a 1 The equation for Z will be

                          4321 DDDDZ = If Z is 0 then the binary code 00 at the output indicates that D0 is selected and if Z is 1 then it indicates that no input line is selected

                          38

                          Logic Design amp Switching Theory 1 Lab Session 08 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                          Figure 81 Circuit Diagram for 4 x 2 Priority Encoder

                          it (figure 81) on a bread board (prepare the to laboratory session 01 for implementation

                          Implementation a Implement the 4 x 2 Priority Encoder circu

                          ram (use appendix A) and refer

                          nd Observations

                          pin diagprocedure) and record the observations in the following table

                          D3 D2 D1 D0 A B 0 0 0 1 0 0 1 x 0 1 x x 1 x x x

                          TESTING OF 74148 8 x 3 Octal Priority Encoder

                          imal digits There are nine of which three represents

                          ing any of the inputs is high

                          then it shows that line 0 is selected and if e inputs selected E0 and GS

                          cannot be in the same state provided that E1 is enabled

                          The 74148 is a priority encoder with active-Low input for dec

                          input) and five output linesinputs lines (including an enablethe binary code for the octal digit Function of various pins of this IC is described below

                          bull 0 through 7 Active low data inputs representing the octal digits A2 A1 A0 Active low output lines representing the binary code bullbull E1 Active low enable Input bull E0 Active low output indicating none of the inputs is high bull GS Active low output indicatbull VCC and GND Supply connections lines Therefore if GS A2 A1 and A0 are all low

                          then it shows that none of thE0 A2 A1 and A0 are all low

                          39

                          Logic Design amp Switching Theory 1 Lab Session 08 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                          Circuit Diagram

                          Figure 82 Pin connections of 74148

                          Testing Procedure bull Make connections as sho

                          binations of 1s and 0s at data inputs d record your observations in the following table

                          GS E0

                          wn in the circuit diagram bull Apply different combull Observe the output an Observations

                          0 1 2 3 4 5 6 7 A2 A1 A0 1 1 1 1 1 1 1 1 x x x x x x x 0 x x x x x x 0 1 x x x x x 0 1 1 x x x x 0 1 1 1 x x x 0 1 1 1 1 x x 0 1 1 1 1 1 x 0 1 1 1 1 1 1 0 1 1 1 1 1 1 1

                          40

                          Logic Design amp Switching Theory 1 Lab Session 08 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                          41

                          CTIVITY

                          Cascade the following two 74148 8 x 3 Priority Encoders to form 16 x 4 Priority

                          A 1

                          Encoder

                          Logic Design amp Switching Theory 1 Lab Session 09 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering `

                          Lab Session 09 OBJECT

                          Designing an Odd Parity Generator and Checker for a 3-bit Data COMPONENTS AND APPARATUS REQUIRED

                          1 Following ICs and their Datasheets

                          bull 7486 Quad 2-input Exclusive-OR Gates bull 7404 Hex Inverter

                          2 Digital Trainer DT-01 or the following components Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches

                          THEORY

                          Parity Generator When binary data is transmitted and processed it is ndash as are all electrical signals ndash susceptible to noise that can either alter or distort its contents 1s may be effectively changed to 0s and 0s to 1s To overcome this problem one or more bits are often added to the data as an aid in detecting errors caused by noise The most common of these is a Parity bit that signifies whether the total number of 1s in a code group is odd or even In an Odd Parity system the parity bit is made 0 or 1 as necessary to make the total number 1s odd (counting the parity bit itself) In an Even Parity system the parity bit is chosen to make the total number of 1s even Table 91 shows how parity bits would be added to BCD code group in both systems

                          Decimal BCD Value Parity Bit ABCD Odd Parity Even Parity

                          0 0000 1 0 1 0001 0 1 2 0010 0 1 3 0011 1 0 4 0100 0 1 5 0101 1 0 6 0110 1 0 7 0111 0 1 8 1000 0 1 9 1001 1 0

                          Table 91 Odd and Even Parity in BCD

                          When digital data is received a parity checking circuit generates an error signal if the total number of 1s is odd in an even parity system or if it is even in an odd parity system Parity check always detects a single error (one bit change from 0 to 1 or 1 to 0) but may not detect

                          42

                          Logic Design amp Switching Theory 1 Lab Session 09 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering ` two or more errors Odd parity is used more often than even parity because even parity does not detect a situation where all 0s are created due to short circuit or other fault condition DESIGN OF A 3-BIT ODD PARITY GENERATOR AND CHECKER Let x y and z be the three bits that constitute the message and are the input to the Odd Parity Generator Circuit Since it is an odd parity system the bit P is generated so as to make the total number of 1s odd (including P) The function P can be expressed as follows P = x oplus y Ο z or P = x Ο y oplus z Since the IC available is 7486 which is quad 2input XOR IC therefore we will convert XNOR also to XOR

                          P = x oplus y Ο z

                          P = ( x oplus y ) Ο z Since for even number of variables ______

                          XOR = XNOR Therefore ___________ _________

                          P = ( x oplus y ) oplus z = x oplus y oplus z This logical expression can be implemented with two XOR gates and an inverter (see figure 91)

                          Figure 91 Circuit Diagram for a 3-bit Parity Generator

                          The 3-bit message and the parity bit are transmitted to their destination where they are applied to a Parity Checker Circuit An error occurs during transmission if the parity of the four bits received is even since the binary information transmitted was originally odd The output C of the parity checker should be a 1 when an error occurs ie when the number of 1s in the four inputs is even Therefore the function C can be expressed as

                          C = x Ο y Ο z Ο P

                          Using the same logic applied for the conversion of the equation of P

                          PzyxC oplusoplusoplus= This logical expression can be implemented with three XOR gates and an inverter (see figure 92)

                          43

                          Logic Design amp Switching Theory 1 Lab Session 09 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering `

                          44

                          Figure 92 Circuit Diagram for a 3-bit Parity Checker Implementation and Observations Implement the 3-bit Parity Generator and Checker circuits (figure 91 and 92) on a bread board (prepare the pin diagram (use appendix A) and refer to laboratory session 01 for implementation procedure) and record the observations in the following table

                          x y z P x y z P C x y z P C 0 0 0 0 0 0 0 1 0 0 0 0 0 1 0 0 0 1 1 0 0 1 0 1 0 0 0 1 0 1 0 1 0 0 1 1 0 0 1 1 1 0 1 1 1 0 0 0 1 0 0 1 1 0 0 1 0 1 0 1 0 1 1 1 0 1 1 1 0 0 1 1 0 1 1 1 0 1 1 1 0 1 1 1 1 1 1 1

                          Odd Parity Generation Odd Parity Check ACTIVITY 1 Try using the parity checker of figure 92 as 3-bit parity generator Write the details here

                          _____________________________________________________________________________________________________________________________________________________________________________________________________________________ ______________________________________________________________________________________________________________________________________________ _______________________________________________________________________ ______________________________________________________________________________________________________________________________________________

                          Logic Design amp Switching Theory 1 Lab Session 10 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                          Lab Session 10 OBJECT

                          Driving a seven segment display using 7447 7448 driver IC COMPONENTS AND APPARATUS REQUIRED

                          1 Following ICs and their Datasheets

                          bull Seven Segment Displays (Common Anode Common Cathode) bull 7447 7448 BCD to Seven Segment Driver

                          2 Digital Trainer DT-01 or the following components Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches

                          THEORY Seven Segment Displays A Seven Segment Display consists of seven light-emitting segments The segments are designated by letters a through g (see figure 101) By illuminating various combinations of segments the numerals 0 through 9 can be displayed Seven Segment Displays are commonly constructed with light-emitting diodes (LEDs) and with liquid-crystal displays (LCDs) LEDs generally provide greater illumination levels but require much greater power than LCDs An LED display can be a common-anode type or common cathode type In common anode type a high voltage is applied at the common terminal of the display and low voltage is applied at a segmentrsquos terminal for illumination In the common-cathode type a low voltage is applied at the common terminal of the display and high voltage is applied at a segmentrsquos terminal for illumination

                          Figure 101 Seven Segment Display

                          a f b g

                          e c d

                          7447 7448 BCD to Seven Segment Driver 7447 7448 IC is particularly used to drive Seven Segment Its input is a BCD number and output drives a seven segment display 7447 is used to drive common-anode displays whereas 7448 is used to drive common cathode displays 7447 7448 is a 16 pin IC Function of various pins of these ICs is described below

                          bull A B C D Inputs representing BCD digits (D being the MSB)

                          45

                          Logic Design amp Switching Theory 1 Lab Session 10 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering bull OA through OG Outputs to drive segments a through g of the display (Active low

                          in 7447 and active high in 7448) bull RBI Ripple Blanking Input Turns off all the segments if kept low provided that LT

                          is kept high and all other inputs (A B C D BI) are kept low Should be kept high otherwise

                          bull BI RBO Wire-AND logic serving as a Blanking Input and or Ripple Blanking Output

                          o BI Turns off all the segments if low o RBO Goes to a low level (response condition) along with other outputs when

                          RBI and inputs A B C and D are low with LT input at high level bull LT Lamp Test input Tests whether all segments are working or not Illuminates all

                          segments if kept low provided that BI is kept high Should be kept high otherwise bull VCC and GND Supply connections lines CIRCUIT DIAGRAM

                          Figure 102 Circuit diagram for 7447driving a common-anode display

                          IMPLEMENTATION AND OBSERVATIONS

                          bull Make connections as shown in the circuit diagram (refer to laboratory session 01 for implementation procedure)

                          bull Apply different combinations of 1s and 0s at data inputs bull Observe the output and record your observations in the following table

                          46

                          Logic Design amp Switching Theory 1 Lab Session 10 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                          47

                          Decimal Digit

                          BCD Inputs Seven Segment Outputs D C B A a b c d e f g

                          0 0 0 0 0 1 0 0 0 1 2 0 0 1 0 3 0 0 1 1 4 0 1 0 0 5 0 1 0 1 6 0 1 1 0 7 0 1 1 1 8 1 0 0 0 9 1 0 0 1

                          ACTIVITY 1 Perform the Lamp Test for the designed circuit and write your observations

                          ____________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________

                          2 How can you use 7447 IC to drive a common-cathode display

                          ____________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________

                          3 What symbols appear in the seven segment display if inputs DCBA are

                          DCBA Symbol

                          1010

                          1011

                          1100

                          1101

                          1110

                          1111

                          Logic Design amp Switching Theory 1 Lab Session 11 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                          48

                          Lab Session 11 OBJECT

                          Testing different modes of JK-FF COMPONENTS AND APPARATUS REQUIRED 1 Following ICs and their Datasheets

                          bull 7473 7476 JK Flip-Flop 2 Digital Trainer DT-01 or the following components

                          Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches

                          THEORY

                          Flip-Flop A flip-flop circuit can maintain a binary state indefinitely (as long as the power is delivered to the circuit) until directed by an input signal to switch states The major differences among various types of flip-flops are in the number of inputs they possess and in the manner in which the inputs affect the binary state

                          JK Flip-Flop JK flip flop is an edge triggered device A typical JK flip flop has three inputs J K and a clock input The flip-flop can be either positive or negative edge triggered The output Q is available in complemented form as well Beside the usual inputs and output most of the flip-flop IC also possess two asynchronous inputs namely Preset and Clear These inputs are usually active low If used Preset and Clear inputs keep the flip-flop in set and reset state respectively irrespective of the other inputs Both of these inputs cannot be used simultaneously otherwise they will bring the flip-flop in unstable state

                          Figure 111 Symbol for JK flip-flop

                          (a) positive-edge triggering (b) active low Preset (PR) and Clear (CLR) with positive-edge triggering

                          (c) active low Preset (PR) and Clear (CLR) with negative-edge triggering

                          Logic Design amp Switching Theory 1 Lab Session 11 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                          49

                          TESTING OF 7473 7476 DUAL JK FLIP-FLOP

                          Both the ICs 7473 and 7476 are similar in functionality except for one difference The flip-flops in 7473 have only one type of active low asynchronous input which is the Clear input whereas the flip-flops in 7476 have both Preset and Clear inputs Both these ICs have negative edge triggered flip-flops

                          Circuit Diagram

                          Figure 112 Pin connections of 7476

                          Testing Procedure

                          bull Make connections as shown in the circuit diagram (figure 112) bull Apply different combinations of 1s and 0s at J and K inputs bull Observe the output and record your observations in the following table

                          Observations

                          J

                          K Q

                          0 0 0 1 1 0 1 1

                          ACTIVITY

                          1 Observe the output Q of JK flip-flop if the clock input is connected to VCC or GND instead of a clock source Write your observations here __________________________________________________________________________________________________________________________________________ _______________________________________________________________________________________________________________________________________________________________________________________________________________

                          Logic Design amp Switching Theory 1 Lab Session 12 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                          50

                          Lab Session 12 OBJECT

                          Designing sequential circuit for the given state diagram using D flip-flop GIVEN STATE DIAGRAM

                          00

                          11

                          Figure 121 State Diagram COMPONENTS AND APPARATUS REQUIRED 1 Following ICs and their Datasheets

                          bull 7474 D Flip-Flop bull ICs of basic gates (AND OR NOT XOR etc) as required

                          2 Digital Trainer DT-01 or the following components Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches

                          THEORY

                          Sequential Circuits In Sequential Circuits the output not only depends on the present inputs but also on previous states of the circuit These circuits use memory elements (latches flip-flops) and the binary information stored in the memory elements at any given time defines the state of the sequential circuit Analysis of a Sequential Circuit The behavior of a sequential circuit is determined from the inputs the outputs and the states of its flip-flops Both the outputs and next state are a function of the inputs and the

                          10

                          01

                          00 11 10

                          00

                          00 11 10 00

                          Logic Design amp Switching Theory 1 Lab Session 12 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                          51

                          present state The analysis of a sequential circuit form a state diagram comprises of the following bull Selecting a particular flip-flop to design the circuit bull Obtaining state table from the state diagram bull Finding input equations for the selected flip-flop bull Finding state equations (not required for the construction of circuit) bull Implementing the circuit using selected flip-flops and their input equations ANALYZING THE GIVEN STATE DIAGRAM D Flip-Flop D flip-flop is also called transparent flip-flop as it simply transfers the input data to the output For our design we require the graphical symbol and excitation table of D flip-flop (see figure 122)

                          Qt Qt+1 T 0 0 0 0 1 1 1 0 0 1 1 1

                          (b) Excitation table of D Flip-Flop

                          (a) Graphical Symbol

                          Figure 122 Characteristic equation of D flip-flop is Q(t+1) = D State Table The given state diagram has four states so we will need two D flip-flops (FF-0 FF-1) Form state table form the given state diagram and record the results in the following table

                          Present State Input Next State Output Input to FF-0 D0

                          Input to FF-1 D1 Q1t Q0t x Q1(t+1) Q0(t+1) z

                          Logic Design amp Switching Theory 1 Lab Session 12 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                          52

                          Input Equations Using Karnaugh map the input equations D0 and D1 for the two flip-flops can be found

                          D0 D1 Q0x

                          Q1

                          _ _ Q0x

                          _ Q0x

                          Q0x

                          _ Q0x

                          Q0x

                          Q1

                          _ _ Q0x

                          _ Q0x

                          Q0x

                          _ Q0x

                          _ Q1

                          _ Q1

                          Q1

                          Q1

                          D0 = _________________ D1 = _________________

                          State Equations Using the characteristic equation of D flip-flop we can find the state equations Q0(t+1) and Q1(t+1) for the to flip flops Q0(t+1) = _______________________ Q1(t+1) = _______________________ _______________________ _______________________ _______________________ _______________________ Circuit Diagram

                          Logic Design amp Switching Theory 1 Lab Session 12 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                          53

                          Implementation Procedure and Observations

                          1 Implement the circuit using digital ICs on a bread board (prepare the pin diagram (use appendix A) and refer to laboratory session 01 for procedure)

                          2 Make the clear inputs of the flip-flops low (to clear the flip-flops) The flip-flops will remain in clear state as long as the clear inputs are connected to low level

                          3 Connect output Q0 and the clock pulse to an oscilloscope 4 Apply 0 to the input x 5 Now make the clear inputs to high 6 Observe the waveform for the first 5 clock pulses and record it 7 Repeat steps 2 to 6 keeping x=1 in step 4 this time 8 Repeat steps 2 to 7 this time connecting Q1 instead of Q0 to the oscilloscope in step

                          3 Record your observations (Keep frequency of the clock pulse low (eg1Hz) so that the output waveforms can be observed easily)

                          1 2 3 4 5 Clock Pulse

                          Output Waveform for Q0 when x=0

                          Output Waveform for Q0 when x=1

                          Output Waveform for Q1 when x=0

                          Output Waveform for Q1 when x=1

                          Logic Design amp Switching Theory 1 Lab Session 13 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                          Lab Session 13 OBJECT

                          Designing a modulo-5 asynchronous up-counter using JK-FF COMPONENTS AND APPARATUS REQUIRED

                          1 Following ICs and their Datasheets

                          bull 7400 Quad 2-input or 7410 Triple 3-input NAND Gates bull 7476 7473 JK Flip-Flop

                          2 Digital Trainer DT-01 or the following components Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches

                          THEORY

                          Digital Counters A digital counter is a set of flip-flops whose states change in response to pulses applied at the input to the counter The flip-flops are interconnected so that their combined state at any time is the binary equivalent of the total number of pulses that have occurred up to that time Every counter resets after a certain number of clock pulses Thus as it name implies a counter is used to count pulses An n stage counter can count up to a maximum of 2n states n is equal to the number of flip-flops required for the construction of counter

                          Modulus Counters The number of input pulses that causes a counter to reset to its initial count is called the modulus of the counter Thus the modulus equals to total number of distinct states (counts) including zero that a counter can store A binary counter with n stages is a modulo-2n (or mod-2n) counter The largest count a mod-N counter can achieve is N-1 ie a mod-N counter never reaches the binary number equal to its modulus N is always equal to or less than 2n Counters can be classified as bull Synchronous Counters which are clock driven All the flip-flops are driven by a

                          single clock bull Asynchronous Counters which are event driven Clock input is given to the first

                          flip-flop only Rest of the flip-flops are driven by their preceding flip-flops

                          DESIGN OF A MOD-5 ASYNCHRONOUS UP COUNTER The number of flip-flops required to construct a mod-5 counter is 3 because 5 should be less than or equal to 2n This counter will count from 0 to 4 a total of 5 distinct states Since a 3-stage counter can count up to 8 states at maximum a NAND gate is used to reset it after 5 clock pulses Figure 131 shows the logic diagram

                          54

                          Logic Design amp Switching Theory 1 Lab Session 13 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                          55

                          Figure 131 A Mod-5 Asynchronous Up Counter

                          Implementation and Observations

                          Implement the mod-5 counter circuit (figure 131) on a bread board (prepare the pin diagram (use appendix A) and refer to laboratory session 01 for implementation procedure) and record the observations in the following table

                          Clock Pulse Q2 Q1 Q0

                          0 1 2 3 4 5 6 7

                          ACTIVITY

                          Draw the timing diagram for mod-5 counter designed in this laboratory session

                          Logic Design amp Switching Theory 1 Lab Session 14 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                          Lab Session 14 OBJECT

                          Experimenting with 74194 4-bit bidirectional universal shift register COMPONENTS AND APPARATUS REQUIRED

                          1 Following ICs and their Datasheets

                          bull 74194 4-bit bidirectional universal shift register 2 Digital Trainer DT-01 or the following components

                          Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches

                          THEORY

                          Shift Registers

                          A Register is a set of flip-flops used to store binary data A register which is capable of shifting its binary information either to the right or left is called a shift register The logical configuration of a register consists of a chain of flip-flops connected in cascade with the output of one flip-flop connected to the input of next flip-flop All flip-flops receive a common clock pulse which causes the shift from one stage to the next

                          Bidirectional Shift Registers A bi-directional shift register is one whose bits can be shifted from left to right or from right to left

                          Universal Shift Registers A universal shift register is a bi-directional register whose input can be in either serial or parallel form and whose output can be in either serial or parallel form

                          74194 4-BIT BIDIRECTIONAL UNIVERSAL SHIFT REGISTER

                          The 74194 register provides parallel as well as serial loading in both directions Function of various pins of this IC is described below

                          bull A B C and D Active high inputs for parallel loading bull QA QB QC and QD Active high outputs bull S0 and S1 Active high mode control inputs The following table shows combinations

                          of S1 and S0 to enable various modes

                          S1 S0 Clock Action 0 0 x No change 0 1 uarr Shift right 1 0 uarr Shift left 1 1 uarr Parallel load

                          uarr shows the rising edge of the clock pulse

                          56

                          Logic Design amp Switching Theory 1 Lab Session 14 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering bull SR Active high serial input for right shifting bull SL Active high serial input for left shifting bull CLR Active low input Clears all the flip-flops of the register if set to 0 should be

                          kept high otherwise bull CLK Clock input bull VCC and GND Supply connections lines Thus A B C and D are inputs for parallel loading whereas SR and SL are inputs for serial loading with right or left shifting respectively S1 and S0 are used to select the loading mode Circuit Diagram

                          Figure 141 Pin connections of 74194 Testing Procedure

                          bull Make connections as shown in the circuit diagram bull Observe the output for the input combinations given in the following table

                          57

                          Logic Design amp Switching Theory 1 Lab Session 14 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                          58

                          Observations

                          S1 S0 SL SR A B C D QA QB QC QD 0 0 0 1 0 0 0 0 0 1 1 0 0 0 0 1 1 0 0 0 0 0 1 0 1 1 0 0 0 0 1 1 0 0 1 1 0 1 0 0 0 1 1 1 0 1 0 1 1 0 1 0 0 1 1 0 1 1 1 0 0 1 1 1 1 1 0 0 1 1 1 1

                          ACTIVITY 1 Show connections of 74194 to convert it into a ring counter with right shifting

                          Logic Design amp Switching Theory 1 Lab Session 15 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                          Lab Session 15

                          OBJECT

                          Experimenting with 74245 octal bus transceivers using parallel port PC interfacing COMPONENTS AND APPARATUS REQUIRED 1 Parallel Port Connectors (DB-25) with Cable 2 Personal Computer with Windows 98 and TurboC Compiler Installed 3 Following ICs and their Datasheets

                          bull 74245 Octal Bus Transceivers with 3-State Outputs 4 Digital Trainer DT-01 or the following components

                          Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches

                          THEORY

                          3-State Logic Sometimes it is necessary to isolate one part of circuit from the other part For this purpose some TTL ICs are designed with 3-state logic Such devices have three possible output states high low and high impedance The device can be put into high impedance state by a control signal applied to an appropriate pin When such a device is in high impedance state there is very high impedance at its output effectively isolating the device from whatever circuitry the output normally drives 74245 Octal Bus Transceivers A bus is any conducting path or set of paths having electrical connections to one or more devices 74245 octal bus transceivers are mainly used to control connectivity between two devices or circuits It also provides direction control for signal flow Function of various pin of this IC is given below

                          bull A1 through A8 Bus A bull B1 through B8 Bus B bull G΄ Active low enable input When high sets all the bus pins to high impedance state bull DIR Direction control for signal flow When set to high logic level transfers bus A

                          data to B bus When set to low logic level transfers bus B data to A bus bull VCC and GND Supply connections lines Serial and Parallel Port Connectors A Parallel Port can consist of only 25 pin port adapter called a DB-25 and a serial port can consist of either a 25 pin port adapter called a DB-25 or 9 pin adapter called a DB-9 port adapter Whether the port is a 9 pin or 25 pin it can accomplish all of the same tasks that serial port communications have been designed for

                          59

                          Logic Design amp Switching Theory 1 Lab Session 15 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                          60

                          Each adapter can be a male type connector with pins or a female type adapter with tiny holes Generally a PRINTER port (called LPT1) on the back of a computer is female type adapter and we need to use MALE DB-25 pin cable on it for PRINTER connection or for parallel LAPLINK cable And a COM port on the back of a computer is male for the serial ports but it may not necessarily be Parallel Port Connector ndash DB-25 The DB-25 connector (named for its B-size D-shaped shell and 25 pins) is practically ubiquitous in the electronics industry The DB-25 connector is used for a variety of purposes Two common applications are RS-232EIA-232 (serial) connections and the parallel printer interface on the IBM PC The DB-25 connector is also used for SCSI connections Normally the parallel port is used for output to a printer or other device It sends data 8-bits or one byte at a time in parallel The other lines available on the DB-25 connector are a combination of status lines control lines and ground lines The status and control lines are used for handshaking commands and feedback when we are talking to a printer

                          Figure 152 DB-25 Female Figure 151 DB-25 Male

                          Figure 153 Pin Layout for DB-25 As can be seen form figure 153 there are four types of pins in this connector

                          bull Data pins (8 pins - D0 to D7) Active high bidirectional lines

                          Logic Design amp Switching Theory 1 Lab Session 15 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering bull Control pins (4 pins - C0 to C3) C0 C1 and C3 are active low whereas C2 is active

                          high These lines also are bidirectional bull Status pins (5 pins ndash S3 to S7) Only S7 is active low rest are active high input lines bull Ground pins (8 pins) Used as a reference signal for the low (below 05 volts) charge

                          Parallel Port Addresses A DB-25 connector at a parallel port has three address one for each kind of pins register data status and control The first or base address generally refers to data register Second address is for status register and the third one is for control register In Windows 98 the base address is usually found to be 278H 378H or 3BCH Now if 378H is the base address then it refers to the data register whereas addresses for status and control register are respectively 379H and 37AH For Windows 98 the base address can be found as follows 1 On your Desktop right-click on My Computer and select Properties 2 Click on the Device Manager tab and find LPT1 under Plug and Play BIOS 3 After selecting LPT1 click the Properties button 4 Next select the Resources tab and the address should then appear next to InputOutput

                          Range Accessing parallel port through C Language Programming There are multiple functions in C Language for accessing external ports The most commonly used are listed below

                          bull unsigned char inportb(int portid) inportb reads a byte from a hardware port

                          bull int inport(int portid) reads a word from a hardware port

                          bull void outportb(int portid unsigned char value) outputs a byte to a hardware port

                          bull void outport(int portid int value) outputs a word to a hardware port

                          portid refers to the port address whereas value refers to the data to be sent TESTING 74245 USING PARALLEL PORT PC INTERFACING At one end the parallel port connector will be connected to the PC via parallel port cable and another connector (to be plugged into the PC parallel port slot) At the other end it will be connected to the buffer IC 74245 Data lines of the connector will be used to transfer 8-bit data between the PC and the buffer Out of the 8-bits of 74245 4-bits will be used to enter data which will be displayed at the monitor through a C language

                          61

                          Logic Design amp Switching Theory 1 Lab Session 15 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering program The remaining 4-bits will receive data from PC as entered by the user via keyboard

                          Circuit Diagram

                          Figure 154 Interface of 74245 to PC via Parallel Port

                          Procedure

                          1 Connect the DB-25 connector to the PC at one end and solder it to the circuit board at the other end

                          2 Connect various pins of the connector and 74245 according to the circuit diagram shown in figure 152

                          3 Using the functions listed in the previous section write a program in C language to operate various pins of the buffer The user interface of the program should provide option to the user whether to send or receive data from the port

                          4 Set DIR switch to 1 5 Try sending some data bits to the port The result should be displayed at the LEDs 6 Set DIR switch to 0 7 Set some binary 4-bit value through the switches Try reading it via parallel port

                          C Language Program

                          A program to access parallel port for data transfers

                          use header file include ltstdiohgt main program void main() define variable

                          62

                          Logic Design amp Switching Theory 1 Lab Session 15 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering unsigned int data=0 char choice while(1) printing option menu clrscr() printf(This program will send or receive a BCD digit from the parallel portn) printf(nPress your choice numbern) printf(n1 Send Data) printf(n2 Receive Data) printf(n3 Exitn) choice = getch() sending entered digit to the port if(choice == 1) input BCD digit printf(nEnter BCD digit to be sent to the port) data = getche() masking the first four bits data = data amp 0x0f sending to the port outportb(0x378data) printf(nThe BCD digit c has been sent to the port data) printing on screen the data received from the port else if(choice == 2) receiving data from the port data = inportb(0x378) masking the last four bits data = data amp 0xf0 shifting first four bits to make them the last four bits datagtgt=4 printf(nThe BCD digit set at the port is c data) exit else if(choice == 3) break key pressed is not in the menu else printf(nEnter valid choice number) printf(nnPress any key to continue) getch()

                          63

                          Logic Design amp Switching Theory 1 Lab Session 15 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                          ACTIVITY 1 In the above circuit DIR and G΄ inputs are hardwired Connect them to status or

                          control pins of the parallel port connector and control their function through your software program Circuit Diagram Program Code ______________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________

                          ___________________________________________________________________________________________________________________________________________________

                          64

                          Logic Design amp Switching Theory 1 Lab Session 15 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                          65

                          _____________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ _____________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ _______________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ _________________________________________________ _________________________________________________

                          Logic Design amp Switching Theory 1 Appendix A NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                          Appendix A

                          PIN DIAGRAMS OF THE ICS REQUIRED FOR THE LABORATORY SESSIONS Consult the TTLIC data book for internal diagrams and electrical characteristics of these ICs 7400 Quad 2-Input NAND 7402 Quad 2-Input NOR

                          7404 Hex Inverter 7408 Quad 2-Input AND

                          7410 Triple 3-Input NAND 7411 Triple 3-Input AND

                          7421 Dual 4-Input AND 7432 Quad 2-Input OR

                          66

                          Logic Design amp Switching Theory 1 Appendix A NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                          BCD-to-Seven Segm 7448 BCD-to-Seven Segment 7447 ent

                          Decoder (15V OC) Decoder (2kΩ pull-up output)

                          7473 Dual JK Flip-Flop 7474 Dual D-Type Flip-Flop

                          7476 Dual JK Flop-Flop -Bit Binary Full Adder 7483 4 with Fast Carry

                          86 Quad 2-Inpu 74138 3-to-8 Line 74 t Exclusive OR Decoder Demultiplexer

                          67

                          Logic Design amp Switching Theory 1 Appendix A NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                          68

                          74148 8-to-3 Line 16-to-1 Line Data

                          Priority Encoder 74150 Selector Multiplexer

                          74245 Oct nsceivers Universal Shift Register (PIPO) (3-State)

                          74194 4-Bit Bidirectional al Bus Tra

                          Logic Design amp Switching Theory 1 Appendix B NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                          Appendix B

                          DEBOUNCING CIRCUITRY FOR MECHANICAL SWITCHES Mechanical switches form the interface between human beings and computers or other digital systems For example a keyboard is a matrix of switches used to supply alphanumeric data to a computer Whatever the switch design it is a potential source of problems due to contact bounce The contact bounce creates a sense of narrow pulses when a switch is opened or closed An example of device whose operation would be adversely affected by contact bounce is a digital counter used to count the number of times a switch is depressed Eliminating the effects of contact bounce is called debouncing When data is entered into a computer via a keyboard a software debounce is often used This type of debouncing is a program that causes the computer to sample the switch terminal (ie to input data from it) many times in succession during the interval of time that contact bounce occurs If the data is sensed to be 1s (or 0s) for a specific number of consecutive samples then it is assumed that contact bounce has ended and the last value sensed is valid Hardware debouncing is the use of electronic circuitry to eliminate the effects of contact bounce There are numerous versions of such circuitry including those that use monostable multivibrators (one-shots) but the most straightforward is simply an RS latch Figure B1 shows the circuit When the switch is in position 1 R = 0 and S = 1 so the latch is set and the output (Q) is 1 When the switch is in position 0 R = 1and S = 0 so the latch is reset and the output is 0 When the switch is moved form one position to the other the latch changes state and bouncing occurs at either the R or the S input The bouncing does not affect the latch after it has change state An RS latch will remain set for example when its R input is 0 and its S input is alternately changed form 1 to 0

                          Figure B1 Use of RS latch to debounce a mechanical switch

                          69

                          • 01-ldst-Outer title
                            • Practical Workbook
                            • Logic Design amp Switching Theory I
                              • Dept of Computer amp Information Systems Engineering
                                • NED University of Engineering amp Technology
                                • Karachi ndash 75270 Pakistan
                                  • 02-ldst-inner Title
                                    • Practical Workbook
                                    • Logic Design amp Switching Theory I
                                      • Dept of Computer amp Information Systems Engineering
                                        • NED University of Engineering amp Technology
                                        • Karachi ndash 75270 Pakistan
                                          • 03-ldst-general info
                                          • 04-ldst-introduction
                                          • 05-Table of Contents
                                            • CONTENTS
                                              • Lab Session No Object Page No
                                              • 1
                                              • Also implementing and testing the given circuit on a bread board
                                                • Working with Electronics Workbench
                                                  • Driving a seven segment display using 7447 7448 driver IC
                                                    • Designing a modulus-5 asynchronous up-counter using JK-FF
                                                      • Experimenting with 74194 4-bit bidirectional universal shift register
                                                          • 13
                                                              • 06-ldst-Exp01
                                                                • Lab Session 01
                                                                • OBJECT
                                                                  • 1 Bread board
                                                                  • 2 5 V - power supply
                                                                  • 3 Multimeter
                                                                  • 4 Logic probe
                                                                  • 5 LEDs with resistors
                                                                  • 6 Connecting wires
                                                                  • 8 Following ICs and their datasheets
                                                                    • THEORY
                                                                      • Logic Gates
                                                                      • 1 The AND Gate ndash An AND gatersquos output is 1 if and only if all its inputs are 1 If A and B are two inputs to an AND gate then output F of the gate is given as F = AB
                                                                      • 2 The OR Gate - An OR gatersquos output is 1 if at least one of its input is 1 If A and B are two inputs to an OR gate then output F of the gate is given as F = A+B
                                                                      • 3 The NOT Gate (Inverter) ndash Its output is 1 when its input is 0 and its output is 0 when the input is 1 ie it complements a digital variable If A is the input to a NOT gate then output F of the gate is given as
                                                                      • 4 The NAND Gate ndash Its output is 1 if at least one of its input is 0 This gate performs the same logic as an AND gate followed by an inverter If A and B are two inputs to a NAND gate then output F of the gate is given as
                                                                        • 5 The NOR Gate - The output of a NOR gate is 1 if and only if all its inputs are 0 This gate performs the same logic function as an OR gate followed by an inverter If A and B are two inputs to a NAND gate then output F of the gate is given as
                                                                            • DATA SHEETS
                                                                              • Logic expression for the given logic diagram __________________________________
                                                                                  • 07-ldst-exp02
                                                                                    • Working with Electronics Workbench
                                                                                      • 08-ldst-exp03
                                                                                        • Designing Half and Full Adder Circuits
                                                                                          • COMPONENTS AND APPARATUS REQUIRED
                                                                                            • 1 Following ICs and their Datasheets
                                                                                            • 7408 Quad 2-input AND Gate
                                                                                            • 2 Digital Trainer DT-01 or the following components
                                                                                              • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                              • Connecting wires Switches
                                                                                                • THEORY
                                                                                                    • IMPLEMENTATION AND OBSERVATIONS
                                                                                                      • 09-ldst-Exp04
                                                                                                        • Lab Session 04
                                                                                                        • 1 Digital ICs and their Datasheets
                                                                                                        • 7408 Quad 2-input AND Gate
                                                                                                        • 2 Digital Trainer DT-01 or the following components
                                                                                                          • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                          • Connecting wires Switches
                                                                                                          • PROCEDURE
                                                                                                          • REDUCTION OF LOGIC EXPRESSION USING KARNAUGH MAP
                                                                                                          • OBSERVATIONS
                                                                                                          • RESULT
                                                                                                              • 10-ldst-Exp05
                                                                                                                • Lab Session 05
                                                                                                                • 1 Following ICs and their Datasheets
                                                                                                                • 7408 Quad 2-input AND Gate
                                                                                                                • 2 Digital Trainer DT-01 or the following components
                                                                                                                  • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                  • (100 Ω) Connecting wires Switches
                                                                                                                  • THEORY
                                                                                                                    • IMPLEMENTATION AND OBSERVATIONS
                                                                                                                      • 11-ldst-Exp06
                                                                                                                        • OBJECT
                                                                                                                        • 1 Following ICs and their Datasheets
                                                                                                                        • 7408 Quad 2-input AND Gates or 7411 Triple 3-input AND Gates
                                                                                                                        • 2 Digital Trainer DT-01 or the following components
                                                                                                                          • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                          • Connecting wires Switches
                                                                                                                            • Figure 62 Circuit Diagram for 4 x 1 Multiplexer
                                                                                                                            • Implementation and Observations
                                                                                                                              • Circuit Diagram
                                                                                                                                • ACTIVITY
                                                                                                                                  • 12-ldst-exp07
                                                                                                                                    • 1 Following ICs and their Datasheets
                                                                                                                                    • 7408 Quad 2-input or 7411 Triple 3-input AND Gates
                                                                                                                                    • 2 Digital Trainer DT-01 or the following components
                                                                                                                                      • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                      • Connecting wires Switches
                                                                                                                                        • THEORY
                                                                                                                                            • Figure 72 Circuit Diagram for 2 x 4 Decoder 1 x 4 Demultiplexer
                                                                                                                                            • Implementation and Observations
                                                                                                                                              • Circuit Diagram
                                                                                                                                                • ACTIVITY
                                                                                                                                                  • 13-ldst-Exp08
                                                                                                                                                    • OBJECT
                                                                                                                                                    • 1 Following ICs and their Datasheets
                                                                                                                                                    • 7408 Quad 2-input or 7421 Dual 4-input AND Gates
                                                                                                                                                    • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                      • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                      • Connecting wires Switches
                                                                                                                                                        • THEORY
                                                                                                                                                            • Figure 81 Circuit Diagram for 4 x 2 Priority Encoder
                                                                                                                                                            • Implementation and Observations
                                                                                                                                                              • Therefore if GS A2 A1 and A0 are all low then it shows that line 0 is selected and if E0 A2 A1 and A0 are all low then it shows that none of the inputs selected E0 and GS cannot be in the same state provided that E1 is enabled
                                                                                                                                                              • Circuit Diagram
                                                                                                                                                                • ACTIVITY
                                                                                                                                                                  • 14-ldst-exp09
                                                                                                                                                                    • OBJECT
                                                                                                                                                                    • 1 Following ICs and their Datasheets
                                                                                                                                                                    • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                      • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                      • Connecting wires Switches
                                                                                                                                                                        • THEORY
                                                                                                                                                                          • Parity Generator
                                                                                                                                                                            • Let x y and z be the three bits that constitute the message and are the input to the Odd Parity Generator Circuit Since it is an odd parity system the bit P is generated so as to make the total number of 1s odd (including P) The function P can be expressed as follows
                                                                                                                                                                            • Figure 91 Circuit Diagram for a 3-bit Parity Generator
                                                                                                                                                                              • C = x Ο y Ο z Ο P
                                                                                                                                                                                • Implementation and Observations
                                                                                                                                                                                  • ACTIVITY
                                                                                                                                                                                      • 15-ldst-exp10
                                                                                                                                                                                        • Driving a seven segment display using 7447 7448 driver IC
                                                                                                                                                                                        • COMPONENTS AND APPARATUS REQUIRED
                                                                                                                                                                                        • 1 Following ICs and their Datasheets
                                                                                                                                                                                        • 7447 7448 BCD to Seven Segment Driver
                                                                                                                                                                                        • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                          • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches
                                                                                                                                                                                            • THEORY
                                                                                                                                                                                            • Seven Segment Displays
                                                                                                                                                                                            • CIRCUIT DIAGRAM
                                                                                                                                                                                            • Figure 102 Circuit diagram for 7447driving a common-anode display
                                                                                                                                                                                                • IMPLEMENTATION AND OBSERVATIONS
                                                                                                                                                                                                  • Decimal Digit
                                                                                                                                                                                                  • BCD Inputs
                                                                                                                                                                                                  • Seven Segment Outputs
                                                                                                                                                                                                  • D
                                                                                                                                                                                                  • C
                                                                                                                                                                                                  • B
                                                                                                                                                                                                  • A
                                                                                                                                                                                                  • a
                                                                                                                                                                                                  • b
                                                                                                                                                                                                  • c
                                                                                                                                                                                                  • d
                                                                                                                                                                                                  • e
                                                                                                                                                                                                  • f
                                                                                                                                                                                                  • g
                                                                                                                                                                                                  • 0
                                                                                                                                                                                                  • 0
                                                                                                                                                                                                  • 0
                                                                                                                                                                                                  • 0
                                                                                                                                                                                                  • 0
                                                                                                                                                                                                  • 1
                                                                                                                                                                                                  • 0
                                                                                                                                                                                                  • 0
                                                                                                                                                                                                  • 0
                                                                                                                                                                                                  • 1
                                                                                                                                                                                                  • 2
                                                                                                                                                                                                  • 0
                                                                                                                                                                                                  • 0
                                                                                                                                                                                                  • 1
                                                                                                                                                                                                  • 0
                                                                                                                                                                                                  • 3
                                                                                                                                                                                                  • 0
                                                                                                                                                                                                  • 0
                                                                                                                                                                                                  • 1
                                                                                                                                                                                                  • 1
                                                                                                                                                                                                  • 4
                                                                                                                                                                                                  • 0
                                                                                                                                                                                                  • 1
                                                                                                                                                                                                  • 0
                                                                                                                                                                                                  • 0
                                                                                                                                                                                                  • 5
                                                                                                                                                                                                  • 0
                                                                                                                                                                                                  • 1
                                                                                                                                                                                                  • 0
                                                                                                                                                                                                  • 1
                                                                                                                                                                                                  • 6
                                                                                                                                                                                                  • 0
                                                                                                                                                                                                  • 1
                                                                                                                                                                                                  • 1
                                                                                                                                                                                                  • 0
                                                                                                                                                                                                  • 7
                                                                                                                                                                                                  • 0
                                                                                                                                                                                                  • 1
                                                                                                                                                                                                  • 1
                                                                                                                                                                                                  • 1
                                                                                                                                                                                                  • 8
                                                                                                                                                                                                  • 1
                                                                                                                                                                                                  • 0
                                                                                                                                                                                                  • 0
                                                                                                                                                                                                  • 0
                                                                                                                                                                                                  • 9
                                                                                                                                                                                                  • 1
                                                                                                                                                                                                  • 0
                                                                                                                                                                                                  • 0
                                                                                                                                                                                                  • 1
                                                                                                                                                                                                    • ACTIVITY
                                                                                                                                                                                                      • 16-ldst-exp11
                                                                                                                                                                                                        • Lab Session 11
                                                                                                                                                                                                          • OBJECT
                                                                                                                                                                                                          • COMPONENTS AND APPARATUS REQUIRED
                                                                                                                                                                                                            • 1 Following ICs and their Datasheets
                                                                                                                                                                                                            • 7473 7476 JK Flip-Flop
                                                                                                                                                                                                            • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                              • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                              • Connecting wires Switches
                                                                                                                                                                                                                • THEORY
                                                                                                                                                                                                                    • Flip-Flop
                                                                                                                                                                                                                    • JK Flip-Flop
                                                                                                                                                                                                                      • Circuit Diagram
                                                                                                                                                                                                                        • Observations
                                                                                                                                                                                                                          • ACTIVITY
                                                                                                                                                                                                                              • 17-ldst-exp12
                                                                                                                                                                                                                                • Lab Session 12
                                                                                                                                                                                                                                  • OBJECT
                                                                                                                                                                                                                                  • GIVEN STATE DIAGRAM
                                                                                                                                                                                                                                  • Figure 121 State Diagram
                                                                                                                                                                                                                                  • COMPONENTS AND APPARATUS REQUIRED
                                                                                                                                                                                                                                    • 1 Following ICs and their Datasheets
                                                                                                                                                                                                                                    • 7474 D Flip-Flop
                                                                                                                                                                                                                                    • ICs of basic gates (AND OR NOT XOR etc) as required
                                                                                                                                                                                                                                    • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                                      • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                                                      • Connecting wires Switches
                                                                                                                                                                                                                                        • THEORY
                                                                                                                                                                                                                                            • Sequential Circuits
                                                                                                                                                                                                                                              • 18-ldst-exp13
                                                                                                                                                                                                                                                • Lab Session 13
                                                                                                                                                                                                                                                  • Designing a modulo-5 asynchronous up-counter using JK-FF
                                                                                                                                                                                                                                                    • 1 Following ICs and their Datasheets
                                                                                                                                                                                                                                                    • 7400 Quad 2-input or 7410 Triple 3-input NAND Gates
                                                                                                                                                                                                                                                    • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                                                      • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                                                                      • Connecting wires Switches
                                                                                                                                                                                                                                                        • THEORY
                                                                                                                                                                                                                                                            • Figure 131 A Mod-5 Asynchronous Up Counter
                                                                                                                                                                                                                                                            • Implementation and Observations
                                                                                                                                                                                                                                                              • ACTIVITY
                                                                                                                                                                                                                                                                  • 19-ldst-exp14
                                                                                                                                                                                                                                                                    • Experimenting with 74194 4-bit bidirectional universal shift register
                                                                                                                                                                                                                                                                    • 1 Following ICs and their Datasheets
                                                                                                                                                                                                                                                                    • 74194 4-bit bidirectional universal shift register
                                                                                                                                                                                                                                                                    • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                                                                      • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                                                                                      • Connecting wires Switches
                                                                                                                                                                                                                                                                        • THEORY
                                                                                                                                                                                                                                                                          • Shift Registers
                                                                                                                                                                                                                                                                          • Bidirectional Shift Registers
                                                                                                                                                                                                                                                                          • Universal Shift Registers
                                                                                                                                                                                                                                                                            • S1
                                                                                                                                                                                                                                                                              • Circuit Diagram
                                                                                                                                                                                                                                                                              • ACTIVITY
                                                                                                                                                                                                                                                                                  • 20-ldst-exp15
                                                                                                                                                                                                                                                                                    • COMPONENTS AND APPARATUS REQUIRED
                                                                                                                                                                                                                                                                                    • 1 Parallel Port Connectors (DB-25) with Cable
                                                                                                                                                                                                                                                                                    • 2 Personal Computer with Windows 98 and TurboC Compiler Installed
                                                                                                                                                                                                                                                                                    • 3 Following ICs and their Datasheets
                                                                                                                                                                                                                                                                                    • 74245 Octal Bus Transceivers with 3-State Outputs
                                                                                                                                                                                                                                                                                    • 4 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                                                                                      • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                                                                                                        • Connecting wires Switches
                                                                                                                                                                                                                                                                                          • THEORY
                                                                                                                                                                                                                                                                                          • 3-State Logic
                                                                                                                                                                                                                                                                                            • Serial and Parallel Port Connectors
                                                                                                                                                                                                                                                                                            • Parallel Port Connector ndash DB-25
                                                                                                                                                                                                                                                                                              • Accessing parallel port through C Language Programming
                                                                                                                                                                                                                                                                                                  • 21-ldst-appendixA
                                                                                                                                                                                                                                                                                                  • 22-ldst-appendixB
                                                                                                                                                                                                                                                                                                    • DEBOUNCING CIRCUITRY FOR MECHANICAL SWITCHES

                            Logic Design amp Switching Theory 1 Lab Session 01 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                            16

                            GIVEN CIRCUIT

                            Figure 12

                            PROCEDURE FOR IMPLEMENTATION OF THE GIVEN CIRCUIT 1 Set the power supply 2 Insert ICs on the bread board and make their supply and ground connections 3 As given in the logic diagram make connections using wires and gates in the ICs 4 Apply different combinations at the three inputs and observe the output OBSERVATIONS Logic expression for the given logic diagram __________________________________

                            A B C Expected Output Observed Output 0 0 0 0 0 1 0 1 0 0 1 1 1 0 0 1 0 1 1 1 0 1 1 1

                            Logic Design amp Switching Theory 1 Lab Session 02 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                            Lab Session 02

                            OBJECT

                            Working with Electronics Workbench

                            ELECTRONICS WORKBENCH - EWB Electronics Workbench is a computer aided design tool that provides you with all the components and instruments necessary to create board-level designs It has complete mixed analog and digital simulation and graphical waveform analysis allowing you to design your circuit and then analyze it using different simulated instruments and analysis options It is fully integrated and interactive thus you can change your circuits quickly allowing fast and repeated what-if analysis Electronics Workbench provides the following kind of components bull Sources parts bin (AC voltage source Vcc source ground battery etc) bull Basic parts bin (resistors capacitors transformers switches etc) bull Diodes parts bin bull Transistors parts bin bull Analog ICs parts bin (op-amps etc) bull Mixed ICs parts bin (ADCs DACs 555 timers etc) bull Digital ICs parts bin (AND OR adders multiplexers etc) bull Indicators parts bin (voltmeter ammeter probe displays etc) bull Controls parts bin (voltage differentiator multiplier etc) bull Instruments parts bin (multimeter oscilloscope function generator etc) bull Miscellaneous parts bin (write data textbox etc)

                            o Write data This component allows you to save simulation results as an ASCII file o Text Box Use this to add descriptive text anywhere in a circuit

                            ACTIVITY

                            Design circuit for the logic expression )( CBDCABAF ++=

                            Procedure 1 From Logic Gates Parts Bin Drag and drop the required logic gates on the design

                            area Use Component Properties dialog box to customize these gates 2 Connect the terminal of these gates according to the given expression Use additional

                            connectors form the Basic Parts Bin if you want to connect more than wire at a single node

                            3 Drag and drop a probe from Indicators Parts Bin Use Component Properties dialog box to customize the color and other properties of the probe Connect this probe at the output terminal of the circuit to indicate results

                            4 Select four switches form Basic Parts Bin Specify the key that controls the switch by typing its name in the Value tab of the Component Properties dialog box For

                            17

                            Logic Design amp Switching Theory 1 Lab Session 02 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                            18

                            example if you want the switch to close or open when digit lsquo1rsquo is pressed type 1 in the Value tab then click OK Assign different keys to all the switches

                            5 Connect the output terminals of these switches to each of the four inputs A B C and D of the circuit

                            6 Drag and drop Vcc and Ground form the Sources Parts Bin 7 Connect Vcc terminal to one end and Ground terminal to the other end of all the

                            switches 8 Label the circuit properly using text boxes found in the miscellaneous parts bin 9 Run the circuit using the Activate Simulation switch Use the keys you have assigned

                            to the switches to toggle them between Vcc and Ground connections thus providing 1 or 0 respectively to the inputs Record the results as indicated by the probe for all possible combinations of 1s and 0s at the inputs

                            EWB Circuit

                            Figure 21

                            Observations

                            A B C D Expected Output Observed Output 0 0 0 0 0 0 0 1 0 0 1 0 0 0 1 1 0 1 0 0 0 1 0 1 0 1 1 0 0 1 1 1 1 0 0 0 1 0 0 1 1 0 1 0 1 0 1 1 1 1 0 0 1 1 0 1 1 1 1 0 1 1 1 1

                            Logic Design amp Switching Theory 1 Lab Session 03 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                            Lab Session 03

                            OBJECT

                            Designing Half and Full Adder Circuits COMPONENTS AND APPARATUS REQUIRED 1 Following ICs and their Datasheets

                            bull 7408 Quad 2-input AND Gate bull 7432 Quad 2-input OR Gate bull 7486 Quad 2-input XOR Gate

                            2 Digital Trainer DT-01 or the following components Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches

                            THEORY Half Adder A combination circuit that performs the addition of two bits without accounting for the previous carry is called half adder It needs two binary inputs and two binary outputs The input variables designate the augend and addend bits The output variables produce the sum and carry The simplified sum of product expressions for a half adder are

                            yxyxyxS oplus=+= yxC =

                            Figure 31 Circuit diagram for Half Adder

                            19

                            Logic Design amp Switching Theory 1 Lab Session 03 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                            bles produce the sum and carry The simplified sum of product expressions for a half adder are

                            Full Adder

                            A combinational circuit that performs the addition of three input bits It consist of three inputs and two outputs Two of the input variables represent the two significant bits to be added The third input represents the carry from the previous lower significant position The output varia

                            zyxzyxzyxzyxzyxS oplusoplus=+++= yxzyxzyzxxyC )( +oplus=++=

                            Figure 32 Circuit diagram for Full Adder

                            efer to laboratory session 01 for procedure) and record the observations in the following ta

                            alf Adde ull Adder Inputs u

                            IMPLEMENTATION AND OBSERVATIONS

                            Implement the half adder and full adder circuits on a bread board (prepare the pin diagram (use appendix A) and r

                            bles H r F

                            Inputs Outputs Outp ts x y Carry Su Carry Sum m x y z 0 0 0 0 0 0 1 0 0 1 1 0 0 1 0 1 1 0 1 1 1 0 0 1 0 1 1 1 0 1 1 1

                            20

                            Logic Design amp Switching Theory 1 Lab Session 03 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                            at of your designed circuit Attach hardcopy of the output form electronic workbench

                            at of your designed circuit Attach hardcopy of the output form lectronic workbench here

                            ACTIVITY

                            1 Simulate half adder circuit using Electronics Workbench Compare the results of simulation with thhere

                            2 Design a full subtractor circuit and simulate it using Electronics Workbench Compare the results of simulation with the

                            21

                            Logic Design amp Switching Theory 1 Lab Session 04 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                            Lab Session 04 OBJECT

                            Use of Karnaugh Map (SOP-Expression) method GIVEN LOGIC EXPRESSION

                            F (A B C D) = sum ( 0 1 2 4 5 6 8 9 12 13 14 ) COMPONENTS AND APPARATUS REQUIRED 1 Digital ICs and their Datasheets

                            bull 7408 Quad 2-input AND Gate bull 7432 Quad 2-input OR Gate bull 7404 Hex Inverter

                            2 Digital Trainer DT-01 or the following components Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches PROCEDURE 1 Use Karnaugh map to reduce the given function 2 Draw the circuit diagram for the obtained reduced function 3 Implement the reduced circuit using digital ICs on a bread board (prepare the pin

                            diagram (use appendix A) and refer to laboratory session 01 for procedure) and record the observations

                            REDUCTION OF LOGIC EXPRESSION USING KARNAUGH MAP F

                            CD

                            AB DC

                            DC DC

                            DC

                            BA0 1 3 2

                            BA4 5 7 6

                            BA12 13 15 14

                            BA8 9 11 10

                            Reduced form of the given logic expression is __________________________________

                            22

                            Logic Design amp Switching Theory 1 Lab Session 04 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                            LOGIC DIAGRAM (REDUCED FORM) OBSERVATIONS

                            A B C D Output 0 0 0 0 0 0 0 1 0 0 1 0 0 0 1 1 0 1 0 0 0 1 0 1 0 1 1 0 0 1 1 1 1 0 0 0 1 0 0 1 1 0 1 0 1 0 1 1 1 1 0 0 1 1 0 1 1 1 1 0 1 1 1 1

                            RESULT The reduced form (SOP Expression) of the given logic function is

                            ____________________________________________________________

                            The observation table reflects the given logic function

                            23

                            Logic Design amp Switching Theory 1 Lab Session 04 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                            ACTIVITY 1 Using Electronics Workbench derive a truth table and logic circuit for the following logic expression

                            BAAF +=

                            Procedure 1 From the Instruments Parts Bin drag and drop Logic Converter on the design area 2 Double click the Logic Converter to reveal Logic Converter dialog box This dialog

                            box shows various conversion options between truth table logic expression and logic circuit

                            3 Enter the given logic expression in the edit box found at the end of the dialog box Use lsquo to represent invert of a variable For example A is written as Arsquo

                            4 Click the Boolean Expression to Truth Table button The truth table appears in the logic converters display

                            5 Now click the Boolean Expression to Circuit button This creates the logic circuit for the given expression in the design area Label the diagram if needed

                            Resulting Logic Circuit For the given expression the final circuit will look like

                            Figure 41

                            24

                            Logic Design amp Switching Theory 1 Lab Session 04 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                            ACTIVITY 2

                            Using Electronics Workbench find a simplified logic expression and circuit for the following truth table

                            A B C Output 0 0 0 1 0 0 1 1 0 1 0 0 0 1 1 1 1 0 0 0 1 0 1 0 1 1 0 0 1 1 1 1

                            Procedure 1 Click three input channels from A to H across the top of the logic converter The

                            display area below the terminals fills up with the necessary combinations of ones and zeros to fulfill the input conditions The values in the output column on the right are initially set to 0

                            2 Edit the output column to specify the desired output for each input condition To change an output value select it and type a new value 1 0 or x An x indicates a donrsquot care condition

                            3 To convert this truth table to a Boolean expression click the Truth Table to Boolean Expression button The Boolean expression will be displayed at the bottom of the logic converter

                            4 Simplify the expression by clicking the Simplify button 5 Now click the Boolean Expression to Circuit button This creates the logic circuit for

                            the given expression in the design area Resulting Logic Circuit For the given truth table the final simplified circuit will look like

                            Figure 42

                            25

                            Logic Design amp Switching Theory 1 Lab Session 04 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                            ACTIVITY 3

                            Using Electronics Workbench find the logic expression and truth table for the following logic circuit

                            Figure 43

                            Procedure 1 Attach the input terminals of the logic converter to up to four input points in the

                            circuit 2 Connect the single output of the circuit to the output terminal on the logic converter

                            icon 3 Click the Circuit to Truth Table button The truth table appears in the logic

                            converters display 4 To convert this truth table to a Boolean expression click the Truth Table to Boolean

                            Expression button The Boolean expression will be displayed at the bottom of the logic converter

                            Resulting Logic Expression Logic Expression for the given circuit is found to be _____________________________

                            26

                            Logic Design amp Switching Theory 1 Lab Session 04 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                            27

                            For activities 1 2 and 3 attach hardcopy of the output (truth table logic expression and logic circuit) form electronic workbench here

                            Logic Design amp Switching Theory 1 Lab Session 05 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                            Lab Session 05 Lab Session 05 OBJECT OBJECT

                            Designing a BCD Adder Designing a BCD Adder COMPONENTS AND APPARATUS REQUIRED COMPONENTS AND APPARATUS REQUIRED

                            1 Following ICs and their Datasheets 1 Following ICs and their Datasheets bull 7408 Quad 2-input AND Gate bull 7408 Quad 2-input AND Gate bull 7432 Quad 2-input OR Gate bull 7432 Quad 2-input OR Gate bull 7483 4-bit Binary Adder bull 7483 4-bit Binary Adder

                            2 Digital Trainer DT-01 or the following components 2 Digital Trainer DT-01 or the following components Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors (100 Ω) Connecting wires Switches (100 Ω) Connecting wires Switches

                            THEORY THEORY

                            A BCD Adder is a combinational circuit that adds two BCD digits in parallel and produces a sum digit also in BCD A BCD Adder is a combinational circuit that adds two BCD digits in parallel and produces a sum digit also in BCD

                            A4 A3 A2 A1 B4 B3 B2 B1

                            7483-BCD ADDER

                            Cout (C4 ) Z4 Z3 Z2 Z1 Cin(C0)

                            A4 A3 A2 A1 B4 B3 B2 B1

                            7483-BCD ADDER

                            Cout

                            (C4 ) Z4 Z3 Z2 Z1 Cin(C0)

                            Figure 51 BCD Adder Circuit

                            28

                            Logic Design amp Switching Theory 1 Lab Session 05 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                            29

                            A BCD adder must include the correction logic in its internal construction The two BCD digits together with the input carry are first added using a 4-bit binary adder to produce the binary sum If no output carry is generated and the binary sum is less than or equal to 9 then the corresponding BCD sum is identical and therefore no conversion is needed When the output carry is equal to 1 or the binary sum is greater than 9 then a binary 0110 is added to the binary sum through another 4-bit binary adder If Cout is the carry output and Z4Z3Z2Z1 is the binary sum form the first 4-bit binary adder then the following equation indicates the condition when a binary 0110 is to be added

                            C = COUT + Z4Z2 + Z4Z3 IMPLEMENTATION AND OBSERVATIONS Implement the BCD adder circuit according to figure 51 on a bread board (prepare the pin diagram (use appendix A) and refer to laboratory session 01 for procedure) A BCD adder has nine input bits (two BCD digits and a carry bit) which can result in a total of 512 combinations of which 312 inputs are donrsquot care Since it is a very lengthy procedure to record results for 200 valid input combinations therefore for simplicity just record results for any eight combinations in the following table

                            Input Carry

                            BCD Digit 1 BCD Digit 2 Carry Output

                            BCD Sum A4 A3 A2 A1 B4 B3 B2 B1 Z4 Z3 Z2 Z1

                            Logic Design amp Switching Theory 1 lab Session 06 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                            Lab Session 06

                            OBJECT

                            bull Designing of a 4 x 1 Multiplexer bull Experimenting with 74150 IC

                            COMPONENTS AND APPARATUS REQUIRED 1 Following ICs and their Datasheets

                            bull 7408 Quad 2-input AND Gates or 7411 Triple 3-input AND Gates bull 7432 Quad 2-input OR Gates bull 7404 Hex Inverter bull 74150 16 x 1 MUX

                            2 Digital Trainer DT-01 or the following components Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches THEORY

                            Multiplexers A digital data Multiplexer (MUX) is a combinational circuit having several data inputs and a single output A set of data-select inputs is used to control which of the data inputs is routed to the single output A multiplexer is also called a data selector because of this ability to select which data input is connected o the output Normally there are 2n input lines and n selection lines whose bit combination determine which input is selected DESIGN OF A 4 x 1 MULTIPLEXER A 4 x 1 multiplexer is capable of selecting one of four data inputs (see figure 61) The 2-bit binary number at the data select inputs S1 and S0 specifies which of the four data inputs is to be routed to the output Since there are two data select inputs therefore they can select 22 = 4 different data inputs lines

                            S0 S1 D0 D1

                            D2 D3

                            Data-select Inputs Output

                            Data Inputs

                            Figure 61 Block Diagram of a 4 x1 Multiplexer

                            30

                            Logic Design amp Switching Theory 1 lab Session 06 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                            Figure 62 Circuit Diagram for 4 x 1 Multiplexer

                            Implementation and Observations

                            Implement the 4 x 1 Multiplexer circuit (figure 62) on a bread board (prepare the pin diagram (use appendix A) and refer to laboratory session 01 for implementation procedure) and record the observations in the following table For each data select combination specify the switch number as well as the binary value present on that selected switch

                            S1 S0 Output 0 0 0 1 1 0 1 1

                            TESTING OF 74150 - 16 x 1 MUX

                            The 74150 IC has sixteen data inputs and four data-selection lines Function of various pins of this IC is described below

                            bull E0 through E15 Data input lines

                            31

                            Logic Design amp Switching Theory 1 lab Session 06 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering bull A B C D Data select lines with D being the MSB bull W Active low output line bull Grsquo Active low enable line bull VCC and GND Supply connections lines

                            Circuit Diagram

                            Figure 63 Pin connections of 74150 for selecting E0

                            Testing Procedure

                            bull Make connections as shown in the circuit diagram bull Apply different data (1 or 0) at data inputs that are labeled as E0 to E15 Only

                            connection for E0 is shown is the figure for simplicity bull Select the data input E0 with the help of data selectors A B C and D bull Observe the output which shows the complement of the data from E0 bull Select all the sixteen data inputs one by one and record your observations in the

                            following table

                            32

                            Logic Design amp Switching Theory 1 lab Session 06 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                            33

                            Observations

                            Grsquo D C B A W Grsquo D C B A W 0 0 0 0 0 0 1 0 0 0 0 0 0 0 1 0 1 0 0 1 0 0 0 1 0 0 1 0 1 0 0 0 0 1 1 0 1 0 1 1 0 0 1 0 0 0 1 1 0 0 0 0 1 0 1 0 1 1 0 1 0 0 1 1 0 0 1 1 1 0 0 0 1 1 1 0 1 1 1 1

                            ACTIVITY 1 Consider 4x1 Multiplexer Draw the output wave-form for the following data inputs

                            (E0 E1 E2 E3) and select lines A B (B being the MSB) Output is W

                            E3 E2 E1 E0 A B

                            W

                            2 Using the 4 x 1 MUX designed in this laboratory session implement the following logical function F (A B C) = Σ (0147)

                            Show your working and input connections in the following block diagram according to the circuit you have implemented

                            4 x 1 MUX

                            S0 S1

                            Output D0

                            D1

                            D2

                            D3

                            Logic Design amp Switching Theory 1 Lab Session 07 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                            Lab Session 07

                            OBJECT

                            bull Designing of a 2 x 4 Decoder 1 x 4 Demultiplexer bull Experimenting with 74138 IC

                            COMPONENTS AND APPARATUS REQUIRED 1 Following ICs and their Datasheets

                            bull 7408 Quad 2-input or 7411 Triple 3-input AND Gates bull 7404 Hex Inverter bull 74138 3 x 8 Decoder

                            2 Digital Trainer DT-01 or the following components Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches THEORY

                            Decoder A Decoder is a combinational circuit that converts binary information form n input lines to a maximum of 2n unique output lines In practical applications decoders are often used for selecting one of several devices

                            Demultiplexer A decoder with an enable input can function as a Demultiplexer A Demultiplexer (DMUX) id a circuit that receives information on a single line and transmits this information on one of 2n possible output lines The selection of a specific output line is controlled by the bit values of n selection lines DESIGN OF A 2 x 4 DECODER 1 x 4 DEMULTIPLEXER A 2 x 4 decoder is capable of selecting one of four output lines (see figure 71 (a)) The 2-bit binary number at the data inputs S1 and S0 specifies which of the four data inputs is to be selected If we add an enable pin and use it as an input line then this decoder can be converted to a 1 x 4 Demultiplexer where S1 and S0 will select a line to which data input is to be routed (see figure 71 (b))

                            Select S0 S0 Inputs

                            S1 D0 D1

                            D2

                            D3

                            Enable (a) Block Diagram of a 2 x 4 Decoder

                            Figure 71

                            S1 D0 D1

                            D2

                            D3

                            Inputs

                            Data Input (b) Block Diagram of a 1 x 4 Demulptiplexer

                            34

                            Logic Design amp Switching Theory 1 Lab Session 07 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                            Figure 72 Circuit Diagram for 2 x 4 Decoder 1 x 4 Demultiplexer

                            Implementation and Observations Implement the 2 x 4 Decoder 1 x 4 Demultiplexer circuit (figure 72) on a bread board (prepare the pin diagram (use appendix A) and refer to laboratory session 01 for implementation procedure) and record the observations in the following table

                            Enable Data Input S1 S0 D0 D1 D2 D3

                            0 0 0 0 0 1 0 1 0 0 1 1 1 0 0 1 0 1 1 1 0 1 1 1

                            TESTING OF 74138 3 x 8 Decoder The 74138 IC has three inputs and eight output lines It has three enable inputs and for the IC to function all three inputs need to be enabled Function of various pins of this IC is described below

                            35

                            Logic Design amp Switching Theory 1 Lab Session 07 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                            bull Y0 through Y7 Active low data outputs bull A B C Input select lines with C being the MSB bull G1 Active high enable Input bull G2Arsquo and G2Brsquo Active low enable Inputs bull VCC and GND Supply connections lines Circuit Diagram

                            Figure 73 Pin connections of 74138

                            Testing Procedure

                            bull Make connections as shown in the circuit diagram bull Apply different combinations of 1s and 0s at data inputs bull Observe the output and record your observations in the following table

                            Observations

                            C B A Y0 Y1 Y2 Y3 Y4 Y5 Y6 Y7 0 0 0 0 0 1 0 1 0 0 1 1 1 0 0 1 0 1 1 1 0 1 1 1

                            36

                            Logic Design amp Switching Theory 1 Lab Session 07 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                            37

                            ACTIVITY ACTIVITY 1 What will be the binary values at the outputs Y0 through Y7 of 74138 if 1 What will be the binary values at the outputs Y0 through Y7 of 74138 if

                            bull All three enable pins are connected to ground bull All three enable pins are connected to ground __________________________________________________________________________________________________________________________________________ __________________________________________________________________________________________________________________________________________ _____________________________________________________________________ _____________________________________________________________________

                            bull All three enable pins are connected to VCC bull All three enable pins are connected to VCC _______________________________________________________________________________________________________________________________________________________________________________________________________________

                            _______________________________________________________________________________________________________________________________________________________________________________________________________________

                            2 Show connections for 74138 in order to use it as a 1 x 8 Demultiplexer 2 Show connections for 74138 in order to use it as a 1 x 8 Demultiplexer

                            3 Consider a 2 x 4 Decoder with two enable inputs (one active high - G and one active low ndash Grsquo) Draw the output wave-forms for D0 D1 D2 and D3 if the two select inputs are A and B (B being the MSB) All outputs are active low

                            Grsquo

                            G

                            A B

                            D0 D1 D2

                            D3

                            Logic Design amp Switching Theory 1 Lab Session 08 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                            Lab Session 08 OBJECT

                            bull Designing of a 4 x 2 Priority Encoder bull Experimenting with 74148 IC

                            COMPONENTS AND APPARATUS REQUIRED

                            1 Following ICs and their Datasheets

                            bull 7408 Quad 2-input or 7421 Dual 4-input AND Gates bull 7432 Quad 2-input OR Gates bull 7404 Hex Inverter bull 74148 Encoder

                            2 Digital Trainer DT-01 or the following components Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches

                            THEORY

                            Encoder An Encoder is a digital function that produces a reverse operation from that of a decoder An Encoder has 2n (or less) input lines and n output lines The output lines generate the binary code for the 2n input variables Priority Encoder

                            A simple encoder may produce an erroneous output if more than one of its inputs is high A Priority Encoder is one that responds to just one input among those that may be simultaneously high in accordance with some priority system The most common priority system is based on the relative magnitudes of the inputs whichever decimal input is largest is the one that is encoded

                            DESIGN OF A 4 x 2 Priority Encoder

                            The following equations represent the outputs of a 4 x 2 priority encoder 32 DDA +=

                            321 DDDB += As can be seen from the equations that input D0 which has a binary code 00 is not used in any equation A binary code 00 at the output indicates two conditions Either D0 is selected or no input is selected In order to differentiate these two conditions we will provide an additional output Z to indicate if at least one of the inputs is a 1 The equation for Z will be

                            4321 DDDDZ = If Z is 0 then the binary code 00 at the output indicates that D0 is selected and if Z is 1 then it indicates that no input line is selected

                            38

                            Logic Design amp Switching Theory 1 Lab Session 08 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                            Figure 81 Circuit Diagram for 4 x 2 Priority Encoder

                            it (figure 81) on a bread board (prepare the to laboratory session 01 for implementation

                            Implementation a Implement the 4 x 2 Priority Encoder circu

                            ram (use appendix A) and refer

                            nd Observations

                            pin diagprocedure) and record the observations in the following table

                            D3 D2 D1 D0 A B 0 0 0 1 0 0 1 x 0 1 x x 1 x x x

                            TESTING OF 74148 8 x 3 Octal Priority Encoder

                            imal digits There are nine of which three represents

                            ing any of the inputs is high

                            then it shows that line 0 is selected and if e inputs selected E0 and GS

                            cannot be in the same state provided that E1 is enabled

                            The 74148 is a priority encoder with active-Low input for dec

                            input) and five output linesinputs lines (including an enablethe binary code for the octal digit Function of various pins of this IC is described below

                            bull 0 through 7 Active low data inputs representing the octal digits A2 A1 A0 Active low output lines representing the binary code bullbull E1 Active low enable Input bull E0 Active low output indicating none of the inputs is high bull GS Active low output indicatbull VCC and GND Supply connections lines Therefore if GS A2 A1 and A0 are all low

                            then it shows that none of thE0 A2 A1 and A0 are all low

                            39

                            Logic Design amp Switching Theory 1 Lab Session 08 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                            Circuit Diagram

                            Figure 82 Pin connections of 74148

                            Testing Procedure bull Make connections as sho

                            binations of 1s and 0s at data inputs d record your observations in the following table

                            GS E0

                            wn in the circuit diagram bull Apply different combull Observe the output an Observations

                            0 1 2 3 4 5 6 7 A2 A1 A0 1 1 1 1 1 1 1 1 x x x x x x x 0 x x x x x x 0 1 x x x x x 0 1 1 x x x x 0 1 1 1 x x x 0 1 1 1 1 x x 0 1 1 1 1 1 x 0 1 1 1 1 1 1 0 1 1 1 1 1 1 1

                            40

                            Logic Design amp Switching Theory 1 Lab Session 08 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                            41

                            CTIVITY

                            Cascade the following two 74148 8 x 3 Priority Encoders to form 16 x 4 Priority

                            A 1

                            Encoder

                            Logic Design amp Switching Theory 1 Lab Session 09 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering `

                            Lab Session 09 OBJECT

                            Designing an Odd Parity Generator and Checker for a 3-bit Data COMPONENTS AND APPARATUS REQUIRED

                            1 Following ICs and their Datasheets

                            bull 7486 Quad 2-input Exclusive-OR Gates bull 7404 Hex Inverter

                            2 Digital Trainer DT-01 or the following components Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches

                            THEORY

                            Parity Generator When binary data is transmitted and processed it is ndash as are all electrical signals ndash susceptible to noise that can either alter or distort its contents 1s may be effectively changed to 0s and 0s to 1s To overcome this problem one or more bits are often added to the data as an aid in detecting errors caused by noise The most common of these is a Parity bit that signifies whether the total number of 1s in a code group is odd or even In an Odd Parity system the parity bit is made 0 or 1 as necessary to make the total number 1s odd (counting the parity bit itself) In an Even Parity system the parity bit is chosen to make the total number of 1s even Table 91 shows how parity bits would be added to BCD code group in both systems

                            Decimal BCD Value Parity Bit ABCD Odd Parity Even Parity

                            0 0000 1 0 1 0001 0 1 2 0010 0 1 3 0011 1 0 4 0100 0 1 5 0101 1 0 6 0110 1 0 7 0111 0 1 8 1000 0 1 9 1001 1 0

                            Table 91 Odd and Even Parity in BCD

                            When digital data is received a parity checking circuit generates an error signal if the total number of 1s is odd in an even parity system or if it is even in an odd parity system Parity check always detects a single error (one bit change from 0 to 1 or 1 to 0) but may not detect

                            42

                            Logic Design amp Switching Theory 1 Lab Session 09 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering ` two or more errors Odd parity is used more often than even parity because even parity does not detect a situation where all 0s are created due to short circuit or other fault condition DESIGN OF A 3-BIT ODD PARITY GENERATOR AND CHECKER Let x y and z be the three bits that constitute the message and are the input to the Odd Parity Generator Circuit Since it is an odd parity system the bit P is generated so as to make the total number of 1s odd (including P) The function P can be expressed as follows P = x oplus y Ο z or P = x Ο y oplus z Since the IC available is 7486 which is quad 2input XOR IC therefore we will convert XNOR also to XOR

                            P = x oplus y Ο z

                            P = ( x oplus y ) Ο z Since for even number of variables ______

                            XOR = XNOR Therefore ___________ _________

                            P = ( x oplus y ) oplus z = x oplus y oplus z This logical expression can be implemented with two XOR gates and an inverter (see figure 91)

                            Figure 91 Circuit Diagram for a 3-bit Parity Generator

                            The 3-bit message and the parity bit are transmitted to their destination where they are applied to a Parity Checker Circuit An error occurs during transmission if the parity of the four bits received is even since the binary information transmitted was originally odd The output C of the parity checker should be a 1 when an error occurs ie when the number of 1s in the four inputs is even Therefore the function C can be expressed as

                            C = x Ο y Ο z Ο P

                            Using the same logic applied for the conversion of the equation of P

                            PzyxC oplusoplusoplus= This logical expression can be implemented with three XOR gates and an inverter (see figure 92)

                            43

                            Logic Design amp Switching Theory 1 Lab Session 09 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering `

                            44

                            Figure 92 Circuit Diagram for a 3-bit Parity Checker Implementation and Observations Implement the 3-bit Parity Generator and Checker circuits (figure 91 and 92) on a bread board (prepare the pin diagram (use appendix A) and refer to laboratory session 01 for implementation procedure) and record the observations in the following table

                            x y z P x y z P C x y z P C 0 0 0 0 0 0 0 1 0 0 0 0 0 1 0 0 0 1 1 0 0 1 0 1 0 0 0 1 0 1 0 1 0 0 1 1 0 0 1 1 1 0 1 1 1 0 0 0 1 0 0 1 1 0 0 1 0 1 0 1 0 1 1 1 0 1 1 1 0 0 1 1 0 1 1 1 0 1 1 1 0 1 1 1 1 1 1 1

                            Odd Parity Generation Odd Parity Check ACTIVITY 1 Try using the parity checker of figure 92 as 3-bit parity generator Write the details here

                            _____________________________________________________________________________________________________________________________________________________________________________________________________________________ ______________________________________________________________________________________________________________________________________________ _______________________________________________________________________ ______________________________________________________________________________________________________________________________________________

                            Logic Design amp Switching Theory 1 Lab Session 10 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                            Lab Session 10 OBJECT

                            Driving a seven segment display using 7447 7448 driver IC COMPONENTS AND APPARATUS REQUIRED

                            1 Following ICs and their Datasheets

                            bull Seven Segment Displays (Common Anode Common Cathode) bull 7447 7448 BCD to Seven Segment Driver

                            2 Digital Trainer DT-01 or the following components Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches

                            THEORY Seven Segment Displays A Seven Segment Display consists of seven light-emitting segments The segments are designated by letters a through g (see figure 101) By illuminating various combinations of segments the numerals 0 through 9 can be displayed Seven Segment Displays are commonly constructed with light-emitting diodes (LEDs) and with liquid-crystal displays (LCDs) LEDs generally provide greater illumination levels but require much greater power than LCDs An LED display can be a common-anode type or common cathode type In common anode type a high voltage is applied at the common terminal of the display and low voltage is applied at a segmentrsquos terminal for illumination In the common-cathode type a low voltage is applied at the common terminal of the display and high voltage is applied at a segmentrsquos terminal for illumination

                            Figure 101 Seven Segment Display

                            a f b g

                            e c d

                            7447 7448 BCD to Seven Segment Driver 7447 7448 IC is particularly used to drive Seven Segment Its input is a BCD number and output drives a seven segment display 7447 is used to drive common-anode displays whereas 7448 is used to drive common cathode displays 7447 7448 is a 16 pin IC Function of various pins of these ICs is described below

                            bull A B C D Inputs representing BCD digits (D being the MSB)

                            45

                            Logic Design amp Switching Theory 1 Lab Session 10 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering bull OA through OG Outputs to drive segments a through g of the display (Active low

                            in 7447 and active high in 7448) bull RBI Ripple Blanking Input Turns off all the segments if kept low provided that LT

                            is kept high and all other inputs (A B C D BI) are kept low Should be kept high otherwise

                            bull BI RBO Wire-AND logic serving as a Blanking Input and or Ripple Blanking Output

                            o BI Turns off all the segments if low o RBO Goes to a low level (response condition) along with other outputs when

                            RBI and inputs A B C and D are low with LT input at high level bull LT Lamp Test input Tests whether all segments are working or not Illuminates all

                            segments if kept low provided that BI is kept high Should be kept high otherwise bull VCC and GND Supply connections lines CIRCUIT DIAGRAM

                            Figure 102 Circuit diagram for 7447driving a common-anode display

                            IMPLEMENTATION AND OBSERVATIONS

                            bull Make connections as shown in the circuit diagram (refer to laboratory session 01 for implementation procedure)

                            bull Apply different combinations of 1s and 0s at data inputs bull Observe the output and record your observations in the following table

                            46

                            Logic Design amp Switching Theory 1 Lab Session 10 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                            47

                            Decimal Digit

                            BCD Inputs Seven Segment Outputs D C B A a b c d e f g

                            0 0 0 0 0 1 0 0 0 1 2 0 0 1 0 3 0 0 1 1 4 0 1 0 0 5 0 1 0 1 6 0 1 1 0 7 0 1 1 1 8 1 0 0 0 9 1 0 0 1

                            ACTIVITY 1 Perform the Lamp Test for the designed circuit and write your observations

                            ____________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________

                            2 How can you use 7447 IC to drive a common-cathode display

                            ____________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________

                            3 What symbols appear in the seven segment display if inputs DCBA are

                            DCBA Symbol

                            1010

                            1011

                            1100

                            1101

                            1110

                            1111

                            Logic Design amp Switching Theory 1 Lab Session 11 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                            48

                            Lab Session 11 OBJECT

                            Testing different modes of JK-FF COMPONENTS AND APPARATUS REQUIRED 1 Following ICs and their Datasheets

                            bull 7473 7476 JK Flip-Flop 2 Digital Trainer DT-01 or the following components

                            Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches

                            THEORY

                            Flip-Flop A flip-flop circuit can maintain a binary state indefinitely (as long as the power is delivered to the circuit) until directed by an input signal to switch states The major differences among various types of flip-flops are in the number of inputs they possess and in the manner in which the inputs affect the binary state

                            JK Flip-Flop JK flip flop is an edge triggered device A typical JK flip flop has three inputs J K and a clock input The flip-flop can be either positive or negative edge triggered The output Q is available in complemented form as well Beside the usual inputs and output most of the flip-flop IC also possess two asynchronous inputs namely Preset and Clear These inputs are usually active low If used Preset and Clear inputs keep the flip-flop in set and reset state respectively irrespective of the other inputs Both of these inputs cannot be used simultaneously otherwise they will bring the flip-flop in unstable state

                            Figure 111 Symbol for JK flip-flop

                            (a) positive-edge triggering (b) active low Preset (PR) and Clear (CLR) with positive-edge triggering

                            (c) active low Preset (PR) and Clear (CLR) with negative-edge triggering

                            Logic Design amp Switching Theory 1 Lab Session 11 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                            49

                            TESTING OF 7473 7476 DUAL JK FLIP-FLOP

                            Both the ICs 7473 and 7476 are similar in functionality except for one difference The flip-flops in 7473 have only one type of active low asynchronous input which is the Clear input whereas the flip-flops in 7476 have both Preset and Clear inputs Both these ICs have negative edge triggered flip-flops

                            Circuit Diagram

                            Figure 112 Pin connections of 7476

                            Testing Procedure

                            bull Make connections as shown in the circuit diagram (figure 112) bull Apply different combinations of 1s and 0s at J and K inputs bull Observe the output and record your observations in the following table

                            Observations

                            J

                            K Q

                            0 0 0 1 1 0 1 1

                            ACTIVITY

                            1 Observe the output Q of JK flip-flop if the clock input is connected to VCC or GND instead of a clock source Write your observations here __________________________________________________________________________________________________________________________________________ _______________________________________________________________________________________________________________________________________________________________________________________________________________

                            Logic Design amp Switching Theory 1 Lab Session 12 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                            50

                            Lab Session 12 OBJECT

                            Designing sequential circuit for the given state diagram using D flip-flop GIVEN STATE DIAGRAM

                            00

                            11

                            Figure 121 State Diagram COMPONENTS AND APPARATUS REQUIRED 1 Following ICs and their Datasheets

                            bull 7474 D Flip-Flop bull ICs of basic gates (AND OR NOT XOR etc) as required

                            2 Digital Trainer DT-01 or the following components Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches

                            THEORY

                            Sequential Circuits In Sequential Circuits the output not only depends on the present inputs but also on previous states of the circuit These circuits use memory elements (latches flip-flops) and the binary information stored in the memory elements at any given time defines the state of the sequential circuit Analysis of a Sequential Circuit The behavior of a sequential circuit is determined from the inputs the outputs and the states of its flip-flops Both the outputs and next state are a function of the inputs and the

                            10

                            01

                            00 11 10

                            00

                            00 11 10 00

                            Logic Design amp Switching Theory 1 Lab Session 12 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                            51

                            present state The analysis of a sequential circuit form a state diagram comprises of the following bull Selecting a particular flip-flop to design the circuit bull Obtaining state table from the state diagram bull Finding input equations for the selected flip-flop bull Finding state equations (not required for the construction of circuit) bull Implementing the circuit using selected flip-flops and their input equations ANALYZING THE GIVEN STATE DIAGRAM D Flip-Flop D flip-flop is also called transparent flip-flop as it simply transfers the input data to the output For our design we require the graphical symbol and excitation table of D flip-flop (see figure 122)

                            Qt Qt+1 T 0 0 0 0 1 1 1 0 0 1 1 1

                            (b) Excitation table of D Flip-Flop

                            (a) Graphical Symbol

                            Figure 122 Characteristic equation of D flip-flop is Q(t+1) = D State Table The given state diagram has four states so we will need two D flip-flops (FF-0 FF-1) Form state table form the given state diagram and record the results in the following table

                            Present State Input Next State Output Input to FF-0 D0

                            Input to FF-1 D1 Q1t Q0t x Q1(t+1) Q0(t+1) z

                            Logic Design amp Switching Theory 1 Lab Session 12 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                            52

                            Input Equations Using Karnaugh map the input equations D0 and D1 for the two flip-flops can be found

                            D0 D1 Q0x

                            Q1

                            _ _ Q0x

                            _ Q0x

                            Q0x

                            _ Q0x

                            Q0x

                            Q1

                            _ _ Q0x

                            _ Q0x

                            Q0x

                            _ Q0x

                            _ Q1

                            _ Q1

                            Q1

                            Q1

                            D0 = _________________ D1 = _________________

                            State Equations Using the characteristic equation of D flip-flop we can find the state equations Q0(t+1) and Q1(t+1) for the to flip flops Q0(t+1) = _______________________ Q1(t+1) = _______________________ _______________________ _______________________ _______________________ _______________________ Circuit Diagram

                            Logic Design amp Switching Theory 1 Lab Session 12 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                            53

                            Implementation Procedure and Observations

                            1 Implement the circuit using digital ICs on a bread board (prepare the pin diagram (use appendix A) and refer to laboratory session 01 for procedure)

                            2 Make the clear inputs of the flip-flops low (to clear the flip-flops) The flip-flops will remain in clear state as long as the clear inputs are connected to low level

                            3 Connect output Q0 and the clock pulse to an oscilloscope 4 Apply 0 to the input x 5 Now make the clear inputs to high 6 Observe the waveform for the first 5 clock pulses and record it 7 Repeat steps 2 to 6 keeping x=1 in step 4 this time 8 Repeat steps 2 to 7 this time connecting Q1 instead of Q0 to the oscilloscope in step

                            3 Record your observations (Keep frequency of the clock pulse low (eg1Hz) so that the output waveforms can be observed easily)

                            1 2 3 4 5 Clock Pulse

                            Output Waveform for Q0 when x=0

                            Output Waveform for Q0 when x=1

                            Output Waveform for Q1 when x=0

                            Output Waveform for Q1 when x=1

                            Logic Design amp Switching Theory 1 Lab Session 13 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                            Lab Session 13 OBJECT

                            Designing a modulo-5 asynchronous up-counter using JK-FF COMPONENTS AND APPARATUS REQUIRED

                            1 Following ICs and their Datasheets

                            bull 7400 Quad 2-input or 7410 Triple 3-input NAND Gates bull 7476 7473 JK Flip-Flop

                            2 Digital Trainer DT-01 or the following components Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches

                            THEORY

                            Digital Counters A digital counter is a set of flip-flops whose states change in response to pulses applied at the input to the counter The flip-flops are interconnected so that their combined state at any time is the binary equivalent of the total number of pulses that have occurred up to that time Every counter resets after a certain number of clock pulses Thus as it name implies a counter is used to count pulses An n stage counter can count up to a maximum of 2n states n is equal to the number of flip-flops required for the construction of counter

                            Modulus Counters The number of input pulses that causes a counter to reset to its initial count is called the modulus of the counter Thus the modulus equals to total number of distinct states (counts) including zero that a counter can store A binary counter with n stages is a modulo-2n (or mod-2n) counter The largest count a mod-N counter can achieve is N-1 ie a mod-N counter never reaches the binary number equal to its modulus N is always equal to or less than 2n Counters can be classified as bull Synchronous Counters which are clock driven All the flip-flops are driven by a

                            single clock bull Asynchronous Counters which are event driven Clock input is given to the first

                            flip-flop only Rest of the flip-flops are driven by their preceding flip-flops

                            DESIGN OF A MOD-5 ASYNCHRONOUS UP COUNTER The number of flip-flops required to construct a mod-5 counter is 3 because 5 should be less than or equal to 2n This counter will count from 0 to 4 a total of 5 distinct states Since a 3-stage counter can count up to 8 states at maximum a NAND gate is used to reset it after 5 clock pulses Figure 131 shows the logic diagram

                            54

                            Logic Design amp Switching Theory 1 Lab Session 13 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                            55

                            Figure 131 A Mod-5 Asynchronous Up Counter

                            Implementation and Observations

                            Implement the mod-5 counter circuit (figure 131) on a bread board (prepare the pin diagram (use appendix A) and refer to laboratory session 01 for implementation procedure) and record the observations in the following table

                            Clock Pulse Q2 Q1 Q0

                            0 1 2 3 4 5 6 7

                            ACTIVITY

                            Draw the timing diagram for mod-5 counter designed in this laboratory session

                            Logic Design amp Switching Theory 1 Lab Session 14 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                            Lab Session 14 OBJECT

                            Experimenting with 74194 4-bit bidirectional universal shift register COMPONENTS AND APPARATUS REQUIRED

                            1 Following ICs and their Datasheets

                            bull 74194 4-bit bidirectional universal shift register 2 Digital Trainer DT-01 or the following components

                            Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches

                            THEORY

                            Shift Registers

                            A Register is a set of flip-flops used to store binary data A register which is capable of shifting its binary information either to the right or left is called a shift register The logical configuration of a register consists of a chain of flip-flops connected in cascade with the output of one flip-flop connected to the input of next flip-flop All flip-flops receive a common clock pulse which causes the shift from one stage to the next

                            Bidirectional Shift Registers A bi-directional shift register is one whose bits can be shifted from left to right or from right to left

                            Universal Shift Registers A universal shift register is a bi-directional register whose input can be in either serial or parallel form and whose output can be in either serial or parallel form

                            74194 4-BIT BIDIRECTIONAL UNIVERSAL SHIFT REGISTER

                            The 74194 register provides parallel as well as serial loading in both directions Function of various pins of this IC is described below

                            bull A B C and D Active high inputs for parallel loading bull QA QB QC and QD Active high outputs bull S0 and S1 Active high mode control inputs The following table shows combinations

                            of S1 and S0 to enable various modes

                            S1 S0 Clock Action 0 0 x No change 0 1 uarr Shift right 1 0 uarr Shift left 1 1 uarr Parallel load

                            uarr shows the rising edge of the clock pulse

                            56

                            Logic Design amp Switching Theory 1 Lab Session 14 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering bull SR Active high serial input for right shifting bull SL Active high serial input for left shifting bull CLR Active low input Clears all the flip-flops of the register if set to 0 should be

                            kept high otherwise bull CLK Clock input bull VCC and GND Supply connections lines Thus A B C and D are inputs for parallel loading whereas SR and SL are inputs for serial loading with right or left shifting respectively S1 and S0 are used to select the loading mode Circuit Diagram

                            Figure 141 Pin connections of 74194 Testing Procedure

                            bull Make connections as shown in the circuit diagram bull Observe the output for the input combinations given in the following table

                            57

                            Logic Design amp Switching Theory 1 Lab Session 14 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                            58

                            Observations

                            S1 S0 SL SR A B C D QA QB QC QD 0 0 0 1 0 0 0 0 0 1 1 0 0 0 0 1 1 0 0 0 0 0 1 0 1 1 0 0 0 0 1 1 0 0 1 1 0 1 0 0 0 1 1 1 0 1 0 1 1 0 1 0 0 1 1 0 1 1 1 0 0 1 1 1 1 1 0 0 1 1 1 1

                            ACTIVITY 1 Show connections of 74194 to convert it into a ring counter with right shifting

                            Logic Design amp Switching Theory 1 Lab Session 15 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                            Lab Session 15

                            OBJECT

                            Experimenting with 74245 octal bus transceivers using parallel port PC interfacing COMPONENTS AND APPARATUS REQUIRED 1 Parallel Port Connectors (DB-25) with Cable 2 Personal Computer with Windows 98 and TurboC Compiler Installed 3 Following ICs and their Datasheets

                            bull 74245 Octal Bus Transceivers with 3-State Outputs 4 Digital Trainer DT-01 or the following components

                            Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches

                            THEORY

                            3-State Logic Sometimes it is necessary to isolate one part of circuit from the other part For this purpose some TTL ICs are designed with 3-state logic Such devices have three possible output states high low and high impedance The device can be put into high impedance state by a control signal applied to an appropriate pin When such a device is in high impedance state there is very high impedance at its output effectively isolating the device from whatever circuitry the output normally drives 74245 Octal Bus Transceivers A bus is any conducting path or set of paths having electrical connections to one or more devices 74245 octal bus transceivers are mainly used to control connectivity between two devices or circuits It also provides direction control for signal flow Function of various pin of this IC is given below

                            bull A1 through A8 Bus A bull B1 through B8 Bus B bull G΄ Active low enable input When high sets all the bus pins to high impedance state bull DIR Direction control for signal flow When set to high logic level transfers bus A

                            data to B bus When set to low logic level transfers bus B data to A bus bull VCC and GND Supply connections lines Serial and Parallel Port Connectors A Parallel Port can consist of only 25 pin port adapter called a DB-25 and a serial port can consist of either a 25 pin port adapter called a DB-25 or 9 pin adapter called a DB-9 port adapter Whether the port is a 9 pin or 25 pin it can accomplish all of the same tasks that serial port communications have been designed for

                            59

                            Logic Design amp Switching Theory 1 Lab Session 15 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                            60

                            Each adapter can be a male type connector with pins or a female type adapter with tiny holes Generally a PRINTER port (called LPT1) on the back of a computer is female type adapter and we need to use MALE DB-25 pin cable on it for PRINTER connection or for parallel LAPLINK cable And a COM port on the back of a computer is male for the serial ports but it may not necessarily be Parallel Port Connector ndash DB-25 The DB-25 connector (named for its B-size D-shaped shell and 25 pins) is practically ubiquitous in the electronics industry The DB-25 connector is used for a variety of purposes Two common applications are RS-232EIA-232 (serial) connections and the parallel printer interface on the IBM PC The DB-25 connector is also used for SCSI connections Normally the parallel port is used for output to a printer or other device It sends data 8-bits or one byte at a time in parallel The other lines available on the DB-25 connector are a combination of status lines control lines and ground lines The status and control lines are used for handshaking commands and feedback when we are talking to a printer

                            Figure 152 DB-25 Female Figure 151 DB-25 Male

                            Figure 153 Pin Layout for DB-25 As can be seen form figure 153 there are four types of pins in this connector

                            bull Data pins (8 pins - D0 to D7) Active high bidirectional lines

                            Logic Design amp Switching Theory 1 Lab Session 15 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering bull Control pins (4 pins - C0 to C3) C0 C1 and C3 are active low whereas C2 is active

                            high These lines also are bidirectional bull Status pins (5 pins ndash S3 to S7) Only S7 is active low rest are active high input lines bull Ground pins (8 pins) Used as a reference signal for the low (below 05 volts) charge

                            Parallel Port Addresses A DB-25 connector at a parallel port has three address one for each kind of pins register data status and control The first or base address generally refers to data register Second address is for status register and the third one is for control register In Windows 98 the base address is usually found to be 278H 378H or 3BCH Now if 378H is the base address then it refers to the data register whereas addresses for status and control register are respectively 379H and 37AH For Windows 98 the base address can be found as follows 1 On your Desktop right-click on My Computer and select Properties 2 Click on the Device Manager tab and find LPT1 under Plug and Play BIOS 3 After selecting LPT1 click the Properties button 4 Next select the Resources tab and the address should then appear next to InputOutput

                            Range Accessing parallel port through C Language Programming There are multiple functions in C Language for accessing external ports The most commonly used are listed below

                            bull unsigned char inportb(int portid) inportb reads a byte from a hardware port

                            bull int inport(int portid) reads a word from a hardware port

                            bull void outportb(int portid unsigned char value) outputs a byte to a hardware port

                            bull void outport(int portid int value) outputs a word to a hardware port

                            portid refers to the port address whereas value refers to the data to be sent TESTING 74245 USING PARALLEL PORT PC INTERFACING At one end the parallel port connector will be connected to the PC via parallel port cable and another connector (to be plugged into the PC parallel port slot) At the other end it will be connected to the buffer IC 74245 Data lines of the connector will be used to transfer 8-bit data between the PC and the buffer Out of the 8-bits of 74245 4-bits will be used to enter data which will be displayed at the monitor through a C language

                            61

                            Logic Design amp Switching Theory 1 Lab Session 15 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering program The remaining 4-bits will receive data from PC as entered by the user via keyboard

                            Circuit Diagram

                            Figure 154 Interface of 74245 to PC via Parallel Port

                            Procedure

                            1 Connect the DB-25 connector to the PC at one end and solder it to the circuit board at the other end

                            2 Connect various pins of the connector and 74245 according to the circuit diagram shown in figure 152

                            3 Using the functions listed in the previous section write a program in C language to operate various pins of the buffer The user interface of the program should provide option to the user whether to send or receive data from the port

                            4 Set DIR switch to 1 5 Try sending some data bits to the port The result should be displayed at the LEDs 6 Set DIR switch to 0 7 Set some binary 4-bit value through the switches Try reading it via parallel port

                            C Language Program

                            A program to access parallel port for data transfers

                            use header file include ltstdiohgt main program void main() define variable

                            62

                            Logic Design amp Switching Theory 1 Lab Session 15 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering unsigned int data=0 char choice while(1) printing option menu clrscr() printf(This program will send or receive a BCD digit from the parallel portn) printf(nPress your choice numbern) printf(n1 Send Data) printf(n2 Receive Data) printf(n3 Exitn) choice = getch() sending entered digit to the port if(choice == 1) input BCD digit printf(nEnter BCD digit to be sent to the port) data = getche() masking the first four bits data = data amp 0x0f sending to the port outportb(0x378data) printf(nThe BCD digit c has been sent to the port data) printing on screen the data received from the port else if(choice == 2) receiving data from the port data = inportb(0x378) masking the last four bits data = data amp 0xf0 shifting first four bits to make them the last four bits datagtgt=4 printf(nThe BCD digit set at the port is c data) exit else if(choice == 3) break key pressed is not in the menu else printf(nEnter valid choice number) printf(nnPress any key to continue) getch()

                            63

                            Logic Design amp Switching Theory 1 Lab Session 15 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                            ACTIVITY 1 In the above circuit DIR and G΄ inputs are hardwired Connect them to status or

                            control pins of the parallel port connector and control their function through your software program Circuit Diagram Program Code ______________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________

                            ___________________________________________________________________________________________________________________________________________________

                            64

                            Logic Design amp Switching Theory 1 Lab Session 15 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                            65

                            _____________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ _____________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ _______________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ _________________________________________________ _________________________________________________

                            Logic Design amp Switching Theory 1 Appendix A NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                            Appendix A

                            PIN DIAGRAMS OF THE ICS REQUIRED FOR THE LABORATORY SESSIONS Consult the TTLIC data book for internal diagrams and electrical characteristics of these ICs 7400 Quad 2-Input NAND 7402 Quad 2-Input NOR

                            7404 Hex Inverter 7408 Quad 2-Input AND

                            7410 Triple 3-Input NAND 7411 Triple 3-Input AND

                            7421 Dual 4-Input AND 7432 Quad 2-Input OR

                            66

                            Logic Design amp Switching Theory 1 Appendix A NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                            BCD-to-Seven Segm 7448 BCD-to-Seven Segment 7447 ent

                            Decoder (15V OC) Decoder (2kΩ pull-up output)

                            7473 Dual JK Flip-Flop 7474 Dual D-Type Flip-Flop

                            7476 Dual JK Flop-Flop -Bit Binary Full Adder 7483 4 with Fast Carry

                            86 Quad 2-Inpu 74138 3-to-8 Line 74 t Exclusive OR Decoder Demultiplexer

                            67

                            Logic Design amp Switching Theory 1 Appendix A NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                            68

                            74148 8-to-3 Line 16-to-1 Line Data

                            Priority Encoder 74150 Selector Multiplexer

                            74245 Oct nsceivers Universal Shift Register (PIPO) (3-State)

                            74194 4-Bit Bidirectional al Bus Tra

                            Logic Design amp Switching Theory 1 Appendix B NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                            Appendix B

                            DEBOUNCING CIRCUITRY FOR MECHANICAL SWITCHES Mechanical switches form the interface between human beings and computers or other digital systems For example a keyboard is a matrix of switches used to supply alphanumeric data to a computer Whatever the switch design it is a potential source of problems due to contact bounce The contact bounce creates a sense of narrow pulses when a switch is opened or closed An example of device whose operation would be adversely affected by contact bounce is a digital counter used to count the number of times a switch is depressed Eliminating the effects of contact bounce is called debouncing When data is entered into a computer via a keyboard a software debounce is often used This type of debouncing is a program that causes the computer to sample the switch terminal (ie to input data from it) many times in succession during the interval of time that contact bounce occurs If the data is sensed to be 1s (or 0s) for a specific number of consecutive samples then it is assumed that contact bounce has ended and the last value sensed is valid Hardware debouncing is the use of electronic circuitry to eliminate the effects of contact bounce There are numerous versions of such circuitry including those that use monostable multivibrators (one-shots) but the most straightforward is simply an RS latch Figure B1 shows the circuit When the switch is in position 1 R = 0 and S = 1 so the latch is set and the output (Q) is 1 When the switch is in position 0 R = 1and S = 0 so the latch is reset and the output is 0 When the switch is moved form one position to the other the latch changes state and bouncing occurs at either the R or the S input The bouncing does not affect the latch after it has change state An RS latch will remain set for example when its R input is 0 and its S input is alternately changed form 1 to 0

                            Figure B1 Use of RS latch to debounce a mechanical switch

                            69

                            • 01-ldst-Outer title
                              • Practical Workbook
                              • Logic Design amp Switching Theory I
                                • Dept of Computer amp Information Systems Engineering
                                  • NED University of Engineering amp Technology
                                  • Karachi ndash 75270 Pakistan
                                    • 02-ldst-inner Title
                                      • Practical Workbook
                                      • Logic Design amp Switching Theory I
                                        • Dept of Computer amp Information Systems Engineering
                                          • NED University of Engineering amp Technology
                                          • Karachi ndash 75270 Pakistan
                                            • 03-ldst-general info
                                            • 04-ldst-introduction
                                            • 05-Table of Contents
                                              • CONTENTS
                                                • Lab Session No Object Page No
                                                • 1
                                                • Also implementing and testing the given circuit on a bread board
                                                  • Working with Electronics Workbench
                                                    • Driving a seven segment display using 7447 7448 driver IC
                                                      • Designing a modulus-5 asynchronous up-counter using JK-FF
                                                        • Experimenting with 74194 4-bit bidirectional universal shift register
                                                            • 13
                                                                • 06-ldst-Exp01
                                                                  • Lab Session 01
                                                                  • OBJECT
                                                                    • 1 Bread board
                                                                    • 2 5 V - power supply
                                                                    • 3 Multimeter
                                                                    • 4 Logic probe
                                                                    • 5 LEDs with resistors
                                                                    • 6 Connecting wires
                                                                    • 8 Following ICs and their datasheets
                                                                      • THEORY
                                                                        • Logic Gates
                                                                        • 1 The AND Gate ndash An AND gatersquos output is 1 if and only if all its inputs are 1 If A and B are two inputs to an AND gate then output F of the gate is given as F = AB
                                                                        • 2 The OR Gate - An OR gatersquos output is 1 if at least one of its input is 1 If A and B are two inputs to an OR gate then output F of the gate is given as F = A+B
                                                                        • 3 The NOT Gate (Inverter) ndash Its output is 1 when its input is 0 and its output is 0 when the input is 1 ie it complements a digital variable If A is the input to a NOT gate then output F of the gate is given as
                                                                        • 4 The NAND Gate ndash Its output is 1 if at least one of its input is 0 This gate performs the same logic as an AND gate followed by an inverter If A and B are two inputs to a NAND gate then output F of the gate is given as
                                                                          • 5 The NOR Gate - The output of a NOR gate is 1 if and only if all its inputs are 0 This gate performs the same logic function as an OR gate followed by an inverter If A and B are two inputs to a NAND gate then output F of the gate is given as
                                                                              • DATA SHEETS
                                                                                • Logic expression for the given logic diagram __________________________________
                                                                                    • 07-ldst-exp02
                                                                                      • Working with Electronics Workbench
                                                                                        • 08-ldst-exp03
                                                                                          • Designing Half and Full Adder Circuits
                                                                                            • COMPONENTS AND APPARATUS REQUIRED
                                                                                              • 1 Following ICs and their Datasheets
                                                                                              • 7408 Quad 2-input AND Gate
                                                                                              • 2 Digital Trainer DT-01 or the following components
                                                                                                • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                • Connecting wires Switches
                                                                                                  • THEORY
                                                                                                      • IMPLEMENTATION AND OBSERVATIONS
                                                                                                        • 09-ldst-Exp04
                                                                                                          • Lab Session 04
                                                                                                          • 1 Digital ICs and their Datasheets
                                                                                                          • 7408 Quad 2-input AND Gate
                                                                                                          • 2 Digital Trainer DT-01 or the following components
                                                                                                            • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                            • Connecting wires Switches
                                                                                                            • PROCEDURE
                                                                                                            • REDUCTION OF LOGIC EXPRESSION USING KARNAUGH MAP
                                                                                                            • OBSERVATIONS
                                                                                                            • RESULT
                                                                                                                • 10-ldst-Exp05
                                                                                                                  • Lab Session 05
                                                                                                                  • 1 Following ICs and their Datasheets
                                                                                                                  • 7408 Quad 2-input AND Gate
                                                                                                                  • 2 Digital Trainer DT-01 or the following components
                                                                                                                    • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                    • (100 Ω) Connecting wires Switches
                                                                                                                    • THEORY
                                                                                                                      • IMPLEMENTATION AND OBSERVATIONS
                                                                                                                        • 11-ldst-Exp06
                                                                                                                          • OBJECT
                                                                                                                          • 1 Following ICs and their Datasheets
                                                                                                                          • 7408 Quad 2-input AND Gates or 7411 Triple 3-input AND Gates
                                                                                                                          • 2 Digital Trainer DT-01 or the following components
                                                                                                                            • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                            • Connecting wires Switches
                                                                                                                              • Figure 62 Circuit Diagram for 4 x 1 Multiplexer
                                                                                                                              • Implementation and Observations
                                                                                                                                • Circuit Diagram
                                                                                                                                  • ACTIVITY
                                                                                                                                    • 12-ldst-exp07
                                                                                                                                      • 1 Following ICs and their Datasheets
                                                                                                                                      • 7408 Quad 2-input or 7411 Triple 3-input AND Gates
                                                                                                                                      • 2 Digital Trainer DT-01 or the following components
                                                                                                                                        • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                        • Connecting wires Switches
                                                                                                                                          • THEORY
                                                                                                                                              • Figure 72 Circuit Diagram for 2 x 4 Decoder 1 x 4 Demultiplexer
                                                                                                                                              • Implementation and Observations
                                                                                                                                                • Circuit Diagram
                                                                                                                                                  • ACTIVITY
                                                                                                                                                    • 13-ldst-Exp08
                                                                                                                                                      • OBJECT
                                                                                                                                                      • 1 Following ICs and their Datasheets
                                                                                                                                                      • 7408 Quad 2-input or 7421 Dual 4-input AND Gates
                                                                                                                                                      • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                        • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                        • Connecting wires Switches
                                                                                                                                                          • THEORY
                                                                                                                                                              • Figure 81 Circuit Diagram for 4 x 2 Priority Encoder
                                                                                                                                                              • Implementation and Observations
                                                                                                                                                                • Therefore if GS A2 A1 and A0 are all low then it shows that line 0 is selected and if E0 A2 A1 and A0 are all low then it shows that none of the inputs selected E0 and GS cannot be in the same state provided that E1 is enabled
                                                                                                                                                                • Circuit Diagram
                                                                                                                                                                  • ACTIVITY
                                                                                                                                                                    • 14-ldst-exp09
                                                                                                                                                                      • OBJECT
                                                                                                                                                                      • 1 Following ICs and their Datasheets
                                                                                                                                                                      • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                        • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                        • Connecting wires Switches
                                                                                                                                                                          • THEORY
                                                                                                                                                                            • Parity Generator
                                                                                                                                                                              • Let x y and z be the three bits that constitute the message and are the input to the Odd Parity Generator Circuit Since it is an odd parity system the bit P is generated so as to make the total number of 1s odd (including P) The function P can be expressed as follows
                                                                                                                                                                              • Figure 91 Circuit Diagram for a 3-bit Parity Generator
                                                                                                                                                                                • C = x Ο y Ο z Ο P
                                                                                                                                                                                  • Implementation and Observations
                                                                                                                                                                                    • ACTIVITY
                                                                                                                                                                                        • 15-ldst-exp10
                                                                                                                                                                                          • Driving a seven segment display using 7447 7448 driver IC
                                                                                                                                                                                          • COMPONENTS AND APPARATUS REQUIRED
                                                                                                                                                                                          • 1 Following ICs and their Datasheets
                                                                                                                                                                                          • 7447 7448 BCD to Seven Segment Driver
                                                                                                                                                                                          • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                            • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches
                                                                                                                                                                                              • THEORY
                                                                                                                                                                                              • Seven Segment Displays
                                                                                                                                                                                              • CIRCUIT DIAGRAM
                                                                                                                                                                                              • Figure 102 Circuit diagram for 7447driving a common-anode display
                                                                                                                                                                                                  • IMPLEMENTATION AND OBSERVATIONS
                                                                                                                                                                                                    • Decimal Digit
                                                                                                                                                                                                    • BCD Inputs
                                                                                                                                                                                                    • Seven Segment Outputs
                                                                                                                                                                                                    • D
                                                                                                                                                                                                    • C
                                                                                                                                                                                                    • B
                                                                                                                                                                                                    • A
                                                                                                                                                                                                    • a
                                                                                                                                                                                                    • b
                                                                                                                                                                                                    • c
                                                                                                                                                                                                    • d
                                                                                                                                                                                                    • e
                                                                                                                                                                                                    • f
                                                                                                                                                                                                    • g
                                                                                                                                                                                                    • 0
                                                                                                                                                                                                    • 0
                                                                                                                                                                                                    • 0
                                                                                                                                                                                                    • 0
                                                                                                                                                                                                    • 0
                                                                                                                                                                                                    • 1
                                                                                                                                                                                                    • 0
                                                                                                                                                                                                    • 0
                                                                                                                                                                                                    • 0
                                                                                                                                                                                                    • 1
                                                                                                                                                                                                    • 2
                                                                                                                                                                                                    • 0
                                                                                                                                                                                                    • 0
                                                                                                                                                                                                    • 1
                                                                                                                                                                                                    • 0
                                                                                                                                                                                                    • 3
                                                                                                                                                                                                    • 0
                                                                                                                                                                                                    • 0
                                                                                                                                                                                                    • 1
                                                                                                                                                                                                    • 1
                                                                                                                                                                                                    • 4
                                                                                                                                                                                                    • 0
                                                                                                                                                                                                    • 1
                                                                                                                                                                                                    • 0
                                                                                                                                                                                                    • 0
                                                                                                                                                                                                    • 5
                                                                                                                                                                                                    • 0
                                                                                                                                                                                                    • 1
                                                                                                                                                                                                    • 0
                                                                                                                                                                                                    • 1
                                                                                                                                                                                                    • 6
                                                                                                                                                                                                    • 0
                                                                                                                                                                                                    • 1
                                                                                                                                                                                                    • 1
                                                                                                                                                                                                    • 0
                                                                                                                                                                                                    • 7
                                                                                                                                                                                                    • 0
                                                                                                                                                                                                    • 1
                                                                                                                                                                                                    • 1
                                                                                                                                                                                                    • 1
                                                                                                                                                                                                    • 8
                                                                                                                                                                                                    • 1
                                                                                                                                                                                                    • 0
                                                                                                                                                                                                    • 0
                                                                                                                                                                                                    • 0
                                                                                                                                                                                                    • 9
                                                                                                                                                                                                    • 1
                                                                                                                                                                                                    • 0
                                                                                                                                                                                                    • 0
                                                                                                                                                                                                    • 1
                                                                                                                                                                                                      • ACTIVITY
                                                                                                                                                                                                        • 16-ldst-exp11
                                                                                                                                                                                                          • Lab Session 11
                                                                                                                                                                                                            • OBJECT
                                                                                                                                                                                                            • COMPONENTS AND APPARATUS REQUIRED
                                                                                                                                                                                                              • 1 Following ICs and their Datasheets
                                                                                                                                                                                                              • 7473 7476 JK Flip-Flop
                                                                                                                                                                                                              • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                                • Connecting wires Switches
                                                                                                                                                                                                                  • THEORY
                                                                                                                                                                                                                      • Flip-Flop
                                                                                                                                                                                                                      • JK Flip-Flop
                                                                                                                                                                                                                        • Circuit Diagram
                                                                                                                                                                                                                          • Observations
                                                                                                                                                                                                                            • ACTIVITY
                                                                                                                                                                                                                                • 17-ldst-exp12
                                                                                                                                                                                                                                  • Lab Session 12
                                                                                                                                                                                                                                    • OBJECT
                                                                                                                                                                                                                                    • GIVEN STATE DIAGRAM
                                                                                                                                                                                                                                    • Figure 121 State Diagram
                                                                                                                                                                                                                                    • COMPONENTS AND APPARATUS REQUIRED
                                                                                                                                                                                                                                      • 1 Following ICs and their Datasheets
                                                                                                                                                                                                                                      • 7474 D Flip-Flop
                                                                                                                                                                                                                                      • ICs of basic gates (AND OR NOT XOR etc) as required
                                                                                                                                                                                                                                      • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                                        • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                                                        • Connecting wires Switches
                                                                                                                                                                                                                                          • THEORY
                                                                                                                                                                                                                                              • Sequential Circuits
                                                                                                                                                                                                                                                • 18-ldst-exp13
                                                                                                                                                                                                                                                  • Lab Session 13
                                                                                                                                                                                                                                                    • Designing a modulo-5 asynchronous up-counter using JK-FF
                                                                                                                                                                                                                                                      • 1 Following ICs and their Datasheets
                                                                                                                                                                                                                                                      • 7400 Quad 2-input or 7410 Triple 3-input NAND Gates
                                                                                                                                                                                                                                                      • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                                                        • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                                                                        • Connecting wires Switches
                                                                                                                                                                                                                                                          • THEORY
                                                                                                                                                                                                                                                              • Figure 131 A Mod-5 Asynchronous Up Counter
                                                                                                                                                                                                                                                              • Implementation and Observations
                                                                                                                                                                                                                                                                • ACTIVITY
                                                                                                                                                                                                                                                                    • 19-ldst-exp14
                                                                                                                                                                                                                                                                      • Experimenting with 74194 4-bit bidirectional universal shift register
                                                                                                                                                                                                                                                                      • 1 Following ICs and their Datasheets
                                                                                                                                                                                                                                                                      • 74194 4-bit bidirectional universal shift register
                                                                                                                                                                                                                                                                      • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                                                                        • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                                                                                        • Connecting wires Switches
                                                                                                                                                                                                                                                                          • THEORY
                                                                                                                                                                                                                                                                            • Shift Registers
                                                                                                                                                                                                                                                                            • Bidirectional Shift Registers
                                                                                                                                                                                                                                                                            • Universal Shift Registers
                                                                                                                                                                                                                                                                              • S1
                                                                                                                                                                                                                                                                                • Circuit Diagram
                                                                                                                                                                                                                                                                                • ACTIVITY
                                                                                                                                                                                                                                                                                    • 20-ldst-exp15
                                                                                                                                                                                                                                                                                      • COMPONENTS AND APPARATUS REQUIRED
                                                                                                                                                                                                                                                                                      • 1 Parallel Port Connectors (DB-25) with Cable
                                                                                                                                                                                                                                                                                      • 2 Personal Computer with Windows 98 and TurboC Compiler Installed
                                                                                                                                                                                                                                                                                      • 3 Following ICs and their Datasheets
                                                                                                                                                                                                                                                                                      • 74245 Octal Bus Transceivers with 3-State Outputs
                                                                                                                                                                                                                                                                                      • 4 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                                                                                        • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                                                                                                          • Connecting wires Switches
                                                                                                                                                                                                                                                                                            • THEORY
                                                                                                                                                                                                                                                                                            • 3-State Logic
                                                                                                                                                                                                                                                                                              • Serial and Parallel Port Connectors
                                                                                                                                                                                                                                                                                              • Parallel Port Connector ndash DB-25
                                                                                                                                                                                                                                                                                                • Accessing parallel port through C Language Programming
                                                                                                                                                                                                                                                                                                    • 21-ldst-appendixA
                                                                                                                                                                                                                                                                                                    • 22-ldst-appendixB
                                                                                                                                                                                                                                                                                                      • DEBOUNCING CIRCUITRY FOR MECHANICAL SWITCHES

                              Logic Design amp Switching Theory 1 Lab Session 02 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                              Lab Session 02

                              OBJECT

                              Working with Electronics Workbench

                              ELECTRONICS WORKBENCH - EWB Electronics Workbench is a computer aided design tool that provides you with all the components and instruments necessary to create board-level designs It has complete mixed analog and digital simulation and graphical waveform analysis allowing you to design your circuit and then analyze it using different simulated instruments and analysis options It is fully integrated and interactive thus you can change your circuits quickly allowing fast and repeated what-if analysis Electronics Workbench provides the following kind of components bull Sources parts bin (AC voltage source Vcc source ground battery etc) bull Basic parts bin (resistors capacitors transformers switches etc) bull Diodes parts bin bull Transistors parts bin bull Analog ICs parts bin (op-amps etc) bull Mixed ICs parts bin (ADCs DACs 555 timers etc) bull Digital ICs parts bin (AND OR adders multiplexers etc) bull Indicators parts bin (voltmeter ammeter probe displays etc) bull Controls parts bin (voltage differentiator multiplier etc) bull Instruments parts bin (multimeter oscilloscope function generator etc) bull Miscellaneous parts bin (write data textbox etc)

                              o Write data This component allows you to save simulation results as an ASCII file o Text Box Use this to add descriptive text anywhere in a circuit

                              ACTIVITY

                              Design circuit for the logic expression )( CBDCABAF ++=

                              Procedure 1 From Logic Gates Parts Bin Drag and drop the required logic gates on the design

                              area Use Component Properties dialog box to customize these gates 2 Connect the terminal of these gates according to the given expression Use additional

                              connectors form the Basic Parts Bin if you want to connect more than wire at a single node

                              3 Drag and drop a probe from Indicators Parts Bin Use Component Properties dialog box to customize the color and other properties of the probe Connect this probe at the output terminal of the circuit to indicate results

                              4 Select four switches form Basic Parts Bin Specify the key that controls the switch by typing its name in the Value tab of the Component Properties dialog box For

                              17

                              Logic Design amp Switching Theory 1 Lab Session 02 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                              18

                              example if you want the switch to close or open when digit lsquo1rsquo is pressed type 1 in the Value tab then click OK Assign different keys to all the switches

                              5 Connect the output terminals of these switches to each of the four inputs A B C and D of the circuit

                              6 Drag and drop Vcc and Ground form the Sources Parts Bin 7 Connect Vcc terminal to one end and Ground terminal to the other end of all the

                              switches 8 Label the circuit properly using text boxes found in the miscellaneous parts bin 9 Run the circuit using the Activate Simulation switch Use the keys you have assigned

                              to the switches to toggle them between Vcc and Ground connections thus providing 1 or 0 respectively to the inputs Record the results as indicated by the probe for all possible combinations of 1s and 0s at the inputs

                              EWB Circuit

                              Figure 21

                              Observations

                              A B C D Expected Output Observed Output 0 0 0 0 0 0 0 1 0 0 1 0 0 0 1 1 0 1 0 0 0 1 0 1 0 1 1 0 0 1 1 1 1 0 0 0 1 0 0 1 1 0 1 0 1 0 1 1 1 1 0 0 1 1 0 1 1 1 1 0 1 1 1 1

                              Logic Design amp Switching Theory 1 Lab Session 03 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                              Lab Session 03

                              OBJECT

                              Designing Half and Full Adder Circuits COMPONENTS AND APPARATUS REQUIRED 1 Following ICs and their Datasheets

                              bull 7408 Quad 2-input AND Gate bull 7432 Quad 2-input OR Gate bull 7486 Quad 2-input XOR Gate

                              2 Digital Trainer DT-01 or the following components Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches

                              THEORY Half Adder A combination circuit that performs the addition of two bits without accounting for the previous carry is called half adder It needs two binary inputs and two binary outputs The input variables designate the augend and addend bits The output variables produce the sum and carry The simplified sum of product expressions for a half adder are

                              yxyxyxS oplus=+= yxC =

                              Figure 31 Circuit diagram for Half Adder

                              19

                              Logic Design amp Switching Theory 1 Lab Session 03 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                              bles produce the sum and carry The simplified sum of product expressions for a half adder are

                              Full Adder

                              A combinational circuit that performs the addition of three input bits It consist of three inputs and two outputs Two of the input variables represent the two significant bits to be added The third input represents the carry from the previous lower significant position The output varia

                              zyxzyxzyxzyxzyxS oplusoplus=+++= yxzyxzyzxxyC )( +oplus=++=

                              Figure 32 Circuit diagram for Full Adder

                              efer to laboratory session 01 for procedure) and record the observations in the following ta

                              alf Adde ull Adder Inputs u

                              IMPLEMENTATION AND OBSERVATIONS

                              Implement the half adder and full adder circuits on a bread board (prepare the pin diagram (use appendix A) and r

                              bles H r F

                              Inputs Outputs Outp ts x y Carry Su Carry Sum m x y z 0 0 0 0 0 0 1 0 0 1 1 0 0 1 0 1 1 0 1 1 1 0 0 1 0 1 1 1 0 1 1 1

                              20

                              Logic Design amp Switching Theory 1 Lab Session 03 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                              at of your designed circuit Attach hardcopy of the output form electronic workbench

                              at of your designed circuit Attach hardcopy of the output form lectronic workbench here

                              ACTIVITY

                              1 Simulate half adder circuit using Electronics Workbench Compare the results of simulation with thhere

                              2 Design a full subtractor circuit and simulate it using Electronics Workbench Compare the results of simulation with the

                              21

                              Logic Design amp Switching Theory 1 Lab Session 04 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                              Lab Session 04 OBJECT

                              Use of Karnaugh Map (SOP-Expression) method GIVEN LOGIC EXPRESSION

                              F (A B C D) = sum ( 0 1 2 4 5 6 8 9 12 13 14 ) COMPONENTS AND APPARATUS REQUIRED 1 Digital ICs and their Datasheets

                              bull 7408 Quad 2-input AND Gate bull 7432 Quad 2-input OR Gate bull 7404 Hex Inverter

                              2 Digital Trainer DT-01 or the following components Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches PROCEDURE 1 Use Karnaugh map to reduce the given function 2 Draw the circuit diagram for the obtained reduced function 3 Implement the reduced circuit using digital ICs on a bread board (prepare the pin

                              diagram (use appendix A) and refer to laboratory session 01 for procedure) and record the observations

                              REDUCTION OF LOGIC EXPRESSION USING KARNAUGH MAP F

                              CD

                              AB DC

                              DC DC

                              DC

                              BA0 1 3 2

                              BA4 5 7 6

                              BA12 13 15 14

                              BA8 9 11 10

                              Reduced form of the given logic expression is __________________________________

                              22

                              Logic Design amp Switching Theory 1 Lab Session 04 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                              LOGIC DIAGRAM (REDUCED FORM) OBSERVATIONS

                              A B C D Output 0 0 0 0 0 0 0 1 0 0 1 0 0 0 1 1 0 1 0 0 0 1 0 1 0 1 1 0 0 1 1 1 1 0 0 0 1 0 0 1 1 0 1 0 1 0 1 1 1 1 0 0 1 1 0 1 1 1 1 0 1 1 1 1

                              RESULT The reduced form (SOP Expression) of the given logic function is

                              ____________________________________________________________

                              The observation table reflects the given logic function

                              23

                              Logic Design amp Switching Theory 1 Lab Session 04 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                              ACTIVITY 1 Using Electronics Workbench derive a truth table and logic circuit for the following logic expression

                              BAAF +=

                              Procedure 1 From the Instruments Parts Bin drag and drop Logic Converter on the design area 2 Double click the Logic Converter to reveal Logic Converter dialog box This dialog

                              box shows various conversion options between truth table logic expression and logic circuit

                              3 Enter the given logic expression in the edit box found at the end of the dialog box Use lsquo to represent invert of a variable For example A is written as Arsquo

                              4 Click the Boolean Expression to Truth Table button The truth table appears in the logic converters display

                              5 Now click the Boolean Expression to Circuit button This creates the logic circuit for the given expression in the design area Label the diagram if needed

                              Resulting Logic Circuit For the given expression the final circuit will look like

                              Figure 41

                              24

                              Logic Design amp Switching Theory 1 Lab Session 04 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                              ACTIVITY 2

                              Using Electronics Workbench find a simplified logic expression and circuit for the following truth table

                              A B C Output 0 0 0 1 0 0 1 1 0 1 0 0 0 1 1 1 1 0 0 0 1 0 1 0 1 1 0 0 1 1 1 1

                              Procedure 1 Click three input channels from A to H across the top of the logic converter The

                              display area below the terminals fills up with the necessary combinations of ones and zeros to fulfill the input conditions The values in the output column on the right are initially set to 0

                              2 Edit the output column to specify the desired output for each input condition To change an output value select it and type a new value 1 0 or x An x indicates a donrsquot care condition

                              3 To convert this truth table to a Boolean expression click the Truth Table to Boolean Expression button The Boolean expression will be displayed at the bottom of the logic converter

                              4 Simplify the expression by clicking the Simplify button 5 Now click the Boolean Expression to Circuit button This creates the logic circuit for

                              the given expression in the design area Resulting Logic Circuit For the given truth table the final simplified circuit will look like

                              Figure 42

                              25

                              Logic Design amp Switching Theory 1 Lab Session 04 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                              ACTIVITY 3

                              Using Electronics Workbench find the logic expression and truth table for the following logic circuit

                              Figure 43

                              Procedure 1 Attach the input terminals of the logic converter to up to four input points in the

                              circuit 2 Connect the single output of the circuit to the output terminal on the logic converter

                              icon 3 Click the Circuit to Truth Table button The truth table appears in the logic

                              converters display 4 To convert this truth table to a Boolean expression click the Truth Table to Boolean

                              Expression button The Boolean expression will be displayed at the bottom of the logic converter

                              Resulting Logic Expression Logic Expression for the given circuit is found to be _____________________________

                              26

                              Logic Design amp Switching Theory 1 Lab Session 04 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                              27

                              For activities 1 2 and 3 attach hardcopy of the output (truth table logic expression and logic circuit) form electronic workbench here

                              Logic Design amp Switching Theory 1 Lab Session 05 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                              Lab Session 05 Lab Session 05 OBJECT OBJECT

                              Designing a BCD Adder Designing a BCD Adder COMPONENTS AND APPARATUS REQUIRED COMPONENTS AND APPARATUS REQUIRED

                              1 Following ICs and their Datasheets 1 Following ICs and their Datasheets bull 7408 Quad 2-input AND Gate bull 7408 Quad 2-input AND Gate bull 7432 Quad 2-input OR Gate bull 7432 Quad 2-input OR Gate bull 7483 4-bit Binary Adder bull 7483 4-bit Binary Adder

                              2 Digital Trainer DT-01 or the following components 2 Digital Trainer DT-01 or the following components Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors (100 Ω) Connecting wires Switches (100 Ω) Connecting wires Switches

                              THEORY THEORY

                              A BCD Adder is a combinational circuit that adds two BCD digits in parallel and produces a sum digit also in BCD A BCD Adder is a combinational circuit that adds two BCD digits in parallel and produces a sum digit also in BCD

                              A4 A3 A2 A1 B4 B3 B2 B1

                              7483-BCD ADDER

                              Cout (C4 ) Z4 Z3 Z2 Z1 Cin(C0)

                              A4 A3 A2 A1 B4 B3 B2 B1

                              7483-BCD ADDER

                              Cout

                              (C4 ) Z4 Z3 Z2 Z1 Cin(C0)

                              Figure 51 BCD Adder Circuit

                              28

                              Logic Design amp Switching Theory 1 Lab Session 05 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                              29

                              A BCD adder must include the correction logic in its internal construction The two BCD digits together with the input carry are first added using a 4-bit binary adder to produce the binary sum If no output carry is generated and the binary sum is less than or equal to 9 then the corresponding BCD sum is identical and therefore no conversion is needed When the output carry is equal to 1 or the binary sum is greater than 9 then a binary 0110 is added to the binary sum through another 4-bit binary adder If Cout is the carry output and Z4Z3Z2Z1 is the binary sum form the first 4-bit binary adder then the following equation indicates the condition when a binary 0110 is to be added

                              C = COUT + Z4Z2 + Z4Z3 IMPLEMENTATION AND OBSERVATIONS Implement the BCD adder circuit according to figure 51 on a bread board (prepare the pin diagram (use appendix A) and refer to laboratory session 01 for procedure) A BCD adder has nine input bits (two BCD digits and a carry bit) which can result in a total of 512 combinations of which 312 inputs are donrsquot care Since it is a very lengthy procedure to record results for 200 valid input combinations therefore for simplicity just record results for any eight combinations in the following table

                              Input Carry

                              BCD Digit 1 BCD Digit 2 Carry Output

                              BCD Sum A4 A3 A2 A1 B4 B3 B2 B1 Z4 Z3 Z2 Z1

                              Logic Design amp Switching Theory 1 lab Session 06 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                              Lab Session 06

                              OBJECT

                              bull Designing of a 4 x 1 Multiplexer bull Experimenting with 74150 IC

                              COMPONENTS AND APPARATUS REQUIRED 1 Following ICs and their Datasheets

                              bull 7408 Quad 2-input AND Gates or 7411 Triple 3-input AND Gates bull 7432 Quad 2-input OR Gates bull 7404 Hex Inverter bull 74150 16 x 1 MUX

                              2 Digital Trainer DT-01 or the following components Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches THEORY

                              Multiplexers A digital data Multiplexer (MUX) is a combinational circuit having several data inputs and a single output A set of data-select inputs is used to control which of the data inputs is routed to the single output A multiplexer is also called a data selector because of this ability to select which data input is connected o the output Normally there are 2n input lines and n selection lines whose bit combination determine which input is selected DESIGN OF A 4 x 1 MULTIPLEXER A 4 x 1 multiplexer is capable of selecting one of four data inputs (see figure 61) The 2-bit binary number at the data select inputs S1 and S0 specifies which of the four data inputs is to be routed to the output Since there are two data select inputs therefore they can select 22 = 4 different data inputs lines

                              S0 S1 D0 D1

                              D2 D3

                              Data-select Inputs Output

                              Data Inputs

                              Figure 61 Block Diagram of a 4 x1 Multiplexer

                              30

                              Logic Design amp Switching Theory 1 lab Session 06 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                              Figure 62 Circuit Diagram for 4 x 1 Multiplexer

                              Implementation and Observations

                              Implement the 4 x 1 Multiplexer circuit (figure 62) on a bread board (prepare the pin diagram (use appendix A) and refer to laboratory session 01 for implementation procedure) and record the observations in the following table For each data select combination specify the switch number as well as the binary value present on that selected switch

                              S1 S0 Output 0 0 0 1 1 0 1 1

                              TESTING OF 74150 - 16 x 1 MUX

                              The 74150 IC has sixteen data inputs and four data-selection lines Function of various pins of this IC is described below

                              bull E0 through E15 Data input lines

                              31

                              Logic Design amp Switching Theory 1 lab Session 06 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering bull A B C D Data select lines with D being the MSB bull W Active low output line bull Grsquo Active low enable line bull VCC and GND Supply connections lines

                              Circuit Diagram

                              Figure 63 Pin connections of 74150 for selecting E0

                              Testing Procedure

                              bull Make connections as shown in the circuit diagram bull Apply different data (1 or 0) at data inputs that are labeled as E0 to E15 Only

                              connection for E0 is shown is the figure for simplicity bull Select the data input E0 with the help of data selectors A B C and D bull Observe the output which shows the complement of the data from E0 bull Select all the sixteen data inputs one by one and record your observations in the

                              following table

                              32

                              Logic Design amp Switching Theory 1 lab Session 06 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                              33

                              Observations

                              Grsquo D C B A W Grsquo D C B A W 0 0 0 0 0 0 1 0 0 0 0 0 0 0 1 0 1 0 0 1 0 0 0 1 0 0 1 0 1 0 0 0 0 1 1 0 1 0 1 1 0 0 1 0 0 0 1 1 0 0 0 0 1 0 1 0 1 1 0 1 0 0 1 1 0 0 1 1 1 0 0 0 1 1 1 0 1 1 1 1

                              ACTIVITY 1 Consider 4x1 Multiplexer Draw the output wave-form for the following data inputs

                              (E0 E1 E2 E3) and select lines A B (B being the MSB) Output is W

                              E3 E2 E1 E0 A B

                              W

                              2 Using the 4 x 1 MUX designed in this laboratory session implement the following logical function F (A B C) = Σ (0147)

                              Show your working and input connections in the following block diagram according to the circuit you have implemented

                              4 x 1 MUX

                              S0 S1

                              Output D0

                              D1

                              D2

                              D3

                              Logic Design amp Switching Theory 1 Lab Session 07 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                              Lab Session 07

                              OBJECT

                              bull Designing of a 2 x 4 Decoder 1 x 4 Demultiplexer bull Experimenting with 74138 IC

                              COMPONENTS AND APPARATUS REQUIRED 1 Following ICs and their Datasheets

                              bull 7408 Quad 2-input or 7411 Triple 3-input AND Gates bull 7404 Hex Inverter bull 74138 3 x 8 Decoder

                              2 Digital Trainer DT-01 or the following components Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches THEORY

                              Decoder A Decoder is a combinational circuit that converts binary information form n input lines to a maximum of 2n unique output lines In practical applications decoders are often used for selecting one of several devices

                              Demultiplexer A decoder with an enable input can function as a Demultiplexer A Demultiplexer (DMUX) id a circuit that receives information on a single line and transmits this information on one of 2n possible output lines The selection of a specific output line is controlled by the bit values of n selection lines DESIGN OF A 2 x 4 DECODER 1 x 4 DEMULTIPLEXER A 2 x 4 decoder is capable of selecting one of four output lines (see figure 71 (a)) The 2-bit binary number at the data inputs S1 and S0 specifies which of the four data inputs is to be selected If we add an enable pin and use it as an input line then this decoder can be converted to a 1 x 4 Demultiplexer where S1 and S0 will select a line to which data input is to be routed (see figure 71 (b))

                              Select S0 S0 Inputs

                              S1 D0 D1

                              D2

                              D3

                              Enable (a) Block Diagram of a 2 x 4 Decoder

                              Figure 71

                              S1 D0 D1

                              D2

                              D3

                              Inputs

                              Data Input (b) Block Diagram of a 1 x 4 Demulptiplexer

                              34

                              Logic Design amp Switching Theory 1 Lab Session 07 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                              Figure 72 Circuit Diagram for 2 x 4 Decoder 1 x 4 Demultiplexer

                              Implementation and Observations Implement the 2 x 4 Decoder 1 x 4 Demultiplexer circuit (figure 72) on a bread board (prepare the pin diagram (use appendix A) and refer to laboratory session 01 for implementation procedure) and record the observations in the following table

                              Enable Data Input S1 S0 D0 D1 D2 D3

                              0 0 0 0 0 1 0 1 0 0 1 1 1 0 0 1 0 1 1 1 0 1 1 1

                              TESTING OF 74138 3 x 8 Decoder The 74138 IC has three inputs and eight output lines It has three enable inputs and for the IC to function all three inputs need to be enabled Function of various pins of this IC is described below

                              35

                              Logic Design amp Switching Theory 1 Lab Session 07 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                              bull Y0 through Y7 Active low data outputs bull A B C Input select lines with C being the MSB bull G1 Active high enable Input bull G2Arsquo and G2Brsquo Active low enable Inputs bull VCC and GND Supply connections lines Circuit Diagram

                              Figure 73 Pin connections of 74138

                              Testing Procedure

                              bull Make connections as shown in the circuit diagram bull Apply different combinations of 1s and 0s at data inputs bull Observe the output and record your observations in the following table

                              Observations

                              C B A Y0 Y1 Y2 Y3 Y4 Y5 Y6 Y7 0 0 0 0 0 1 0 1 0 0 1 1 1 0 0 1 0 1 1 1 0 1 1 1

                              36

                              Logic Design amp Switching Theory 1 Lab Session 07 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                              37

                              ACTIVITY ACTIVITY 1 What will be the binary values at the outputs Y0 through Y7 of 74138 if 1 What will be the binary values at the outputs Y0 through Y7 of 74138 if

                              bull All three enable pins are connected to ground bull All three enable pins are connected to ground __________________________________________________________________________________________________________________________________________ __________________________________________________________________________________________________________________________________________ _____________________________________________________________________ _____________________________________________________________________

                              bull All three enable pins are connected to VCC bull All three enable pins are connected to VCC _______________________________________________________________________________________________________________________________________________________________________________________________________________

                              _______________________________________________________________________________________________________________________________________________________________________________________________________________

                              2 Show connections for 74138 in order to use it as a 1 x 8 Demultiplexer 2 Show connections for 74138 in order to use it as a 1 x 8 Demultiplexer

                              3 Consider a 2 x 4 Decoder with two enable inputs (one active high - G and one active low ndash Grsquo) Draw the output wave-forms for D0 D1 D2 and D3 if the two select inputs are A and B (B being the MSB) All outputs are active low

                              Grsquo

                              G

                              A B

                              D0 D1 D2

                              D3

                              Logic Design amp Switching Theory 1 Lab Session 08 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                              Lab Session 08 OBJECT

                              bull Designing of a 4 x 2 Priority Encoder bull Experimenting with 74148 IC

                              COMPONENTS AND APPARATUS REQUIRED

                              1 Following ICs and their Datasheets

                              bull 7408 Quad 2-input or 7421 Dual 4-input AND Gates bull 7432 Quad 2-input OR Gates bull 7404 Hex Inverter bull 74148 Encoder

                              2 Digital Trainer DT-01 or the following components Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches

                              THEORY

                              Encoder An Encoder is a digital function that produces a reverse operation from that of a decoder An Encoder has 2n (or less) input lines and n output lines The output lines generate the binary code for the 2n input variables Priority Encoder

                              A simple encoder may produce an erroneous output if more than one of its inputs is high A Priority Encoder is one that responds to just one input among those that may be simultaneously high in accordance with some priority system The most common priority system is based on the relative magnitudes of the inputs whichever decimal input is largest is the one that is encoded

                              DESIGN OF A 4 x 2 Priority Encoder

                              The following equations represent the outputs of a 4 x 2 priority encoder 32 DDA +=

                              321 DDDB += As can be seen from the equations that input D0 which has a binary code 00 is not used in any equation A binary code 00 at the output indicates two conditions Either D0 is selected or no input is selected In order to differentiate these two conditions we will provide an additional output Z to indicate if at least one of the inputs is a 1 The equation for Z will be

                              4321 DDDDZ = If Z is 0 then the binary code 00 at the output indicates that D0 is selected and if Z is 1 then it indicates that no input line is selected

                              38

                              Logic Design amp Switching Theory 1 Lab Session 08 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                              Figure 81 Circuit Diagram for 4 x 2 Priority Encoder

                              it (figure 81) on a bread board (prepare the to laboratory session 01 for implementation

                              Implementation a Implement the 4 x 2 Priority Encoder circu

                              ram (use appendix A) and refer

                              nd Observations

                              pin diagprocedure) and record the observations in the following table

                              D3 D2 D1 D0 A B 0 0 0 1 0 0 1 x 0 1 x x 1 x x x

                              TESTING OF 74148 8 x 3 Octal Priority Encoder

                              imal digits There are nine of which three represents

                              ing any of the inputs is high

                              then it shows that line 0 is selected and if e inputs selected E0 and GS

                              cannot be in the same state provided that E1 is enabled

                              The 74148 is a priority encoder with active-Low input for dec

                              input) and five output linesinputs lines (including an enablethe binary code for the octal digit Function of various pins of this IC is described below

                              bull 0 through 7 Active low data inputs representing the octal digits A2 A1 A0 Active low output lines representing the binary code bullbull E1 Active low enable Input bull E0 Active low output indicating none of the inputs is high bull GS Active low output indicatbull VCC and GND Supply connections lines Therefore if GS A2 A1 and A0 are all low

                              then it shows that none of thE0 A2 A1 and A0 are all low

                              39

                              Logic Design amp Switching Theory 1 Lab Session 08 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                              Circuit Diagram

                              Figure 82 Pin connections of 74148

                              Testing Procedure bull Make connections as sho

                              binations of 1s and 0s at data inputs d record your observations in the following table

                              GS E0

                              wn in the circuit diagram bull Apply different combull Observe the output an Observations

                              0 1 2 3 4 5 6 7 A2 A1 A0 1 1 1 1 1 1 1 1 x x x x x x x 0 x x x x x x 0 1 x x x x x 0 1 1 x x x x 0 1 1 1 x x x 0 1 1 1 1 x x 0 1 1 1 1 1 x 0 1 1 1 1 1 1 0 1 1 1 1 1 1 1

                              40

                              Logic Design amp Switching Theory 1 Lab Session 08 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                              41

                              CTIVITY

                              Cascade the following two 74148 8 x 3 Priority Encoders to form 16 x 4 Priority

                              A 1

                              Encoder

                              Logic Design amp Switching Theory 1 Lab Session 09 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering `

                              Lab Session 09 OBJECT

                              Designing an Odd Parity Generator and Checker for a 3-bit Data COMPONENTS AND APPARATUS REQUIRED

                              1 Following ICs and their Datasheets

                              bull 7486 Quad 2-input Exclusive-OR Gates bull 7404 Hex Inverter

                              2 Digital Trainer DT-01 or the following components Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches

                              THEORY

                              Parity Generator When binary data is transmitted and processed it is ndash as are all electrical signals ndash susceptible to noise that can either alter or distort its contents 1s may be effectively changed to 0s and 0s to 1s To overcome this problem one or more bits are often added to the data as an aid in detecting errors caused by noise The most common of these is a Parity bit that signifies whether the total number of 1s in a code group is odd or even In an Odd Parity system the parity bit is made 0 or 1 as necessary to make the total number 1s odd (counting the parity bit itself) In an Even Parity system the parity bit is chosen to make the total number of 1s even Table 91 shows how parity bits would be added to BCD code group in both systems

                              Decimal BCD Value Parity Bit ABCD Odd Parity Even Parity

                              0 0000 1 0 1 0001 0 1 2 0010 0 1 3 0011 1 0 4 0100 0 1 5 0101 1 0 6 0110 1 0 7 0111 0 1 8 1000 0 1 9 1001 1 0

                              Table 91 Odd and Even Parity in BCD

                              When digital data is received a parity checking circuit generates an error signal if the total number of 1s is odd in an even parity system or if it is even in an odd parity system Parity check always detects a single error (one bit change from 0 to 1 or 1 to 0) but may not detect

                              42

                              Logic Design amp Switching Theory 1 Lab Session 09 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering ` two or more errors Odd parity is used more often than even parity because even parity does not detect a situation where all 0s are created due to short circuit or other fault condition DESIGN OF A 3-BIT ODD PARITY GENERATOR AND CHECKER Let x y and z be the three bits that constitute the message and are the input to the Odd Parity Generator Circuit Since it is an odd parity system the bit P is generated so as to make the total number of 1s odd (including P) The function P can be expressed as follows P = x oplus y Ο z or P = x Ο y oplus z Since the IC available is 7486 which is quad 2input XOR IC therefore we will convert XNOR also to XOR

                              P = x oplus y Ο z

                              P = ( x oplus y ) Ο z Since for even number of variables ______

                              XOR = XNOR Therefore ___________ _________

                              P = ( x oplus y ) oplus z = x oplus y oplus z This logical expression can be implemented with two XOR gates and an inverter (see figure 91)

                              Figure 91 Circuit Diagram for a 3-bit Parity Generator

                              The 3-bit message and the parity bit are transmitted to their destination where they are applied to a Parity Checker Circuit An error occurs during transmission if the parity of the four bits received is even since the binary information transmitted was originally odd The output C of the parity checker should be a 1 when an error occurs ie when the number of 1s in the four inputs is even Therefore the function C can be expressed as

                              C = x Ο y Ο z Ο P

                              Using the same logic applied for the conversion of the equation of P

                              PzyxC oplusoplusoplus= This logical expression can be implemented with three XOR gates and an inverter (see figure 92)

                              43

                              Logic Design amp Switching Theory 1 Lab Session 09 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering `

                              44

                              Figure 92 Circuit Diagram for a 3-bit Parity Checker Implementation and Observations Implement the 3-bit Parity Generator and Checker circuits (figure 91 and 92) on a bread board (prepare the pin diagram (use appendix A) and refer to laboratory session 01 for implementation procedure) and record the observations in the following table

                              x y z P x y z P C x y z P C 0 0 0 0 0 0 0 1 0 0 0 0 0 1 0 0 0 1 1 0 0 1 0 1 0 0 0 1 0 1 0 1 0 0 1 1 0 0 1 1 1 0 1 1 1 0 0 0 1 0 0 1 1 0 0 1 0 1 0 1 0 1 1 1 0 1 1 1 0 0 1 1 0 1 1 1 0 1 1 1 0 1 1 1 1 1 1 1

                              Odd Parity Generation Odd Parity Check ACTIVITY 1 Try using the parity checker of figure 92 as 3-bit parity generator Write the details here

                              _____________________________________________________________________________________________________________________________________________________________________________________________________________________ ______________________________________________________________________________________________________________________________________________ _______________________________________________________________________ ______________________________________________________________________________________________________________________________________________

                              Logic Design amp Switching Theory 1 Lab Session 10 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                              Lab Session 10 OBJECT

                              Driving a seven segment display using 7447 7448 driver IC COMPONENTS AND APPARATUS REQUIRED

                              1 Following ICs and their Datasheets

                              bull Seven Segment Displays (Common Anode Common Cathode) bull 7447 7448 BCD to Seven Segment Driver

                              2 Digital Trainer DT-01 or the following components Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches

                              THEORY Seven Segment Displays A Seven Segment Display consists of seven light-emitting segments The segments are designated by letters a through g (see figure 101) By illuminating various combinations of segments the numerals 0 through 9 can be displayed Seven Segment Displays are commonly constructed with light-emitting diodes (LEDs) and with liquid-crystal displays (LCDs) LEDs generally provide greater illumination levels but require much greater power than LCDs An LED display can be a common-anode type or common cathode type In common anode type a high voltage is applied at the common terminal of the display and low voltage is applied at a segmentrsquos terminal for illumination In the common-cathode type a low voltage is applied at the common terminal of the display and high voltage is applied at a segmentrsquos terminal for illumination

                              Figure 101 Seven Segment Display

                              a f b g

                              e c d

                              7447 7448 BCD to Seven Segment Driver 7447 7448 IC is particularly used to drive Seven Segment Its input is a BCD number and output drives a seven segment display 7447 is used to drive common-anode displays whereas 7448 is used to drive common cathode displays 7447 7448 is a 16 pin IC Function of various pins of these ICs is described below

                              bull A B C D Inputs representing BCD digits (D being the MSB)

                              45

                              Logic Design amp Switching Theory 1 Lab Session 10 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering bull OA through OG Outputs to drive segments a through g of the display (Active low

                              in 7447 and active high in 7448) bull RBI Ripple Blanking Input Turns off all the segments if kept low provided that LT

                              is kept high and all other inputs (A B C D BI) are kept low Should be kept high otherwise

                              bull BI RBO Wire-AND logic serving as a Blanking Input and or Ripple Blanking Output

                              o BI Turns off all the segments if low o RBO Goes to a low level (response condition) along with other outputs when

                              RBI and inputs A B C and D are low with LT input at high level bull LT Lamp Test input Tests whether all segments are working or not Illuminates all

                              segments if kept low provided that BI is kept high Should be kept high otherwise bull VCC and GND Supply connections lines CIRCUIT DIAGRAM

                              Figure 102 Circuit diagram for 7447driving a common-anode display

                              IMPLEMENTATION AND OBSERVATIONS

                              bull Make connections as shown in the circuit diagram (refer to laboratory session 01 for implementation procedure)

                              bull Apply different combinations of 1s and 0s at data inputs bull Observe the output and record your observations in the following table

                              46

                              Logic Design amp Switching Theory 1 Lab Session 10 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                              47

                              Decimal Digit

                              BCD Inputs Seven Segment Outputs D C B A a b c d e f g

                              0 0 0 0 0 1 0 0 0 1 2 0 0 1 0 3 0 0 1 1 4 0 1 0 0 5 0 1 0 1 6 0 1 1 0 7 0 1 1 1 8 1 0 0 0 9 1 0 0 1

                              ACTIVITY 1 Perform the Lamp Test for the designed circuit and write your observations

                              ____________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________

                              2 How can you use 7447 IC to drive a common-cathode display

                              ____________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________

                              3 What symbols appear in the seven segment display if inputs DCBA are

                              DCBA Symbol

                              1010

                              1011

                              1100

                              1101

                              1110

                              1111

                              Logic Design amp Switching Theory 1 Lab Session 11 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                              48

                              Lab Session 11 OBJECT

                              Testing different modes of JK-FF COMPONENTS AND APPARATUS REQUIRED 1 Following ICs and their Datasheets

                              bull 7473 7476 JK Flip-Flop 2 Digital Trainer DT-01 or the following components

                              Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches

                              THEORY

                              Flip-Flop A flip-flop circuit can maintain a binary state indefinitely (as long as the power is delivered to the circuit) until directed by an input signal to switch states The major differences among various types of flip-flops are in the number of inputs they possess and in the manner in which the inputs affect the binary state

                              JK Flip-Flop JK flip flop is an edge triggered device A typical JK flip flop has three inputs J K and a clock input The flip-flop can be either positive or negative edge triggered The output Q is available in complemented form as well Beside the usual inputs and output most of the flip-flop IC also possess two asynchronous inputs namely Preset and Clear These inputs are usually active low If used Preset and Clear inputs keep the flip-flop in set and reset state respectively irrespective of the other inputs Both of these inputs cannot be used simultaneously otherwise they will bring the flip-flop in unstable state

                              Figure 111 Symbol for JK flip-flop

                              (a) positive-edge triggering (b) active low Preset (PR) and Clear (CLR) with positive-edge triggering

                              (c) active low Preset (PR) and Clear (CLR) with negative-edge triggering

                              Logic Design amp Switching Theory 1 Lab Session 11 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                              49

                              TESTING OF 7473 7476 DUAL JK FLIP-FLOP

                              Both the ICs 7473 and 7476 are similar in functionality except for one difference The flip-flops in 7473 have only one type of active low asynchronous input which is the Clear input whereas the flip-flops in 7476 have both Preset and Clear inputs Both these ICs have negative edge triggered flip-flops

                              Circuit Diagram

                              Figure 112 Pin connections of 7476

                              Testing Procedure

                              bull Make connections as shown in the circuit diagram (figure 112) bull Apply different combinations of 1s and 0s at J and K inputs bull Observe the output and record your observations in the following table

                              Observations

                              J

                              K Q

                              0 0 0 1 1 0 1 1

                              ACTIVITY

                              1 Observe the output Q of JK flip-flop if the clock input is connected to VCC or GND instead of a clock source Write your observations here __________________________________________________________________________________________________________________________________________ _______________________________________________________________________________________________________________________________________________________________________________________________________________

                              Logic Design amp Switching Theory 1 Lab Session 12 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                              50

                              Lab Session 12 OBJECT

                              Designing sequential circuit for the given state diagram using D flip-flop GIVEN STATE DIAGRAM

                              00

                              11

                              Figure 121 State Diagram COMPONENTS AND APPARATUS REQUIRED 1 Following ICs and their Datasheets

                              bull 7474 D Flip-Flop bull ICs of basic gates (AND OR NOT XOR etc) as required

                              2 Digital Trainer DT-01 or the following components Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches

                              THEORY

                              Sequential Circuits In Sequential Circuits the output not only depends on the present inputs but also on previous states of the circuit These circuits use memory elements (latches flip-flops) and the binary information stored in the memory elements at any given time defines the state of the sequential circuit Analysis of a Sequential Circuit The behavior of a sequential circuit is determined from the inputs the outputs and the states of its flip-flops Both the outputs and next state are a function of the inputs and the

                              10

                              01

                              00 11 10

                              00

                              00 11 10 00

                              Logic Design amp Switching Theory 1 Lab Session 12 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                              51

                              present state The analysis of a sequential circuit form a state diagram comprises of the following bull Selecting a particular flip-flop to design the circuit bull Obtaining state table from the state diagram bull Finding input equations for the selected flip-flop bull Finding state equations (not required for the construction of circuit) bull Implementing the circuit using selected flip-flops and their input equations ANALYZING THE GIVEN STATE DIAGRAM D Flip-Flop D flip-flop is also called transparent flip-flop as it simply transfers the input data to the output For our design we require the graphical symbol and excitation table of D flip-flop (see figure 122)

                              Qt Qt+1 T 0 0 0 0 1 1 1 0 0 1 1 1

                              (b) Excitation table of D Flip-Flop

                              (a) Graphical Symbol

                              Figure 122 Characteristic equation of D flip-flop is Q(t+1) = D State Table The given state diagram has four states so we will need two D flip-flops (FF-0 FF-1) Form state table form the given state diagram and record the results in the following table

                              Present State Input Next State Output Input to FF-0 D0

                              Input to FF-1 D1 Q1t Q0t x Q1(t+1) Q0(t+1) z

                              Logic Design amp Switching Theory 1 Lab Session 12 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                              52

                              Input Equations Using Karnaugh map the input equations D0 and D1 for the two flip-flops can be found

                              D0 D1 Q0x

                              Q1

                              _ _ Q0x

                              _ Q0x

                              Q0x

                              _ Q0x

                              Q0x

                              Q1

                              _ _ Q0x

                              _ Q0x

                              Q0x

                              _ Q0x

                              _ Q1

                              _ Q1

                              Q1

                              Q1

                              D0 = _________________ D1 = _________________

                              State Equations Using the characteristic equation of D flip-flop we can find the state equations Q0(t+1) and Q1(t+1) for the to flip flops Q0(t+1) = _______________________ Q1(t+1) = _______________________ _______________________ _______________________ _______________________ _______________________ Circuit Diagram

                              Logic Design amp Switching Theory 1 Lab Session 12 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                              53

                              Implementation Procedure and Observations

                              1 Implement the circuit using digital ICs on a bread board (prepare the pin diagram (use appendix A) and refer to laboratory session 01 for procedure)

                              2 Make the clear inputs of the flip-flops low (to clear the flip-flops) The flip-flops will remain in clear state as long as the clear inputs are connected to low level

                              3 Connect output Q0 and the clock pulse to an oscilloscope 4 Apply 0 to the input x 5 Now make the clear inputs to high 6 Observe the waveform for the first 5 clock pulses and record it 7 Repeat steps 2 to 6 keeping x=1 in step 4 this time 8 Repeat steps 2 to 7 this time connecting Q1 instead of Q0 to the oscilloscope in step

                              3 Record your observations (Keep frequency of the clock pulse low (eg1Hz) so that the output waveforms can be observed easily)

                              1 2 3 4 5 Clock Pulse

                              Output Waveform for Q0 when x=0

                              Output Waveform for Q0 when x=1

                              Output Waveform for Q1 when x=0

                              Output Waveform for Q1 when x=1

                              Logic Design amp Switching Theory 1 Lab Session 13 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                              Lab Session 13 OBJECT

                              Designing a modulo-5 asynchronous up-counter using JK-FF COMPONENTS AND APPARATUS REQUIRED

                              1 Following ICs and their Datasheets

                              bull 7400 Quad 2-input or 7410 Triple 3-input NAND Gates bull 7476 7473 JK Flip-Flop

                              2 Digital Trainer DT-01 or the following components Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches

                              THEORY

                              Digital Counters A digital counter is a set of flip-flops whose states change in response to pulses applied at the input to the counter The flip-flops are interconnected so that their combined state at any time is the binary equivalent of the total number of pulses that have occurred up to that time Every counter resets after a certain number of clock pulses Thus as it name implies a counter is used to count pulses An n stage counter can count up to a maximum of 2n states n is equal to the number of flip-flops required for the construction of counter

                              Modulus Counters The number of input pulses that causes a counter to reset to its initial count is called the modulus of the counter Thus the modulus equals to total number of distinct states (counts) including zero that a counter can store A binary counter with n stages is a modulo-2n (or mod-2n) counter The largest count a mod-N counter can achieve is N-1 ie a mod-N counter never reaches the binary number equal to its modulus N is always equal to or less than 2n Counters can be classified as bull Synchronous Counters which are clock driven All the flip-flops are driven by a

                              single clock bull Asynchronous Counters which are event driven Clock input is given to the first

                              flip-flop only Rest of the flip-flops are driven by their preceding flip-flops

                              DESIGN OF A MOD-5 ASYNCHRONOUS UP COUNTER The number of flip-flops required to construct a mod-5 counter is 3 because 5 should be less than or equal to 2n This counter will count from 0 to 4 a total of 5 distinct states Since a 3-stage counter can count up to 8 states at maximum a NAND gate is used to reset it after 5 clock pulses Figure 131 shows the logic diagram

                              54

                              Logic Design amp Switching Theory 1 Lab Session 13 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                              55

                              Figure 131 A Mod-5 Asynchronous Up Counter

                              Implementation and Observations

                              Implement the mod-5 counter circuit (figure 131) on a bread board (prepare the pin diagram (use appendix A) and refer to laboratory session 01 for implementation procedure) and record the observations in the following table

                              Clock Pulse Q2 Q1 Q0

                              0 1 2 3 4 5 6 7

                              ACTIVITY

                              Draw the timing diagram for mod-5 counter designed in this laboratory session

                              Logic Design amp Switching Theory 1 Lab Session 14 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                              Lab Session 14 OBJECT

                              Experimenting with 74194 4-bit bidirectional universal shift register COMPONENTS AND APPARATUS REQUIRED

                              1 Following ICs and their Datasheets

                              bull 74194 4-bit bidirectional universal shift register 2 Digital Trainer DT-01 or the following components

                              Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches

                              THEORY

                              Shift Registers

                              A Register is a set of flip-flops used to store binary data A register which is capable of shifting its binary information either to the right or left is called a shift register The logical configuration of a register consists of a chain of flip-flops connected in cascade with the output of one flip-flop connected to the input of next flip-flop All flip-flops receive a common clock pulse which causes the shift from one stage to the next

                              Bidirectional Shift Registers A bi-directional shift register is one whose bits can be shifted from left to right or from right to left

                              Universal Shift Registers A universal shift register is a bi-directional register whose input can be in either serial or parallel form and whose output can be in either serial or parallel form

                              74194 4-BIT BIDIRECTIONAL UNIVERSAL SHIFT REGISTER

                              The 74194 register provides parallel as well as serial loading in both directions Function of various pins of this IC is described below

                              bull A B C and D Active high inputs for parallel loading bull QA QB QC and QD Active high outputs bull S0 and S1 Active high mode control inputs The following table shows combinations

                              of S1 and S0 to enable various modes

                              S1 S0 Clock Action 0 0 x No change 0 1 uarr Shift right 1 0 uarr Shift left 1 1 uarr Parallel load

                              uarr shows the rising edge of the clock pulse

                              56

                              Logic Design amp Switching Theory 1 Lab Session 14 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering bull SR Active high serial input for right shifting bull SL Active high serial input for left shifting bull CLR Active low input Clears all the flip-flops of the register if set to 0 should be

                              kept high otherwise bull CLK Clock input bull VCC and GND Supply connections lines Thus A B C and D are inputs for parallel loading whereas SR and SL are inputs for serial loading with right or left shifting respectively S1 and S0 are used to select the loading mode Circuit Diagram

                              Figure 141 Pin connections of 74194 Testing Procedure

                              bull Make connections as shown in the circuit diagram bull Observe the output for the input combinations given in the following table

                              57

                              Logic Design amp Switching Theory 1 Lab Session 14 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                              58

                              Observations

                              S1 S0 SL SR A B C D QA QB QC QD 0 0 0 1 0 0 0 0 0 1 1 0 0 0 0 1 1 0 0 0 0 0 1 0 1 1 0 0 0 0 1 1 0 0 1 1 0 1 0 0 0 1 1 1 0 1 0 1 1 0 1 0 0 1 1 0 1 1 1 0 0 1 1 1 1 1 0 0 1 1 1 1

                              ACTIVITY 1 Show connections of 74194 to convert it into a ring counter with right shifting

                              Logic Design amp Switching Theory 1 Lab Session 15 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                              Lab Session 15

                              OBJECT

                              Experimenting with 74245 octal bus transceivers using parallel port PC interfacing COMPONENTS AND APPARATUS REQUIRED 1 Parallel Port Connectors (DB-25) with Cable 2 Personal Computer with Windows 98 and TurboC Compiler Installed 3 Following ICs and their Datasheets

                              bull 74245 Octal Bus Transceivers with 3-State Outputs 4 Digital Trainer DT-01 or the following components

                              Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches

                              THEORY

                              3-State Logic Sometimes it is necessary to isolate one part of circuit from the other part For this purpose some TTL ICs are designed with 3-state logic Such devices have three possible output states high low and high impedance The device can be put into high impedance state by a control signal applied to an appropriate pin When such a device is in high impedance state there is very high impedance at its output effectively isolating the device from whatever circuitry the output normally drives 74245 Octal Bus Transceivers A bus is any conducting path or set of paths having electrical connections to one or more devices 74245 octal bus transceivers are mainly used to control connectivity between two devices or circuits It also provides direction control for signal flow Function of various pin of this IC is given below

                              bull A1 through A8 Bus A bull B1 through B8 Bus B bull G΄ Active low enable input When high sets all the bus pins to high impedance state bull DIR Direction control for signal flow When set to high logic level transfers bus A

                              data to B bus When set to low logic level transfers bus B data to A bus bull VCC and GND Supply connections lines Serial and Parallel Port Connectors A Parallel Port can consist of only 25 pin port adapter called a DB-25 and a serial port can consist of either a 25 pin port adapter called a DB-25 or 9 pin adapter called a DB-9 port adapter Whether the port is a 9 pin or 25 pin it can accomplish all of the same tasks that serial port communications have been designed for

                              59

                              Logic Design amp Switching Theory 1 Lab Session 15 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                              60

                              Each adapter can be a male type connector with pins or a female type adapter with tiny holes Generally a PRINTER port (called LPT1) on the back of a computer is female type adapter and we need to use MALE DB-25 pin cable on it for PRINTER connection or for parallel LAPLINK cable And a COM port on the back of a computer is male for the serial ports but it may not necessarily be Parallel Port Connector ndash DB-25 The DB-25 connector (named for its B-size D-shaped shell and 25 pins) is practically ubiquitous in the electronics industry The DB-25 connector is used for a variety of purposes Two common applications are RS-232EIA-232 (serial) connections and the parallel printer interface on the IBM PC The DB-25 connector is also used for SCSI connections Normally the parallel port is used for output to a printer or other device It sends data 8-bits or one byte at a time in parallel The other lines available on the DB-25 connector are a combination of status lines control lines and ground lines The status and control lines are used for handshaking commands and feedback when we are talking to a printer

                              Figure 152 DB-25 Female Figure 151 DB-25 Male

                              Figure 153 Pin Layout for DB-25 As can be seen form figure 153 there are four types of pins in this connector

                              bull Data pins (8 pins - D0 to D7) Active high bidirectional lines

                              Logic Design amp Switching Theory 1 Lab Session 15 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering bull Control pins (4 pins - C0 to C3) C0 C1 and C3 are active low whereas C2 is active

                              high These lines also are bidirectional bull Status pins (5 pins ndash S3 to S7) Only S7 is active low rest are active high input lines bull Ground pins (8 pins) Used as a reference signal for the low (below 05 volts) charge

                              Parallel Port Addresses A DB-25 connector at a parallel port has three address one for each kind of pins register data status and control The first or base address generally refers to data register Second address is for status register and the third one is for control register In Windows 98 the base address is usually found to be 278H 378H or 3BCH Now if 378H is the base address then it refers to the data register whereas addresses for status and control register are respectively 379H and 37AH For Windows 98 the base address can be found as follows 1 On your Desktop right-click on My Computer and select Properties 2 Click on the Device Manager tab and find LPT1 under Plug and Play BIOS 3 After selecting LPT1 click the Properties button 4 Next select the Resources tab and the address should then appear next to InputOutput

                              Range Accessing parallel port through C Language Programming There are multiple functions in C Language for accessing external ports The most commonly used are listed below

                              bull unsigned char inportb(int portid) inportb reads a byte from a hardware port

                              bull int inport(int portid) reads a word from a hardware port

                              bull void outportb(int portid unsigned char value) outputs a byte to a hardware port

                              bull void outport(int portid int value) outputs a word to a hardware port

                              portid refers to the port address whereas value refers to the data to be sent TESTING 74245 USING PARALLEL PORT PC INTERFACING At one end the parallel port connector will be connected to the PC via parallel port cable and another connector (to be plugged into the PC parallel port slot) At the other end it will be connected to the buffer IC 74245 Data lines of the connector will be used to transfer 8-bit data between the PC and the buffer Out of the 8-bits of 74245 4-bits will be used to enter data which will be displayed at the monitor through a C language

                              61

                              Logic Design amp Switching Theory 1 Lab Session 15 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering program The remaining 4-bits will receive data from PC as entered by the user via keyboard

                              Circuit Diagram

                              Figure 154 Interface of 74245 to PC via Parallel Port

                              Procedure

                              1 Connect the DB-25 connector to the PC at one end and solder it to the circuit board at the other end

                              2 Connect various pins of the connector and 74245 according to the circuit diagram shown in figure 152

                              3 Using the functions listed in the previous section write a program in C language to operate various pins of the buffer The user interface of the program should provide option to the user whether to send or receive data from the port

                              4 Set DIR switch to 1 5 Try sending some data bits to the port The result should be displayed at the LEDs 6 Set DIR switch to 0 7 Set some binary 4-bit value through the switches Try reading it via parallel port

                              C Language Program

                              A program to access parallel port for data transfers

                              use header file include ltstdiohgt main program void main() define variable

                              62

                              Logic Design amp Switching Theory 1 Lab Session 15 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering unsigned int data=0 char choice while(1) printing option menu clrscr() printf(This program will send or receive a BCD digit from the parallel portn) printf(nPress your choice numbern) printf(n1 Send Data) printf(n2 Receive Data) printf(n3 Exitn) choice = getch() sending entered digit to the port if(choice == 1) input BCD digit printf(nEnter BCD digit to be sent to the port) data = getche() masking the first four bits data = data amp 0x0f sending to the port outportb(0x378data) printf(nThe BCD digit c has been sent to the port data) printing on screen the data received from the port else if(choice == 2) receiving data from the port data = inportb(0x378) masking the last four bits data = data amp 0xf0 shifting first four bits to make them the last four bits datagtgt=4 printf(nThe BCD digit set at the port is c data) exit else if(choice == 3) break key pressed is not in the menu else printf(nEnter valid choice number) printf(nnPress any key to continue) getch()

                              63

                              Logic Design amp Switching Theory 1 Lab Session 15 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                              ACTIVITY 1 In the above circuit DIR and G΄ inputs are hardwired Connect them to status or

                              control pins of the parallel port connector and control their function through your software program Circuit Diagram Program Code ______________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________

                              ___________________________________________________________________________________________________________________________________________________

                              64

                              Logic Design amp Switching Theory 1 Lab Session 15 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                              65

                              _____________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ _____________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ _______________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ _________________________________________________ _________________________________________________

                              Logic Design amp Switching Theory 1 Appendix A NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                              Appendix A

                              PIN DIAGRAMS OF THE ICS REQUIRED FOR THE LABORATORY SESSIONS Consult the TTLIC data book for internal diagrams and electrical characteristics of these ICs 7400 Quad 2-Input NAND 7402 Quad 2-Input NOR

                              7404 Hex Inverter 7408 Quad 2-Input AND

                              7410 Triple 3-Input NAND 7411 Triple 3-Input AND

                              7421 Dual 4-Input AND 7432 Quad 2-Input OR

                              66

                              Logic Design amp Switching Theory 1 Appendix A NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                              BCD-to-Seven Segm 7448 BCD-to-Seven Segment 7447 ent

                              Decoder (15V OC) Decoder (2kΩ pull-up output)

                              7473 Dual JK Flip-Flop 7474 Dual D-Type Flip-Flop

                              7476 Dual JK Flop-Flop -Bit Binary Full Adder 7483 4 with Fast Carry

                              86 Quad 2-Inpu 74138 3-to-8 Line 74 t Exclusive OR Decoder Demultiplexer

                              67

                              Logic Design amp Switching Theory 1 Appendix A NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                              68

                              74148 8-to-3 Line 16-to-1 Line Data

                              Priority Encoder 74150 Selector Multiplexer

                              74245 Oct nsceivers Universal Shift Register (PIPO) (3-State)

                              74194 4-Bit Bidirectional al Bus Tra

                              Logic Design amp Switching Theory 1 Appendix B NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                              Appendix B

                              DEBOUNCING CIRCUITRY FOR MECHANICAL SWITCHES Mechanical switches form the interface between human beings and computers or other digital systems For example a keyboard is a matrix of switches used to supply alphanumeric data to a computer Whatever the switch design it is a potential source of problems due to contact bounce The contact bounce creates a sense of narrow pulses when a switch is opened or closed An example of device whose operation would be adversely affected by contact bounce is a digital counter used to count the number of times a switch is depressed Eliminating the effects of contact bounce is called debouncing When data is entered into a computer via a keyboard a software debounce is often used This type of debouncing is a program that causes the computer to sample the switch terminal (ie to input data from it) many times in succession during the interval of time that contact bounce occurs If the data is sensed to be 1s (or 0s) for a specific number of consecutive samples then it is assumed that contact bounce has ended and the last value sensed is valid Hardware debouncing is the use of electronic circuitry to eliminate the effects of contact bounce There are numerous versions of such circuitry including those that use monostable multivibrators (one-shots) but the most straightforward is simply an RS latch Figure B1 shows the circuit When the switch is in position 1 R = 0 and S = 1 so the latch is set and the output (Q) is 1 When the switch is in position 0 R = 1and S = 0 so the latch is reset and the output is 0 When the switch is moved form one position to the other the latch changes state and bouncing occurs at either the R or the S input The bouncing does not affect the latch after it has change state An RS latch will remain set for example when its R input is 0 and its S input is alternately changed form 1 to 0

                              Figure B1 Use of RS latch to debounce a mechanical switch

                              69

                              • 01-ldst-Outer title
                                • Practical Workbook
                                • Logic Design amp Switching Theory I
                                  • Dept of Computer amp Information Systems Engineering
                                    • NED University of Engineering amp Technology
                                    • Karachi ndash 75270 Pakistan
                                      • 02-ldst-inner Title
                                        • Practical Workbook
                                        • Logic Design amp Switching Theory I
                                          • Dept of Computer amp Information Systems Engineering
                                            • NED University of Engineering amp Technology
                                            • Karachi ndash 75270 Pakistan
                                              • 03-ldst-general info
                                              • 04-ldst-introduction
                                              • 05-Table of Contents
                                                • CONTENTS
                                                  • Lab Session No Object Page No
                                                  • 1
                                                  • Also implementing and testing the given circuit on a bread board
                                                    • Working with Electronics Workbench
                                                      • Driving a seven segment display using 7447 7448 driver IC
                                                        • Designing a modulus-5 asynchronous up-counter using JK-FF
                                                          • Experimenting with 74194 4-bit bidirectional universal shift register
                                                              • 13
                                                                  • 06-ldst-Exp01
                                                                    • Lab Session 01
                                                                    • OBJECT
                                                                      • 1 Bread board
                                                                      • 2 5 V - power supply
                                                                      • 3 Multimeter
                                                                      • 4 Logic probe
                                                                      • 5 LEDs with resistors
                                                                      • 6 Connecting wires
                                                                      • 8 Following ICs and their datasheets
                                                                        • THEORY
                                                                          • Logic Gates
                                                                          • 1 The AND Gate ndash An AND gatersquos output is 1 if and only if all its inputs are 1 If A and B are two inputs to an AND gate then output F of the gate is given as F = AB
                                                                          • 2 The OR Gate - An OR gatersquos output is 1 if at least one of its input is 1 If A and B are two inputs to an OR gate then output F of the gate is given as F = A+B
                                                                          • 3 The NOT Gate (Inverter) ndash Its output is 1 when its input is 0 and its output is 0 when the input is 1 ie it complements a digital variable If A is the input to a NOT gate then output F of the gate is given as
                                                                          • 4 The NAND Gate ndash Its output is 1 if at least one of its input is 0 This gate performs the same logic as an AND gate followed by an inverter If A and B are two inputs to a NAND gate then output F of the gate is given as
                                                                            • 5 The NOR Gate - The output of a NOR gate is 1 if and only if all its inputs are 0 This gate performs the same logic function as an OR gate followed by an inverter If A and B are two inputs to a NAND gate then output F of the gate is given as
                                                                                • DATA SHEETS
                                                                                  • Logic expression for the given logic diagram __________________________________
                                                                                      • 07-ldst-exp02
                                                                                        • Working with Electronics Workbench
                                                                                          • 08-ldst-exp03
                                                                                            • Designing Half and Full Adder Circuits
                                                                                              • COMPONENTS AND APPARATUS REQUIRED
                                                                                                • 1 Following ICs and their Datasheets
                                                                                                • 7408 Quad 2-input AND Gate
                                                                                                • 2 Digital Trainer DT-01 or the following components
                                                                                                  • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                  • Connecting wires Switches
                                                                                                    • THEORY
                                                                                                        • IMPLEMENTATION AND OBSERVATIONS
                                                                                                          • 09-ldst-Exp04
                                                                                                            • Lab Session 04
                                                                                                            • 1 Digital ICs and their Datasheets
                                                                                                            • 7408 Quad 2-input AND Gate
                                                                                                            • 2 Digital Trainer DT-01 or the following components
                                                                                                              • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                              • Connecting wires Switches
                                                                                                              • PROCEDURE
                                                                                                              • REDUCTION OF LOGIC EXPRESSION USING KARNAUGH MAP
                                                                                                              • OBSERVATIONS
                                                                                                              • RESULT
                                                                                                                  • 10-ldst-Exp05
                                                                                                                    • Lab Session 05
                                                                                                                    • 1 Following ICs and their Datasheets
                                                                                                                    • 7408 Quad 2-input AND Gate
                                                                                                                    • 2 Digital Trainer DT-01 or the following components
                                                                                                                      • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                      • (100 Ω) Connecting wires Switches
                                                                                                                      • THEORY
                                                                                                                        • IMPLEMENTATION AND OBSERVATIONS
                                                                                                                          • 11-ldst-Exp06
                                                                                                                            • OBJECT
                                                                                                                            • 1 Following ICs and their Datasheets
                                                                                                                            • 7408 Quad 2-input AND Gates or 7411 Triple 3-input AND Gates
                                                                                                                            • 2 Digital Trainer DT-01 or the following components
                                                                                                                              • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                              • Connecting wires Switches
                                                                                                                                • Figure 62 Circuit Diagram for 4 x 1 Multiplexer
                                                                                                                                • Implementation and Observations
                                                                                                                                  • Circuit Diagram
                                                                                                                                    • ACTIVITY
                                                                                                                                      • 12-ldst-exp07
                                                                                                                                        • 1 Following ICs and their Datasheets
                                                                                                                                        • 7408 Quad 2-input or 7411 Triple 3-input AND Gates
                                                                                                                                        • 2 Digital Trainer DT-01 or the following components
                                                                                                                                          • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                          • Connecting wires Switches
                                                                                                                                            • THEORY
                                                                                                                                                • Figure 72 Circuit Diagram for 2 x 4 Decoder 1 x 4 Demultiplexer
                                                                                                                                                • Implementation and Observations
                                                                                                                                                  • Circuit Diagram
                                                                                                                                                    • ACTIVITY
                                                                                                                                                      • 13-ldst-Exp08
                                                                                                                                                        • OBJECT
                                                                                                                                                        • 1 Following ICs and their Datasheets
                                                                                                                                                        • 7408 Quad 2-input or 7421 Dual 4-input AND Gates
                                                                                                                                                        • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                          • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                          • Connecting wires Switches
                                                                                                                                                            • THEORY
                                                                                                                                                                • Figure 81 Circuit Diagram for 4 x 2 Priority Encoder
                                                                                                                                                                • Implementation and Observations
                                                                                                                                                                  • Therefore if GS A2 A1 and A0 are all low then it shows that line 0 is selected and if E0 A2 A1 and A0 are all low then it shows that none of the inputs selected E0 and GS cannot be in the same state provided that E1 is enabled
                                                                                                                                                                  • Circuit Diagram
                                                                                                                                                                    • ACTIVITY
                                                                                                                                                                      • 14-ldst-exp09
                                                                                                                                                                        • OBJECT
                                                                                                                                                                        • 1 Following ICs and their Datasheets
                                                                                                                                                                        • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                          • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                          • Connecting wires Switches
                                                                                                                                                                            • THEORY
                                                                                                                                                                              • Parity Generator
                                                                                                                                                                                • Let x y and z be the three bits that constitute the message and are the input to the Odd Parity Generator Circuit Since it is an odd parity system the bit P is generated so as to make the total number of 1s odd (including P) The function P can be expressed as follows
                                                                                                                                                                                • Figure 91 Circuit Diagram for a 3-bit Parity Generator
                                                                                                                                                                                  • C = x Ο y Ο z Ο P
                                                                                                                                                                                    • Implementation and Observations
                                                                                                                                                                                      • ACTIVITY
                                                                                                                                                                                          • 15-ldst-exp10
                                                                                                                                                                                            • Driving a seven segment display using 7447 7448 driver IC
                                                                                                                                                                                            • COMPONENTS AND APPARATUS REQUIRED
                                                                                                                                                                                            • 1 Following ICs and their Datasheets
                                                                                                                                                                                            • 7447 7448 BCD to Seven Segment Driver
                                                                                                                                                                                            • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                              • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches
                                                                                                                                                                                                • THEORY
                                                                                                                                                                                                • Seven Segment Displays
                                                                                                                                                                                                • CIRCUIT DIAGRAM
                                                                                                                                                                                                • Figure 102 Circuit diagram for 7447driving a common-anode display
                                                                                                                                                                                                    • IMPLEMENTATION AND OBSERVATIONS
                                                                                                                                                                                                      • Decimal Digit
                                                                                                                                                                                                      • BCD Inputs
                                                                                                                                                                                                      • Seven Segment Outputs
                                                                                                                                                                                                      • D
                                                                                                                                                                                                      • C
                                                                                                                                                                                                      • B
                                                                                                                                                                                                      • A
                                                                                                                                                                                                      • a
                                                                                                                                                                                                      • b
                                                                                                                                                                                                      • c
                                                                                                                                                                                                      • d
                                                                                                                                                                                                      • e
                                                                                                                                                                                                      • f
                                                                                                                                                                                                      • g
                                                                                                                                                                                                      • 0
                                                                                                                                                                                                      • 0
                                                                                                                                                                                                      • 0
                                                                                                                                                                                                      • 0
                                                                                                                                                                                                      • 0
                                                                                                                                                                                                      • 1
                                                                                                                                                                                                      • 0
                                                                                                                                                                                                      • 0
                                                                                                                                                                                                      • 0
                                                                                                                                                                                                      • 1
                                                                                                                                                                                                      • 2
                                                                                                                                                                                                      • 0
                                                                                                                                                                                                      • 0
                                                                                                                                                                                                      • 1
                                                                                                                                                                                                      • 0
                                                                                                                                                                                                      • 3
                                                                                                                                                                                                      • 0
                                                                                                                                                                                                      • 0
                                                                                                                                                                                                      • 1
                                                                                                                                                                                                      • 1
                                                                                                                                                                                                      • 4
                                                                                                                                                                                                      • 0
                                                                                                                                                                                                      • 1
                                                                                                                                                                                                      • 0
                                                                                                                                                                                                      • 0
                                                                                                                                                                                                      • 5
                                                                                                                                                                                                      • 0
                                                                                                                                                                                                      • 1
                                                                                                                                                                                                      • 0
                                                                                                                                                                                                      • 1
                                                                                                                                                                                                      • 6
                                                                                                                                                                                                      • 0
                                                                                                                                                                                                      • 1
                                                                                                                                                                                                      • 1
                                                                                                                                                                                                      • 0
                                                                                                                                                                                                      • 7
                                                                                                                                                                                                      • 0
                                                                                                                                                                                                      • 1
                                                                                                                                                                                                      • 1
                                                                                                                                                                                                      • 1
                                                                                                                                                                                                      • 8
                                                                                                                                                                                                      • 1
                                                                                                                                                                                                      • 0
                                                                                                                                                                                                      • 0
                                                                                                                                                                                                      • 0
                                                                                                                                                                                                      • 9
                                                                                                                                                                                                      • 1
                                                                                                                                                                                                      • 0
                                                                                                                                                                                                      • 0
                                                                                                                                                                                                      • 1
                                                                                                                                                                                                        • ACTIVITY
                                                                                                                                                                                                          • 16-ldst-exp11
                                                                                                                                                                                                            • Lab Session 11
                                                                                                                                                                                                              • OBJECT
                                                                                                                                                                                                              • COMPONENTS AND APPARATUS REQUIRED
                                                                                                                                                                                                                • 1 Following ICs and their Datasheets
                                                                                                                                                                                                                • 7473 7476 JK Flip-Flop
                                                                                                                                                                                                                • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                  • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                                  • Connecting wires Switches
                                                                                                                                                                                                                    • THEORY
                                                                                                                                                                                                                        • Flip-Flop
                                                                                                                                                                                                                        • JK Flip-Flop
                                                                                                                                                                                                                          • Circuit Diagram
                                                                                                                                                                                                                            • Observations
                                                                                                                                                                                                                              • ACTIVITY
                                                                                                                                                                                                                                  • 17-ldst-exp12
                                                                                                                                                                                                                                    • Lab Session 12
                                                                                                                                                                                                                                      • OBJECT
                                                                                                                                                                                                                                      • GIVEN STATE DIAGRAM
                                                                                                                                                                                                                                      • Figure 121 State Diagram
                                                                                                                                                                                                                                      • COMPONENTS AND APPARATUS REQUIRED
                                                                                                                                                                                                                                        • 1 Following ICs and their Datasheets
                                                                                                                                                                                                                                        • 7474 D Flip-Flop
                                                                                                                                                                                                                                        • ICs of basic gates (AND OR NOT XOR etc) as required
                                                                                                                                                                                                                                        • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                                          • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                                                          • Connecting wires Switches
                                                                                                                                                                                                                                            • THEORY
                                                                                                                                                                                                                                                • Sequential Circuits
                                                                                                                                                                                                                                                  • 18-ldst-exp13
                                                                                                                                                                                                                                                    • Lab Session 13
                                                                                                                                                                                                                                                      • Designing a modulo-5 asynchronous up-counter using JK-FF
                                                                                                                                                                                                                                                        • 1 Following ICs and their Datasheets
                                                                                                                                                                                                                                                        • 7400 Quad 2-input or 7410 Triple 3-input NAND Gates
                                                                                                                                                                                                                                                        • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                                                          • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                                                                          • Connecting wires Switches
                                                                                                                                                                                                                                                            • THEORY
                                                                                                                                                                                                                                                                • Figure 131 A Mod-5 Asynchronous Up Counter
                                                                                                                                                                                                                                                                • Implementation and Observations
                                                                                                                                                                                                                                                                  • ACTIVITY
                                                                                                                                                                                                                                                                      • 19-ldst-exp14
                                                                                                                                                                                                                                                                        • Experimenting with 74194 4-bit bidirectional universal shift register
                                                                                                                                                                                                                                                                        • 1 Following ICs and their Datasheets
                                                                                                                                                                                                                                                                        • 74194 4-bit bidirectional universal shift register
                                                                                                                                                                                                                                                                        • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                                                                          • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                                                                                          • Connecting wires Switches
                                                                                                                                                                                                                                                                            • THEORY
                                                                                                                                                                                                                                                                              • Shift Registers
                                                                                                                                                                                                                                                                              • Bidirectional Shift Registers
                                                                                                                                                                                                                                                                              • Universal Shift Registers
                                                                                                                                                                                                                                                                                • S1
                                                                                                                                                                                                                                                                                  • Circuit Diagram
                                                                                                                                                                                                                                                                                  • ACTIVITY
                                                                                                                                                                                                                                                                                      • 20-ldst-exp15
                                                                                                                                                                                                                                                                                        • COMPONENTS AND APPARATUS REQUIRED
                                                                                                                                                                                                                                                                                        • 1 Parallel Port Connectors (DB-25) with Cable
                                                                                                                                                                                                                                                                                        • 2 Personal Computer with Windows 98 and TurboC Compiler Installed
                                                                                                                                                                                                                                                                                        • 3 Following ICs and their Datasheets
                                                                                                                                                                                                                                                                                        • 74245 Octal Bus Transceivers with 3-State Outputs
                                                                                                                                                                                                                                                                                        • 4 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                                                                                          • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                                                                                                            • Connecting wires Switches
                                                                                                                                                                                                                                                                                              • THEORY
                                                                                                                                                                                                                                                                                              • 3-State Logic
                                                                                                                                                                                                                                                                                                • Serial and Parallel Port Connectors
                                                                                                                                                                                                                                                                                                • Parallel Port Connector ndash DB-25
                                                                                                                                                                                                                                                                                                  • Accessing parallel port through C Language Programming
                                                                                                                                                                                                                                                                                                      • 21-ldst-appendixA
                                                                                                                                                                                                                                                                                                      • 22-ldst-appendixB
                                                                                                                                                                                                                                                                                                        • DEBOUNCING CIRCUITRY FOR MECHANICAL SWITCHES

                                Logic Design amp Switching Theory 1 Lab Session 02 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                18

                                example if you want the switch to close or open when digit lsquo1rsquo is pressed type 1 in the Value tab then click OK Assign different keys to all the switches

                                5 Connect the output terminals of these switches to each of the four inputs A B C and D of the circuit

                                6 Drag and drop Vcc and Ground form the Sources Parts Bin 7 Connect Vcc terminal to one end and Ground terminal to the other end of all the

                                switches 8 Label the circuit properly using text boxes found in the miscellaneous parts bin 9 Run the circuit using the Activate Simulation switch Use the keys you have assigned

                                to the switches to toggle them between Vcc and Ground connections thus providing 1 or 0 respectively to the inputs Record the results as indicated by the probe for all possible combinations of 1s and 0s at the inputs

                                EWB Circuit

                                Figure 21

                                Observations

                                A B C D Expected Output Observed Output 0 0 0 0 0 0 0 1 0 0 1 0 0 0 1 1 0 1 0 0 0 1 0 1 0 1 1 0 0 1 1 1 1 0 0 0 1 0 0 1 1 0 1 0 1 0 1 1 1 1 0 0 1 1 0 1 1 1 1 0 1 1 1 1

                                Logic Design amp Switching Theory 1 Lab Session 03 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                Lab Session 03

                                OBJECT

                                Designing Half and Full Adder Circuits COMPONENTS AND APPARATUS REQUIRED 1 Following ICs and their Datasheets

                                bull 7408 Quad 2-input AND Gate bull 7432 Quad 2-input OR Gate bull 7486 Quad 2-input XOR Gate

                                2 Digital Trainer DT-01 or the following components Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches

                                THEORY Half Adder A combination circuit that performs the addition of two bits without accounting for the previous carry is called half adder It needs two binary inputs and two binary outputs The input variables designate the augend and addend bits The output variables produce the sum and carry The simplified sum of product expressions for a half adder are

                                yxyxyxS oplus=+= yxC =

                                Figure 31 Circuit diagram for Half Adder

                                19

                                Logic Design amp Switching Theory 1 Lab Session 03 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                bles produce the sum and carry The simplified sum of product expressions for a half adder are

                                Full Adder

                                A combinational circuit that performs the addition of three input bits It consist of three inputs and two outputs Two of the input variables represent the two significant bits to be added The third input represents the carry from the previous lower significant position The output varia

                                zyxzyxzyxzyxzyxS oplusoplus=+++= yxzyxzyzxxyC )( +oplus=++=

                                Figure 32 Circuit diagram for Full Adder

                                efer to laboratory session 01 for procedure) and record the observations in the following ta

                                alf Adde ull Adder Inputs u

                                IMPLEMENTATION AND OBSERVATIONS

                                Implement the half adder and full adder circuits on a bread board (prepare the pin diagram (use appendix A) and r

                                bles H r F

                                Inputs Outputs Outp ts x y Carry Su Carry Sum m x y z 0 0 0 0 0 0 1 0 0 1 1 0 0 1 0 1 1 0 1 1 1 0 0 1 0 1 1 1 0 1 1 1

                                20

                                Logic Design amp Switching Theory 1 Lab Session 03 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                at of your designed circuit Attach hardcopy of the output form electronic workbench

                                at of your designed circuit Attach hardcopy of the output form lectronic workbench here

                                ACTIVITY

                                1 Simulate half adder circuit using Electronics Workbench Compare the results of simulation with thhere

                                2 Design a full subtractor circuit and simulate it using Electronics Workbench Compare the results of simulation with the

                                21

                                Logic Design amp Switching Theory 1 Lab Session 04 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                Lab Session 04 OBJECT

                                Use of Karnaugh Map (SOP-Expression) method GIVEN LOGIC EXPRESSION

                                F (A B C D) = sum ( 0 1 2 4 5 6 8 9 12 13 14 ) COMPONENTS AND APPARATUS REQUIRED 1 Digital ICs and their Datasheets

                                bull 7408 Quad 2-input AND Gate bull 7432 Quad 2-input OR Gate bull 7404 Hex Inverter

                                2 Digital Trainer DT-01 or the following components Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches PROCEDURE 1 Use Karnaugh map to reduce the given function 2 Draw the circuit diagram for the obtained reduced function 3 Implement the reduced circuit using digital ICs on a bread board (prepare the pin

                                diagram (use appendix A) and refer to laboratory session 01 for procedure) and record the observations

                                REDUCTION OF LOGIC EXPRESSION USING KARNAUGH MAP F

                                CD

                                AB DC

                                DC DC

                                DC

                                BA0 1 3 2

                                BA4 5 7 6

                                BA12 13 15 14

                                BA8 9 11 10

                                Reduced form of the given logic expression is __________________________________

                                22

                                Logic Design amp Switching Theory 1 Lab Session 04 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                LOGIC DIAGRAM (REDUCED FORM) OBSERVATIONS

                                A B C D Output 0 0 0 0 0 0 0 1 0 0 1 0 0 0 1 1 0 1 0 0 0 1 0 1 0 1 1 0 0 1 1 1 1 0 0 0 1 0 0 1 1 0 1 0 1 0 1 1 1 1 0 0 1 1 0 1 1 1 1 0 1 1 1 1

                                RESULT The reduced form (SOP Expression) of the given logic function is

                                ____________________________________________________________

                                The observation table reflects the given logic function

                                23

                                Logic Design amp Switching Theory 1 Lab Session 04 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                ACTIVITY 1 Using Electronics Workbench derive a truth table and logic circuit for the following logic expression

                                BAAF +=

                                Procedure 1 From the Instruments Parts Bin drag and drop Logic Converter on the design area 2 Double click the Logic Converter to reveal Logic Converter dialog box This dialog

                                box shows various conversion options between truth table logic expression and logic circuit

                                3 Enter the given logic expression in the edit box found at the end of the dialog box Use lsquo to represent invert of a variable For example A is written as Arsquo

                                4 Click the Boolean Expression to Truth Table button The truth table appears in the logic converters display

                                5 Now click the Boolean Expression to Circuit button This creates the logic circuit for the given expression in the design area Label the diagram if needed

                                Resulting Logic Circuit For the given expression the final circuit will look like

                                Figure 41

                                24

                                Logic Design amp Switching Theory 1 Lab Session 04 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                ACTIVITY 2

                                Using Electronics Workbench find a simplified logic expression and circuit for the following truth table

                                A B C Output 0 0 0 1 0 0 1 1 0 1 0 0 0 1 1 1 1 0 0 0 1 0 1 0 1 1 0 0 1 1 1 1

                                Procedure 1 Click three input channels from A to H across the top of the logic converter The

                                display area below the terminals fills up with the necessary combinations of ones and zeros to fulfill the input conditions The values in the output column on the right are initially set to 0

                                2 Edit the output column to specify the desired output for each input condition To change an output value select it and type a new value 1 0 or x An x indicates a donrsquot care condition

                                3 To convert this truth table to a Boolean expression click the Truth Table to Boolean Expression button The Boolean expression will be displayed at the bottom of the logic converter

                                4 Simplify the expression by clicking the Simplify button 5 Now click the Boolean Expression to Circuit button This creates the logic circuit for

                                the given expression in the design area Resulting Logic Circuit For the given truth table the final simplified circuit will look like

                                Figure 42

                                25

                                Logic Design amp Switching Theory 1 Lab Session 04 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                ACTIVITY 3

                                Using Electronics Workbench find the logic expression and truth table for the following logic circuit

                                Figure 43

                                Procedure 1 Attach the input terminals of the logic converter to up to four input points in the

                                circuit 2 Connect the single output of the circuit to the output terminal on the logic converter

                                icon 3 Click the Circuit to Truth Table button The truth table appears in the logic

                                converters display 4 To convert this truth table to a Boolean expression click the Truth Table to Boolean

                                Expression button The Boolean expression will be displayed at the bottom of the logic converter

                                Resulting Logic Expression Logic Expression for the given circuit is found to be _____________________________

                                26

                                Logic Design amp Switching Theory 1 Lab Session 04 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                27

                                For activities 1 2 and 3 attach hardcopy of the output (truth table logic expression and logic circuit) form electronic workbench here

                                Logic Design amp Switching Theory 1 Lab Session 05 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                Lab Session 05 Lab Session 05 OBJECT OBJECT

                                Designing a BCD Adder Designing a BCD Adder COMPONENTS AND APPARATUS REQUIRED COMPONENTS AND APPARATUS REQUIRED

                                1 Following ICs and their Datasheets 1 Following ICs and their Datasheets bull 7408 Quad 2-input AND Gate bull 7408 Quad 2-input AND Gate bull 7432 Quad 2-input OR Gate bull 7432 Quad 2-input OR Gate bull 7483 4-bit Binary Adder bull 7483 4-bit Binary Adder

                                2 Digital Trainer DT-01 or the following components 2 Digital Trainer DT-01 or the following components Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors (100 Ω) Connecting wires Switches (100 Ω) Connecting wires Switches

                                THEORY THEORY

                                A BCD Adder is a combinational circuit that adds two BCD digits in parallel and produces a sum digit also in BCD A BCD Adder is a combinational circuit that adds two BCD digits in parallel and produces a sum digit also in BCD

                                A4 A3 A2 A1 B4 B3 B2 B1

                                7483-BCD ADDER

                                Cout (C4 ) Z4 Z3 Z2 Z1 Cin(C0)

                                A4 A3 A2 A1 B4 B3 B2 B1

                                7483-BCD ADDER

                                Cout

                                (C4 ) Z4 Z3 Z2 Z1 Cin(C0)

                                Figure 51 BCD Adder Circuit

                                28

                                Logic Design amp Switching Theory 1 Lab Session 05 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                29

                                A BCD adder must include the correction logic in its internal construction The two BCD digits together with the input carry are first added using a 4-bit binary adder to produce the binary sum If no output carry is generated and the binary sum is less than or equal to 9 then the corresponding BCD sum is identical and therefore no conversion is needed When the output carry is equal to 1 or the binary sum is greater than 9 then a binary 0110 is added to the binary sum through another 4-bit binary adder If Cout is the carry output and Z4Z3Z2Z1 is the binary sum form the first 4-bit binary adder then the following equation indicates the condition when a binary 0110 is to be added

                                C = COUT + Z4Z2 + Z4Z3 IMPLEMENTATION AND OBSERVATIONS Implement the BCD adder circuit according to figure 51 on a bread board (prepare the pin diagram (use appendix A) and refer to laboratory session 01 for procedure) A BCD adder has nine input bits (two BCD digits and a carry bit) which can result in a total of 512 combinations of which 312 inputs are donrsquot care Since it is a very lengthy procedure to record results for 200 valid input combinations therefore for simplicity just record results for any eight combinations in the following table

                                Input Carry

                                BCD Digit 1 BCD Digit 2 Carry Output

                                BCD Sum A4 A3 A2 A1 B4 B3 B2 B1 Z4 Z3 Z2 Z1

                                Logic Design amp Switching Theory 1 lab Session 06 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                Lab Session 06

                                OBJECT

                                bull Designing of a 4 x 1 Multiplexer bull Experimenting with 74150 IC

                                COMPONENTS AND APPARATUS REQUIRED 1 Following ICs and their Datasheets

                                bull 7408 Quad 2-input AND Gates or 7411 Triple 3-input AND Gates bull 7432 Quad 2-input OR Gates bull 7404 Hex Inverter bull 74150 16 x 1 MUX

                                2 Digital Trainer DT-01 or the following components Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches THEORY

                                Multiplexers A digital data Multiplexer (MUX) is a combinational circuit having several data inputs and a single output A set of data-select inputs is used to control which of the data inputs is routed to the single output A multiplexer is also called a data selector because of this ability to select which data input is connected o the output Normally there are 2n input lines and n selection lines whose bit combination determine which input is selected DESIGN OF A 4 x 1 MULTIPLEXER A 4 x 1 multiplexer is capable of selecting one of four data inputs (see figure 61) The 2-bit binary number at the data select inputs S1 and S0 specifies which of the four data inputs is to be routed to the output Since there are two data select inputs therefore they can select 22 = 4 different data inputs lines

                                S0 S1 D0 D1

                                D2 D3

                                Data-select Inputs Output

                                Data Inputs

                                Figure 61 Block Diagram of a 4 x1 Multiplexer

                                30

                                Logic Design amp Switching Theory 1 lab Session 06 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                Figure 62 Circuit Diagram for 4 x 1 Multiplexer

                                Implementation and Observations

                                Implement the 4 x 1 Multiplexer circuit (figure 62) on a bread board (prepare the pin diagram (use appendix A) and refer to laboratory session 01 for implementation procedure) and record the observations in the following table For each data select combination specify the switch number as well as the binary value present on that selected switch

                                S1 S0 Output 0 0 0 1 1 0 1 1

                                TESTING OF 74150 - 16 x 1 MUX

                                The 74150 IC has sixteen data inputs and four data-selection lines Function of various pins of this IC is described below

                                bull E0 through E15 Data input lines

                                31

                                Logic Design amp Switching Theory 1 lab Session 06 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering bull A B C D Data select lines with D being the MSB bull W Active low output line bull Grsquo Active low enable line bull VCC and GND Supply connections lines

                                Circuit Diagram

                                Figure 63 Pin connections of 74150 for selecting E0

                                Testing Procedure

                                bull Make connections as shown in the circuit diagram bull Apply different data (1 or 0) at data inputs that are labeled as E0 to E15 Only

                                connection for E0 is shown is the figure for simplicity bull Select the data input E0 with the help of data selectors A B C and D bull Observe the output which shows the complement of the data from E0 bull Select all the sixteen data inputs one by one and record your observations in the

                                following table

                                32

                                Logic Design amp Switching Theory 1 lab Session 06 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                33

                                Observations

                                Grsquo D C B A W Grsquo D C B A W 0 0 0 0 0 0 1 0 0 0 0 0 0 0 1 0 1 0 0 1 0 0 0 1 0 0 1 0 1 0 0 0 0 1 1 0 1 0 1 1 0 0 1 0 0 0 1 1 0 0 0 0 1 0 1 0 1 1 0 1 0 0 1 1 0 0 1 1 1 0 0 0 1 1 1 0 1 1 1 1

                                ACTIVITY 1 Consider 4x1 Multiplexer Draw the output wave-form for the following data inputs

                                (E0 E1 E2 E3) and select lines A B (B being the MSB) Output is W

                                E3 E2 E1 E0 A B

                                W

                                2 Using the 4 x 1 MUX designed in this laboratory session implement the following logical function F (A B C) = Σ (0147)

                                Show your working and input connections in the following block diagram according to the circuit you have implemented

                                4 x 1 MUX

                                S0 S1

                                Output D0

                                D1

                                D2

                                D3

                                Logic Design amp Switching Theory 1 Lab Session 07 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                Lab Session 07

                                OBJECT

                                bull Designing of a 2 x 4 Decoder 1 x 4 Demultiplexer bull Experimenting with 74138 IC

                                COMPONENTS AND APPARATUS REQUIRED 1 Following ICs and their Datasheets

                                bull 7408 Quad 2-input or 7411 Triple 3-input AND Gates bull 7404 Hex Inverter bull 74138 3 x 8 Decoder

                                2 Digital Trainer DT-01 or the following components Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches THEORY

                                Decoder A Decoder is a combinational circuit that converts binary information form n input lines to a maximum of 2n unique output lines In practical applications decoders are often used for selecting one of several devices

                                Demultiplexer A decoder with an enable input can function as a Demultiplexer A Demultiplexer (DMUX) id a circuit that receives information on a single line and transmits this information on one of 2n possible output lines The selection of a specific output line is controlled by the bit values of n selection lines DESIGN OF A 2 x 4 DECODER 1 x 4 DEMULTIPLEXER A 2 x 4 decoder is capable of selecting one of four output lines (see figure 71 (a)) The 2-bit binary number at the data inputs S1 and S0 specifies which of the four data inputs is to be selected If we add an enable pin and use it as an input line then this decoder can be converted to a 1 x 4 Demultiplexer where S1 and S0 will select a line to which data input is to be routed (see figure 71 (b))

                                Select S0 S0 Inputs

                                S1 D0 D1

                                D2

                                D3

                                Enable (a) Block Diagram of a 2 x 4 Decoder

                                Figure 71

                                S1 D0 D1

                                D2

                                D3

                                Inputs

                                Data Input (b) Block Diagram of a 1 x 4 Demulptiplexer

                                34

                                Logic Design amp Switching Theory 1 Lab Session 07 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                Figure 72 Circuit Diagram for 2 x 4 Decoder 1 x 4 Demultiplexer

                                Implementation and Observations Implement the 2 x 4 Decoder 1 x 4 Demultiplexer circuit (figure 72) on a bread board (prepare the pin diagram (use appendix A) and refer to laboratory session 01 for implementation procedure) and record the observations in the following table

                                Enable Data Input S1 S0 D0 D1 D2 D3

                                0 0 0 0 0 1 0 1 0 0 1 1 1 0 0 1 0 1 1 1 0 1 1 1

                                TESTING OF 74138 3 x 8 Decoder The 74138 IC has three inputs and eight output lines It has three enable inputs and for the IC to function all three inputs need to be enabled Function of various pins of this IC is described below

                                35

                                Logic Design amp Switching Theory 1 Lab Session 07 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                bull Y0 through Y7 Active low data outputs bull A B C Input select lines with C being the MSB bull G1 Active high enable Input bull G2Arsquo and G2Brsquo Active low enable Inputs bull VCC and GND Supply connections lines Circuit Diagram

                                Figure 73 Pin connections of 74138

                                Testing Procedure

                                bull Make connections as shown in the circuit diagram bull Apply different combinations of 1s and 0s at data inputs bull Observe the output and record your observations in the following table

                                Observations

                                C B A Y0 Y1 Y2 Y3 Y4 Y5 Y6 Y7 0 0 0 0 0 1 0 1 0 0 1 1 1 0 0 1 0 1 1 1 0 1 1 1

                                36

                                Logic Design amp Switching Theory 1 Lab Session 07 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                37

                                ACTIVITY ACTIVITY 1 What will be the binary values at the outputs Y0 through Y7 of 74138 if 1 What will be the binary values at the outputs Y0 through Y7 of 74138 if

                                bull All three enable pins are connected to ground bull All three enable pins are connected to ground __________________________________________________________________________________________________________________________________________ __________________________________________________________________________________________________________________________________________ _____________________________________________________________________ _____________________________________________________________________

                                bull All three enable pins are connected to VCC bull All three enable pins are connected to VCC _______________________________________________________________________________________________________________________________________________________________________________________________________________

                                _______________________________________________________________________________________________________________________________________________________________________________________________________________

                                2 Show connections for 74138 in order to use it as a 1 x 8 Demultiplexer 2 Show connections for 74138 in order to use it as a 1 x 8 Demultiplexer

                                3 Consider a 2 x 4 Decoder with two enable inputs (one active high - G and one active low ndash Grsquo) Draw the output wave-forms for D0 D1 D2 and D3 if the two select inputs are A and B (B being the MSB) All outputs are active low

                                Grsquo

                                G

                                A B

                                D0 D1 D2

                                D3

                                Logic Design amp Switching Theory 1 Lab Session 08 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                Lab Session 08 OBJECT

                                bull Designing of a 4 x 2 Priority Encoder bull Experimenting with 74148 IC

                                COMPONENTS AND APPARATUS REQUIRED

                                1 Following ICs and their Datasheets

                                bull 7408 Quad 2-input or 7421 Dual 4-input AND Gates bull 7432 Quad 2-input OR Gates bull 7404 Hex Inverter bull 74148 Encoder

                                2 Digital Trainer DT-01 or the following components Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches

                                THEORY

                                Encoder An Encoder is a digital function that produces a reverse operation from that of a decoder An Encoder has 2n (or less) input lines and n output lines The output lines generate the binary code for the 2n input variables Priority Encoder

                                A simple encoder may produce an erroneous output if more than one of its inputs is high A Priority Encoder is one that responds to just one input among those that may be simultaneously high in accordance with some priority system The most common priority system is based on the relative magnitudes of the inputs whichever decimal input is largest is the one that is encoded

                                DESIGN OF A 4 x 2 Priority Encoder

                                The following equations represent the outputs of a 4 x 2 priority encoder 32 DDA +=

                                321 DDDB += As can be seen from the equations that input D0 which has a binary code 00 is not used in any equation A binary code 00 at the output indicates two conditions Either D0 is selected or no input is selected In order to differentiate these two conditions we will provide an additional output Z to indicate if at least one of the inputs is a 1 The equation for Z will be

                                4321 DDDDZ = If Z is 0 then the binary code 00 at the output indicates that D0 is selected and if Z is 1 then it indicates that no input line is selected

                                38

                                Logic Design amp Switching Theory 1 Lab Session 08 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                Figure 81 Circuit Diagram for 4 x 2 Priority Encoder

                                it (figure 81) on a bread board (prepare the to laboratory session 01 for implementation

                                Implementation a Implement the 4 x 2 Priority Encoder circu

                                ram (use appendix A) and refer

                                nd Observations

                                pin diagprocedure) and record the observations in the following table

                                D3 D2 D1 D0 A B 0 0 0 1 0 0 1 x 0 1 x x 1 x x x

                                TESTING OF 74148 8 x 3 Octal Priority Encoder

                                imal digits There are nine of which three represents

                                ing any of the inputs is high

                                then it shows that line 0 is selected and if e inputs selected E0 and GS

                                cannot be in the same state provided that E1 is enabled

                                The 74148 is a priority encoder with active-Low input for dec

                                input) and five output linesinputs lines (including an enablethe binary code for the octal digit Function of various pins of this IC is described below

                                bull 0 through 7 Active low data inputs representing the octal digits A2 A1 A0 Active low output lines representing the binary code bullbull E1 Active low enable Input bull E0 Active low output indicating none of the inputs is high bull GS Active low output indicatbull VCC and GND Supply connections lines Therefore if GS A2 A1 and A0 are all low

                                then it shows that none of thE0 A2 A1 and A0 are all low

                                39

                                Logic Design amp Switching Theory 1 Lab Session 08 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                Circuit Diagram

                                Figure 82 Pin connections of 74148

                                Testing Procedure bull Make connections as sho

                                binations of 1s and 0s at data inputs d record your observations in the following table

                                GS E0

                                wn in the circuit diagram bull Apply different combull Observe the output an Observations

                                0 1 2 3 4 5 6 7 A2 A1 A0 1 1 1 1 1 1 1 1 x x x x x x x 0 x x x x x x 0 1 x x x x x 0 1 1 x x x x 0 1 1 1 x x x 0 1 1 1 1 x x 0 1 1 1 1 1 x 0 1 1 1 1 1 1 0 1 1 1 1 1 1 1

                                40

                                Logic Design amp Switching Theory 1 Lab Session 08 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                41

                                CTIVITY

                                Cascade the following two 74148 8 x 3 Priority Encoders to form 16 x 4 Priority

                                A 1

                                Encoder

                                Logic Design amp Switching Theory 1 Lab Session 09 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering `

                                Lab Session 09 OBJECT

                                Designing an Odd Parity Generator and Checker for a 3-bit Data COMPONENTS AND APPARATUS REQUIRED

                                1 Following ICs and their Datasheets

                                bull 7486 Quad 2-input Exclusive-OR Gates bull 7404 Hex Inverter

                                2 Digital Trainer DT-01 or the following components Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches

                                THEORY

                                Parity Generator When binary data is transmitted and processed it is ndash as are all electrical signals ndash susceptible to noise that can either alter or distort its contents 1s may be effectively changed to 0s and 0s to 1s To overcome this problem one or more bits are often added to the data as an aid in detecting errors caused by noise The most common of these is a Parity bit that signifies whether the total number of 1s in a code group is odd or even In an Odd Parity system the parity bit is made 0 or 1 as necessary to make the total number 1s odd (counting the parity bit itself) In an Even Parity system the parity bit is chosen to make the total number of 1s even Table 91 shows how parity bits would be added to BCD code group in both systems

                                Decimal BCD Value Parity Bit ABCD Odd Parity Even Parity

                                0 0000 1 0 1 0001 0 1 2 0010 0 1 3 0011 1 0 4 0100 0 1 5 0101 1 0 6 0110 1 0 7 0111 0 1 8 1000 0 1 9 1001 1 0

                                Table 91 Odd and Even Parity in BCD

                                When digital data is received a parity checking circuit generates an error signal if the total number of 1s is odd in an even parity system or if it is even in an odd parity system Parity check always detects a single error (one bit change from 0 to 1 or 1 to 0) but may not detect

                                42

                                Logic Design amp Switching Theory 1 Lab Session 09 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering ` two or more errors Odd parity is used more often than even parity because even parity does not detect a situation where all 0s are created due to short circuit or other fault condition DESIGN OF A 3-BIT ODD PARITY GENERATOR AND CHECKER Let x y and z be the three bits that constitute the message and are the input to the Odd Parity Generator Circuit Since it is an odd parity system the bit P is generated so as to make the total number of 1s odd (including P) The function P can be expressed as follows P = x oplus y Ο z or P = x Ο y oplus z Since the IC available is 7486 which is quad 2input XOR IC therefore we will convert XNOR also to XOR

                                P = x oplus y Ο z

                                P = ( x oplus y ) Ο z Since for even number of variables ______

                                XOR = XNOR Therefore ___________ _________

                                P = ( x oplus y ) oplus z = x oplus y oplus z This logical expression can be implemented with two XOR gates and an inverter (see figure 91)

                                Figure 91 Circuit Diagram for a 3-bit Parity Generator

                                The 3-bit message and the parity bit are transmitted to their destination where they are applied to a Parity Checker Circuit An error occurs during transmission if the parity of the four bits received is even since the binary information transmitted was originally odd The output C of the parity checker should be a 1 when an error occurs ie when the number of 1s in the four inputs is even Therefore the function C can be expressed as

                                C = x Ο y Ο z Ο P

                                Using the same logic applied for the conversion of the equation of P

                                PzyxC oplusoplusoplus= This logical expression can be implemented with three XOR gates and an inverter (see figure 92)

                                43

                                Logic Design amp Switching Theory 1 Lab Session 09 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering `

                                44

                                Figure 92 Circuit Diagram for a 3-bit Parity Checker Implementation and Observations Implement the 3-bit Parity Generator and Checker circuits (figure 91 and 92) on a bread board (prepare the pin diagram (use appendix A) and refer to laboratory session 01 for implementation procedure) and record the observations in the following table

                                x y z P x y z P C x y z P C 0 0 0 0 0 0 0 1 0 0 0 0 0 1 0 0 0 1 1 0 0 1 0 1 0 0 0 1 0 1 0 1 0 0 1 1 0 0 1 1 1 0 1 1 1 0 0 0 1 0 0 1 1 0 0 1 0 1 0 1 0 1 1 1 0 1 1 1 0 0 1 1 0 1 1 1 0 1 1 1 0 1 1 1 1 1 1 1

                                Odd Parity Generation Odd Parity Check ACTIVITY 1 Try using the parity checker of figure 92 as 3-bit parity generator Write the details here

                                _____________________________________________________________________________________________________________________________________________________________________________________________________________________ ______________________________________________________________________________________________________________________________________________ _______________________________________________________________________ ______________________________________________________________________________________________________________________________________________

                                Logic Design amp Switching Theory 1 Lab Session 10 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                Lab Session 10 OBJECT

                                Driving a seven segment display using 7447 7448 driver IC COMPONENTS AND APPARATUS REQUIRED

                                1 Following ICs and their Datasheets

                                bull Seven Segment Displays (Common Anode Common Cathode) bull 7447 7448 BCD to Seven Segment Driver

                                2 Digital Trainer DT-01 or the following components Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches

                                THEORY Seven Segment Displays A Seven Segment Display consists of seven light-emitting segments The segments are designated by letters a through g (see figure 101) By illuminating various combinations of segments the numerals 0 through 9 can be displayed Seven Segment Displays are commonly constructed with light-emitting diodes (LEDs) and with liquid-crystal displays (LCDs) LEDs generally provide greater illumination levels but require much greater power than LCDs An LED display can be a common-anode type or common cathode type In common anode type a high voltage is applied at the common terminal of the display and low voltage is applied at a segmentrsquos terminal for illumination In the common-cathode type a low voltage is applied at the common terminal of the display and high voltage is applied at a segmentrsquos terminal for illumination

                                Figure 101 Seven Segment Display

                                a f b g

                                e c d

                                7447 7448 BCD to Seven Segment Driver 7447 7448 IC is particularly used to drive Seven Segment Its input is a BCD number and output drives a seven segment display 7447 is used to drive common-anode displays whereas 7448 is used to drive common cathode displays 7447 7448 is a 16 pin IC Function of various pins of these ICs is described below

                                bull A B C D Inputs representing BCD digits (D being the MSB)

                                45

                                Logic Design amp Switching Theory 1 Lab Session 10 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering bull OA through OG Outputs to drive segments a through g of the display (Active low

                                in 7447 and active high in 7448) bull RBI Ripple Blanking Input Turns off all the segments if kept low provided that LT

                                is kept high and all other inputs (A B C D BI) are kept low Should be kept high otherwise

                                bull BI RBO Wire-AND logic serving as a Blanking Input and or Ripple Blanking Output

                                o BI Turns off all the segments if low o RBO Goes to a low level (response condition) along with other outputs when

                                RBI and inputs A B C and D are low with LT input at high level bull LT Lamp Test input Tests whether all segments are working or not Illuminates all

                                segments if kept low provided that BI is kept high Should be kept high otherwise bull VCC and GND Supply connections lines CIRCUIT DIAGRAM

                                Figure 102 Circuit diagram for 7447driving a common-anode display

                                IMPLEMENTATION AND OBSERVATIONS

                                bull Make connections as shown in the circuit diagram (refer to laboratory session 01 for implementation procedure)

                                bull Apply different combinations of 1s and 0s at data inputs bull Observe the output and record your observations in the following table

                                46

                                Logic Design amp Switching Theory 1 Lab Session 10 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                47

                                Decimal Digit

                                BCD Inputs Seven Segment Outputs D C B A a b c d e f g

                                0 0 0 0 0 1 0 0 0 1 2 0 0 1 0 3 0 0 1 1 4 0 1 0 0 5 0 1 0 1 6 0 1 1 0 7 0 1 1 1 8 1 0 0 0 9 1 0 0 1

                                ACTIVITY 1 Perform the Lamp Test for the designed circuit and write your observations

                                ____________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________

                                2 How can you use 7447 IC to drive a common-cathode display

                                ____________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________

                                3 What symbols appear in the seven segment display if inputs DCBA are

                                DCBA Symbol

                                1010

                                1011

                                1100

                                1101

                                1110

                                1111

                                Logic Design amp Switching Theory 1 Lab Session 11 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                48

                                Lab Session 11 OBJECT

                                Testing different modes of JK-FF COMPONENTS AND APPARATUS REQUIRED 1 Following ICs and their Datasheets

                                bull 7473 7476 JK Flip-Flop 2 Digital Trainer DT-01 or the following components

                                Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches

                                THEORY

                                Flip-Flop A flip-flop circuit can maintain a binary state indefinitely (as long as the power is delivered to the circuit) until directed by an input signal to switch states The major differences among various types of flip-flops are in the number of inputs they possess and in the manner in which the inputs affect the binary state

                                JK Flip-Flop JK flip flop is an edge triggered device A typical JK flip flop has three inputs J K and a clock input The flip-flop can be either positive or negative edge triggered The output Q is available in complemented form as well Beside the usual inputs and output most of the flip-flop IC also possess two asynchronous inputs namely Preset and Clear These inputs are usually active low If used Preset and Clear inputs keep the flip-flop in set and reset state respectively irrespective of the other inputs Both of these inputs cannot be used simultaneously otherwise they will bring the flip-flop in unstable state

                                Figure 111 Symbol for JK flip-flop

                                (a) positive-edge triggering (b) active low Preset (PR) and Clear (CLR) with positive-edge triggering

                                (c) active low Preset (PR) and Clear (CLR) with negative-edge triggering

                                Logic Design amp Switching Theory 1 Lab Session 11 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                49

                                TESTING OF 7473 7476 DUAL JK FLIP-FLOP

                                Both the ICs 7473 and 7476 are similar in functionality except for one difference The flip-flops in 7473 have only one type of active low asynchronous input which is the Clear input whereas the flip-flops in 7476 have both Preset and Clear inputs Both these ICs have negative edge triggered flip-flops

                                Circuit Diagram

                                Figure 112 Pin connections of 7476

                                Testing Procedure

                                bull Make connections as shown in the circuit diagram (figure 112) bull Apply different combinations of 1s and 0s at J and K inputs bull Observe the output and record your observations in the following table

                                Observations

                                J

                                K Q

                                0 0 0 1 1 0 1 1

                                ACTIVITY

                                1 Observe the output Q of JK flip-flop if the clock input is connected to VCC or GND instead of a clock source Write your observations here __________________________________________________________________________________________________________________________________________ _______________________________________________________________________________________________________________________________________________________________________________________________________________

                                Logic Design amp Switching Theory 1 Lab Session 12 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                50

                                Lab Session 12 OBJECT

                                Designing sequential circuit for the given state diagram using D flip-flop GIVEN STATE DIAGRAM

                                00

                                11

                                Figure 121 State Diagram COMPONENTS AND APPARATUS REQUIRED 1 Following ICs and their Datasheets

                                bull 7474 D Flip-Flop bull ICs of basic gates (AND OR NOT XOR etc) as required

                                2 Digital Trainer DT-01 or the following components Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches

                                THEORY

                                Sequential Circuits In Sequential Circuits the output not only depends on the present inputs but also on previous states of the circuit These circuits use memory elements (latches flip-flops) and the binary information stored in the memory elements at any given time defines the state of the sequential circuit Analysis of a Sequential Circuit The behavior of a sequential circuit is determined from the inputs the outputs and the states of its flip-flops Both the outputs and next state are a function of the inputs and the

                                10

                                01

                                00 11 10

                                00

                                00 11 10 00

                                Logic Design amp Switching Theory 1 Lab Session 12 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                51

                                present state The analysis of a sequential circuit form a state diagram comprises of the following bull Selecting a particular flip-flop to design the circuit bull Obtaining state table from the state diagram bull Finding input equations for the selected flip-flop bull Finding state equations (not required for the construction of circuit) bull Implementing the circuit using selected flip-flops and their input equations ANALYZING THE GIVEN STATE DIAGRAM D Flip-Flop D flip-flop is also called transparent flip-flop as it simply transfers the input data to the output For our design we require the graphical symbol and excitation table of D flip-flop (see figure 122)

                                Qt Qt+1 T 0 0 0 0 1 1 1 0 0 1 1 1

                                (b) Excitation table of D Flip-Flop

                                (a) Graphical Symbol

                                Figure 122 Characteristic equation of D flip-flop is Q(t+1) = D State Table The given state diagram has four states so we will need two D flip-flops (FF-0 FF-1) Form state table form the given state diagram and record the results in the following table

                                Present State Input Next State Output Input to FF-0 D0

                                Input to FF-1 D1 Q1t Q0t x Q1(t+1) Q0(t+1) z

                                Logic Design amp Switching Theory 1 Lab Session 12 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                52

                                Input Equations Using Karnaugh map the input equations D0 and D1 for the two flip-flops can be found

                                D0 D1 Q0x

                                Q1

                                _ _ Q0x

                                _ Q0x

                                Q0x

                                _ Q0x

                                Q0x

                                Q1

                                _ _ Q0x

                                _ Q0x

                                Q0x

                                _ Q0x

                                _ Q1

                                _ Q1

                                Q1

                                Q1

                                D0 = _________________ D1 = _________________

                                State Equations Using the characteristic equation of D flip-flop we can find the state equations Q0(t+1) and Q1(t+1) for the to flip flops Q0(t+1) = _______________________ Q1(t+1) = _______________________ _______________________ _______________________ _______________________ _______________________ Circuit Diagram

                                Logic Design amp Switching Theory 1 Lab Session 12 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                53

                                Implementation Procedure and Observations

                                1 Implement the circuit using digital ICs on a bread board (prepare the pin diagram (use appendix A) and refer to laboratory session 01 for procedure)

                                2 Make the clear inputs of the flip-flops low (to clear the flip-flops) The flip-flops will remain in clear state as long as the clear inputs are connected to low level

                                3 Connect output Q0 and the clock pulse to an oscilloscope 4 Apply 0 to the input x 5 Now make the clear inputs to high 6 Observe the waveform for the first 5 clock pulses and record it 7 Repeat steps 2 to 6 keeping x=1 in step 4 this time 8 Repeat steps 2 to 7 this time connecting Q1 instead of Q0 to the oscilloscope in step

                                3 Record your observations (Keep frequency of the clock pulse low (eg1Hz) so that the output waveforms can be observed easily)

                                1 2 3 4 5 Clock Pulse

                                Output Waveform for Q0 when x=0

                                Output Waveform for Q0 when x=1

                                Output Waveform for Q1 when x=0

                                Output Waveform for Q1 when x=1

                                Logic Design amp Switching Theory 1 Lab Session 13 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                Lab Session 13 OBJECT

                                Designing a modulo-5 asynchronous up-counter using JK-FF COMPONENTS AND APPARATUS REQUIRED

                                1 Following ICs and their Datasheets

                                bull 7400 Quad 2-input or 7410 Triple 3-input NAND Gates bull 7476 7473 JK Flip-Flop

                                2 Digital Trainer DT-01 or the following components Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches

                                THEORY

                                Digital Counters A digital counter is a set of flip-flops whose states change in response to pulses applied at the input to the counter The flip-flops are interconnected so that their combined state at any time is the binary equivalent of the total number of pulses that have occurred up to that time Every counter resets after a certain number of clock pulses Thus as it name implies a counter is used to count pulses An n stage counter can count up to a maximum of 2n states n is equal to the number of flip-flops required for the construction of counter

                                Modulus Counters The number of input pulses that causes a counter to reset to its initial count is called the modulus of the counter Thus the modulus equals to total number of distinct states (counts) including zero that a counter can store A binary counter with n stages is a modulo-2n (or mod-2n) counter The largest count a mod-N counter can achieve is N-1 ie a mod-N counter never reaches the binary number equal to its modulus N is always equal to or less than 2n Counters can be classified as bull Synchronous Counters which are clock driven All the flip-flops are driven by a

                                single clock bull Asynchronous Counters which are event driven Clock input is given to the first

                                flip-flop only Rest of the flip-flops are driven by their preceding flip-flops

                                DESIGN OF A MOD-5 ASYNCHRONOUS UP COUNTER The number of flip-flops required to construct a mod-5 counter is 3 because 5 should be less than or equal to 2n This counter will count from 0 to 4 a total of 5 distinct states Since a 3-stage counter can count up to 8 states at maximum a NAND gate is used to reset it after 5 clock pulses Figure 131 shows the logic diagram

                                54

                                Logic Design amp Switching Theory 1 Lab Session 13 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                55

                                Figure 131 A Mod-5 Asynchronous Up Counter

                                Implementation and Observations

                                Implement the mod-5 counter circuit (figure 131) on a bread board (prepare the pin diagram (use appendix A) and refer to laboratory session 01 for implementation procedure) and record the observations in the following table

                                Clock Pulse Q2 Q1 Q0

                                0 1 2 3 4 5 6 7

                                ACTIVITY

                                Draw the timing diagram for mod-5 counter designed in this laboratory session

                                Logic Design amp Switching Theory 1 Lab Session 14 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                Lab Session 14 OBJECT

                                Experimenting with 74194 4-bit bidirectional universal shift register COMPONENTS AND APPARATUS REQUIRED

                                1 Following ICs and their Datasheets

                                bull 74194 4-bit bidirectional universal shift register 2 Digital Trainer DT-01 or the following components

                                Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches

                                THEORY

                                Shift Registers

                                A Register is a set of flip-flops used to store binary data A register which is capable of shifting its binary information either to the right or left is called a shift register The logical configuration of a register consists of a chain of flip-flops connected in cascade with the output of one flip-flop connected to the input of next flip-flop All flip-flops receive a common clock pulse which causes the shift from one stage to the next

                                Bidirectional Shift Registers A bi-directional shift register is one whose bits can be shifted from left to right or from right to left

                                Universal Shift Registers A universal shift register is a bi-directional register whose input can be in either serial or parallel form and whose output can be in either serial or parallel form

                                74194 4-BIT BIDIRECTIONAL UNIVERSAL SHIFT REGISTER

                                The 74194 register provides parallel as well as serial loading in both directions Function of various pins of this IC is described below

                                bull A B C and D Active high inputs for parallel loading bull QA QB QC and QD Active high outputs bull S0 and S1 Active high mode control inputs The following table shows combinations

                                of S1 and S0 to enable various modes

                                S1 S0 Clock Action 0 0 x No change 0 1 uarr Shift right 1 0 uarr Shift left 1 1 uarr Parallel load

                                uarr shows the rising edge of the clock pulse

                                56

                                Logic Design amp Switching Theory 1 Lab Session 14 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering bull SR Active high serial input for right shifting bull SL Active high serial input for left shifting bull CLR Active low input Clears all the flip-flops of the register if set to 0 should be

                                kept high otherwise bull CLK Clock input bull VCC and GND Supply connections lines Thus A B C and D are inputs for parallel loading whereas SR and SL are inputs for serial loading with right or left shifting respectively S1 and S0 are used to select the loading mode Circuit Diagram

                                Figure 141 Pin connections of 74194 Testing Procedure

                                bull Make connections as shown in the circuit diagram bull Observe the output for the input combinations given in the following table

                                57

                                Logic Design amp Switching Theory 1 Lab Session 14 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                58

                                Observations

                                S1 S0 SL SR A B C D QA QB QC QD 0 0 0 1 0 0 0 0 0 1 1 0 0 0 0 1 1 0 0 0 0 0 1 0 1 1 0 0 0 0 1 1 0 0 1 1 0 1 0 0 0 1 1 1 0 1 0 1 1 0 1 0 0 1 1 0 1 1 1 0 0 1 1 1 1 1 0 0 1 1 1 1

                                ACTIVITY 1 Show connections of 74194 to convert it into a ring counter with right shifting

                                Logic Design amp Switching Theory 1 Lab Session 15 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                Lab Session 15

                                OBJECT

                                Experimenting with 74245 octal bus transceivers using parallel port PC interfacing COMPONENTS AND APPARATUS REQUIRED 1 Parallel Port Connectors (DB-25) with Cable 2 Personal Computer with Windows 98 and TurboC Compiler Installed 3 Following ICs and their Datasheets

                                bull 74245 Octal Bus Transceivers with 3-State Outputs 4 Digital Trainer DT-01 or the following components

                                Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches

                                THEORY

                                3-State Logic Sometimes it is necessary to isolate one part of circuit from the other part For this purpose some TTL ICs are designed with 3-state logic Such devices have three possible output states high low and high impedance The device can be put into high impedance state by a control signal applied to an appropriate pin When such a device is in high impedance state there is very high impedance at its output effectively isolating the device from whatever circuitry the output normally drives 74245 Octal Bus Transceivers A bus is any conducting path or set of paths having electrical connections to one or more devices 74245 octal bus transceivers are mainly used to control connectivity between two devices or circuits It also provides direction control for signal flow Function of various pin of this IC is given below

                                bull A1 through A8 Bus A bull B1 through B8 Bus B bull G΄ Active low enable input When high sets all the bus pins to high impedance state bull DIR Direction control for signal flow When set to high logic level transfers bus A

                                data to B bus When set to low logic level transfers bus B data to A bus bull VCC and GND Supply connections lines Serial and Parallel Port Connectors A Parallel Port can consist of only 25 pin port adapter called a DB-25 and a serial port can consist of either a 25 pin port adapter called a DB-25 or 9 pin adapter called a DB-9 port adapter Whether the port is a 9 pin or 25 pin it can accomplish all of the same tasks that serial port communications have been designed for

                                59

                                Logic Design amp Switching Theory 1 Lab Session 15 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                60

                                Each adapter can be a male type connector with pins or a female type adapter with tiny holes Generally a PRINTER port (called LPT1) on the back of a computer is female type adapter and we need to use MALE DB-25 pin cable on it for PRINTER connection or for parallel LAPLINK cable And a COM port on the back of a computer is male for the serial ports but it may not necessarily be Parallel Port Connector ndash DB-25 The DB-25 connector (named for its B-size D-shaped shell and 25 pins) is practically ubiquitous in the electronics industry The DB-25 connector is used for a variety of purposes Two common applications are RS-232EIA-232 (serial) connections and the parallel printer interface on the IBM PC The DB-25 connector is also used for SCSI connections Normally the parallel port is used for output to a printer or other device It sends data 8-bits or one byte at a time in parallel The other lines available on the DB-25 connector are a combination of status lines control lines and ground lines The status and control lines are used for handshaking commands and feedback when we are talking to a printer

                                Figure 152 DB-25 Female Figure 151 DB-25 Male

                                Figure 153 Pin Layout for DB-25 As can be seen form figure 153 there are four types of pins in this connector

                                bull Data pins (8 pins - D0 to D7) Active high bidirectional lines

                                Logic Design amp Switching Theory 1 Lab Session 15 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering bull Control pins (4 pins - C0 to C3) C0 C1 and C3 are active low whereas C2 is active

                                high These lines also are bidirectional bull Status pins (5 pins ndash S3 to S7) Only S7 is active low rest are active high input lines bull Ground pins (8 pins) Used as a reference signal for the low (below 05 volts) charge

                                Parallel Port Addresses A DB-25 connector at a parallel port has three address one for each kind of pins register data status and control The first or base address generally refers to data register Second address is for status register and the third one is for control register In Windows 98 the base address is usually found to be 278H 378H or 3BCH Now if 378H is the base address then it refers to the data register whereas addresses for status and control register are respectively 379H and 37AH For Windows 98 the base address can be found as follows 1 On your Desktop right-click on My Computer and select Properties 2 Click on the Device Manager tab and find LPT1 under Plug and Play BIOS 3 After selecting LPT1 click the Properties button 4 Next select the Resources tab and the address should then appear next to InputOutput

                                Range Accessing parallel port through C Language Programming There are multiple functions in C Language for accessing external ports The most commonly used are listed below

                                bull unsigned char inportb(int portid) inportb reads a byte from a hardware port

                                bull int inport(int portid) reads a word from a hardware port

                                bull void outportb(int portid unsigned char value) outputs a byte to a hardware port

                                bull void outport(int portid int value) outputs a word to a hardware port

                                portid refers to the port address whereas value refers to the data to be sent TESTING 74245 USING PARALLEL PORT PC INTERFACING At one end the parallel port connector will be connected to the PC via parallel port cable and another connector (to be plugged into the PC parallel port slot) At the other end it will be connected to the buffer IC 74245 Data lines of the connector will be used to transfer 8-bit data between the PC and the buffer Out of the 8-bits of 74245 4-bits will be used to enter data which will be displayed at the monitor through a C language

                                61

                                Logic Design amp Switching Theory 1 Lab Session 15 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering program The remaining 4-bits will receive data from PC as entered by the user via keyboard

                                Circuit Diagram

                                Figure 154 Interface of 74245 to PC via Parallel Port

                                Procedure

                                1 Connect the DB-25 connector to the PC at one end and solder it to the circuit board at the other end

                                2 Connect various pins of the connector and 74245 according to the circuit diagram shown in figure 152

                                3 Using the functions listed in the previous section write a program in C language to operate various pins of the buffer The user interface of the program should provide option to the user whether to send or receive data from the port

                                4 Set DIR switch to 1 5 Try sending some data bits to the port The result should be displayed at the LEDs 6 Set DIR switch to 0 7 Set some binary 4-bit value through the switches Try reading it via parallel port

                                C Language Program

                                A program to access parallel port for data transfers

                                use header file include ltstdiohgt main program void main() define variable

                                62

                                Logic Design amp Switching Theory 1 Lab Session 15 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering unsigned int data=0 char choice while(1) printing option menu clrscr() printf(This program will send or receive a BCD digit from the parallel portn) printf(nPress your choice numbern) printf(n1 Send Data) printf(n2 Receive Data) printf(n3 Exitn) choice = getch() sending entered digit to the port if(choice == 1) input BCD digit printf(nEnter BCD digit to be sent to the port) data = getche() masking the first four bits data = data amp 0x0f sending to the port outportb(0x378data) printf(nThe BCD digit c has been sent to the port data) printing on screen the data received from the port else if(choice == 2) receiving data from the port data = inportb(0x378) masking the last four bits data = data amp 0xf0 shifting first four bits to make them the last four bits datagtgt=4 printf(nThe BCD digit set at the port is c data) exit else if(choice == 3) break key pressed is not in the menu else printf(nEnter valid choice number) printf(nnPress any key to continue) getch()

                                63

                                Logic Design amp Switching Theory 1 Lab Session 15 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                ACTIVITY 1 In the above circuit DIR and G΄ inputs are hardwired Connect them to status or

                                control pins of the parallel port connector and control their function through your software program Circuit Diagram Program Code ______________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________

                                ___________________________________________________________________________________________________________________________________________________

                                64

                                Logic Design amp Switching Theory 1 Lab Session 15 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                65

                                _____________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ _____________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ _______________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ _________________________________________________ _________________________________________________

                                Logic Design amp Switching Theory 1 Appendix A NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                Appendix A

                                PIN DIAGRAMS OF THE ICS REQUIRED FOR THE LABORATORY SESSIONS Consult the TTLIC data book for internal diagrams and electrical characteristics of these ICs 7400 Quad 2-Input NAND 7402 Quad 2-Input NOR

                                7404 Hex Inverter 7408 Quad 2-Input AND

                                7410 Triple 3-Input NAND 7411 Triple 3-Input AND

                                7421 Dual 4-Input AND 7432 Quad 2-Input OR

                                66

                                Logic Design amp Switching Theory 1 Appendix A NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                BCD-to-Seven Segm 7448 BCD-to-Seven Segment 7447 ent

                                Decoder (15V OC) Decoder (2kΩ pull-up output)

                                7473 Dual JK Flip-Flop 7474 Dual D-Type Flip-Flop

                                7476 Dual JK Flop-Flop -Bit Binary Full Adder 7483 4 with Fast Carry

                                86 Quad 2-Inpu 74138 3-to-8 Line 74 t Exclusive OR Decoder Demultiplexer

                                67

                                Logic Design amp Switching Theory 1 Appendix A NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                68

                                74148 8-to-3 Line 16-to-1 Line Data

                                Priority Encoder 74150 Selector Multiplexer

                                74245 Oct nsceivers Universal Shift Register (PIPO) (3-State)

                                74194 4-Bit Bidirectional al Bus Tra

                                Logic Design amp Switching Theory 1 Appendix B NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                Appendix B

                                DEBOUNCING CIRCUITRY FOR MECHANICAL SWITCHES Mechanical switches form the interface between human beings and computers or other digital systems For example a keyboard is a matrix of switches used to supply alphanumeric data to a computer Whatever the switch design it is a potential source of problems due to contact bounce The contact bounce creates a sense of narrow pulses when a switch is opened or closed An example of device whose operation would be adversely affected by contact bounce is a digital counter used to count the number of times a switch is depressed Eliminating the effects of contact bounce is called debouncing When data is entered into a computer via a keyboard a software debounce is often used This type of debouncing is a program that causes the computer to sample the switch terminal (ie to input data from it) many times in succession during the interval of time that contact bounce occurs If the data is sensed to be 1s (or 0s) for a specific number of consecutive samples then it is assumed that contact bounce has ended and the last value sensed is valid Hardware debouncing is the use of electronic circuitry to eliminate the effects of contact bounce There are numerous versions of such circuitry including those that use monostable multivibrators (one-shots) but the most straightforward is simply an RS latch Figure B1 shows the circuit When the switch is in position 1 R = 0 and S = 1 so the latch is set and the output (Q) is 1 When the switch is in position 0 R = 1and S = 0 so the latch is reset and the output is 0 When the switch is moved form one position to the other the latch changes state and bouncing occurs at either the R or the S input The bouncing does not affect the latch after it has change state An RS latch will remain set for example when its R input is 0 and its S input is alternately changed form 1 to 0

                                Figure B1 Use of RS latch to debounce a mechanical switch

                                69

                                • 01-ldst-Outer title
                                  • Practical Workbook
                                  • Logic Design amp Switching Theory I
                                    • Dept of Computer amp Information Systems Engineering
                                      • NED University of Engineering amp Technology
                                      • Karachi ndash 75270 Pakistan
                                        • 02-ldst-inner Title
                                          • Practical Workbook
                                          • Logic Design amp Switching Theory I
                                            • Dept of Computer amp Information Systems Engineering
                                              • NED University of Engineering amp Technology
                                              • Karachi ndash 75270 Pakistan
                                                • 03-ldst-general info
                                                • 04-ldst-introduction
                                                • 05-Table of Contents
                                                  • CONTENTS
                                                    • Lab Session No Object Page No
                                                    • 1
                                                    • Also implementing and testing the given circuit on a bread board
                                                      • Working with Electronics Workbench
                                                        • Driving a seven segment display using 7447 7448 driver IC
                                                          • Designing a modulus-5 asynchronous up-counter using JK-FF
                                                            • Experimenting with 74194 4-bit bidirectional universal shift register
                                                                • 13
                                                                    • 06-ldst-Exp01
                                                                      • Lab Session 01
                                                                      • OBJECT
                                                                        • 1 Bread board
                                                                        • 2 5 V - power supply
                                                                        • 3 Multimeter
                                                                        • 4 Logic probe
                                                                        • 5 LEDs with resistors
                                                                        • 6 Connecting wires
                                                                        • 8 Following ICs and their datasheets
                                                                          • THEORY
                                                                            • Logic Gates
                                                                            • 1 The AND Gate ndash An AND gatersquos output is 1 if and only if all its inputs are 1 If A and B are two inputs to an AND gate then output F of the gate is given as F = AB
                                                                            • 2 The OR Gate - An OR gatersquos output is 1 if at least one of its input is 1 If A and B are two inputs to an OR gate then output F of the gate is given as F = A+B
                                                                            • 3 The NOT Gate (Inverter) ndash Its output is 1 when its input is 0 and its output is 0 when the input is 1 ie it complements a digital variable If A is the input to a NOT gate then output F of the gate is given as
                                                                            • 4 The NAND Gate ndash Its output is 1 if at least one of its input is 0 This gate performs the same logic as an AND gate followed by an inverter If A and B are two inputs to a NAND gate then output F of the gate is given as
                                                                              • 5 The NOR Gate - The output of a NOR gate is 1 if and only if all its inputs are 0 This gate performs the same logic function as an OR gate followed by an inverter If A and B are two inputs to a NAND gate then output F of the gate is given as
                                                                                  • DATA SHEETS
                                                                                    • Logic expression for the given logic diagram __________________________________
                                                                                        • 07-ldst-exp02
                                                                                          • Working with Electronics Workbench
                                                                                            • 08-ldst-exp03
                                                                                              • Designing Half and Full Adder Circuits
                                                                                                • COMPONENTS AND APPARATUS REQUIRED
                                                                                                  • 1 Following ICs and their Datasheets
                                                                                                  • 7408 Quad 2-input AND Gate
                                                                                                  • 2 Digital Trainer DT-01 or the following components
                                                                                                    • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                    • Connecting wires Switches
                                                                                                      • THEORY
                                                                                                          • IMPLEMENTATION AND OBSERVATIONS
                                                                                                            • 09-ldst-Exp04
                                                                                                              • Lab Session 04
                                                                                                              • 1 Digital ICs and their Datasheets
                                                                                                              • 7408 Quad 2-input AND Gate
                                                                                                              • 2 Digital Trainer DT-01 or the following components
                                                                                                                • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                • Connecting wires Switches
                                                                                                                • PROCEDURE
                                                                                                                • REDUCTION OF LOGIC EXPRESSION USING KARNAUGH MAP
                                                                                                                • OBSERVATIONS
                                                                                                                • RESULT
                                                                                                                    • 10-ldst-Exp05
                                                                                                                      • Lab Session 05
                                                                                                                      • 1 Following ICs and their Datasheets
                                                                                                                      • 7408 Quad 2-input AND Gate
                                                                                                                      • 2 Digital Trainer DT-01 or the following components
                                                                                                                        • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                        • (100 Ω) Connecting wires Switches
                                                                                                                        • THEORY
                                                                                                                          • IMPLEMENTATION AND OBSERVATIONS
                                                                                                                            • 11-ldst-Exp06
                                                                                                                              • OBJECT
                                                                                                                              • 1 Following ICs and their Datasheets
                                                                                                                              • 7408 Quad 2-input AND Gates or 7411 Triple 3-input AND Gates
                                                                                                                              • 2 Digital Trainer DT-01 or the following components
                                                                                                                                • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                • Connecting wires Switches
                                                                                                                                  • Figure 62 Circuit Diagram for 4 x 1 Multiplexer
                                                                                                                                  • Implementation and Observations
                                                                                                                                    • Circuit Diagram
                                                                                                                                      • ACTIVITY
                                                                                                                                        • 12-ldst-exp07
                                                                                                                                          • 1 Following ICs and their Datasheets
                                                                                                                                          • 7408 Quad 2-input or 7411 Triple 3-input AND Gates
                                                                                                                                          • 2 Digital Trainer DT-01 or the following components
                                                                                                                                            • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                            • Connecting wires Switches
                                                                                                                                              • THEORY
                                                                                                                                                  • Figure 72 Circuit Diagram for 2 x 4 Decoder 1 x 4 Demultiplexer
                                                                                                                                                  • Implementation and Observations
                                                                                                                                                    • Circuit Diagram
                                                                                                                                                      • ACTIVITY
                                                                                                                                                        • 13-ldst-Exp08
                                                                                                                                                          • OBJECT
                                                                                                                                                          • 1 Following ICs and their Datasheets
                                                                                                                                                          • 7408 Quad 2-input or 7421 Dual 4-input AND Gates
                                                                                                                                                          • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                            • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                            • Connecting wires Switches
                                                                                                                                                              • THEORY
                                                                                                                                                                  • Figure 81 Circuit Diagram for 4 x 2 Priority Encoder
                                                                                                                                                                  • Implementation and Observations
                                                                                                                                                                    • Therefore if GS A2 A1 and A0 are all low then it shows that line 0 is selected and if E0 A2 A1 and A0 are all low then it shows that none of the inputs selected E0 and GS cannot be in the same state provided that E1 is enabled
                                                                                                                                                                    • Circuit Diagram
                                                                                                                                                                      • ACTIVITY
                                                                                                                                                                        • 14-ldst-exp09
                                                                                                                                                                          • OBJECT
                                                                                                                                                                          • 1 Following ICs and their Datasheets
                                                                                                                                                                          • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                            • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                            • Connecting wires Switches
                                                                                                                                                                              • THEORY
                                                                                                                                                                                • Parity Generator
                                                                                                                                                                                  • Let x y and z be the three bits that constitute the message and are the input to the Odd Parity Generator Circuit Since it is an odd parity system the bit P is generated so as to make the total number of 1s odd (including P) The function P can be expressed as follows
                                                                                                                                                                                  • Figure 91 Circuit Diagram for a 3-bit Parity Generator
                                                                                                                                                                                    • C = x Ο y Ο z Ο P
                                                                                                                                                                                      • Implementation and Observations
                                                                                                                                                                                        • ACTIVITY
                                                                                                                                                                                            • 15-ldst-exp10
                                                                                                                                                                                              • Driving a seven segment display using 7447 7448 driver IC
                                                                                                                                                                                              • COMPONENTS AND APPARATUS REQUIRED
                                                                                                                                                                                              • 1 Following ICs and their Datasheets
                                                                                                                                                                                              • 7447 7448 BCD to Seven Segment Driver
                                                                                                                                                                                              • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches
                                                                                                                                                                                                  • THEORY
                                                                                                                                                                                                  • Seven Segment Displays
                                                                                                                                                                                                  • CIRCUIT DIAGRAM
                                                                                                                                                                                                  • Figure 102 Circuit diagram for 7447driving a common-anode display
                                                                                                                                                                                                      • IMPLEMENTATION AND OBSERVATIONS
                                                                                                                                                                                                        • Decimal Digit
                                                                                                                                                                                                        • BCD Inputs
                                                                                                                                                                                                        • Seven Segment Outputs
                                                                                                                                                                                                        • D
                                                                                                                                                                                                        • C
                                                                                                                                                                                                        • B
                                                                                                                                                                                                        • A
                                                                                                                                                                                                        • a
                                                                                                                                                                                                        • b
                                                                                                                                                                                                        • c
                                                                                                                                                                                                        • d
                                                                                                                                                                                                        • e
                                                                                                                                                                                                        • f
                                                                                                                                                                                                        • g
                                                                                                                                                                                                        • 0
                                                                                                                                                                                                        • 0
                                                                                                                                                                                                        • 0
                                                                                                                                                                                                        • 0
                                                                                                                                                                                                        • 0
                                                                                                                                                                                                        • 1
                                                                                                                                                                                                        • 0
                                                                                                                                                                                                        • 0
                                                                                                                                                                                                        • 0
                                                                                                                                                                                                        • 1
                                                                                                                                                                                                        • 2
                                                                                                                                                                                                        • 0
                                                                                                                                                                                                        • 0
                                                                                                                                                                                                        • 1
                                                                                                                                                                                                        • 0
                                                                                                                                                                                                        • 3
                                                                                                                                                                                                        • 0
                                                                                                                                                                                                        • 0
                                                                                                                                                                                                        • 1
                                                                                                                                                                                                        • 1
                                                                                                                                                                                                        • 4
                                                                                                                                                                                                        • 0
                                                                                                                                                                                                        • 1
                                                                                                                                                                                                        • 0
                                                                                                                                                                                                        • 0
                                                                                                                                                                                                        • 5
                                                                                                                                                                                                        • 0
                                                                                                                                                                                                        • 1
                                                                                                                                                                                                        • 0
                                                                                                                                                                                                        • 1
                                                                                                                                                                                                        • 6
                                                                                                                                                                                                        • 0
                                                                                                                                                                                                        • 1
                                                                                                                                                                                                        • 1
                                                                                                                                                                                                        • 0
                                                                                                                                                                                                        • 7
                                                                                                                                                                                                        • 0
                                                                                                                                                                                                        • 1
                                                                                                                                                                                                        • 1
                                                                                                                                                                                                        • 1
                                                                                                                                                                                                        • 8
                                                                                                                                                                                                        • 1
                                                                                                                                                                                                        • 0
                                                                                                                                                                                                        • 0
                                                                                                                                                                                                        • 0
                                                                                                                                                                                                        • 9
                                                                                                                                                                                                        • 1
                                                                                                                                                                                                        • 0
                                                                                                                                                                                                        • 0
                                                                                                                                                                                                        • 1
                                                                                                                                                                                                          • ACTIVITY
                                                                                                                                                                                                            • 16-ldst-exp11
                                                                                                                                                                                                              • Lab Session 11
                                                                                                                                                                                                                • OBJECT
                                                                                                                                                                                                                • COMPONENTS AND APPARATUS REQUIRED
                                                                                                                                                                                                                  • 1 Following ICs and their Datasheets
                                                                                                                                                                                                                  • 7473 7476 JK Flip-Flop
                                                                                                                                                                                                                  • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                    • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                                    • Connecting wires Switches
                                                                                                                                                                                                                      • THEORY
                                                                                                                                                                                                                          • Flip-Flop
                                                                                                                                                                                                                          • JK Flip-Flop
                                                                                                                                                                                                                            • Circuit Diagram
                                                                                                                                                                                                                              • Observations
                                                                                                                                                                                                                                • ACTIVITY
                                                                                                                                                                                                                                    • 17-ldst-exp12
                                                                                                                                                                                                                                      • Lab Session 12
                                                                                                                                                                                                                                        • OBJECT
                                                                                                                                                                                                                                        • GIVEN STATE DIAGRAM
                                                                                                                                                                                                                                        • Figure 121 State Diagram
                                                                                                                                                                                                                                        • COMPONENTS AND APPARATUS REQUIRED
                                                                                                                                                                                                                                          • 1 Following ICs and their Datasheets
                                                                                                                                                                                                                                          • 7474 D Flip-Flop
                                                                                                                                                                                                                                          • ICs of basic gates (AND OR NOT XOR etc) as required
                                                                                                                                                                                                                                          • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                                            • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                                                            • Connecting wires Switches
                                                                                                                                                                                                                                              • THEORY
                                                                                                                                                                                                                                                  • Sequential Circuits
                                                                                                                                                                                                                                                    • 18-ldst-exp13
                                                                                                                                                                                                                                                      • Lab Session 13
                                                                                                                                                                                                                                                        • Designing a modulo-5 asynchronous up-counter using JK-FF
                                                                                                                                                                                                                                                          • 1 Following ICs and their Datasheets
                                                                                                                                                                                                                                                          • 7400 Quad 2-input or 7410 Triple 3-input NAND Gates
                                                                                                                                                                                                                                                          • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                                                            • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                                                                            • Connecting wires Switches
                                                                                                                                                                                                                                                              • THEORY
                                                                                                                                                                                                                                                                  • Figure 131 A Mod-5 Asynchronous Up Counter
                                                                                                                                                                                                                                                                  • Implementation and Observations
                                                                                                                                                                                                                                                                    • ACTIVITY
                                                                                                                                                                                                                                                                        • 19-ldst-exp14
                                                                                                                                                                                                                                                                          • Experimenting with 74194 4-bit bidirectional universal shift register
                                                                                                                                                                                                                                                                          • 1 Following ICs and their Datasheets
                                                                                                                                                                                                                                                                          • 74194 4-bit bidirectional universal shift register
                                                                                                                                                                                                                                                                          • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                                                                            • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                                                                                            • Connecting wires Switches
                                                                                                                                                                                                                                                                              • THEORY
                                                                                                                                                                                                                                                                                • Shift Registers
                                                                                                                                                                                                                                                                                • Bidirectional Shift Registers
                                                                                                                                                                                                                                                                                • Universal Shift Registers
                                                                                                                                                                                                                                                                                  • S1
                                                                                                                                                                                                                                                                                    • Circuit Diagram
                                                                                                                                                                                                                                                                                    • ACTIVITY
                                                                                                                                                                                                                                                                                        • 20-ldst-exp15
                                                                                                                                                                                                                                                                                          • COMPONENTS AND APPARATUS REQUIRED
                                                                                                                                                                                                                                                                                          • 1 Parallel Port Connectors (DB-25) with Cable
                                                                                                                                                                                                                                                                                          • 2 Personal Computer with Windows 98 and TurboC Compiler Installed
                                                                                                                                                                                                                                                                                          • 3 Following ICs and their Datasheets
                                                                                                                                                                                                                                                                                          • 74245 Octal Bus Transceivers with 3-State Outputs
                                                                                                                                                                                                                                                                                          • 4 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                                                                                            • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                                                                                                              • Connecting wires Switches
                                                                                                                                                                                                                                                                                                • THEORY
                                                                                                                                                                                                                                                                                                • 3-State Logic
                                                                                                                                                                                                                                                                                                  • Serial and Parallel Port Connectors
                                                                                                                                                                                                                                                                                                  • Parallel Port Connector ndash DB-25
                                                                                                                                                                                                                                                                                                    • Accessing parallel port through C Language Programming
                                                                                                                                                                                                                                                                                                        • 21-ldst-appendixA
                                                                                                                                                                                                                                                                                                        • 22-ldst-appendixB
                                                                                                                                                                                                                                                                                                          • DEBOUNCING CIRCUITRY FOR MECHANICAL SWITCHES

                                  Logic Design amp Switching Theory 1 Lab Session 03 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                  Lab Session 03

                                  OBJECT

                                  Designing Half and Full Adder Circuits COMPONENTS AND APPARATUS REQUIRED 1 Following ICs and their Datasheets

                                  bull 7408 Quad 2-input AND Gate bull 7432 Quad 2-input OR Gate bull 7486 Quad 2-input XOR Gate

                                  2 Digital Trainer DT-01 or the following components Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches

                                  THEORY Half Adder A combination circuit that performs the addition of two bits without accounting for the previous carry is called half adder It needs two binary inputs and two binary outputs The input variables designate the augend and addend bits The output variables produce the sum and carry The simplified sum of product expressions for a half adder are

                                  yxyxyxS oplus=+= yxC =

                                  Figure 31 Circuit diagram for Half Adder

                                  19

                                  Logic Design amp Switching Theory 1 Lab Session 03 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                  bles produce the sum and carry The simplified sum of product expressions for a half adder are

                                  Full Adder

                                  A combinational circuit that performs the addition of three input bits It consist of three inputs and two outputs Two of the input variables represent the two significant bits to be added The third input represents the carry from the previous lower significant position The output varia

                                  zyxzyxzyxzyxzyxS oplusoplus=+++= yxzyxzyzxxyC )( +oplus=++=

                                  Figure 32 Circuit diagram for Full Adder

                                  efer to laboratory session 01 for procedure) and record the observations in the following ta

                                  alf Adde ull Adder Inputs u

                                  IMPLEMENTATION AND OBSERVATIONS

                                  Implement the half adder and full adder circuits on a bread board (prepare the pin diagram (use appendix A) and r

                                  bles H r F

                                  Inputs Outputs Outp ts x y Carry Su Carry Sum m x y z 0 0 0 0 0 0 1 0 0 1 1 0 0 1 0 1 1 0 1 1 1 0 0 1 0 1 1 1 0 1 1 1

                                  20

                                  Logic Design amp Switching Theory 1 Lab Session 03 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                  at of your designed circuit Attach hardcopy of the output form electronic workbench

                                  at of your designed circuit Attach hardcopy of the output form lectronic workbench here

                                  ACTIVITY

                                  1 Simulate half adder circuit using Electronics Workbench Compare the results of simulation with thhere

                                  2 Design a full subtractor circuit and simulate it using Electronics Workbench Compare the results of simulation with the

                                  21

                                  Logic Design amp Switching Theory 1 Lab Session 04 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                  Lab Session 04 OBJECT

                                  Use of Karnaugh Map (SOP-Expression) method GIVEN LOGIC EXPRESSION

                                  F (A B C D) = sum ( 0 1 2 4 5 6 8 9 12 13 14 ) COMPONENTS AND APPARATUS REQUIRED 1 Digital ICs and their Datasheets

                                  bull 7408 Quad 2-input AND Gate bull 7432 Quad 2-input OR Gate bull 7404 Hex Inverter

                                  2 Digital Trainer DT-01 or the following components Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches PROCEDURE 1 Use Karnaugh map to reduce the given function 2 Draw the circuit diagram for the obtained reduced function 3 Implement the reduced circuit using digital ICs on a bread board (prepare the pin

                                  diagram (use appendix A) and refer to laboratory session 01 for procedure) and record the observations

                                  REDUCTION OF LOGIC EXPRESSION USING KARNAUGH MAP F

                                  CD

                                  AB DC

                                  DC DC

                                  DC

                                  BA0 1 3 2

                                  BA4 5 7 6

                                  BA12 13 15 14

                                  BA8 9 11 10

                                  Reduced form of the given logic expression is __________________________________

                                  22

                                  Logic Design amp Switching Theory 1 Lab Session 04 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                  LOGIC DIAGRAM (REDUCED FORM) OBSERVATIONS

                                  A B C D Output 0 0 0 0 0 0 0 1 0 0 1 0 0 0 1 1 0 1 0 0 0 1 0 1 0 1 1 0 0 1 1 1 1 0 0 0 1 0 0 1 1 0 1 0 1 0 1 1 1 1 0 0 1 1 0 1 1 1 1 0 1 1 1 1

                                  RESULT The reduced form (SOP Expression) of the given logic function is

                                  ____________________________________________________________

                                  The observation table reflects the given logic function

                                  23

                                  Logic Design amp Switching Theory 1 Lab Session 04 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                  ACTIVITY 1 Using Electronics Workbench derive a truth table and logic circuit for the following logic expression

                                  BAAF +=

                                  Procedure 1 From the Instruments Parts Bin drag and drop Logic Converter on the design area 2 Double click the Logic Converter to reveal Logic Converter dialog box This dialog

                                  box shows various conversion options between truth table logic expression and logic circuit

                                  3 Enter the given logic expression in the edit box found at the end of the dialog box Use lsquo to represent invert of a variable For example A is written as Arsquo

                                  4 Click the Boolean Expression to Truth Table button The truth table appears in the logic converters display

                                  5 Now click the Boolean Expression to Circuit button This creates the logic circuit for the given expression in the design area Label the diagram if needed

                                  Resulting Logic Circuit For the given expression the final circuit will look like

                                  Figure 41

                                  24

                                  Logic Design amp Switching Theory 1 Lab Session 04 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                  ACTIVITY 2

                                  Using Electronics Workbench find a simplified logic expression and circuit for the following truth table

                                  A B C Output 0 0 0 1 0 0 1 1 0 1 0 0 0 1 1 1 1 0 0 0 1 0 1 0 1 1 0 0 1 1 1 1

                                  Procedure 1 Click three input channels from A to H across the top of the logic converter The

                                  display area below the terminals fills up with the necessary combinations of ones and zeros to fulfill the input conditions The values in the output column on the right are initially set to 0

                                  2 Edit the output column to specify the desired output for each input condition To change an output value select it and type a new value 1 0 or x An x indicates a donrsquot care condition

                                  3 To convert this truth table to a Boolean expression click the Truth Table to Boolean Expression button The Boolean expression will be displayed at the bottom of the logic converter

                                  4 Simplify the expression by clicking the Simplify button 5 Now click the Boolean Expression to Circuit button This creates the logic circuit for

                                  the given expression in the design area Resulting Logic Circuit For the given truth table the final simplified circuit will look like

                                  Figure 42

                                  25

                                  Logic Design amp Switching Theory 1 Lab Session 04 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                  ACTIVITY 3

                                  Using Electronics Workbench find the logic expression and truth table for the following logic circuit

                                  Figure 43

                                  Procedure 1 Attach the input terminals of the logic converter to up to four input points in the

                                  circuit 2 Connect the single output of the circuit to the output terminal on the logic converter

                                  icon 3 Click the Circuit to Truth Table button The truth table appears in the logic

                                  converters display 4 To convert this truth table to a Boolean expression click the Truth Table to Boolean

                                  Expression button The Boolean expression will be displayed at the bottom of the logic converter

                                  Resulting Logic Expression Logic Expression for the given circuit is found to be _____________________________

                                  26

                                  Logic Design amp Switching Theory 1 Lab Session 04 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                  27

                                  For activities 1 2 and 3 attach hardcopy of the output (truth table logic expression and logic circuit) form electronic workbench here

                                  Logic Design amp Switching Theory 1 Lab Session 05 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                  Lab Session 05 Lab Session 05 OBJECT OBJECT

                                  Designing a BCD Adder Designing a BCD Adder COMPONENTS AND APPARATUS REQUIRED COMPONENTS AND APPARATUS REQUIRED

                                  1 Following ICs and their Datasheets 1 Following ICs and their Datasheets bull 7408 Quad 2-input AND Gate bull 7408 Quad 2-input AND Gate bull 7432 Quad 2-input OR Gate bull 7432 Quad 2-input OR Gate bull 7483 4-bit Binary Adder bull 7483 4-bit Binary Adder

                                  2 Digital Trainer DT-01 or the following components 2 Digital Trainer DT-01 or the following components Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors (100 Ω) Connecting wires Switches (100 Ω) Connecting wires Switches

                                  THEORY THEORY

                                  A BCD Adder is a combinational circuit that adds two BCD digits in parallel and produces a sum digit also in BCD A BCD Adder is a combinational circuit that adds two BCD digits in parallel and produces a sum digit also in BCD

                                  A4 A3 A2 A1 B4 B3 B2 B1

                                  7483-BCD ADDER

                                  Cout (C4 ) Z4 Z3 Z2 Z1 Cin(C0)

                                  A4 A3 A2 A1 B4 B3 B2 B1

                                  7483-BCD ADDER

                                  Cout

                                  (C4 ) Z4 Z3 Z2 Z1 Cin(C0)

                                  Figure 51 BCD Adder Circuit

                                  28

                                  Logic Design amp Switching Theory 1 Lab Session 05 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                  29

                                  A BCD adder must include the correction logic in its internal construction The two BCD digits together with the input carry are first added using a 4-bit binary adder to produce the binary sum If no output carry is generated and the binary sum is less than or equal to 9 then the corresponding BCD sum is identical and therefore no conversion is needed When the output carry is equal to 1 or the binary sum is greater than 9 then a binary 0110 is added to the binary sum through another 4-bit binary adder If Cout is the carry output and Z4Z3Z2Z1 is the binary sum form the first 4-bit binary adder then the following equation indicates the condition when a binary 0110 is to be added

                                  C = COUT + Z4Z2 + Z4Z3 IMPLEMENTATION AND OBSERVATIONS Implement the BCD adder circuit according to figure 51 on a bread board (prepare the pin diagram (use appendix A) and refer to laboratory session 01 for procedure) A BCD adder has nine input bits (two BCD digits and a carry bit) which can result in a total of 512 combinations of which 312 inputs are donrsquot care Since it is a very lengthy procedure to record results for 200 valid input combinations therefore for simplicity just record results for any eight combinations in the following table

                                  Input Carry

                                  BCD Digit 1 BCD Digit 2 Carry Output

                                  BCD Sum A4 A3 A2 A1 B4 B3 B2 B1 Z4 Z3 Z2 Z1

                                  Logic Design amp Switching Theory 1 lab Session 06 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                  Lab Session 06

                                  OBJECT

                                  bull Designing of a 4 x 1 Multiplexer bull Experimenting with 74150 IC

                                  COMPONENTS AND APPARATUS REQUIRED 1 Following ICs and their Datasheets

                                  bull 7408 Quad 2-input AND Gates or 7411 Triple 3-input AND Gates bull 7432 Quad 2-input OR Gates bull 7404 Hex Inverter bull 74150 16 x 1 MUX

                                  2 Digital Trainer DT-01 or the following components Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches THEORY

                                  Multiplexers A digital data Multiplexer (MUX) is a combinational circuit having several data inputs and a single output A set of data-select inputs is used to control which of the data inputs is routed to the single output A multiplexer is also called a data selector because of this ability to select which data input is connected o the output Normally there are 2n input lines and n selection lines whose bit combination determine which input is selected DESIGN OF A 4 x 1 MULTIPLEXER A 4 x 1 multiplexer is capable of selecting one of four data inputs (see figure 61) The 2-bit binary number at the data select inputs S1 and S0 specifies which of the four data inputs is to be routed to the output Since there are two data select inputs therefore they can select 22 = 4 different data inputs lines

                                  S0 S1 D0 D1

                                  D2 D3

                                  Data-select Inputs Output

                                  Data Inputs

                                  Figure 61 Block Diagram of a 4 x1 Multiplexer

                                  30

                                  Logic Design amp Switching Theory 1 lab Session 06 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                  Figure 62 Circuit Diagram for 4 x 1 Multiplexer

                                  Implementation and Observations

                                  Implement the 4 x 1 Multiplexer circuit (figure 62) on a bread board (prepare the pin diagram (use appendix A) and refer to laboratory session 01 for implementation procedure) and record the observations in the following table For each data select combination specify the switch number as well as the binary value present on that selected switch

                                  S1 S0 Output 0 0 0 1 1 0 1 1

                                  TESTING OF 74150 - 16 x 1 MUX

                                  The 74150 IC has sixteen data inputs and four data-selection lines Function of various pins of this IC is described below

                                  bull E0 through E15 Data input lines

                                  31

                                  Logic Design amp Switching Theory 1 lab Session 06 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering bull A B C D Data select lines with D being the MSB bull W Active low output line bull Grsquo Active low enable line bull VCC and GND Supply connections lines

                                  Circuit Diagram

                                  Figure 63 Pin connections of 74150 for selecting E0

                                  Testing Procedure

                                  bull Make connections as shown in the circuit diagram bull Apply different data (1 or 0) at data inputs that are labeled as E0 to E15 Only

                                  connection for E0 is shown is the figure for simplicity bull Select the data input E0 with the help of data selectors A B C and D bull Observe the output which shows the complement of the data from E0 bull Select all the sixteen data inputs one by one and record your observations in the

                                  following table

                                  32

                                  Logic Design amp Switching Theory 1 lab Session 06 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                  33

                                  Observations

                                  Grsquo D C B A W Grsquo D C B A W 0 0 0 0 0 0 1 0 0 0 0 0 0 0 1 0 1 0 0 1 0 0 0 1 0 0 1 0 1 0 0 0 0 1 1 0 1 0 1 1 0 0 1 0 0 0 1 1 0 0 0 0 1 0 1 0 1 1 0 1 0 0 1 1 0 0 1 1 1 0 0 0 1 1 1 0 1 1 1 1

                                  ACTIVITY 1 Consider 4x1 Multiplexer Draw the output wave-form for the following data inputs

                                  (E0 E1 E2 E3) and select lines A B (B being the MSB) Output is W

                                  E3 E2 E1 E0 A B

                                  W

                                  2 Using the 4 x 1 MUX designed in this laboratory session implement the following logical function F (A B C) = Σ (0147)

                                  Show your working and input connections in the following block diagram according to the circuit you have implemented

                                  4 x 1 MUX

                                  S0 S1

                                  Output D0

                                  D1

                                  D2

                                  D3

                                  Logic Design amp Switching Theory 1 Lab Session 07 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                  Lab Session 07

                                  OBJECT

                                  bull Designing of a 2 x 4 Decoder 1 x 4 Demultiplexer bull Experimenting with 74138 IC

                                  COMPONENTS AND APPARATUS REQUIRED 1 Following ICs and their Datasheets

                                  bull 7408 Quad 2-input or 7411 Triple 3-input AND Gates bull 7404 Hex Inverter bull 74138 3 x 8 Decoder

                                  2 Digital Trainer DT-01 or the following components Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches THEORY

                                  Decoder A Decoder is a combinational circuit that converts binary information form n input lines to a maximum of 2n unique output lines In practical applications decoders are often used for selecting one of several devices

                                  Demultiplexer A decoder with an enable input can function as a Demultiplexer A Demultiplexer (DMUX) id a circuit that receives information on a single line and transmits this information on one of 2n possible output lines The selection of a specific output line is controlled by the bit values of n selection lines DESIGN OF A 2 x 4 DECODER 1 x 4 DEMULTIPLEXER A 2 x 4 decoder is capable of selecting one of four output lines (see figure 71 (a)) The 2-bit binary number at the data inputs S1 and S0 specifies which of the four data inputs is to be selected If we add an enable pin and use it as an input line then this decoder can be converted to a 1 x 4 Demultiplexer where S1 and S0 will select a line to which data input is to be routed (see figure 71 (b))

                                  Select S0 S0 Inputs

                                  S1 D0 D1

                                  D2

                                  D3

                                  Enable (a) Block Diagram of a 2 x 4 Decoder

                                  Figure 71

                                  S1 D0 D1

                                  D2

                                  D3

                                  Inputs

                                  Data Input (b) Block Diagram of a 1 x 4 Demulptiplexer

                                  34

                                  Logic Design amp Switching Theory 1 Lab Session 07 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                  Figure 72 Circuit Diagram for 2 x 4 Decoder 1 x 4 Demultiplexer

                                  Implementation and Observations Implement the 2 x 4 Decoder 1 x 4 Demultiplexer circuit (figure 72) on a bread board (prepare the pin diagram (use appendix A) and refer to laboratory session 01 for implementation procedure) and record the observations in the following table

                                  Enable Data Input S1 S0 D0 D1 D2 D3

                                  0 0 0 0 0 1 0 1 0 0 1 1 1 0 0 1 0 1 1 1 0 1 1 1

                                  TESTING OF 74138 3 x 8 Decoder The 74138 IC has three inputs and eight output lines It has three enable inputs and for the IC to function all three inputs need to be enabled Function of various pins of this IC is described below

                                  35

                                  Logic Design amp Switching Theory 1 Lab Session 07 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                  bull Y0 through Y7 Active low data outputs bull A B C Input select lines with C being the MSB bull G1 Active high enable Input bull G2Arsquo and G2Brsquo Active low enable Inputs bull VCC and GND Supply connections lines Circuit Diagram

                                  Figure 73 Pin connections of 74138

                                  Testing Procedure

                                  bull Make connections as shown in the circuit diagram bull Apply different combinations of 1s and 0s at data inputs bull Observe the output and record your observations in the following table

                                  Observations

                                  C B A Y0 Y1 Y2 Y3 Y4 Y5 Y6 Y7 0 0 0 0 0 1 0 1 0 0 1 1 1 0 0 1 0 1 1 1 0 1 1 1

                                  36

                                  Logic Design amp Switching Theory 1 Lab Session 07 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                  37

                                  ACTIVITY ACTIVITY 1 What will be the binary values at the outputs Y0 through Y7 of 74138 if 1 What will be the binary values at the outputs Y0 through Y7 of 74138 if

                                  bull All three enable pins are connected to ground bull All three enable pins are connected to ground __________________________________________________________________________________________________________________________________________ __________________________________________________________________________________________________________________________________________ _____________________________________________________________________ _____________________________________________________________________

                                  bull All three enable pins are connected to VCC bull All three enable pins are connected to VCC _______________________________________________________________________________________________________________________________________________________________________________________________________________

                                  _______________________________________________________________________________________________________________________________________________________________________________________________________________

                                  2 Show connections for 74138 in order to use it as a 1 x 8 Demultiplexer 2 Show connections for 74138 in order to use it as a 1 x 8 Demultiplexer

                                  3 Consider a 2 x 4 Decoder with two enable inputs (one active high - G and one active low ndash Grsquo) Draw the output wave-forms for D0 D1 D2 and D3 if the two select inputs are A and B (B being the MSB) All outputs are active low

                                  Grsquo

                                  G

                                  A B

                                  D0 D1 D2

                                  D3

                                  Logic Design amp Switching Theory 1 Lab Session 08 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                  Lab Session 08 OBJECT

                                  bull Designing of a 4 x 2 Priority Encoder bull Experimenting with 74148 IC

                                  COMPONENTS AND APPARATUS REQUIRED

                                  1 Following ICs and their Datasheets

                                  bull 7408 Quad 2-input or 7421 Dual 4-input AND Gates bull 7432 Quad 2-input OR Gates bull 7404 Hex Inverter bull 74148 Encoder

                                  2 Digital Trainer DT-01 or the following components Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches

                                  THEORY

                                  Encoder An Encoder is a digital function that produces a reverse operation from that of a decoder An Encoder has 2n (or less) input lines and n output lines The output lines generate the binary code for the 2n input variables Priority Encoder

                                  A simple encoder may produce an erroneous output if more than one of its inputs is high A Priority Encoder is one that responds to just one input among those that may be simultaneously high in accordance with some priority system The most common priority system is based on the relative magnitudes of the inputs whichever decimal input is largest is the one that is encoded

                                  DESIGN OF A 4 x 2 Priority Encoder

                                  The following equations represent the outputs of a 4 x 2 priority encoder 32 DDA +=

                                  321 DDDB += As can be seen from the equations that input D0 which has a binary code 00 is not used in any equation A binary code 00 at the output indicates two conditions Either D0 is selected or no input is selected In order to differentiate these two conditions we will provide an additional output Z to indicate if at least one of the inputs is a 1 The equation for Z will be

                                  4321 DDDDZ = If Z is 0 then the binary code 00 at the output indicates that D0 is selected and if Z is 1 then it indicates that no input line is selected

                                  38

                                  Logic Design amp Switching Theory 1 Lab Session 08 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                  Figure 81 Circuit Diagram for 4 x 2 Priority Encoder

                                  it (figure 81) on a bread board (prepare the to laboratory session 01 for implementation

                                  Implementation a Implement the 4 x 2 Priority Encoder circu

                                  ram (use appendix A) and refer

                                  nd Observations

                                  pin diagprocedure) and record the observations in the following table

                                  D3 D2 D1 D0 A B 0 0 0 1 0 0 1 x 0 1 x x 1 x x x

                                  TESTING OF 74148 8 x 3 Octal Priority Encoder

                                  imal digits There are nine of which three represents

                                  ing any of the inputs is high

                                  then it shows that line 0 is selected and if e inputs selected E0 and GS

                                  cannot be in the same state provided that E1 is enabled

                                  The 74148 is a priority encoder with active-Low input for dec

                                  input) and five output linesinputs lines (including an enablethe binary code for the octal digit Function of various pins of this IC is described below

                                  bull 0 through 7 Active low data inputs representing the octal digits A2 A1 A0 Active low output lines representing the binary code bullbull E1 Active low enable Input bull E0 Active low output indicating none of the inputs is high bull GS Active low output indicatbull VCC and GND Supply connections lines Therefore if GS A2 A1 and A0 are all low

                                  then it shows that none of thE0 A2 A1 and A0 are all low

                                  39

                                  Logic Design amp Switching Theory 1 Lab Session 08 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                  Circuit Diagram

                                  Figure 82 Pin connections of 74148

                                  Testing Procedure bull Make connections as sho

                                  binations of 1s and 0s at data inputs d record your observations in the following table

                                  GS E0

                                  wn in the circuit diagram bull Apply different combull Observe the output an Observations

                                  0 1 2 3 4 5 6 7 A2 A1 A0 1 1 1 1 1 1 1 1 x x x x x x x 0 x x x x x x 0 1 x x x x x 0 1 1 x x x x 0 1 1 1 x x x 0 1 1 1 1 x x 0 1 1 1 1 1 x 0 1 1 1 1 1 1 0 1 1 1 1 1 1 1

                                  40

                                  Logic Design amp Switching Theory 1 Lab Session 08 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                  41

                                  CTIVITY

                                  Cascade the following two 74148 8 x 3 Priority Encoders to form 16 x 4 Priority

                                  A 1

                                  Encoder

                                  Logic Design amp Switching Theory 1 Lab Session 09 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering `

                                  Lab Session 09 OBJECT

                                  Designing an Odd Parity Generator and Checker for a 3-bit Data COMPONENTS AND APPARATUS REQUIRED

                                  1 Following ICs and their Datasheets

                                  bull 7486 Quad 2-input Exclusive-OR Gates bull 7404 Hex Inverter

                                  2 Digital Trainer DT-01 or the following components Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches

                                  THEORY

                                  Parity Generator When binary data is transmitted and processed it is ndash as are all electrical signals ndash susceptible to noise that can either alter or distort its contents 1s may be effectively changed to 0s and 0s to 1s To overcome this problem one or more bits are often added to the data as an aid in detecting errors caused by noise The most common of these is a Parity bit that signifies whether the total number of 1s in a code group is odd or even In an Odd Parity system the parity bit is made 0 or 1 as necessary to make the total number 1s odd (counting the parity bit itself) In an Even Parity system the parity bit is chosen to make the total number of 1s even Table 91 shows how parity bits would be added to BCD code group in both systems

                                  Decimal BCD Value Parity Bit ABCD Odd Parity Even Parity

                                  0 0000 1 0 1 0001 0 1 2 0010 0 1 3 0011 1 0 4 0100 0 1 5 0101 1 0 6 0110 1 0 7 0111 0 1 8 1000 0 1 9 1001 1 0

                                  Table 91 Odd and Even Parity in BCD

                                  When digital data is received a parity checking circuit generates an error signal if the total number of 1s is odd in an even parity system or if it is even in an odd parity system Parity check always detects a single error (one bit change from 0 to 1 or 1 to 0) but may not detect

                                  42

                                  Logic Design amp Switching Theory 1 Lab Session 09 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering ` two or more errors Odd parity is used more often than even parity because even parity does not detect a situation where all 0s are created due to short circuit or other fault condition DESIGN OF A 3-BIT ODD PARITY GENERATOR AND CHECKER Let x y and z be the three bits that constitute the message and are the input to the Odd Parity Generator Circuit Since it is an odd parity system the bit P is generated so as to make the total number of 1s odd (including P) The function P can be expressed as follows P = x oplus y Ο z or P = x Ο y oplus z Since the IC available is 7486 which is quad 2input XOR IC therefore we will convert XNOR also to XOR

                                  P = x oplus y Ο z

                                  P = ( x oplus y ) Ο z Since for even number of variables ______

                                  XOR = XNOR Therefore ___________ _________

                                  P = ( x oplus y ) oplus z = x oplus y oplus z This logical expression can be implemented with two XOR gates and an inverter (see figure 91)

                                  Figure 91 Circuit Diagram for a 3-bit Parity Generator

                                  The 3-bit message and the parity bit are transmitted to their destination where they are applied to a Parity Checker Circuit An error occurs during transmission if the parity of the four bits received is even since the binary information transmitted was originally odd The output C of the parity checker should be a 1 when an error occurs ie when the number of 1s in the four inputs is even Therefore the function C can be expressed as

                                  C = x Ο y Ο z Ο P

                                  Using the same logic applied for the conversion of the equation of P

                                  PzyxC oplusoplusoplus= This logical expression can be implemented with three XOR gates and an inverter (see figure 92)

                                  43

                                  Logic Design amp Switching Theory 1 Lab Session 09 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering `

                                  44

                                  Figure 92 Circuit Diagram for a 3-bit Parity Checker Implementation and Observations Implement the 3-bit Parity Generator and Checker circuits (figure 91 and 92) on a bread board (prepare the pin diagram (use appendix A) and refer to laboratory session 01 for implementation procedure) and record the observations in the following table

                                  x y z P x y z P C x y z P C 0 0 0 0 0 0 0 1 0 0 0 0 0 1 0 0 0 1 1 0 0 1 0 1 0 0 0 1 0 1 0 1 0 0 1 1 0 0 1 1 1 0 1 1 1 0 0 0 1 0 0 1 1 0 0 1 0 1 0 1 0 1 1 1 0 1 1 1 0 0 1 1 0 1 1 1 0 1 1 1 0 1 1 1 1 1 1 1

                                  Odd Parity Generation Odd Parity Check ACTIVITY 1 Try using the parity checker of figure 92 as 3-bit parity generator Write the details here

                                  _____________________________________________________________________________________________________________________________________________________________________________________________________________________ ______________________________________________________________________________________________________________________________________________ _______________________________________________________________________ ______________________________________________________________________________________________________________________________________________

                                  Logic Design amp Switching Theory 1 Lab Session 10 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                  Lab Session 10 OBJECT

                                  Driving a seven segment display using 7447 7448 driver IC COMPONENTS AND APPARATUS REQUIRED

                                  1 Following ICs and their Datasheets

                                  bull Seven Segment Displays (Common Anode Common Cathode) bull 7447 7448 BCD to Seven Segment Driver

                                  2 Digital Trainer DT-01 or the following components Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches

                                  THEORY Seven Segment Displays A Seven Segment Display consists of seven light-emitting segments The segments are designated by letters a through g (see figure 101) By illuminating various combinations of segments the numerals 0 through 9 can be displayed Seven Segment Displays are commonly constructed with light-emitting diodes (LEDs) and with liquid-crystal displays (LCDs) LEDs generally provide greater illumination levels but require much greater power than LCDs An LED display can be a common-anode type or common cathode type In common anode type a high voltage is applied at the common terminal of the display and low voltage is applied at a segmentrsquos terminal for illumination In the common-cathode type a low voltage is applied at the common terminal of the display and high voltage is applied at a segmentrsquos terminal for illumination

                                  Figure 101 Seven Segment Display

                                  a f b g

                                  e c d

                                  7447 7448 BCD to Seven Segment Driver 7447 7448 IC is particularly used to drive Seven Segment Its input is a BCD number and output drives a seven segment display 7447 is used to drive common-anode displays whereas 7448 is used to drive common cathode displays 7447 7448 is a 16 pin IC Function of various pins of these ICs is described below

                                  bull A B C D Inputs representing BCD digits (D being the MSB)

                                  45

                                  Logic Design amp Switching Theory 1 Lab Session 10 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering bull OA through OG Outputs to drive segments a through g of the display (Active low

                                  in 7447 and active high in 7448) bull RBI Ripple Blanking Input Turns off all the segments if kept low provided that LT

                                  is kept high and all other inputs (A B C D BI) are kept low Should be kept high otherwise

                                  bull BI RBO Wire-AND logic serving as a Blanking Input and or Ripple Blanking Output

                                  o BI Turns off all the segments if low o RBO Goes to a low level (response condition) along with other outputs when

                                  RBI and inputs A B C and D are low with LT input at high level bull LT Lamp Test input Tests whether all segments are working or not Illuminates all

                                  segments if kept low provided that BI is kept high Should be kept high otherwise bull VCC and GND Supply connections lines CIRCUIT DIAGRAM

                                  Figure 102 Circuit diagram for 7447driving a common-anode display

                                  IMPLEMENTATION AND OBSERVATIONS

                                  bull Make connections as shown in the circuit diagram (refer to laboratory session 01 for implementation procedure)

                                  bull Apply different combinations of 1s and 0s at data inputs bull Observe the output and record your observations in the following table

                                  46

                                  Logic Design amp Switching Theory 1 Lab Session 10 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                  47

                                  Decimal Digit

                                  BCD Inputs Seven Segment Outputs D C B A a b c d e f g

                                  0 0 0 0 0 1 0 0 0 1 2 0 0 1 0 3 0 0 1 1 4 0 1 0 0 5 0 1 0 1 6 0 1 1 0 7 0 1 1 1 8 1 0 0 0 9 1 0 0 1

                                  ACTIVITY 1 Perform the Lamp Test for the designed circuit and write your observations

                                  ____________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________

                                  2 How can you use 7447 IC to drive a common-cathode display

                                  ____________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________

                                  3 What symbols appear in the seven segment display if inputs DCBA are

                                  DCBA Symbol

                                  1010

                                  1011

                                  1100

                                  1101

                                  1110

                                  1111

                                  Logic Design amp Switching Theory 1 Lab Session 11 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                  48

                                  Lab Session 11 OBJECT

                                  Testing different modes of JK-FF COMPONENTS AND APPARATUS REQUIRED 1 Following ICs and their Datasheets

                                  bull 7473 7476 JK Flip-Flop 2 Digital Trainer DT-01 or the following components

                                  Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches

                                  THEORY

                                  Flip-Flop A flip-flop circuit can maintain a binary state indefinitely (as long as the power is delivered to the circuit) until directed by an input signal to switch states The major differences among various types of flip-flops are in the number of inputs they possess and in the manner in which the inputs affect the binary state

                                  JK Flip-Flop JK flip flop is an edge triggered device A typical JK flip flop has three inputs J K and a clock input The flip-flop can be either positive or negative edge triggered The output Q is available in complemented form as well Beside the usual inputs and output most of the flip-flop IC also possess two asynchronous inputs namely Preset and Clear These inputs are usually active low If used Preset and Clear inputs keep the flip-flop in set and reset state respectively irrespective of the other inputs Both of these inputs cannot be used simultaneously otherwise they will bring the flip-flop in unstable state

                                  Figure 111 Symbol for JK flip-flop

                                  (a) positive-edge triggering (b) active low Preset (PR) and Clear (CLR) with positive-edge triggering

                                  (c) active low Preset (PR) and Clear (CLR) with negative-edge triggering

                                  Logic Design amp Switching Theory 1 Lab Session 11 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                  49

                                  TESTING OF 7473 7476 DUAL JK FLIP-FLOP

                                  Both the ICs 7473 and 7476 are similar in functionality except for one difference The flip-flops in 7473 have only one type of active low asynchronous input which is the Clear input whereas the flip-flops in 7476 have both Preset and Clear inputs Both these ICs have negative edge triggered flip-flops

                                  Circuit Diagram

                                  Figure 112 Pin connections of 7476

                                  Testing Procedure

                                  bull Make connections as shown in the circuit diagram (figure 112) bull Apply different combinations of 1s and 0s at J and K inputs bull Observe the output and record your observations in the following table

                                  Observations

                                  J

                                  K Q

                                  0 0 0 1 1 0 1 1

                                  ACTIVITY

                                  1 Observe the output Q of JK flip-flop if the clock input is connected to VCC or GND instead of a clock source Write your observations here __________________________________________________________________________________________________________________________________________ _______________________________________________________________________________________________________________________________________________________________________________________________________________

                                  Logic Design amp Switching Theory 1 Lab Session 12 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                  50

                                  Lab Session 12 OBJECT

                                  Designing sequential circuit for the given state diagram using D flip-flop GIVEN STATE DIAGRAM

                                  00

                                  11

                                  Figure 121 State Diagram COMPONENTS AND APPARATUS REQUIRED 1 Following ICs and their Datasheets

                                  bull 7474 D Flip-Flop bull ICs of basic gates (AND OR NOT XOR etc) as required

                                  2 Digital Trainer DT-01 or the following components Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches

                                  THEORY

                                  Sequential Circuits In Sequential Circuits the output not only depends on the present inputs but also on previous states of the circuit These circuits use memory elements (latches flip-flops) and the binary information stored in the memory elements at any given time defines the state of the sequential circuit Analysis of a Sequential Circuit The behavior of a sequential circuit is determined from the inputs the outputs and the states of its flip-flops Both the outputs and next state are a function of the inputs and the

                                  10

                                  01

                                  00 11 10

                                  00

                                  00 11 10 00

                                  Logic Design amp Switching Theory 1 Lab Session 12 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                  51

                                  present state The analysis of a sequential circuit form a state diagram comprises of the following bull Selecting a particular flip-flop to design the circuit bull Obtaining state table from the state diagram bull Finding input equations for the selected flip-flop bull Finding state equations (not required for the construction of circuit) bull Implementing the circuit using selected flip-flops and their input equations ANALYZING THE GIVEN STATE DIAGRAM D Flip-Flop D flip-flop is also called transparent flip-flop as it simply transfers the input data to the output For our design we require the graphical symbol and excitation table of D flip-flop (see figure 122)

                                  Qt Qt+1 T 0 0 0 0 1 1 1 0 0 1 1 1

                                  (b) Excitation table of D Flip-Flop

                                  (a) Graphical Symbol

                                  Figure 122 Characteristic equation of D flip-flop is Q(t+1) = D State Table The given state diagram has four states so we will need two D flip-flops (FF-0 FF-1) Form state table form the given state diagram and record the results in the following table

                                  Present State Input Next State Output Input to FF-0 D0

                                  Input to FF-1 D1 Q1t Q0t x Q1(t+1) Q0(t+1) z

                                  Logic Design amp Switching Theory 1 Lab Session 12 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                  52

                                  Input Equations Using Karnaugh map the input equations D0 and D1 for the two flip-flops can be found

                                  D0 D1 Q0x

                                  Q1

                                  _ _ Q0x

                                  _ Q0x

                                  Q0x

                                  _ Q0x

                                  Q0x

                                  Q1

                                  _ _ Q0x

                                  _ Q0x

                                  Q0x

                                  _ Q0x

                                  _ Q1

                                  _ Q1

                                  Q1

                                  Q1

                                  D0 = _________________ D1 = _________________

                                  State Equations Using the characteristic equation of D flip-flop we can find the state equations Q0(t+1) and Q1(t+1) for the to flip flops Q0(t+1) = _______________________ Q1(t+1) = _______________________ _______________________ _______________________ _______________________ _______________________ Circuit Diagram

                                  Logic Design amp Switching Theory 1 Lab Session 12 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                  53

                                  Implementation Procedure and Observations

                                  1 Implement the circuit using digital ICs on a bread board (prepare the pin diagram (use appendix A) and refer to laboratory session 01 for procedure)

                                  2 Make the clear inputs of the flip-flops low (to clear the flip-flops) The flip-flops will remain in clear state as long as the clear inputs are connected to low level

                                  3 Connect output Q0 and the clock pulse to an oscilloscope 4 Apply 0 to the input x 5 Now make the clear inputs to high 6 Observe the waveform for the first 5 clock pulses and record it 7 Repeat steps 2 to 6 keeping x=1 in step 4 this time 8 Repeat steps 2 to 7 this time connecting Q1 instead of Q0 to the oscilloscope in step

                                  3 Record your observations (Keep frequency of the clock pulse low (eg1Hz) so that the output waveforms can be observed easily)

                                  1 2 3 4 5 Clock Pulse

                                  Output Waveform for Q0 when x=0

                                  Output Waveform for Q0 when x=1

                                  Output Waveform for Q1 when x=0

                                  Output Waveform for Q1 when x=1

                                  Logic Design amp Switching Theory 1 Lab Session 13 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                  Lab Session 13 OBJECT

                                  Designing a modulo-5 asynchronous up-counter using JK-FF COMPONENTS AND APPARATUS REQUIRED

                                  1 Following ICs and their Datasheets

                                  bull 7400 Quad 2-input or 7410 Triple 3-input NAND Gates bull 7476 7473 JK Flip-Flop

                                  2 Digital Trainer DT-01 or the following components Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches

                                  THEORY

                                  Digital Counters A digital counter is a set of flip-flops whose states change in response to pulses applied at the input to the counter The flip-flops are interconnected so that their combined state at any time is the binary equivalent of the total number of pulses that have occurred up to that time Every counter resets after a certain number of clock pulses Thus as it name implies a counter is used to count pulses An n stage counter can count up to a maximum of 2n states n is equal to the number of flip-flops required for the construction of counter

                                  Modulus Counters The number of input pulses that causes a counter to reset to its initial count is called the modulus of the counter Thus the modulus equals to total number of distinct states (counts) including zero that a counter can store A binary counter with n stages is a modulo-2n (or mod-2n) counter The largest count a mod-N counter can achieve is N-1 ie a mod-N counter never reaches the binary number equal to its modulus N is always equal to or less than 2n Counters can be classified as bull Synchronous Counters which are clock driven All the flip-flops are driven by a

                                  single clock bull Asynchronous Counters which are event driven Clock input is given to the first

                                  flip-flop only Rest of the flip-flops are driven by their preceding flip-flops

                                  DESIGN OF A MOD-5 ASYNCHRONOUS UP COUNTER The number of flip-flops required to construct a mod-5 counter is 3 because 5 should be less than or equal to 2n This counter will count from 0 to 4 a total of 5 distinct states Since a 3-stage counter can count up to 8 states at maximum a NAND gate is used to reset it after 5 clock pulses Figure 131 shows the logic diagram

                                  54

                                  Logic Design amp Switching Theory 1 Lab Session 13 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                  55

                                  Figure 131 A Mod-5 Asynchronous Up Counter

                                  Implementation and Observations

                                  Implement the mod-5 counter circuit (figure 131) on a bread board (prepare the pin diagram (use appendix A) and refer to laboratory session 01 for implementation procedure) and record the observations in the following table

                                  Clock Pulse Q2 Q1 Q0

                                  0 1 2 3 4 5 6 7

                                  ACTIVITY

                                  Draw the timing diagram for mod-5 counter designed in this laboratory session

                                  Logic Design amp Switching Theory 1 Lab Session 14 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                  Lab Session 14 OBJECT

                                  Experimenting with 74194 4-bit bidirectional universal shift register COMPONENTS AND APPARATUS REQUIRED

                                  1 Following ICs and their Datasheets

                                  bull 74194 4-bit bidirectional universal shift register 2 Digital Trainer DT-01 or the following components

                                  Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches

                                  THEORY

                                  Shift Registers

                                  A Register is a set of flip-flops used to store binary data A register which is capable of shifting its binary information either to the right or left is called a shift register The logical configuration of a register consists of a chain of flip-flops connected in cascade with the output of one flip-flop connected to the input of next flip-flop All flip-flops receive a common clock pulse which causes the shift from one stage to the next

                                  Bidirectional Shift Registers A bi-directional shift register is one whose bits can be shifted from left to right or from right to left

                                  Universal Shift Registers A universal shift register is a bi-directional register whose input can be in either serial or parallel form and whose output can be in either serial or parallel form

                                  74194 4-BIT BIDIRECTIONAL UNIVERSAL SHIFT REGISTER

                                  The 74194 register provides parallel as well as serial loading in both directions Function of various pins of this IC is described below

                                  bull A B C and D Active high inputs for parallel loading bull QA QB QC and QD Active high outputs bull S0 and S1 Active high mode control inputs The following table shows combinations

                                  of S1 and S0 to enable various modes

                                  S1 S0 Clock Action 0 0 x No change 0 1 uarr Shift right 1 0 uarr Shift left 1 1 uarr Parallel load

                                  uarr shows the rising edge of the clock pulse

                                  56

                                  Logic Design amp Switching Theory 1 Lab Session 14 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering bull SR Active high serial input for right shifting bull SL Active high serial input for left shifting bull CLR Active low input Clears all the flip-flops of the register if set to 0 should be

                                  kept high otherwise bull CLK Clock input bull VCC and GND Supply connections lines Thus A B C and D are inputs for parallel loading whereas SR and SL are inputs for serial loading with right or left shifting respectively S1 and S0 are used to select the loading mode Circuit Diagram

                                  Figure 141 Pin connections of 74194 Testing Procedure

                                  bull Make connections as shown in the circuit diagram bull Observe the output for the input combinations given in the following table

                                  57

                                  Logic Design amp Switching Theory 1 Lab Session 14 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                  58

                                  Observations

                                  S1 S0 SL SR A B C D QA QB QC QD 0 0 0 1 0 0 0 0 0 1 1 0 0 0 0 1 1 0 0 0 0 0 1 0 1 1 0 0 0 0 1 1 0 0 1 1 0 1 0 0 0 1 1 1 0 1 0 1 1 0 1 0 0 1 1 0 1 1 1 0 0 1 1 1 1 1 0 0 1 1 1 1

                                  ACTIVITY 1 Show connections of 74194 to convert it into a ring counter with right shifting

                                  Logic Design amp Switching Theory 1 Lab Session 15 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                  Lab Session 15

                                  OBJECT

                                  Experimenting with 74245 octal bus transceivers using parallel port PC interfacing COMPONENTS AND APPARATUS REQUIRED 1 Parallel Port Connectors (DB-25) with Cable 2 Personal Computer with Windows 98 and TurboC Compiler Installed 3 Following ICs and their Datasheets

                                  bull 74245 Octal Bus Transceivers with 3-State Outputs 4 Digital Trainer DT-01 or the following components

                                  Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches

                                  THEORY

                                  3-State Logic Sometimes it is necessary to isolate one part of circuit from the other part For this purpose some TTL ICs are designed with 3-state logic Such devices have three possible output states high low and high impedance The device can be put into high impedance state by a control signal applied to an appropriate pin When such a device is in high impedance state there is very high impedance at its output effectively isolating the device from whatever circuitry the output normally drives 74245 Octal Bus Transceivers A bus is any conducting path or set of paths having electrical connections to one or more devices 74245 octal bus transceivers are mainly used to control connectivity between two devices or circuits It also provides direction control for signal flow Function of various pin of this IC is given below

                                  bull A1 through A8 Bus A bull B1 through B8 Bus B bull G΄ Active low enable input When high sets all the bus pins to high impedance state bull DIR Direction control for signal flow When set to high logic level transfers bus A

                                  data to B bus When set to low logic level transfers bus B data to A bus bull VCC and GND Supply connections lines Serial and Parallel Port Connectors A Parallel Port can consist of only 25 pin port adapter called a DB-25 and a serial port can consist of either a 25 pin port adapter called a DB-25 or 9 pin adapter called a DB-9 port adapter Whether the port is a 9 pin or 25 pin it can accomplish all of the same tasks that serial port communications have been designed for

                                  59

                                  Logic Design amp Switching Theory 1 Lab Session 15 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                  60

                                  Each adapter can be a male type connector with pins or a female type adapter with tiny holes Generally a PRINTER port (called LPT1) on the back of a computer is female type adapter and we need to use MALE DB-25 pin cable on it for PRINTER connection or for parallel LAPLINK cable And a COM port on the back of a computer is male for the serial ports but it may not necessarily be Parallel Port Connector ndash DB-25 The DB-25 connector (named for its B-size D-shaped shell and 25 pins) is practically ubiquitous in the electronics industry The DB-25 connector is used for a variety of purposes Two common applications are RS-232EIA-232 (serial) connections and the parallel printer interface on the IBM PC The DB-25 connector is also used for SCSI connections Normally the parallel port is used for output to a printer or other device It sends data 8-bits or one byte at a time in parallel The other lines available on the DB-25 connector are a combination of status lines control lines and ground lines The status and control lines are used for handshaking commands and feedback when we are talking to a printer

                                  Figure 152 DB-25 Female Figure 151 DB-25 Male

                                  Figure 153 Pin Layout for DB-25 As can be seen form figure 153 there are four types of pins in this connector

                                  bull Data pins (8 pins - D0 to D7) Active high bidirectional lines

                                  Logic Design amp Switching Theory 1 Lab Session 15 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering bull Control pins (4 pins - C0 to C3) C0 C1 and C3 are active low whereas C2 is active

                                  high These lines also are bidirectional bull Status pins (5 pins ndash S3 to S7) Only S7 is active low rest are active high input lines bull Ground pins (8 pins) Used as a reference signal for the low (below 05 volts) charge

                                  Parallel Port Addresses A DB-25 connector at a parallel port has three address one for each kind of pins register data status and control The first or base address generally refers to data register Second address is for status register and the third one is for control register In Windows 98 the base address is usually found to be 278H 378H or 3BCH Now if 378H is the base address then it refers to the data register whereas addresses for status and control register are respectively 379H and 37AH For Windows 98 the base address can be found as follows 1 On your Desktop right-click on My Computer and select Properties 2 Click on the Device Manager tab and find LPT1 under Plug and Play BIOS 3 After selecting LPT1 click the Properties button 4 Next select the Resources tab and the address should then appear next to InputOutput

                                  Range Accessing parallel port through C Language Programming There are multiple functions in C Language for accessing external ports The most commonly used are listed below

                                  bull unsigned char inportb(int portid) inportb reads a byte from a hardware port

                                  bull int inport(int portid) reads a word from a hardware port

                                  bull void outportb(int portid unsigned char value) outputs a byte to a hardware port

                                  bull void outport(int portid int value) outputs a word to a hardware port

                                  portid refers to the port address whereas value refers to the data to be sent TESTING 74245 USING PARALLEL PORT PC INTERFACING At one end the parallel port connector will be connected to the PC via parallel port cable and another connector (to be plugged into the PC parallel port slot) At the other end it will be connected to the buffer IC 74245 Data lines of the connector will be used to transfer 8-bit data between the PC and the buffer Out of the 8-bits of 74245 4-bits will be used to enter data which will be displayed at the monitor through a C language

                                  61

                                  Logic Design amp Switching Theory 1 Lab Session 15 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering program The remaining 4-bits will receive data from PC as entered by the user via keyboard

                                  Circuit Diagram

                                  Figure 154 Interface of 74245 to PC via Parallel Port

                                  Procedure

                                  1 Connect the DB-25 connector to the PC at one end and solder it to the circuit board at the other end

                                  2 Connect various pins of the connector and 74245 according to the circuit diagram shown in figure 152

                                  3 Using the functions listed in the previous section write a program in C language to operate various pins of the buffer The user interface of the program should provide option to the user whether to send or receive data from the port

                                  4 Set DIR switch to 1 5 Try sending some data bits to the port The result should be displayed at the LEDs 6 Set DIR switch to 0 7 Set some binary 4-bit value through the switches Try reading it via parallel port

                                  C Language Program

                                  A program to access parallel port for data transfers

                                  use header file include ltstdiohgt main program void main() define variable

                                  62

                                  Logic Design amp Switching Theory 1 Lab Session 15 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering unsigned int data=0 char choice while(1) printing option menu clrscr() printf(This program will send or receive a BCD digit from the parallel portn) printf(nPress your choice numbern) printf(n1 Send Data) printf(n2 Receive Data) printf(n3 Exitn) choice = getch() sending entered digit to the port if(choice == 1) input BCD digit printf(nEnter BCD digit to be sent to the port) data = getche() masking the first four bits data = data amp 0x0f sending to the port outportb(0x378data) printf(nThe BCD digit c has been sent to the port data) printing on screen the data received from the port else if(choice == 2) receiving data from the port data = inportb(0x378) masking the last four bits data = data amp 0xf0 shifting first four bits to make them the last four bits datagtgt=4 printf(nThe BCD digit set at the port is c data) exit else if(choice == 3) break key pressed is not in the menu else printf(nEnter valid choice number) printf(nnPress any key to continue) getch()

                                  63

                                  Logic Design amp Switching Theory 1 Lab Session 15 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                  ACTIVITY 1 In the above circuit DIR and G΄ inputs are hardwired Connect them to status or

                                  control pins of the parallel port connector and control their function through your software program Circuit Diagram Program Code ______________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________

                                  ___________________________________________________________________________________________________________________________________________________

                                  64

                                  Logic Design amp Switching Theory 1 Lab Session 15 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                  65

                                  _____________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ _____________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ _______________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ _________________________________________________ _________________________________________________

                                  Logic Design amp Switching Theory 1 Appendix A NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                  Appendix A

                                  PIN DIAGRAMS OF THE ICS REQUIRED FOR THE LABORATORY SESSIONS Consult the TTLIC data book for internal diagrams and electrical characteristics of these ICs 7400 Quad 2-Input NAND 7402 Quad 2-Input NOR

                                  7404 Hex Inverter 7408 Quad 2-Input AND

                                  7410 Triple 3-Input NAND 7411 Triple 3-Input AND

                                  7421 Dual 4-Input AND 7432 Quad 2-Input OR

                                  66

                                  Logic Design amp Switching Theory 1 Appendix A NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                  BCD-to-Seven Segm 7448 BCD-to-Seven Segment 7447 ent

                                  Decoder (15V OC) Decoder (2kΩ pull-up output)

                                  7473 Dual JK Flip-Flop 7474 Dual D-Type Flip-Flop

                                  7476 Dual JK Flop-Flop -Bit Binary Full Adder 7483 4 with Fast Carry

                                  86 Quad 2-Inpu 74138 3-to-8 Line 74 t Exclusive OR Decoder Demultiplexer

                                  67

                                  Logic Design amp Switching Theory 1 Appendix A NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                  68

                                  74148 8-to-3 Line 16-to-1 Line Data

                                  Priority Encoder 74150 Selector Multiplexer

                                  74245 Oct nsceivers Universal Shift Register (PIPO) (3-State)

                                  74194 4-Bit Bidirectional al Bus Tra

                                  Logic Design amp Switching Theory 1 Appendix B NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                  Appendix B

                                  DEBOUNCING CIRCUITRY FOR MECHANICAL SWITCHES Mechanical switches form the interface between human beings and computers or other digital systems For example a keyboard is a matrix of switches used to supply alphanumeric data to a computer Whatever the switch design it is a potential source of problems due to contact bounce The contact bounce creates a sense of narrow pulses when a switch is opened or closed An example of device whose operation would be adversely affected by contact bounce is a digital counter used to count the number of times a switch is depressed Eliminating the effects of contact bounce is called debouncing When data is entered into a computer via a keyboard a software debounce is often used This type of debouncing is a program that causes the computer to sample the switch terminal (ie to input data from it) many times in succession during the interval of time that contact bounce occurs If the data is sensed to be 1s (or 0s) for a specific number of consecutive samples then it is assumed that contact bounce has ended and the last value sensed is valid Hardware debouncing is the use of electronic circuitry to eliminate the effects of contact bounce There are numerous versions of such circuitry including those that use monostable multivibrators (one-shots) but the most straightforward is simply an RS latch Figure B1 shows the circuit When the switch is in position 1 R = 0 and S = 1 so the latch is set and the output (Q) is 1 When the switch is in position 0 R = 1and S = 0 so the latch is reset and the output is 0 When the switch is moved form one position to the other the latch changes state and bouncing occurs at either the R or the S input The bouncing does not affect the latch after it has change state An RS latch will remain set for example when its R input is 0 and its S input is alternately changed form 1 to 0

                                  Figure B1 Use of RS latch to debounce a mechanical switch

                                  69

                                  • 01-ldst-Outer title
                                    • Practical Workbook
                                    • Logic Design amp Switching Theory I
                                      • Dept of Computer amp Information Systems Engineering
                                        • NED University of Engineering amp Technology
                                        • Karachi ndash 75270 Pakistan
                                          • 02-ldst-inner Title
                                            • Practical Workbook
                                            • Logic Design amp Switching Theory I
                                              • Dept of Computer amp Information Systems Engineering
                                                • NED University of Engineering amp Technology
                                                • Karachi ndash 75270 Pakistan
                                                  • 03-ldst-general info
                                                  • 04-ldst-introduction
                                                  • 05-Table of Contents
                                                    • CONTENTS
                                                      • Lab Session No Object Page No
                                                      • 1
                                                      • Also implementing and testing the given circuit on a bread board
                                                        • Working with Electronics Workbench
                                                          • Driving a seven segment display using 7447 7448 driver IC
                                                            • Designing a modulus-5 asynchronous up-counter using JK-FF
                                                              • Experimenting with 74194 4-bit bidirectional universal shift register
                                                                  • 13
                                                                      • 06-ldst-Exp01
                                                                        • Lab Session 01
                                                                        • OBJECT
                                                                          • 1 Bread board
                                                                          • 2 5 V - power supply
                                                                          • 3 Multimeter
                                                                          • 4 Logic probe
                                                                          • 5 LEDs with resistors
                                                                          • 6 Connecting wires
                                                                          • 8 Following ICs and their datasheets
                                                                            • THEORY
                                                                              • Logic Gates
                                                                              • 1 The AND Gate ndash An AND gatersquos output is 1 if and only if all its inputs are 1 If A and B are two inputs to an AND gate then output F of the gate is given as F = AB
                                                                              • 2 The OR Gate - An OR gatersquos output is 1 if at least one of its input is 1 If A and B are two inputs to an OR gate then output F of the gate is given as F = A+B
                                                                              • 3 The NOT Gate (Inverter) ndash Its output is 1 when its input is 0 and its output is 0 when the input is 1 ie it complements a digital variable If A is the input to a NOT gate then output F of the gate is given as
                                                                              • 4 The NAND Gate ndash Its output is 1 if at least one of its input is 0 This gate performs the same logic as an AND gate followed by an inverter If A and B are two inputs to a NAND gate then output F of the gate is given as
                                                                                • 5 The NOR Gate - The output of a NOR gate is 1 if and only if all its inputs are 0 This gate performs the same logic function as an OR gate followed by an inverter If A and B are two inputs to a NAND gate then output F of the gate is given as
                                                                                    • DATA SHEETS
                                                                                      • Logic expression for the given logic diagram __________________________________
                                                                                          • 07-ldst-exp02
                                                                                            • Working with Electronics Workbench
                                                                                              • 08-ldst-exp03
                                                                                                • Designing Half and Full Adder Circuits
                                                                                                  • COMPONENTS AND APPARATUS REQUIRED
                                                                                                    • 1 Following ICs and their Datasheets
                                                                                                    • 7408 Quad 2-input AND Gate
                                                                                                    • 2 Digital Trainer DT-01 or the following components
                                                                                                      • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                      • Connecting wires Switches
                                                                                                        • THEORY
                                                                                                            • IMPLEMENTATION AND OBSERVATIONS
                                                                                                              • 09-ldst-Exp04
                                                                                                                • Lab Session 04
                                                                                                                • 1 Digital ICs and their Datasheets
                                                                                                                • 7408 Quad 2-input AND Gate
                                                                                                                • 2 Digital Trainer DT-01 or the following components
                                                                                                                  • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                  • Connecting wires Switches
                                                                                                                  • PROCEDURE
                                                                                                                  • REDUCTION OF LOGIC EXPRESSION USING KARNAUGH MAP
                                                                                                                  • OBSERVATIONS
                                                                                                                  • RESULT
                                                                                                                      • 10-ldst-Exp05
                                                                                                                        • Lab Session 05
                                                                                                                        • 1 Following ICs and their Datasheets
                                                                                                                        • 7408 Quad 2-input AND Gate
                                                                                                                        • 2 Digital Trainer DT-01 or the following components
                                                                                                                          • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                          • (100 Ω) Connecting wires Switches
                                                                                                                          • THEORY
                                                                                                                            • IMPLEMENTATION AND OBSERVATIONS
                                                                                                                              • 11-ldst-Exp06
                                                                                                                                • OBJECT
                                                                                                                                • 1 Following ICs and their Datasheets
                                                                                                                                • 7408 Quad 2-input AND Gates or 7411 Triple 3-input AND Gates
                                                                                                                                • 2 Digital Trainer DT-01 or the following components
                                                                                                                                  • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                  • Connecting wires Switches
                                                                                                                                    • Figure 62 Circuit Diagram for 4 x 1 Multiplexer
                                                                                                                                    • Implementation and Observations
                                                                                                                                      • Circuit Diagram
                                                                                                                                        • ACTIVITY
                                                                                                                                          • 12-ldst-exp07
                                                                                                                                            • 1 Following ICs and their Datasheets
                                                                                                                                            • 7408 Quad 2-input or 7411 Triple 3-input AND Gates
                                                                                                                                            • 2 Digital Trainer DT-01 or the following components
                                                                                                                                              • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                              • Connecting wires Switches
                                                                                                                                                • THEORY
                                                                                                                                                    • Figure 72 Circuit Diagram for 2 x 4 Decoder 1 x 4 Demultiplexer
                                                                                                                                                    • Implementation and Observations
                                                                                                                                                      • Circuit Diagram
                                                                                                                                                        • ACTIVITY
                                                                                                                                                          • 13-ldst-Exp08
                                                                                                                                                            • OBJECT
                                                                                                                                                            • 1 Following ICs and their Datasheets
                                                                                                                                                            • 7408 Quad 2-input or 7421 Dual 4-input AND Gates
                                                                                                                                                            • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                              • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                              • Connecting wires Switches
                                                                                                                                                                • THEORY
                                                                                                                                                                    • Figure 81 Circuit Diagram for 4 x 2 Priority Encoder
                                                                                                                                                                    • Implementation and Observations
                                                                                                                                                                      • Therefore if GS A2 A1 and A0 are all low then it shows that line 0 is selected and if E0 A2 A1 and A0 are all low then it shows that none of the inputs selected E0 and GS cannot be in the same state provided that E1 is enabled
                                                                                                                                                                      • Circuit Diagram
                                                                                                                                                                        • ACTIVITY
                                                                                                                                                                          • 14-ldst-exp09
                                                                                                                                                                            • OBJECT
                                                                                                                                                                            • 1 Following ICs and their Datasheets
                                                                                                                                                                            • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                              • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                              • Connecting wires Switches
                                                                                                                                                                                • THEORY
                                                                                                                                                                                  • Parity Generator
                                                                                                                                                                                    • Let x y and z be the three bits that constitute the message and are the input to the Odd Parity Generator Circuit Since it is an odd parity system the bit P is generated so as to make the total number of 1s odd (including P) The function P can be expressed as follows
                                                                                                                                                                                    • Figure 91 Circuit Diagram for a 3-bit Parity Generator
                                                                                                                                                                                      • C = x Ο y Ο z Ο P
                                                                                                                                                                                        • Implementation and Observations
                                                                                                                                                                                          • ACTIVITY
                                                                                                                                                                                              • 15-ldst-exp10
                                                                                                                                                                                                • Driving a seven segment display using 7447 7448 driver IC
                                                                                                                                                                                                • COMPONENTS AND APPARATUS REQUIRED
                                                                                                                                                                                                • 1 Following ICs and their Datasheets
                                                                                                                                                                                                • 7447 7448 BCD to Seven Segment Driver
                                                                                                                                                                                                • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                  • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches
                                                                                                                                                                                                    • THEORY
                                                                                                                                                                                                    • Seven Segment Displays
                                                                                                                                                                                                    • CIRCUIT DIAGRAM
                                                                                                                                                                                                    • Figure 102 Circuit diagram for 7447driving a common-anode display
                                                                                                                                                                                                        • IMPLEMENTATION AND OBSERVATIONS
                                                                                                                                                                                                          • Decimal Digit
                                                                                                                                                                                                          • BCD Inputs
                                                                                                                                                                                                          • Seven Segment Outputs
                                                                                                                                                                                                          • D
                                                                                                                                                                                                          • C
                                                                                                                                                                                                          • B
                                                                                                                                                                                                          • A
                                                                                                                                                                                                          • a
                                                                                                                                                                                                          • b
                                                                                                                                                                                                          • c
                                                                                                                                                                                                          • d
                                                                                                                                                                                                          • e
                                                                                                                                                                                                          • f
                                                                                                                                                                                                          • g
                                                                                                                                                                                                          • 0
                                                                                                                                                                                                          • 0
                                                                                                                                                                                                          • 0
                                                                                                                                                                                                          • 0
                                                                                                                                                                                                          • 0
                                                                                                                                                                                                          • 1
                                                                                                                                                                                                          • 0
                                                                                                                                                                                                          • 0
                                                                                                                                                                                                          • 0
                                                                                                                                                                                                          • 1
                                                                                                                                                                                                          • 2
                                                                                                                                                                                                          • 0
                                                                                                                                                                                                          • 0
                                                                                                                                                                                                          • 1
                                                                                                                                                                                                          • 0
                                                                                                                                                                                                          • 3
                                                                                                                                                                                                          • 0
                                                                                                                                                                                                          • 0
                                                                                                                                                                                                          • 1
                                                                                                                                                                                                          • 1
                                                                                                                                                                                                          • 4
                                                                                                                                                                                                          • 0
                                                                                                                                                                                                          • 1
                                                                                                                                                                                                          • 0
                                                                                                                                                                                                          • 0
                                                                                                                                                                                                          • 5
                                                                                                                                                                                                          • 0
                                                                                                                                                                                                          • 1
                                                                                                                                                                                                          • 0
                                                                                                                                                                                                          • 1
                                                                                                                                                                                                          • 6
                                                                                                                                                                                                          • 0
                                                                                                                                                                                                          • 1
                                                                                                                                                                                                          • 1
                                                                                                                                                                                                          • 0
                                                                                                                                                                                                          • 7
                                                                                                                                                                                                          • 0
                                                                                                                                                                                                          • 1
                                                                                                                                                                                                          • 1
                                                                                                                                                                                                          • 1
                                                                                                                                                                                                          • 8
                                                                                                                                                                                                          • 1
                                                                                                                                                                                                          • 0
                                                                                                                                                                                                          • 0
                                                                                                                                                                                                          • 0
                                                                                                                                                                                                          • 9
                                                                                                                                                                                                          • 1
                                                                                                                                                                                                          • 0
                                                                                                                                                                                                          • 0
                                                                                                                                                                                                          • 1
                                                                                                                                                                                                            • ACTIVITY
                                                                                                                                                                                                              • 16-ldst-exp11
                                                                                                                                                                                                                • Lab Session 11
                                                                                                                                                                                                                  • OBJECT
                                                                                                                                                                                                                  • COMPONENTS AND APPARATUS REQUIRED
                                                                                                                                                                                                                    • 1 Following ICs and their Datasheets
                                                                                                                                                                                                                    • 7473 7476 JK Flip-Flop
                                                                                                                                                                                                                    • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                      • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                                      • Connecting wires Switches
                                                                                                                                                                                                                        • THEORY
                                                                                                                                                                                                                            • Flip-Flop
                                                                                                                                                                                                                            • JK Flip-Flop
                                                                                                                                                                                                                              • Circuit Diagram
                                                                                                                                                                                                                                • Observations
                                                                                                                                                                                                                                  • ACTIVITY
                                                                                                                                                                                                                                      • 17-ldst-exp12
                                                                                                                                                                                                                                        • Lab Session 12
                                                                                                                                                                                                                                          • OBJECT
                                                                                                                                                                                                                                          • GIVEN STATE DIAGRAM
                                                                                                                                                                                                                                          • Figure 121 State Diagram
                                                                                                                                                                                                                                          • COMPONENTS AND APPARATUS REQUIRED
                                                                                                                                                                                                                                            • 1 Following ICs and their Datasheets
                                                                                                                                                                                                                                            • 7474 D Flip-Flop
                                                                                                                                                                                                                                            • ICs of basic gates (AND OR NOT XOR etc) as required
                                                                                                                                                                                                                                            • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                                              • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                                                              • Connecting wires Switches
                                                                                                                                                                                                                                                • THEORY
                                                                                                                                                                                                                                                    • Sequential Circuits
                                                                                                                                                                                                                                                      • 18-ldst-exp13
                                                                                                                                                                                                                                                        • Lab Session 13
                                                                                                                                                                                                                                                          • Designing a modulo-5 asynchronous up-counter using JK-FF
                                                                                                                                                                                                                                                            • 1 Following ICs and their Datasheets
                                                                                                                                                                                                                                                            • 7400 Quad 2-input or 7410 Triple 3-input NAND Gates
                                                                                                                                                                                                                                                            • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                                                              • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                                                                              • Connecting wires Switches
                                                                                                                                                                                                                                                                • THEORY
                                                                                                                                                                                                                                                                    • Figure 131 A Mod-5 Asynchronous Up Counter
                                                                                                                                                                                                                                                                    • Implementation and Observations
                                                                                                                                                                                                                                                                      • ACTIVITY
                                                                                                                                                                                                                                                                          • 19-ldst-exp14
                                                                                                                                                                                                                                                                            • Experimenting with 74194 4-bit bidirectional universal shift register
                                                                                                                                                                                                                                                                            • 1 Following ICs and their Datasheets
                                                                                                                                                                                                                                                                            • 74194 4-bit bidirectional universal shift register
                                                                                                                                                                                                                                                                            • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                                                                              • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                                                                                              • Connecting wires Switches
                                                                                                                                                                                                                                                                                • THEORY
                                                                                                                                                                                                                                                                                  • Shift Registers
                                                                                                                                                                                                                                                                                  • Bidirectional Shift Registers
                                                                                                                                                                                                                                                                                  • Universal Shift Registers
                                                                                                                                                                                                                                                                                    • S1
                                                                                                                                                                                                                                                                                      • Circuit Diagram
                                                                                                                                                                                                                                                                                      • ACTIVITY
                                                                                                                                                                                                                                                                                          • 20-ldst-exp15
                                                                                                                                                                                                                                                                                            • COMPONENTS AND APPARATUS REQUIRED
                                                                                                                                                                                                                                                                                            • 1 Parallel Port Connectors (DB-25) with Cable
                                                                                                                                                                                                                                                                                            • 2 Personal Computer with Windows 98 and TurboC Compiler Installed
                                                                                                                                                                                                                                                                                            • 3 Following ICs and their Datasheets
                                                                                                                                                                                                                                                                                            • 74245 Octal Bus Transceivers with 3-State Outputs
                                                                                                                                                                                                                                                                                            • 4 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                                                                                              • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                                                                                                                • Connecting wires Switches
                                                                                                                                                                                                                                                                                                  • THEORY
                                                                                                                                                                                                                                                                                                  • 3-State Logic
                                                                                                                                                                                                                                                                                                    • Serial and Parallel Port Connectors
                                                                                                                                                                                                                                                                                                    • Parallel Port Connector ndash DB-25
                                                                                                                                                                                                                                                                                                      • Accessing parallel port through C Language Programming
                                                                                                                                                                                                                                                                                                          • 21-ldst-appendixA
                                                                                                                                                                                                                                                                                                          • 22-ldst-appendixB
                                                                                                                                                                                                                                                                                                            • DEBOUNCING CIRCUITRY FOR MECHANICAL SWITCHES

                                    Logic Design amp Switching Theory 1 Lab Session 03 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                    bles produce the sum and carry The simplified sum of product expressions for a half adder are

                                    Full Adder

                                    A combinational circuit that performs the addition of three input bits It consist of three inputs and two outputs Two of the input variables represent the two significant bits to be added The third input represents the carry from the previous lower significant position The output varia

                                    zyxzyxzyxzyxzyxS oplusoplus=+++= yxzyxzyzxxyC )( +oplus=++=

                                    Figure 32 Circuit diagram for Full Adder

                                    efer to laboratory session 01 for procedure) and record the observations in the following ta

                                    alf Adde ull Adder Inputs u

                                    IMPLEMENTATION AND OBSERVATIONS

                                    Implement the half adder and full adder circuits on a bread board (prepare the pin diagram (use appendix A) and r

                                    bles H r F

                                    Inputs Outputs Outp ts x y Carry Su Carry Sum m x y z 0 0 0 0 0 0 1 0 0 1 1 0 0 1 0 1 1 0 1 1 1 0 0 1 0 1 1 1 0 1 1 1

                                    20

                                    Logic Design amp Switching Theory 1 Lab Session 03 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                    at of your designed circuit Attach hardcopy of the output form electronic workbench

                                    at of your designed circuit Attach hardcopy of the output form lectronic workbench here

                                    ACTIVITY

                                    1 Simulate half adder circuit using Electronics Workbench Compare the results of simulation with thhere

                                    2 Design a full subtractor circuit and simulate it using Electronics Workbench Compare the results of simulation with the

                                    21

                                    Logic Design amp Switching Theory 1 Lab Session 04 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                    Lab Session 04 OBJECT

                                    Use of Karnaugh Map (SOP-Expression) method GIVEN LOGIC EXPRESSION

                                    F (A B C D) = sum ( 0 1 2 4 5 6 8 9 12 13 14 ) COMPONENTS AND APPARATUS REQUIRED 1 Digital ICs and their Datasheets

                                    bull 7408 Quad 2-input AND Gate bull 7432 Quad 2-input OR Gate bull 7404 Hex Inverter

                                    2 Digital Trainer DT-01 or the following components Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches PROCEDURE 1 Use Karnaugh map to reduce the given function 2 Draw the circuit diagram for the obtained reduced function 3 Implement the reduced circuit using digital ICs on a bread board (prepare the pin

                                    diagram (use appendix A) and refer to laboratory session 01 for procedure) and record the observations

                                    REDUCTION OF LOGIC EXPRESSION USING KARNAUGH MAP F

                                    CD

                                    AB DC

                                    DC DC

                                    DC

                                    BA0 1 3 2

                                    BA4 5 7 6

                                    BA12 13 15 14

                                    BA8 9 11 10

                                    Reduced form of the given logic expression is __________________________________

                                    22

                                    Logic Design amp Switching Theory 1 Lab Session 04 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                    LOGIC DIAGRAM (REDUCED FORM) OBSERVATIONS

                                    A B C D Output 0 0 0 0 0 0 0 1 0 0 1 0 0 0 1 1 0 1 0 0 0 1 0 1 0 1 1 0 0 1 1 1 1 0 0 0 1 0 0 1 1 0 1 0 1 0 1 1 1 1 0 0 1 1 0 1 1 1 1 0 1 1 1 1

                                    RESULT The reduced form (SOP Expression) of the given logic function is

                                    ____________________________________________________________

                                    The observation table reflects the given logic function

                                    23

                                    Logic Design amp Switching Theory 1 Lab Session 04 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                    ACTIVITY 1 Using Electronics Workbench derive a truth table and logic circuit for the following logic expression

                                    BAAF +=

                                    Procedure 1 From the Instruments Parts Bin drag and drop Logic Converter on the design area 2 Double click the Logic Converter to reveal Logic Converter dialog box This dialog

                                    box shows various conversion options between truth table logic expression and logic circuit

                                    3 Enter the given logic expression in the edit box found at the end of the dialog box Use lsquo to represent invert of a variable For example A is written as Arsquo

                                    4 Click the Boolean Expression to Truth Table button The truth table appears in the logic converters display

                                    5 Now click the Boolean Expression to Circuit button This creates the logic circuit for the given expression in the design area Label the diagram if needed

                                    Resulting Logic Circuit For the given expression the final circuit will look like

                                    Figure 41

                                    24

                                    Logic Design amp Switching Theory 1 Lab Session 04 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                    ACTIVITY 2

                                    Using Electronics Workbench find a simplified logic expression and circuit for the following truth table

                                    A B C Output 0 0 0 1 0 0 1 1 0 1 0 0 0 1 1 1 1 0 0 0 1 0 1 0 1 1 0 0 1 1 1 1

                                    Procedure 1 Click three input channels from A to H across the top of the logic converter The

                                    display area below the terminals fills up with the necessary combinations of ones and zeros to fulfill the input conditions The values in the output column on the right are initially set to 0

                                    2 Edit the output column to specify the desired output for each input condition To change an output value select it and type a new value 1 0 or x An x indicates a donrsquot care condition

                                    3 To convert this truth table to a Boolean expression click the Truth Table to Boolean Expression button The Boolean expression will be displayed at the bottom of the logic converter

                                    4 Simplify the expression by clicking the Simplify button 5 Now click the Boolean Expression to Circuit button This creates the logic circuit for

                                    the given expression in the design area Resulting Logic Circuit For the given truth table the final simplified circuit will look like

                                    Figure 42

                                    25

                                    Logic Design amp Switching Theory 1 Lab Session 04 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                    ACTIVITY 3

                                    Using Electronics Workbench find the logic expression and truth table for the following logic circuit

                                    Figure 43

                                    Procedure 1 Attach the input terminals of the logic converter to up to four input points in the

                                    circuit 2 Connect the single output of the circuit to the output terminal on the logic converter

                                    icon 3 Click the Circuit to Truth Table button The truth table appears in the logic

                                    converters display 4 To convert this truth table to a Boolean expression click the Truth Table to Boolean

                                    Expression button The Boolean expression will be displayed at the bottom of the logic converter

                                    Resulting Logic Expression Logic Expression for the given circuit is found to be _____________________________

                                    26

                                    Logic Design amp Switching Theory 1 Lab Session 04 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                    27

                                    For activities 1 2 and 3 attach hardcopy of the output (truth table logic expression and logic circuit) form electronic workbench here

                                    Logic Design amp Switching Theory 1 Lab Session 05 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                    Lab Session 05 Lab Session 05 OBJECT OBJECT

                                    Designing a BCD Adder Designing a BCD Adder COMPONENTS AND APPARATUS REQUIRED COMPONENTS AND APPARATUS REQUIRED

                                    1 Following ICs and their Datasheets 1 Following ICs and their Datasheets bull 7408 Quad 2-input AND Gate bull 7408 Quad 2-input AND Gate bull 7432 Quad 2-input OR Gate bull 7432 Quad 2-input OR Gate bull 7483 4-bit Binary Adder bull 7483 4-bit Binary Adder

                                    2 Digital Trainer DT-01 or the following components 2 Digital Trainer DT-01 or the following components Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors (100 Ω) Connecting wires Switches (100 Ω) Connecting wires Switches

                                    THEORY THEORY

                                    A BCD Adder is a combinational circuit that adds two BCD digits in parallel and produces a sum digit also in BCD A BCD Adder is a combinational circuit that adds two BCD digits in parallel and produces a sum digit also in BCD

                                    A4 A3 A2 A1 B4 B3 B2 B1

                                    7483-BCD ADDER

                                    Cout (C4 ) Z4 Z3 Z2 Z1 Cin(C0)

                                    A4 A3 A2 A1 B4 B3 B2 B1

                                    7483-BCD ADDER

                                    Cout

                                    (C4 ) Z4 Z3 Z2 Z1 Cin(C0)

                                    Figure 51 BCD Adder Circuit

                                    28

                                    Logic Design amp Switching Theory 1 Lab Session 05 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                    29

                                    A BCD adder must include the correction logic in its internal construction The two BCD digits together with the input carry are first added using a 4-bit binary adder to produce the binary sum If no output carry is generated and the binary sum is less than or equal to 9 then the corresponding BCD sum is identical and therefore no conversion is needed When the output carry is equal to 1 or the binary sum is greater than 9 then a binary 0110 is added to the binary sum through another 4-bit binary adder If Cout is the carry output and Z4Z3Z2Z1 is the binary sum form the first 4-bit binary adder then the following equation indicates the condition when a binary 0110 is to be added

                                    C = COUT + Z4Z2 + Z4Z3 IMPLEMENTATION AND OBSERVATIONS Implement the BCD adder circuit according to figure 51 on a bread board (prepare the pin diagram (use appendix A) and refer to laboratory session 01 for procedure) A BCD adder has nine input bits (two BCD digits and a carry bit) which can result in a total of 512 combinations of which 312 inputs are donrsquot care Since it is a very lengthy procedure to record results for 200 valid input combinations therefore for simplicity just record results for any eight combinations in the following table

                                    Input Carry

                                    BCD Digit 1 BCD Digit 2 Carry Output

                                    BCD Sum A4 A3 A2 A1 B4 B3 B2 B1 Z4 Z3 Z2 Z1

                                    Logic Design amp Switching Theory 1 lab Session 06 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                    Lab Session 06

                                    OBJECT

                                    bull Designing of a 4 x 1 Multiplexer bull Experimenting with 74150 IC

                                    COMPONENTS AND APPARATUS REQUIRED 1 Following ICs and their Datasheets

                                    bull 7408 Quad 2-input AND Gates or 7411 Triple 3-input AND Gates bull 7432 Quad 2-input OR Gates bull 7404 Hex Inverter bull 74150 16 x 1 MUX

                                    2 Digital Trainer DT-01 or the following components Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches THEORY

                                    Multiplexers A digital data Multiplexer (MUX) is a combinational circuit having several data inputs and a single output A set of data-select inputs is used to control which of the data inputs is routed to the single output A multiplexer is also called a data selector because of this ability to select which data input is connected o the output Normally there are 2n input lines and n selection lines whose bit combination determine which input is selected DESIGN OF A 4 x 1 MULTIPLEXER A 4 x 1 multiplexer is capable of selecting one of four data inputs (see figure 61) The 2-bit binary number at the data select inputs S1 and S0 specifies which of the four data inputs is to be routed to the output Since there are two data select inputs therefore they can select 22 = 4 different data inputs lines

                                    S0 S1 D0 D1

                                    D2 D3

                                    Data-select Inputs Output

                                    Data Inputs

                                    Figure 61 Block Diagram of a 4 x1 Multiplexer

                                    30

                                    Logic Design amp Switching Theory 1 lab Session 06 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                    Figure 62 Circuit Diagram for 4 x 1 Multiplexer

                                    Implementation and Observations

                                    Implement the 4 x 1 Multiplexer circuit (figure 62) on a bread board (prepare the pin diagram (use appendix A) and refer to laboratory session 01 for implementation procedure) and record the observations in the following table For each data select combination specify the switch number as well as the binary value present on that selected switch

                                    S1 S0 Output 0 0 0 1 1 0 1 1

                                    TESTING OF 74150 - 16 x 1 MUX

                                    The 74150 IC has sixteen data inputs and four data-selection lines Function of various pins of this IC is described below

                                    bull E0 through E15 Data input lines

                                    31

                                    Logic Design amp Switching Theory 1 lab Session 06 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering bull A B C D Data select lines with D being the MSB bull W Active low output line bull Grsquo Active low enable line bull VCC and GND Supply connections lines

                                    Circuit Diagram

                                    Figure 63 Pin connections of 74150 for selecting E0

                                    Testing Procedure

                                    bull Make connections as shown in the circuit diagram bull Apply different data (1 or 0) at data inputs that are labeled as E0 to E15 Only

                                    connection for E0 is shown is the figure for simplicity bull Select the data input E0 with the help of data selectors A B C and D bull Observe the output which shows the complement of the data from E0 bull Select all the sixteen data inputs one by one and record your observations in the

                                    following table

                                    32

                                    Logic Design amp Switching Theory 1 lab Session 06 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                    33

                                    Observations

                                    Grsquo D C B A W Grsquo D C B A W 0 0 0 0 0 0 1 0 0 0 0 0 0 0 1 0 1 0 0 1 0 0 0 1 0 0 1 0 1 0 0 0 0 1 1 0 1 0 1 1 0 0 1 0 0 0 1 1 0 0 0 0 1 0 1 0 1 1 0 1 0 0 1 1 0 0 1 1 1 0 0 0 1 1 1 0 1 1 1 1

                                    ACTIVITY 1 Consider 4x1 Multiplexer Draw the output wave-form for the following data inputs

                                    (E0 E1 E2 E3) and select lines A B (B being the MSB) Output is W

                                    E3 E2 E1 E0 A B

                                    W

                                    2 Using the 4 x 1 MUX designed in this laboratory session implement the following logical function F (A B C) = Σ (0147)

                                    Show your working and input connections in the following block diagram according to the circuit you have implemented

                                    4 x 1 MUX

                                    S0 S1

                                    Output D0

                                    D1

                                    D2

                                    D3

                                    Logic Design amp Switching Theory 1 Lab Session 07 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                    Lab Session 07

                                    OBJECT

                                    bull Designing of a 2 x 4 Decoder 1 x 4 Demultiplexer bull Experimenting with 74138 IC

                                    COMPONENTS AND APPARATUS REQUIRED 1 Following ICs and their Datasheets

                                    bull 7408 Quad 2-input or 7411 Triple 3-input AND Gates bull 7404 Hex Inverter bull 74138 3 x 8 Decoder

                                    2 Digital Trainer DT-01 or the following components Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches THEORY

                                    Decoder A Decoder is a combinational circuit that converts binary information form n input lines to a maximum of 2n unique output lines In practical applications decoders are often used for selecting one of several devices

                                    Demultiplexer A decoder with an enable input can function as a Demultiplexer A Demultiplexer (DMUX) id a circuit that receives information on a single line and transmits this information on one of 2n possible output lines The selection of a specific output line is controlled by the bit values of n selection lines DESIGN OF A 2 x 4 DECODER 1 x 4 DEMULTIPLEXER A 2 x 4 decoder is capable of selecting one of four output lines (see figure 71 (a)) The 2-bit binary number at the data inputs S1 and S0 specifies which of the four data inputs is to be selected If we add an enable pin and use it as an input line then this decoder can be converted to a 1 x 4 Demultiplexer where S1 and S0 will select a line to which data input is to be routed (see figure 71 (b))

                                    Select S0 S0 Inputs

                                    S1 D0 D1

                                    D2

                                    D3

                                    Enable (a) Block Diagram of a 2 x 4 Decoder

                                    Figure 71

                                    S1 D0 D1

                                    D2

                                    D3

                                    Inputs

                                    Data Input (b) Block Diagram of a 1 x 4 Demulptiplexer

                                    34

                                    Logic Design amp Switching Theory 1 Lab Session 07 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                    Figure 72 Circuit Diagram for 2 x 4 Decoder 1 x 4 Demultiplexer

                                    Implementation and Observations Implement the 2 x 4 Decoder 1 x 4 Demultiplexer circuit (figure 72) on a bread board (prepare the pin diagram (use appendix A) and refer to laboratory session 01 for implementation procedure) and record the observations in the following table

                                    Enable Data Input S1 S0 D0 D1 D2 D3

                                    0 0 0 0 0 1 0 1 0 0 1 1 1 0 0 1 0 1 1 1 0 1 1 1

                                    TESTING OF 74138 3 x 8 Decoder The 74138 IC has three inputs and eight output lines It has three enable inputs and for the IC to function all three inputs need to be enabled Function of various pins of this IC is described below

                                    35

                                    Logic Design amp Switching Theory 1 Lab Session 07 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                    bull Y0 through Y7 Active low data outputs bull A B C Input select lines with C being the MSB bull G1 Active high enable Input bull G2Arsquo and G2Brsquo Active low enable Inputs bull VCC and GND Supply connections lines Circuit Diagram

                                    Figure 73 Pin connections of 74138

                                    Testing Procedure

                                    bull Make connections as shown in the circuit diagram bull Apply different combinations of 1s and 0s at data inputs bull Observe the output and record your observations in the following table

                                    Observations

                                    C B A Y0 Y1 Y2 Y3 Y4 Y5 Y6 Y7 0 0 0 0 0 1 0 1 0 0 1 1 1 0 0 1 0 1 1 1 0 1 1 1

                                    36

                                    Logic Design amp Switching Theory 1 Lab Session 07 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                    37

                                    ACTIVITY ACTIVITY 1 What will be the binary values at the outputs Y0 through Y7 of 74138 if 1 What will be the binary values at the outputs Y0 through Y7 of 74138 if

                                    bull All three enable pins are connected to ground bull All three enable pins are connected to ground __________________________________________________________________________________________________________________________________________ __________________________________________________________________________________________________________________________________________ _____________________________________________________________________ _____________________________________________________________________

                                    bull All three enable pins are connected to VCC bull All three enable pins are connected to VCC _______________________________________________________________________________________________________________________________________________________________________________________________________________

                                    _______________________________________________________________________________________________________________________________________________________________________________________________________________

                                    2 Show connections for 74138 in order to use it as a 1 x 8 Demultiplexer 2 Show connections for 74138 in order to use it as a 1 x 8 Demultiplexer

                                    3 Consider a 2 x 4 Decoder with two enable inputs (one active high - G and one active low ndash Grsquo) Draw the output wave-forms for D0 D1 D2 and D3 if the two select inputs are A and B (B being the MSB) All outputs are active low

                                    Grsquo

                                    G

                                    A B

                                    D0 D1 D2

                                    D3

                                    Logic Design amp Switching Theory 1 Lab Session 08 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                    Lab Session 08 OBJECT

                                    bull Designing of a 4 x 2 Priority Encoder bull Experimenting with 74148 IC

                                    COMPONENTS AND APPARATUS REQUIRED

                                    1 Following ICs and their Datasheets

                                    bull 7408 Quad 2-input or 7421 Dual 4-input AND Gates bull 7432 Quad 2-input OR Gates bull 7404 Hex Inverter bull 74148 Encoder

                                    2 Digital Trainer DT-01 or the following components Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches

                                    THEORY

                                    Encoder An Encoder is a digital function that produces a reverse operation from that of a decoder An Encoder has 2n (or less) input lines and n output lines The output lines generate the binary code for the 2n input variables Priority Encoder

                                    A simple encoder may produce an erroneous output if more than one of its inputs is high A Priority Encoder is one that responds to just one input among those that may be simultaneously high in accordance with some priority system The most common priority system is based on the relative magnitudes of the inputs whichever decimal input is largest is the one that is encoded

                                    DESIGN OF A 4 x 2 Priority Encoder

                                    The following equations represent the outputs of a 4 x 2 priority encoder 32 DDA +=

                                    321 DDDB += As can be seen from the equations that input D0 which has a binary code 00 is not used in any equation A binary code 00 at the output indicates two conditions Either D0 is selected or no input is selected In order to differentiate these two conditions we will provide an additional output Z to indicate if at least one of the inputs is a 1 The equation for Z will be

                                    4321 DDDDZ = If Z is 0 then the binary code 00 at the output indicates that D0 is selected and if Z is 1 then it indicates that no input line is selected

                                    38

                                    Logic Design amp Switching Theory 1 Lab Session 08 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                    Figure 81 Circuit Diagram for 4 x 2 Priority Encoder

                                    it (figure 81) on a bread board (prepare the to laboratory session 01 for implementation

                                    Implementation a Implement the 4 x 2 Priority Encoder circu

                                    ram (use appendix A) and refer

                                    nd Observations

                                    pin diagprocedure) and record the observations in the following table

                                    D3 D2 D1 D0 A B 0 0 0 1 0 0 1 x 0 1 x x 1 x x x

                                    TESTING OF 74148 8 x 3 Octal Priority Encoder

                                    imal digits There are nine of which three represents

                                    ing any of the inputs is high

                                    then it shows that line 0 is selected and if e inputs selected E0 and GS

                                    cannot be in the same state provided that E1 is enabled

                                    The 74148 is a priority encoder with active-Low input for dec

                                    input) and five output linesinputs lines (including an enablethe binary code for the octal digit Function of various pins of this IC is described below

                                    bull 0 through 7 Active low data inputs representing the octal digits A2 A1 A0 Active low output lines representing the binary code bullbull E1 Active low enable Input bull E0 Active low output indicating none of the inputs is high bull GS Active low output indicatbull VCC and GND Supply connections lines Therefore if GS A2 A1 and A0 are all low

                                    then it shows that none of thE0 A2 A1 and A0 are all low

                                    39

                                    Logic Design amp Switching Theory 1 Lab Session 08 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                    Circuit Diagram

                                    Figure 82 Pin connections of 74148

                                    Testing Procedure bull Make connections as sho

                                    binations of 1s and 0s at data inputs d record your observations in the following table

                                    GS E0

                                    wn in the circuit diagram bull Apply different combull Observe the output an Observations

                                    0 1 2 3 4 5 6 7 A2 A1 A0 1 1 1 1 1 1 1 1 x x x x x x x 0 x x x x x x 0 1 x x x x x 0 1 1 x x x x 0 1 1 1 x x x 0 1 1 1 1 x x 0 1 1 1 1 1 x 0 1 1 1 1 1 1 0 1 1 1 1 1 1 1

                                    40

                                    Logic Design amp Switching Theory 1 Lab Session 08 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                    41

                                    CTIVITY

                                    Cascade the following two 74148 8 x 3 Priority Encoders to form 16 x 4 Priority

                                    A 1

                                    Encoder

                                    Logic Design amp Switching Theory 1 Lab Session 09 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering `

                                    Lab Session 09 OBJECT

                                    Designing an Odd Parity Generator and Checker for a 3-bit Data COMPONENTS AND APPARATUS REQUIRED

                                    1 Following ICs and their Datasheets

                                    bull 7486 Quad 2-input Exclusive-OR Gates bull 7404 Hex Inverter

                                    2 Digital Trainer DT-01 or the following components Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches

                                    THEORY

                                    Parity Generator When binary data is transmitted and processed it is ndash as are all electrical signals ndash susceptible to noise that can either alter or distort its contents 1s may be effectively changed to 0s and 0s to 1s To overcome this problem one or more bits are often added to the data as an aid in detecting errors caused by noise The most common of these is a Parity bit that signifies whether the total number of 1s in a code group is odd or even In an Odd Parity system the parity bit is made 0 or 1 as necessary to make the total number 1s odd (counting the parity bit itself) In an Even Parity system the parity bit is chosen to make the total number of 1s even Table 91 shows how parity bits would be added to BCD code group in both systems

                                    Decimal BCD Value Parity Bit ABCD Odd Parity Even Parity

                                    0 0000 1 0 1 0001 0 1 2 0010 0 1 3 0011 1 0 4 0100 0 1 5 0101 1 0 6 0110 1 0 7 0111 0 1 8 1000 0 1 9 1001 1 0

                                    Table 91 Odd and Even Parity in BCD

                                    When digital data is received a parity checking circuit generates an error signal if the total number of 1s is odd in an even parity system or if it is even in an odd parity system Parity check always detects a single error (one bit change from 0 to 1 or 1 to 0) but may not detect

                                    42

                                    Logic Design amp Switching Theory 1 Lab Session 09 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering ` two or more errors Odd parity is used more often than even parity because even parity does not detect a situation where all 0s are created due to short circuit or other fault condition DESIGN OF A 3-BIT ODD PARITY GENERATOR AND CHECKER Let x y and z be the three bits that constitute the message and are the input to the Odd Parity Generator Circuit Since it is an odd parity system the bit P is generated so as to make the total number of 1s odd (including P) The function P can be expressed as follows P = x oplus y Ο z or P = x Ο y oplus z Since the IC available is 7486 which is quad 2input XOR IC therefore we will convert XNOR also to XOR

                                    P = x oplus y Ο z

                                    P = ( x oplus y ) Ο z Since for even number of variables ______

                                    XOR = XNOR Therefore ___________ _________

                                    P = ( x oplus y ) oplus z = x oplus y oplus z This logical expression can be implemented with two XOR gates and an inverter (see figure 91)

                                    Figure 91 Circuit Diagram for a 3-bit Parity Generator

                                    The 3-bit message and the parity bit are transmitted to their destination where they are applied to a Parity Checker Circuit An error occurs during transmission if the parity of the four bits received is even since the binary information transmitted was originally odd The output C of the parity checker should be a 1 when an error occurs ie when the number of 1s in the four inputs is even Therefore the function C can be expressed as

                                    C = x Ο y Ο z Ο P

                                    Using the same logic applied for the conversion of the equation of P

                                    PzyxC oplusoplusoplus= This logical expression can be implemented with three XOR gates and an inverter (see figure 92)

                                    43

                                    Logic Design amp Switching Theory 1 Lab Session 09 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering `

                                    44

                                    Figure 92 Circuit Diagram for a 3-bit Parity Checker Implementation and Observations Implement the 3-bit Parity Generator and Checker circuits (figure 91 and 92) on a bread board (prepare the pin diagram (use appendix A) and refer to laboratory session 01 for implementation procedure) and record the observations in the following table

                                    x y z P x y z P C x y z P C 0 0 0 0 0 0 0 1 0 0 0 0 0 1 0 0 0 1 1 0 0 1 0 1 0 0 0 1 0 1 0 1 0 0 1 1 0 0 1 1 1 0 1 1 1 0 0 0 1 0 0 1 1 0 0 1 0 1 0 1 0 1 1 1 0 1 1 1 0 0 1 1 0 1 1 1 0 1 1 1 0 1 1 1 1 1 1 1

                                    Odd Parity Generation Odd Parity Check ACTIVITY 1 Try using the parity checker of figure 92 as 3-bit parity generator Write the details here

                                    _____________________________________________________________________________________________________________________________________________________________________________________________________________________ ______________________________________________________________________________________________________________________________________________ _______________________________________________________________________ ______________________________________________________________________________________________________________________________________________

                                    Logic Design amp Switching Theory 1 Lab Session 10 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                    Lab Session 10 OBJECT

                                    Driving a seven segment display using 7447 7448 driver IC COMPONENTS AND APPARATUS REQUIRED

                                    1 Following ICs and their Datasheets

                                    bull Seven Segment Displays (Common Anode Common Cathode) bull 7447 7448 BCD to Seven Segment Driver

                                    2 Digital Trainer DT-01 or the following components Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches

                                    THEORY Seven Segment Displays A Seven Segment Display consists of seven light-emitting segments The segments are designated by letters a through g (see figure 101) By illuminating various combinations of segments the numerals 0 through 9 can be displayed Seven Segment Displays are commonly constructed with light-emitting diodes (LEDs) and with liquid-crystal displays (LCDs) LEDs generally provide greater illumination levels but require much greater power than LCDs An LED display can be a common-anode type or common cathode type In common anode type a high voltage is applied at the common terminal of the display and low voltage is applied at a segmentrsquos terminal for illumination In the common-cathode type a low voltage is applied at the common terminal of the display and high voltage is applied at a segmentrsquos terminal for illumination

                                    Figure 101 Seven Segment Display

                                    a f b g

                                    e c d

                                    7447 7448 BCD to Seven Segment Driver 7447 7448 IC is particularly used to drive Seven Segment Its input is a BCD number and output drives a seven segment display 7447 is used to drive common-anode displays whereas 7448 is used to drive common cathode displays 7447 7448 is a 16 pin IC Function of various pins of these ICs is described below

                                    bull A B C D Inputs representing BCD digits (D being the MSB)

                                    45

                                    Logic Design amp Switching Theory 1 Lab Session 10 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering bull OA through OG Outputs to drive segments a through g of the display (Active low

                                    in 7447 and active high in 7448) bull RBI Ripple Blanking Input Turns off all the segments if kept low provided that LT

                                    is kept high and all other inputs (A B C D BI) are kept low Should be kept high otherwise

                                    bull BI RBO Wire-AND logic serving as a Blanking Input and or Ripple Blanking Output

                                    o BI Turns off all the segments if low o RBO Goes to a low level (response condition) along with other outputs when

                                    RBI and inputs A B C and D are low with LT input at high level bull LT Lamp Test input Tests whether all segments are working or not Illuminates all

                                    segments if kept low provided that BI is kept high Should be kept high otherwise bull VCC and GND Supply connections lines CIRCUIT DIAGRAM

                                    Figure 102 Circuit diagram for 7447driving a common-anode display

                                    IMPLEMENTATION AND OBSERVATIONS

                                    bull Make connections as shown in the circuit diagram (refer to laboratory session 01 for implementation procedure)

                                    bull Apply different combinations of 1s and 0s at data inputs bull Observe the output and record your observations in the following table

                                    46

                                    Logic Design amp Switching Theory 1 Lab Session 10 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                    47

                                    Decimal Digit

                                    BCD Inputs Seven Segment Outputs D C B A a b c d e f g

                                    0 0 0 0 0 1 0 0 0 1 2 0 0 1 0 3 0 0 1 1 4 0 1 0 0 5 0 1 0 1 6 0 1 1 0 7 0 1 1 1 8 1 0 0 0 9 1 0 0 1

                                    ACTIVITY 1 Perform the Lamp Test for the designed circuit and write your observations

                                    ____________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________

                                    2 How can you use 7447 IC to drive a common-cathode display

                                    ____________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________

                                    3 What symbols appear in the seven segment display if inputs DCBA are

                                    DCBA Symbol

                                    1010

                                    1011

                                    1100

                                    1101

                                    1110

                                    1111

                                    Logic Design amp Switching Theory 1 Lab Session 11 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                    48

                                    Lab Session 11 OBJECT

                                    Testing different modes of JK-FF COMPONENTS AND APPARATUS REQUIRED 1 Following ICs and their Datasheets

                                    bull 7473 7476 JK Flip-Flop 2 Digital Trainer DT-01 or the following components

                                    Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches

                                    THEORY

                                    Flip-Flop A flip-flop circuit can maintain a binary state indefinitely (as long as the power is delivered to the circuit) until directed by an input signal to switch states The major differences among various types of flip-flops are in the number of inputs they possess and in the manner in which the inputs affect the binary state

                                    JK Flip-Flop JK flip flop is an edge triggered device A typical JK flip flop has three inputs J K and a clock input The flip-flop can be either positive or negative edge triggered The output Q is available in complemented form as well Beside the usual inputs and output most of the flip-flop IC also possess two asynchronous inputs namely Preset and Clear These inputs are usually active low If used Preset and Clear inputs keep the flip-flop in set and reset state respectively irrespective of the other inputs Both of these inputs cannot be used simultaneously otherwise they will bring the flip-flop in unstable state

                                    Figure 111 Symbol for JK flip-flop

                                    (a) positive-edge triggering (b) active low Preset (PR) and Clear (CLR) with positive-edge triggering

                                    (c) active low Preset (PR) and Clear (CLR) with negative-edge triggering

                                    Logic Design amp Switching Theory 1 Lab Session 11 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                    49

                                    TESTING OF 7473 7476 DUAL JK FLIP-FLOP

                                    Both the ICs 7473 and 7476 are similar in functionality except for one difference The flip-flops in 7473 have only one type of active low asynchronous input which is the Clear input whereas the flip-flops in 7476 have both Preset and Clear inputs Both these ICs have negative edge triggered flip-flops

                                    Circuit Diagram

                                    Figure 112 Pin connections of 7476

                                    Testing Procedure

                                    bull Make connections as shown in the circuit diagram (figure 112) bull Apply different combinations of 1s and 0s at J and K inputs bull Observe the output and record your observations in the following table

                                    Observations

                                    J

                                    K Q

                                    0 0 0 1 1 0 1 1

                                    ACTIVITY

                                    1 Observe the output Q of JK flip-flop if the clock input is connected to VCC or GND instead of a clock source Write your observations here __________________________________________________________________________________________________________________________________________ _______________________________________________________________________________________________________________________________________________________________________________________________________________

                                    Logic Design amp Switching Theory 1 Lab Session 12 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                    50

                                    Lab Session 12 OBJECT

                                    Designing sequential circuit for the given state diagram using D flip-flop GIVEN STATE DIAGRAM

                                    00

                                    11

                                    Figure 121 State Diagram COMPONENTS AND APPARATUS REQUIRED 1 Following ICs and their Datasheets

                                    bull 7474 D Flip-Flop bull ICs of basic gates (AND OR NOT XOR etc) as required

                                    2 Digital Trainer DT-01 or the following components Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches

                                    THEORY

                                    Sequential Circuits In Sequential Circuits the output not only depends on the present inputs but also on previous states of the circuit These circuits use memory elements (latches flip-flops) and the binary information stored in the memory elements at any given time defines the state of the sequential circuit Analysis of a Sequential Circuit The behavior of a sequential circuit is determined from the inputs the outputs and the states of its flip-flops Both the outputs and next state are a function of the inputs and the

                                    10

                                    01

                                    00 11 10

                                    00

                                    00 11 10 00

                                    Logic Design amp Switching Theory 1 Lab Session 12 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                    51

                                    present state The analysis of a sequential circuit form a state diagram comprises of the following bull Selecting a particular flip-flop to design the circuit bull Obtaining state table from the state diagram bull Finding input equations for the selected flip-flop bull Finding state equations (not required for the construction of circuit) bull Implementing the circuit using selected flip-flops and their input equations ANALYZING THE GIVEN STATE DIAGRAM D Flip-Flop D flip-flop is also called transparent flip-flop as it simply transfers the input data to the output For our design we require the graphical symbol and excitation table of D flip-flop (see figure 122)

                                    Qt Qt+1 T 0 0 0 0 1 1 1 0 0 1 1 1

                                    (b) Excitation table of D Flip-Flop

                                    (a) Graphical Symbol

                                    Figure 122 Characteristic equation of D flip-flop is Q(t+1) = D State Table The given state diagram has four states so we will need two D flip-flops (FF-0 FF-1) Form state table form the given state diagram and record the results in the following table

                                    Present State Input Next State Output Input to FF-0 D0

                                    Input to FF-1 D1 Q1t Q0t x Q1(t+1) Q0(t+1) z

                                    Logic Design amp Switching Theory 1 Lab Session 12 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                    52

                                    Input Equations Using Karnaugh map the input equations D0 and D1 for the two flip-flops can be found

                                    D0 D1 Q0x

                                    Q1

                                    _ _ Q0x

                                    _ Q0x

                                    Q0x

                                    _ Q0x

                                    Q0x

                                    Q1

                                    _ _ Q0x

                                    _ Q0x

                                    Q0x

                                    _ Q0x

                                    _ Q1

                                    _ Q1

                                    Q1

                                    Q1

                                    D0 = _________________ D1 = _________________

                                    State Equations Using the characteristic equation of D flip-flop we can find the state equations Q0(t+1) and Q1(t+1) for the to flip flops Q0(t+1) = _______________________ Q1(t+1) = _______________________ _______________________ _______________________ _______________________ _______________________ Circuit Diagram

                                    Logic Design amp Switching Theory 1 Lab Session 12 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                    53

                                    Implementation Procedure and Observations

                                    1 Implement the circuit using digital ICs on a bread board (prepare the pin diagram (use appendix A) and refer to laboratory session 01 for procedure)

                                    2 Make the clear inputs of the flip-flops low (to clear the flip-flops) The flip-flops will remain in clear state as long as the clear inputs are connected to low level

                                    3 Connect output Q0 and the clock pulse to an oscilloscope 4 Apply 0 to the input x 5 Now make the clear inputs to high 6 Observe the waveform for the first 5 clock pulses and record it 7 Repeat steps 2 to 6 keeping x=1 in step 4 this time 8 Repeat steps 2 to 7 this time connecting Q1 instead of Q0 to the oscilloscope in step

                                    3 Record your observations (Keep frequency of the clock pulse low (eg1Hz) so that the output waveforms can be observed easily)

                                    1 2 3 4 5 Clock Pulse

                                    Output Waveform for Q0 when x=0

                                    Output Waveform for Q0 when x=1

                                    Output Waveform for Q1 when x=0

                                    Output Waveform for Q1 when x=1

                                    Logic Design amp Switching Theory 1 Lab Session 13 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                    Lab Session 13 OBJECT

                                    Designing a modulo-5 asynchronous up-counter using JK-FF COMPONENTS AND APPARATUS REQUIRED

                                    1 Following ICs and their Datasheets

                                    bull 7400 Quad 2-input or 7410 Triple 3-input NAND Gates bull 7476 7473 JK Flip-Flop

                                    2 Digital Trainer DT-01 or the following components Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches

                                    THEORY

                                    Digital Counters A digital counter is a set of flip-flops whose states change in response to pulses applied at the input to the counter The flip-flops are interconnected so that their combined state at any time is the binary equivalent of the total number of pulses that have occurred up to that time Every counter resets after a certain number of clock pulses Thus as it name implies a counter is used to count pulses An n stage counter can count up to a maximum of 2n states n is equal to the number of flip-flops required for the construction of counter

                                    Modulus Counters The number of input pulses that causes a counter to reset to its initial count is called the modulus of the counter Thus the modulus equals to total number of distinct states (counts) including zero that a counter can store A binary counter with n stages is a modulo-2n (or mod-2n) counter The largest count a mod-N counter can achieve is N-1 ie a mod-N counter never reaches the binary number equal to its modulus N is always equal to or less than 2n Counters can be classified as bull Synchronous Counters which are clock driven All the flip-flops are driven by a

                                    single clock bull Asynchronous Counters which are event driven Clock input is given to the first

                                    flip-flop only Rest of the flip-flops are driven by their preceding flip-flops

                                    DESIGN OF A MOD-5 ASYNCHRONOUS UP COUNTER The number of flip-flops required to construct a mod-5 counter is 3 because 5 should be less than or equal to 2n This counter will count from 0 to 4 a total of 5 distinct states Since a 3-stage counter can count up to 8 states at maximum a NAND gate is used to reset it after 5 clock pulses Figure 131 shows the logic diagram

                                    54

                                    Logic Design amp Switching Theory 1 Lab Session 13 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                    55

                                    Figure 131 A Mod-5 Asynchronous Up Counter

                                    Implementation and Observations

                                    Implement the mod-5 counter circuit (figure 131) on a bread board (prepare the pin diagram (use appendix A) and refer to laboratory session 01 for implementation procedure) and record the observations in the following table

                                    Clock Pulse Q2 Q1 Q0

                                    0 1 2 3 4 5 6 7

                                    ACTIVITY

                                    Draw the timing diagram for mod-5 counter designed in this laboratory session

                                    Logic Design amp Switching Theory 1 Lab Session 14 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                    Lab Session 14 OBJECT

                                    Experimenting with 74194 4-bit bidirectional universal shift register COMPONENTS AND APPARATUS REQUIRED

                                    1 Following ICs and their Datasheets

                                    bull 74194 4-bit bidirectional universal shift register 2 Digital Trainer DT-01 or the following components

                                    Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches

                                    THEORY

                                    Shift Registers

                                    A Register is a set of flip-flops used to store binary data A register which is capable of shifting its binary information either to the right or left is called a shift register The logical configuration of a register consists of a chain of flip-flops connected in cascade with the output of one flip-flop connected to the input of next flip-flop All flip-flops receive a common clock pulse which causes the shift from one stage to the next

                                    Bidirectional Shift Registers A bi-directional shift register is one whose bits can be shifted from left to right or from right to left

                                    Universal Shift Registers A universal shift register is a bi-directional register whose input can be in either serial or parallel form and whose output can be in either serial or parallel form

                                    74194 4-BIT BIDIRECTIONAL UNIVERSAL SHIFT REGISTER

                                    The 74194 register provides parallel as well as serial loading in both directions Function of various pins of this IC is described below

                                    bull A B C and D Active high inputs for parallel loading bull QA QB QC and QD Active high outputs bull S0 and S1 Active high mode control inputs The following table shows combinations

                                    of S1 and S0 to enable various modes

                                    S1 S0 Clock Action 0 0 x No change 0 1 uarr Shift right 1 0 uarr Shift left 1 1 uarr Parallel load

                                    uarr shows the rising edge of the clock pulse

                                    56

                                    Logic Design amp Switching Theory 1 Lab Session 14 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering bull SR Active high serial input for right shifting bull SL Active high serial input for left shifting bull CLR Active low input Clears all the flip-flops of the register if set to 0 should be

                                    kept high otherwise bull CLK Clock input bull VCC and GND Supply connections lines Thus A B C and D are inputs for parallel loading whereas SR and SL are inputs for serial loading with right or left shifting respectively S1 and S0 are used to select the loading mode Circuit Diagram

                                    Figure 141 Pin connections of 74194 Testing Procedure

                                    bull Make connections as shown in the circuit diagram bull Observe the output for the input combinations given in the following table

                                    57

                                    Logic Design amp Switching Theory 1 Lab Session 14 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                    58

                                    Observations

                                    S1 S0 SL SR A B C D QA QB QC QD 0 0 0 1 0 0 0 0 0 1 1 0 0 0 0 1 1 0 0 0 0 0 1 0 1 1 0 0 0 0 1 1 0 0 1 1 0 1 0 0 0 1 1 1 0 1 0 1 1 0 1 0 0 1 1 0 1 1 1 0 0 1 1 1 1 1 0 0 1 1 1 1

                                    ACTIVITY 1 Show connections of 74194 to convert it into a ring counter with right shifting

                                    Logic Design amp Switching Theory 1 Lab Session 15 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                    Lab Session 15

                                    OBJECT

                                    Experimenting with 74245 octal bus transceivers using parallel port PC interfacing COMPONENTS AND APPARATUS REQUIRED 1 Parallel Port Connectors (DB-25) with Cable 2 Personal Computer with Windows 98 and TurboC Compiler Installed 3 Following ICs and their Datasheets

                                    bull 74245 Octal Bus Transceivers with 3-State Outputs 4 Digital Trainer DT-01 or the following components

                                    Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches

                                    THEORY

                                    3-State Logic Sometimes it is necessary to isolate one part of circuit from the other part For this purpose some TTL ICs are designed with 3-state logic Such devices have three possible output states high low and high impedance The device can be put into high impedance state by a control signal applied to an appropriate pin When such a device is in high impedance state there is very high impedance at its output effectively isolating the device from whatever circuitry the output normally drives 74245 Octal Bus Transceivers A bus is any conducting path or set of paths having electrical connections to one or more devices 74245 octal bus transceivers are mainly used to control connectivity between two devices or circuits It also provides direction control for signal flow Function of various pin of this IC is given below

                                    bull A1 through A8 Bus A bull B1 through B8 Bus B bull G΄ Active low enable input When high sets all the bus pins to high impedance state bull DIR Direction control for signal flow When set to high logic level transfers bus A

                                    data to B bus When set to low logic level transfers bus B data to A bus bull VCC and GND Supply connections lines Serial and Parallel Port Connectors A Parallel Port can consist of only 25 pin port adapter called a DB-25 and a serial port can consist of either a 25 pin port adapter called a DB-25 or 9 pin adapter called a DB-9 port adapter Whether the port is a 9 pin or 25 pin it can accomplish all of the same tasks that serial port communications have been designed for

                                    59

                                    Logic Design amp Switching Theory 1 Lab Session 15 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                    60

                                    Each adapter can be a male type connector with pins or a female type adapter with tiny holes Generally a PRINTER port (called LPT1) on the back of a computer is female type adapter and we need to use MALE DB-25 pin cable on it for PRINTER connection or for parallel LAPLINK cable And a COM port on the back of a computer is male for the serial ports but it may not necessarily be Parallel Port Connector ndash DB-25 The DB-25 connector (named for its B-size D-shaped shell and 25 pins) is practically ubiquitous in the electronics industry The DB-25 connector is used for a variety of purposes Two common applications are RS-232EIA-232 (serial) connections and the parallel printer interface on the IBM PC The DB-25 connector is also used for SCSI connections Normally the parallel port is used for output to a printer or other device It sends data 8-bits or one byte at a time in parallel The other lines available on the DB-25 connector are a combination of status lines control lines and ground lines The status and control lines are used for handshaking commands and feedback when we are talking to a printer

                                    Figure 152 DB-25 Female Figure 151 DB-25 Male

                                    Figure 153 Pin Layout for DB-25 As can be seen form figure 153 there are four types of pins in this connector

                                    bull Data pins (8 pins - D0 to D7) Active high bidirectional lines

                                    Logic Design amp Switching Theory 1 Lab Session 15 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering bull Control pins (4 pins - C0 to C3) C0 C1 and C3 are active low whereas C2 is active

                                    high These lines also are bidirectional bull Status pins (5 pins ndash S3 to S7) Only S7 is active low rest are active high input lines bull Ground pins (8 pins) Used as a reference signal for the low (below 05 volts) charge

                                    Parallel Port Addresses A DB-25 connector at a parallel port has three address one for each kind of pins register data status and control The first or base address generally refers to data register Second address is for status register and the third one is for control register In Windows 98 the base address is usually found to be 278H 378H or 3BCH Now if 378H is the base address then it refers to the data register whereas addresses for status and control register are respectively 379H and 37AH For Windows 98 the base address can be found as follows 1 On your Desktop right-click on My Computer and select Properties 2 Click on the Device Manager tab and find LPT1 under Plug and Play BIOS 3 After selecting LPT1 click the Properties button 4 Next select the Resources tab and the address should then appear next to InputOutput

                                    Range Accessing parallel port through C Language Programming There are multiple functions in C Language for accessing external ports The most commonly used are listed below

                                    bull unsigned char inportb(int portid) inportb reads a byte from a hardware port

                                    bull int inport(int portid) reads a word from a hardware port

                                    bull void outportb(int portid unsigned char value) outputs a byte to a hardware port

                                    bull void outport(int portid int value) outputs a word to a hardware port

                                    portid refers to the port address whereas value refers to the data to be sent TESTING 74245 USING PARALLEL PORT PC INTERFACING At one end the parallel port connector will be connected to the PC via parallel port cable and another connector (to be plugged into the PC parallel port slot) At the other end it will be connected to the buffer IC 74245 Data lines of the connector will be used to transfer 8-bit data between the PC and the buffer Out of the 8-bits of 74245 4-bits will be used to enter data which will be displayed at the monitor through a C language

                                    61

                                    Logic Design amp Switching Theory 1 Lab Session 15 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering program The remaining 4-bits will receive data from PC as entered by the user via keyboard

                                    Circuit Diagram

                                    Figure 154 Interface of 74245 to PC via Parallel Port

                                    Procedure

                                    1 Connect the DB-25 connector to the PC at one end and solder it to the circuit board at the other end

                                    2 Connect various pins of the connector and 74245 according to the circuit diagram shown in figure 152

                                    3 Using the functions listed in the previous section write a program in C language to operate various pins of the buffer The user interface of the program should provide option to the user whether to send or receive data from the port

                                    4 Set DIR switch to 1 5 Try sending some data bits to the port The result should be displayed at the LEDs 6 Set DIR switch to 0 7 Set some binary 4-bit value through the switches Try reading it via parallel port

                                    C Language Program

                                    A program to access parallel port for data transfers

                                    use header file include ltstdiohgt main program void main() define variable

                                    62

                                    Logic Design amp Switching Theory 1 Lab Session 15 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering unsigned int data=0 char choice while(1) printing option menu clrscr() printf(This program will send or receive a BCD digit from the parallel portn) printf(nPress your choice numbern) printf(n1 Send Data) printf(n2 Receive Data) printf(n3 Exitn) choice = getch() sending entered digit to the port if(choice == 1) input BCD digit printf(nEnter BCD digit to be sent to the port) data = getche() masking the first four bits data = data amp 0x0f sending to the port outportb(0x378data) printf(nThe BCD digit c has been sent to the port data) printing on screen the data received from the port else if(choice == 2) receiving data from the port data = inportb(0x378) masking the last four bits data = data amp 0xf0 shifting first four bits to make them the last four bits datagtgt=4 printf(nThe BCD digit set at the port is c data) exit else if(choice == 3) break key pressed is not in the menu else printf(nEnter valid choice number) printf(nnPress any key to continue) getch()

                                    63

                                    Logic Design amp Switching Theory 1 Lab Session 15 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                    ACTIVITY 1 In the above circuit DIR and G΄ inputs are hardwired Connect them to status or

                                    control pins of the parallel port connector and control their function through your software program Circuit Diagram Program Code ______________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________

                                    ___________________________________________________________________________________________________________________________________________________

                                    64

                                    Logic Design amp Switching Theory 1 Lab Session 15 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                    65

                                    _____________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ _____________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ _______________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ _________________________________________________ _________________________________________________

                                    Logic Design amp Switching Theory 1 Appendix A NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                    Appendix A

                                    PIN DIAGRAMS OF THE ICS REQUIRED FOR THE LABORATORY SESSIONS Consult the TTLIC data book for internal diagrams and electrical characteristics of these ICs 7400 Quad 2-Input NAND 7402 Quad 2-Input NOR

                                    7404 Hex Inverter 7408 Quad 2-Input AND

                                    7410 Triple 3-Input NAND 7411 Triple 3-Input AND

                                    7421 Dual 4-Input AND 7432 Quad 2-Input OR

                                    66

                                    Logic Design amp Switching Theory 1 Appendix A NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                    BCD-to-Seven Segm 7448 BCD-to-Seven Segment 7447 ent

                                    Decoder (15V OC) Decoder (2kΩ pull-up output)

                                    7473 Dual JK Flip-Flop 7474 Dual D-Type Flip-Flop

                                    7476 Dual JK Flop-Flop -Bit Binary Full Adder 7483 4 with Fast Carry

                                    86 Quad 2-Inpu 74138 3-to-8 Line 74 t Exclusive OR Decoder Demultiplexer

                                    67

                                    Logic Design amp Switching Theory 1 Appendix A NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                    68

                                    74148 8-to-3 Line 16-to-1 Line Data

                                    Priority Encoder 74150 Selector Multiplexer

                                    74245 Oct nsceivers Universal Shift Register (PIPO) (3-State)

                                    74194 4-Bit Bidirectional al Bus Tra

                                    Logic Design amp Switching Theory 1 Appendix B NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                    Appendix B

                                    DEBOUNCING CIRCUITRY FOR MECHANICAL SWITCHES Mechanical switches form the interface between human beings and computers or other digital systems For example a keyboard is a matrix of switches used to supply alphanumeric data to a computer Whatever the switch design it is a potential source of problems due to contact bounce The contact bounce creates a sense of narrow pulses when a switch is opened or closed An example of device whose operation would be adversely affected by contact bounce is a digital counter used to count the number of times a switch is depressed Eliminating the effects of contact bounce is called debouncing When data is entered into a computer via a keyboard a software debounce is often used This type of debouncing is a program that causes the computer to sample the switch terminal (ie to input data from it) many times in succession during the interval of time that contact bounce occurs If the data is sensed to be 1s (or 0s) for a specific number of consecutive samples then it is assumed that contact bounce has ended and the last value sensed is valid Hardware debouncing is the use of electronic circuitry to eliminate the effects of contact bounce There are numerous versions of such circuitry including those that use monostable multivibrators (one-shots) but the most straightforward is simply an RS latch Figure B1 shows the circuit When the switch is in position 1 R = 0 and S = 1 so the latch is set and the output (Q) is 1 When the switch is in position 0 R = 1and S = 0 so the latch is reset and the output is 0 When the switch is moved form one position to the other the latch changes state and bouncing occurs at either the R or the S input The bouncing does not affect the latch after it has change state An RS latch will remain set for example when its R input is 0 and its S input is alternately changed form 1 to 0

                                    Figure B1 Use of RS latch to debounce a mechanical switch

                                    69

                                    • 01-ldst-Outer title
                                      • Practical Workbook
                                      • Logic Design amp Switching Theory I
                                        • Dept of Computer amp Information Systems Engineering
                                          • NED University of Engineering amp Technology
                                          • Karachi ndash 75270 Pakistan
                                            • 02-ldst-inner Title
                                              • Practical Workbook
                                              • Logic Design amp Switching Theory I
                                                • Dept of Computer amp Information Systems Engineering
                                                  • NED University of Engineering amp Technology
                                                  • Karachi ndash 75270 Pakistan
                                                    • 03-ldst-general info
                                                    • 04-ldst-introduction
                                                    • 05-Table of Contents
                                                      • CONTENTS
                                                        • Lab Session No Object Page No
                                                        • 1
                                                        • Also implementing and testing the given circuit on a bread board
                                                          • Working with Electronics Workbench
                                                            • Driving a seven segment display using 7447 7448 driver IC
                                                              • Designing a modulus-5 asynchronous up-counter using JK-FF
                                                                • Experimenting with 74194 4-bit bidirectional universal shift register
                                                                    • 13
                                                                        • 06-ldst-Exp01
                                                                          • Lab Session 01
                                                                          • OBJECT
                                                                            • 1 Bread board
                                                                            • 2 5 V - power supply
                                                                            • 3 Multimeter
                                                                            • 4 Logic probe
                                                                            • 5 LEDs with resistors
                                                                            • 6 Connecting wires
                                                                            • 8 Following ICs and their datasheets
                                                                              • THEORY
                                                                                • Logic Gates
                                                                                • 1 The AND Gate ndash An AND gatersquos output is 1 if and only if all its inputs are 1 If A and B are two inputs to an AND gate then output F of the gate is given as F = AB
                                                                                • 2 The OR Gate - An OR gatersquos output is 1 if at least one of its input is 1 If A and B are two inputs to an OR gate then output F of the gate is given as F = A+B
                                                                                • 3 The NOT Gate (Inverter) ndash Its output is 1 when its input is 0 and its output is 0 when the input is 1 ie it complements a digital variable If A is the input to a NOT gate then output F of the gate is given as
                                                                                • 4 The NAND Gate ndash Its output is 1 if at least one of its input is 0 This gate performs the same logic as an AND gate followed by an inverter If A and B are two inputs to a NAND gate then output F of the gate is given as
                                                                                  • 5 The NOR Gate - The output of a NOR gate is 1 if and only if all its inputs are 0 This gate performs the same logic function as an OR gate followed by an inverter If A and B are two inputs to a NAND gate then output F of the gate is given as
                                                                                      • DATA SHEETS
                                                                                        • Logic expression for the given logic diagram __________________________________
                                                                                            • 07-ldst-exp02
                                                                                              • Working with Electronics Workbench
                                                                                                • 08-ldst-exp03
                                                                                                  • Designing Half and Full Adder Circuits
                                                                                                    • COMPONENTS AND APPARATUS REQUIRED
                                                                                                      • 1 Following ICs and their Datasheets
                                                                                                      • 7408 Quad 2-input AND Gate
                                                                                                      • 2 Digital Trainer DT-01 or the following components
                                                                                                        • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                        • Connecting wires Switches
                                                                                                          • THEORY
                                                                                                              • IMPLEMENTATION AND OBSERVATIONS
                                                                                                                • 09-ldst-Exp04
                                                                                                                  • Lab Session 04
                                                                                                                  • 1 Digital ICs and their Datasheets
                                                                                                                  • 7408 Quad 2-input AND Gate
                                                                                                                  • 2 Digital Trainer DT-01 or the following components
                                                                                                                    • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                    • Connecting wires Switches
                                                                                                                    • PROCEDURE
                                                                                                                    • REDUCTION OF LOGIC EXPRESSION USING KARNAUGH MAP
                                                                                                                    • OBSERVATIONS
                                                                                                                    • RESULT
                                                                                                                        • 10-ldst-Exp05
                                                                                                                          • Lab Session 05
                                                                                                                          • 1 Following ICs and their Datasheets
                                                                                                                          • 7408 Quad 2-input AND Gate
                                                                                                                          • 2 Digital Trainer DT-01 or the following components
                                                                                                                            • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                            • (100 Ω) Connecting wires Switches
                                                                                                                            • THEORY
                                                                                                                              • IMPLEMENTATION AND OBSERVATIONS
                                                                                                                                • 11-ldst-Exp06
                                                                                                                                  • OBJECT
                                                                                                                                  • 1 Following ICs and their Datasheets
                                                                                                                                  • 7408 Quad 2-input AND Gates or 7411 Triple 3-input AND Gates
                                                                                                                                  • 2 Digital Trainer DT-01 or the following components
                                                                                                                                    • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                    • Connecting wires Switches
                                                                                                                                      • Figure 62 Circuit Diagram for 4 x 1 Multiplexer
                                                                                                                                      • Implementation and Observations
                                                                                                                                        • Circuit Diagram
                                                                                                                                          • ACTIVITY
                                                                                                                                            • 12-ldst-exp07
                                                                                                                                              • 1 Following ICs and their Datasheets
                                                                                                                                              • 7408 Quad 2-input or 7411 Triple 3-input AND Gates
                                                                                                                                              • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                • Connecting wires Switches
                                                                                                                                                  • THEORY
                                                                                                                                                      • Figure 72 Circuit Diagram for 2 x 4 Decoder 1 x 4 Demultiplexer
                                                                                                                                                      • Implementation and Observations
                                                                                                                                                        • Circuit Diagram
                                                                                                                                                          • ACTIVITY
                                                                                                                                                            • 13-ldst-Exp08
                                                                                                                                                              • OBJECT
                                                                                                                                                              • 1 Following ICs and their Datasheets
                                                                                                                                                              • 7408 Quad 2-input or 7421 Dual 4-input AND Gates
                                                                                                                                                              • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                • Connecting wires Switches
                                                                                                                                                                  • THEORY
                                                                                                                                                                      • Figure 81 Circuit Diagram for 4 x 2 Priority Encoder
                                                                                                                                                                      • Implementation and Observations
                                                                                                                                                                        • Therefore if GS A2 A1 and A0 are all low then it shows that line 0 is selected and if E0 A2 A1 and A0 are all low then it shows that none of the inputs selected E0 and GS cannot be in the same state provided that E1 is enabled
                                                                                                                                                                        • Circuit Diagram
                                                                                                                                                                          • ACTIVITY
                                                                                                                                                                            • 14-ldst-exp09
                                                                                                                                                                              • OBJECT
                                                                                                                                                                              • 1 Following ICs and their Datasheets
                                                                                                                                                                              • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                • Connecting wires Switches
                                                                                                                                                                                  • THEORY
                                                                                                                                                                                    • Parity Generator
                                                                                                                                                                                      • Let x y and z be the three bits that constitute the message and are the input to the Odd Parity Generator Circuit Since it is an odd parity system the bit P is generated so as to make the total number of 1s odd (including P) The function P can be expressed as follows
                                                                                                                                                                                      • Figure 91 Circuit Diagram for a 3-bit Parity Generator
                                                                                                                                                                                        • C = x Ο y Ο z Ο P
                                                                                                                                                                                          • Implementation and Observations
                                                                                                                                                                                            • ACTIVITY
                                                                                                                                                                                                • 15-ldst-exp10
                                                                                                                                                                                                  • Driving a seven segment display using 7447 7448 driver IC
                                                                                                                                                                                                  • COMPONENTS AND APPARATUS REQUIRED
                                                                                                                                                                                                  • 1 Following ICs and their Datasheets
                                                                                                                                                                                                  • 7447 7448 BCD to Seven Segment Driver
                                                                                                                                                                                                  • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                    • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches
                                                                                                                                                                                                      • THEORY
                                                                                                                                                                                                      • Seven Segment Displays
                                                                                                                                                                                                      • CIRCUIT DIAGRAM
                                                                                                                                                                                                      • Figure 102 Circuit diagram for 7447driving a common-anode display
                                                                                                                                                                                                          • IMPLEMENTATION AND OBSERVATIONS
                                                                                                                                                                                                            • Decimal Digit
                                                                                                                                                                                                            • BCD Inputs
                                                                                                                                                                                                            • Seven Segment Outputs
                                                                                                                                                                                                            • D
                                                                                                                                                                                                            • C
                                                                                                                                                                                                            • B
                                                                                                                                                                                                            • A
                                                                                                                                                                                                            • a
                                                                                                                                                                                                            • b
                                                                                                                                                                                                            • c
                                                                                                                                                                                                            • d
                                                                                                                                                                                                            • e
                                                                                                                                                                                                            • f
                                                                                                                                                                                                            • g
                                                                                                                                                                                                            • 0
                                                                                                                                                                                                            • 0
                                                                                                                                                                                                            • 0
                                                                                                                                                                                                            • 0
                                                                                                                                                                                                            • 0
                                                                                                                                                                                                            • 1
                                                                                                                                                                                                            • 0
                                                                                                                                                                                                            • 0
                                                                                                                                                                                                            • 0
                                                                                                                                                                                                            • 1
                                                                                                                                                                                                            • 2
                                                                                                                                                                                                            • 0
                                                                                                                                                                                                            • 0
                                                                                                                                                                                                            • 1
                                                                                                                                                                                                            • 0
                                                                                                                                                                                                            • 3
                                                                                                                                                                                                            • 0
                                                                                                                                                                                                            • 0
                                                                                                                                                                                                            • 1
                                                                                                                                                                                                            • 1
                                                                                                                                                                                                            • 4
                                                                                                                                                                                                            • 0
                                                                                                                                                                                                            • 1
                                                                                                                                                                                                            • 0
                                                                                                                                                                                                            • 0
                                                                                                                                                                                                            • 5
                                                                                                                                                                                                            • 0
                                                                                                                                                                                                            • 1
                                                                                                                                                                                                            • 0
                                                                                                                                                                                                            • 1
                                                                                                                                                                                                            • 6
                                                                                                                                                                                                            • 0
                                                                                                                                                                                                            • 1
                                                                                                                                                                                                            • 1
                                                                                                                                                                                                            • 0
                                                                                                                                                                                                            • 7
                                                                                                                                                                                                            • 0
                                                                                                                                                                                                            • 1
                                                                                                                                                                                                            • 1
                                                                                                                                                                                                            • 1
                                                                                                                                                                                                            • 8
                                                                                                                                                                                                            • 1
                                                                                                                                                                                                            • 0
                                                                                                                                                                                                            • 0
                                                                                                                                                                                                            • 0
                                                                                                                                                                                                            • 9
                                                                                                                                                                                                            • 1
                                                                                                                                                                                                            • 0
                                                                                                                                                                                                            • 0
                                                                                                                                                                                                            • 1
                                                                                                                                                                                                              • ACTIVITY
                                                                                                                                                                                                                • 16-ldst-exp11
                                                                                                                                                                                                                  • Lab Session 11
                                                                                                                                                                                                                    • OBJECT
                                                                                                                                                                                                                    • COMPONENTS AND APPARATUS REQUIRED
                                                                                                                                                                                                                      • 1 Following ICs and their Datasheets
                                                                                                                                                                                                                      • 7473 7476 JK Flip-Flop
                                                                                                                                                                                                                      • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                        • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                                        • Connecting wires Switches
                                                                                                                                                                                                                          • THEORY
                                                                                                                                                                                                                              • Flip-Flop
                                                                                                                                                                                                                              • JK Flip-Flop
                                                                                                                                                                                                                                • Circuit Diagram
                                                                                                                                                                                                                                  • Observations
                                                                                                                                                                                                                                    • ACTIVITY
                                                                                                                                                                                                                                        • 17-ldst-exp12
                                                                                                                                                                                                                                          • Lab Session 12
                                                                                                                                                                                                                                            • OBJECT
                                                                                                                                                                                                                                            • GIVEN STATE DIAGRAM
                                                                                                                                                                                                                                            • Figure 121 State Diagram
                                                                                                                                                                                                                                            • COMPONENTS AND APPARATUS REQUIRED
                                                                                                                                                                                                                                              • 1 Following ICs and their Datasheets
                                                                                                                                                                                                                                              • 7474 D Flip-Flop
                                                                                                                                                                                                                                              • ICs of basic gates (AND OR NOT XOR etc) as required
                                                                                                                                                                                                                                              • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                                                • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                                                                • Connecting wires Switches
                                                                                                                                                                                                                                                  • THEORY
                                                                                                                                                                                                                                                      • Sequential Circuits
                                                                                                                                                                                                                                                        • 18-ldst-exp13
                                                                                                                                                                                                                                                          • Lab Session 13
                                                                                                                                                                                                                                                            • Designing a modulo-5 asynchronous up-counter using JK-FF
                                                                                                                                                                                                                                                              • 1 Following ICs and their Datasheets
                                                                                                                                                                                                                                                              • 7400 Quad 2-input or 7410 Triple 3-input NAND Gates
                                                                                                                                                                                                                                                              • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                                                                • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                                                                                • Connecting wires Switches
                                                                                                                                                                                                                                                                  • THEORY
                                                                                                                                                                                                                                                                      • Figure 131 A Mod-5 Asynchronous Up Counter
                                                                                                                                                                                                                                                                      • Implementation and Observations
                                                                                                                                                                                                                                                                        • ACTIVITY
                                                                                                                                                                                                                                                                            • 19-ldst-exp14
                                                                                                                                                                                                                                                                              • Experimenting with 74194 4-bit bidirectional universal shift register
                                                                                                                                                                                                                                                                              • 1 Following ICs and their Datasheets
                                                                                                                                                                                                                                                                              • 74194 4-bit bidirectional universal shift register
                                                                                                                                                                                                                                                                              • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                                                                                • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                                                                                                • Connecting wires Switches
                                                                                                                                                                                                                                                                                  • THEORY
                                                                                                                                                                                                                                                                                    • Shift Registers
                                                                                                                                                                                                                                                                                    • Bidirectional Shift Registers
                                                                                                                                                                                                                                                                                    • Universal Shift Registers
                                                                                                                                                                                                                                                                                      • S1
                                                                                                                                                                                                                                                                                        • Circuit Diagram
                                                                                                                                                                                                                                                                                        • ACTIVITY
                                                                                                                                                                                                                                                                                            • 20-ldst-exp15
                                                                                                                                                                                                                                                                                              • COMPONENTS AND APPARATUS REQUIRED
                                                                                                                                                                                                                                                                                              • 1 Parallel Port Connectors (DB-25) with Cable
                                                                                                                                                                                                                                                                                              • 2 Personal Computer with Windows 98 and TurboC Compiler Installed
                                                                                                                                                                                                                                                                                              • 3 Following ICs and their Datasheets
                                                                                                                                                                                                                                                                                              • 74245 Octal Bus Transceivers with 3-State Outputs
                                                                                                                                                                                                                                                                                              • 4 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                                                                                                • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                                                                                                                  • Connecting wires Switches
                                                                                                                                                                                                                                                                                                    • THEORY
                                                                                                                                                                                                                                                                                                    • 3-State Logic
                                                                                                                                                                                                                                                                                                      • Serial and Parallel Port Connectors
                                                                                                                                                                                                                                                                                                      • Parallel Port Connector ndash DB-25
                                                                                                                                                                                                                                                                                                        • Accessing parallel port through C Language Programming
                                                                                                                                                                                                                                                                                                            • 21-ldst-appendixA
                                                                                                                                                                                                                                                                                                            • 22-ldst-appendixB
                                                                                                                                                                                                                                                                                                              • DEBOUNCING CIRCUITRY FOR MECHANICAL SWITCHES

                                      Logic Design amp Switching Theory 1 Lab Session 03 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                      at of your designed circuit Attach hardcopy of the output form electronic workbench

                                      at of your designed circuit Attach hardcopy of the output form lectronic workbench here

                                      ACTIVITY

                                      1 Simulate half adder circuit using Electronics Workbench Compare the results of simulation with thhere

                                      2 Design a full subtractor circuit and simulate it using Electronics Workbench Compare the results of simulation with the

                                      21

                                      Logic Design amp Switching Theory 1 Lab Session 04 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                      Lab Session 04 OBJECT

                                      Use of Karnaugh Map (SOP-Expression) method GIVEN LOGIC EXPRESSION

                                      F (A B C D) = sum ( 0 1 2 4 5 6 8 9 12 13 14 ) COMPONENTS AND APPARATUS REQUIRED 1 Digital ICs and their Datasheets

                                      bull 7408 Quad 2-input AND Gate bull 7432 Quad 2-input OR Gate bull 7404 Hex Inverter

                                      2 Digital Trainer DT-01 or the following components Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches PROCEDURE 1 Use Karnaugh map to reduce the given function 2 Draw the circuit diagram for the obtained reduced function 3 Implement the reduced circuit using digital ICs on a bread board (prepare the pin

                                      diagram (use appendix A) and refer to laboratory session 01 for procedure) and record the observations

                                      REDUCTION OF LOGIC EXPRESSION USING KARNAUGH MAP F

                                      CD

                                      AB DC

                                      DC DC

                                      DC

                                      BA0 1 3 2

                                      BA4 5 7 6

                                      BA12 13 15 14

                                      BA8 9 11 10

                                      Reduced form of the given logic expression is __________________________________

                                      22

                                      Logic Design amp Switching Theory 1 Lab Session 04 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                      LOGIC DIAGRAM (REDUCED FORM) OBSERVATIONS

                                      A B C D Output 0 0 0 0 0 0 0 1 0 0 1 0 0 0 1 1 0 1 0 0 0 1 0 1 0 1 1 0 0 1 1 1 1 0 0 0 1 0 0 1 1 0 1 0 1 0 1 1 1 1 0 0 1 1 0 1 1 1 1 0 1 1 1 1

                                      RESULT The reduced form (SOP Expression) of the given logic function is

                                      ____________________________________________________________

                                      The observation table reflects the given logic function

                                      23

                                      Logic Design amp Switching Theory 1 Lab Session 04 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                      ACTIVITY 1 Using Electronics Workbench derive a truth table and logic circuit for the following logic expression

                                      BAAF +=

                                      Procedure 1 From the Instruments Parts Bin drag and drop Logic Converter on the design area 2 Double click the Logic Converter to reveal Logic Converter dialog box This dialog

                                      box shows various conversion options between truth table logic expression and logic circuit

                                      3 Enter the given logic expression in the edit box found at the end of the dialog box Use lsquo to represent invert of a variable For example A is written as Arsquo

                                      4 Click the Boolean Expression to Truth Table button The truth table appears in the logic converters display

                                      5 Now click the Boolean Expression to Circuit button This creates the logic circuit for the given expression in the design area Label the diagram if needed

                                      Resulting Logic Circuit For the given expression the final circuit will look like

                                      Figure 41

                                      24

                                      Logic Design amp Switching Theory 1 Lab Session 04 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                      ACTIVITY 2

                                      Using Electronics Workbench find a simplified logic expression and circuit for the following truth table

                                      A B C Output 0 0 0 1 0 0 1 1 0 1 0 0 0 1 1 1 1 0 0 0 1 0 1 0 1 1 0 0 1 1 1 1

                                      Procedure 1 Click three input channels from A to H across the top of the logic converter The

                                      display area below the terminals fills up with the necessary combinations of ones and zeros to fulfill the input conditions The values in the output column on the right are initially set to 0

                                      2 Edit the output column to specify the desired output for each input condition To change an output value select it and type a new value 1 0 or x An x indicates a donrsquot care condition

                                      3 To convert this truth table to a Boolean expression click the Truth Table to Boolean Expression button The Boolean expression will be displayed at the bottom of the logic converter

                                      4 Simplify the expression by clicking the Simplify button 5 Now click the Boolean Expression to Circuit button This creates the logic circuit for

                                      the given expression in the design area Resulting Logic Circuit For the given truth table the final simplified circuit will look like

                                      Figure 42

                                      25

                                      Logic Design amp Switching Theory 1 Lab Session 04 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                      ACTIVITY 3

                                      Using Electronics Workbench find the logic expression and truth table for the following logic circuit

                                      Figure 43

                                      Procedure 1 Attach the input terminals of the logic converter to up to four input points in the

                                      circuit 2 Connect the single output of the circuit to the output terminal on the logic converter

                                      icon 3 Click the Circuit to Truth Table button The truth table appears in the logic

                                      converters display 4 To convert this truth table to a Boolean expression click the Truth Table to Boolean

                                      Expression button The Boolean expression will be displayed at the bottom of the logic converter

                                      Resulting Logic Expression Logic Expression for the given circuit is found to be _____________________________

                                      26

                                      Logic Design amp Switching Theory 1 Lab Session 04 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                      27

                                      For activities 1 2 and 3 attach hardcopy of the output (truth table logic expression and logic circuit) form electronic workbench here

                                      Logic Design amp Switching Theory 1 Lab Session 05 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                      Lab Session 05 Lab Session 05 OBJECT OBJECT

                                      Designing a BCD Adder Designing a BCD Adder COMPONENTS AND APPARATUS REQUIRED COMPONENTS AND APPARATUS REQUIRED

                                      1 Following ICs and their Datasheets 1 Following ICs and their Datasheets bull 7408 Quad 2-input AND Gate bull 7408 Quad 2-input AND Gate bull 7432 Quad 2-input OR Gate bull 7432 Quad 2-input OR Gate bull 7483 4-bit Binary Adder bull 7483 4-bit Binary Adder

                                      2 Digital Trainer DT-01 or the following components 2 Digital Trainer DT-01 or the following components Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors (100 Ω) Connecting wires Switches (100 Ω) Connecting wires Switches

                                      THEORY THEORY

                                      A BCD Adder is a combinational circuit that adds two BCD digits in parallel and produces a sum digit also in BCD A BCD Adder is a combinational circuit that adds two BCD digits in parallel and produces a sum digit also in BCD

                                      A4 A3 A2 A1 B4 B3 B2 B1

                                      7483-BCD ADDER

                                      Cout (C4 ) Z4 Z3 Z2 Z1 Cin(C0)

                                      A4 A3 A2 A1 B4 B3 B2 B1

                                      7483-BCD ADDER

                                      Cout

                                      (C4 ) Z4 Z3 Z2 Z1 Cin(C0)

                                      Figure 51 BCD Adder Circuit

                                      28

                                      Logic Design amp Switching Theory 1 Lab Session 05 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                      29

                                      A BCD adder must include the correction logic in its internal construction The two BCD digits together with the input carry are first added using a 4-bit binary adder to produce the binary sum If no output carry is generated and the binary sum is less than or equal to 9 then the corresponding BCD sum is identical and therefore no conversion is needed When the output carry is equal to 1 or the binary sum is greater than 9 then a binary 0110 is added to the binary sum through another 4-bit binary adder If Cout is the carry output and Z4Z3Z2Z1 is the binary sum form the first 4-bit binary adder then the following equation indicates the condition when a binary 0110 is to be added

                                      C = COUT + Z4Z2 + Z4Z3 IMPLEMENTATION AND OBSERVATIONS Implement the BCD adder circuit according to figure 51 on a bread board (prepare the pin diagram (use appendix A) and refer to laboratory session 01 for procedure) A BCD adder has nine input bits (two BCD digits and a carry bit) which can result in a total of 512 combinations of which 312 inputs are donrsquot care Since it is a very lengthy procedure to record results for 200 valid input combinations therefore for simplicity just record results for any eight combinations in the following table

                                      Input Carry

                                      BCD Digit 1 BCD Digit 2 Carry Output

                                      BCD Sum A4 A3 A2 A1 B4 B3 B2 B1 Z4 Z3 Z2 Z1

                                      Logic Design amp Switching Theory 1 lab Session 06 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                      Lab Session 06

                                      OBJECT

                                      bull Designing of a 4 x 1 Multiplexer bull Experimenting with 74150 IC

                                      COMPONENTS AND APPARATUS REQUIRED 1 Following ICs and their Datasheets

                                      bull 7408 Quad 2-input AND Gates or 7411 Triple 3-input AND Gates bull 7432 Quad 2-input OR Gates bull 7404 Hex Inverter bull 74150 16 x 1 MUX

                                      2 Digital Trainer DT-01 or the following components Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches THEORY

                                      Multiplexers A digital data Multiplexer (MUX) is a combinational circuit having several data inputs and a single output A set of data-select inputs is used to control which of the data inputs is routed to the single output A multiplexer is also called a data selector because of this ability to select which data input is connected o the output Normally there are 2n input lines and n selection lines whose bit combination determine which input is selected DESIGN OF A 4 x 1 MULTIPLEXER A 4 x 1 multiplexer is capable of selecting one of four data inputs (see figure 61) The 2-bit binary number at the data select inputs S1 and S0 specifies which of the four data inputs is to be routed to the output Since there are two data select inputs therefore they can select 22 = 4 different data inputs lines

                                      S0 S1 D0 D1

                                      D2 D3

                                      Data-select Inputs Output

                                      Data Inputs

                                      Figure 61 Block Diagram of a 4 x1 Multiplexer

                                      30

                                      Logic Design amp Switching Theory 1 lab Session 06 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                      Figure 62 Circuit Diagram for 4 x 1 Multiplexer

                                      Implementation and Observations

                                      Implement the 4 x 1 Multiplexer circuit (figure 62) on a bread board (prepare the pin diagram (use appendix A) and refer to laboratory session 01 for implementation procedure) and record the observations in the following table For each data select combination specify the switch number as well as the binary value present on that selected switch

                                      S1 S0 Output 0 0 0 1 1 0 1 1

                                      TESTING OF 74150 - 16 x 1 MUX

                                      The 74150 IC has sixteen data inputs and four data-selection lines Function of various pins of this IC is described below

                                      bull E0 through E15 Data input lines

                                      31

                                      Logic Design amp Switching Theory 1 lab Session 06 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering bull A B C D Data select lines with D being the MSB bull W Active low output line bull Grsquo Active low enable line bull VCC and GND Supply connections lines

                                      Circuit Diagram

                                      Figure 63 Pin connections of 74150 for selecting E0

                                      Testing Procedure

                                      bull Make connections as shown in the circuit diagram bull Apply different data (1 or 0) at data inputs that are labeled as E0 to E15 Only

                                      connection for E0 is shown is the figure for simplicity bull Select the data input E0 with the help of data selectors A B C and D bull Observe the output which shows the complement of the data from E0 bull Select all the sixteen data inputs one by one and record your observations in the

                                      following table

                                      32

                                      Logic Design amp Switching Theory 1 lab Session 06 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                      33

                                      Observations

                                      Grsquo D C B A W Grsquo D C B A W 0 0 0 0 0 0 1 0 0 0 0 0 0 0 1 0 1 0 0 1 0 0 0 1 0 0 1 0 1 0 0 0 0 1 1 0 1 0 1 1 0 0 1 0 0 0 1 1 0 0 0 0 1 0 1 0 1 1 0 1 0 0 1 1 0 0 1 1 1 0 0 0 1 1 1 0 1 1 1 1

                                      ACTIVITY 1 Consider 4x1 Multiplexer Draw the output wave-form for the following data inputs

                                      (E0 E1 E2 E3) and select lines A B (B being the MSB) Output is W

                                      E3 E2 E1 E0 A B

                                      W

                                      2 Using the 4 x 1 MUX designed in this laboratory session implement the following logical function F (A B C) = Σ (0147)

                                      Show your working and input connections in the following block diagram according to the circuit you have implemented

                                      4 x 1 MUX

                                      S0 S1

                                      Output D0

                                      D1

                                      D2

                                      D3

                                      Logic Design amp Switching Theory 1 Lab Session 07 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                      Lab Session 07

                                      OBJECT

                                      bull Designing of a 2 x 4 Decoder 1 x 4 Demultiplexer bull Experimenting with 74138 IC

                                      COMPONENTS AND APPARATUS REQUIRED 1 Following ICs and their Datasheets

                                      bull 7408 Quad 2-input or 7411 Triple 3-input AND Gates bull 7404 Hex Inverter bull 74138 3 x 8 Decoder

                                      2 Digital Trainer DT-01 or the following components Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches THEORY

                                      Decoder A Decoder is a combinational circuit that converts binary information form n input lines to a maximum of 2n unique output lines In practical applications decoders are often used for selecting one of several devices

                                      Demultiplexer A decoder with an enable input can function as a Demultiplexer A Demultiplexer (DMUX) id a circuit that receives information on a single line and transmits this information on one of 2n possible output lines The selection of a specific output line is controlled by the bit values of n selection lines DESIGN OF A 2 x 4 DECODER 1 x 4 DEMULTIPLEXER A 2 x 4 decoder is capable of selecting one of four output lines (see figure 71 (a)) The 2-bit binary number at the data inputs S1 and S0 specifies which of the four data inputs is to be selected If we add an enable pin and use it as an input line then this decoder can be converted to a 1 x 4 Demultiplexer where S1 and S0 will select a line to which data input is to be routed (see figure 71 (b))

                                      Select S0 S0 Inputs

                                      S1 D0 D1

                                      D2

                                      D3

                                      Enable (a) Block Diagram of a 2 x 4 Decoder

                                      Figure 71

                                      S1 D0 D1

                                      D2

                                      D3

                                      Inputs

                                      Data Input (b) Block Diagram of a 1 x 4 Demulptiplexer

                                      34

                                      Logic Design amp Switching Theory 1 Lab Session 07 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                      Figure 72 Circuit Diagram for 2 x 4 Decoder 1 x 4 Demultiplexer

                                      Implementation and Observations Implement the 2 x 4 Decoder 1 x 4 Demultiplexer circuit (figure 72) on a bread board (prepare the pin diagram (use appendix A) and refer to laboratory session 01 for implementation procedure) and record the observations in the following table

                                      Enable Data Input S1 S0 D0 D1 D2 D3

                                      0 0 0 0 0 1 0 1 0 0 1 1 1 0 0 1 0 1 1 1 0 1 1 1

                                      TESTING OF 74138 3 x 8 Decoder The 74138 IC has three inputs and eight output lines It has three enable inputs and for the IC to function all three inputs need to be enabled Function of various pins of this IC is described below

                                      35

                                      Logic Design amp Switching Theory 1 Lab Session 07 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                      bull Y0 through Y7 Active low data outputs bull A B C Input select lines with C being the MSB bull G1 Active high enable Input bull G2Arsquo and G2Brsquo Active low enable Inputs bull VCC and GND Supply connections lines Circuit Diagram

                                      Figure 73 Pin connections of 74138

                                      Testing Procedure

                                      bull Make connections as shown in the circuit diagram bull Apply different combinations of 1s and 0s at data inputs bull Observe the output and record your observations in the following table

                                      Observations

                                      C B A Y0 Y1 Y2 Y3 Y4 Y5 Y6 Y7 0 0 0 0 0 1 0 1 0 0 1 1 1 0 0 1 0 1 1 1 0 1 1 1

                                      36

                                      Logic Design amp Switching Theory 1 Lab Session 07 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                      37

                                      ACTIVITY ACTIVITY 1 What will be the binary values at the outputs Y0 through Y7 of 74138 if 1 What will be the binary values at the outputs Y0 through Y7 of 74138 if

                                      bull All three enable pins are connected to ground bull All three enable pins are connected to ground __________________________________________________________________________________________________________________________________________ __________________________________________________________________________________________________________________________________________ _____________________________________________________________________ _____________________________________________________________________

                                      bull All three enable pins are connected to VCC bull All three enable pins are connected to VCC _______________________________________________________________________________________________________________________________________________________________________________________________________________

                                      _______________________________________________________________________________________________________________________________________________________________________________________________________________

                                      2 Show connections for 74138 in order to use it as a 1 x 8 Demultiplexer 2 Show connections for 74138 in order to use it as a 1 x 8 Demultiplexer

                                      3 Consider a 2 x 4 Decoder with two enable inputs (one active high - G and one active low ndash Grsquo) Draw the output wave-forms for D0 D1 D2 and D3 if the two select inputs are A and B (B being the MSB) All outputs are active low

                                      Grsquo

                                      G

                                      A B

                                      D0 D1 D2

                                      D3

                                      Logic Design amp Switching Theory 1 Lab Session 08 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                      Lab Session 08 OBJECT

                                      bull Designing of a 4 x 2 Priority Encoder bull Experimenting with 74148 IC

                                      COMPONENTS AND APPARATUS REQUIRED

                                      1 Following ICs and their Datasheets

                                      bull 7408 Quad 2-input or 7421 Dual 4-input AND Gates bull 7432 Quad 2-input OR Gates bull 7404 Hex Inverter bull 74148 Encoder

                                      2 Digital Trainer DT-01 or the following components Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches

                                      THEORY

                                      Encoder An Encoder is a digital function that produces a reverse operation from that of a decoder An Encoder has 2n (or less) input lines and n output lines The output lines generate the binary code for the 2n input variables Priority Encoder

                                      A simple encoder may produce an erroneous output if more than one of its inputs is high A Priority Encoder is one that responds to just one input among those that may be simultaneously high in accordance with some priority system The most common priority system is based on the relative magnitudes of the inputs whichever decimal input is largest is the one that is encoded

                                      DESIGN OF A 4 x 2 Priority Encoder

                                      The following equations represent the outputs of a 4 x 2 priority encoder 32 DDA +=

                                      321 DDDB += As can be seen from the equations that input D0 which has a binary code 00 is not used in any equation A binary code 00 at the output indicates two conditions Either D0 is selected or no input is selected In order to differentiate these two conditions we will provide an additional output Z to indicate if at least one of the inputs is a 1 The equation for Z will be

                                      4321 DDDDZ = If Z is 0 then the binary code 00 at the output indicates that D0 is selected and if Z is 1 then it indicates that no input line is selected

                                      38

                                      Logic Design amp Switching Theory 1 Lab Session 08 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                      Figure 81 Circuit Diagram for 4 x 2 Priority Encoder

                                      it (figure 81) on a bread board (prepare the to laboratory session 01 for implementation

                                      Implementation a Implement the 4 x 2 Priority Encoder circu

                                      ram (use appendix A) and refer

                                      nd Observations

                                      pin diagprocedure) and record the observations in the following table

                                      D3 D2 D1 D0 A B 0 0 0 1 0 0 1 x 0 1 x x 1 x x x

                                      TESTING OF 74148 8 x 3 Octal Priority Encoder

                                      imal digits There are nine of which three represents

                                      ing any of the inputs is high

                                      then it shows that line 0 is selected and if e inputs selected E0 and GS

                                      cannot be in the same state provided that E1 is enabled

                                      The 74148 is a priority encoder with active-Low input for dec

                                      input) and five output linesinputs lines (including an enablethe binary code for the octal digit Function of various pins of this IC is described below

                                      bull 0 through 7 Active low data inputs representing the octal digits A2 A1 A0 Active low output lines representing the binary code bullbull E1 Active low enable Input bull E0 Active low output indicating none of the inputs is high bull GS Active low output indicatbull VCC and GND Supply connections lines Therefore if GS A2 A1 and A0 are all low

                                      then it shows that none of thE0 A2 A1 and A0 are all low

                                      39

                                      Logic Design amp Switching Theory 1 Lab Session 08 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                      Circuit Diagram

                                      Figure 82 Pin connections of 74148

                                      Testing Procedure bull Make connections as sho

                                      binations of 1s and 0s at data inputs d record your observations in the following table

                                      GS E0

                                      wn in the circuit diagram bull Apply different combull Observe the output an Observations

                                      0 1 2 3 4 5 6 7 A2 A1 A0 1 1 1 1 1 1 1 1 x x x x x x x 0 x x x x x x 0 1 x x x x x 0 1 1 x x x x 0 1 1 1 x x x 0 1 1 1 1 x x 0 1 1 1 1 1 x 0 1 1 1 1 1 1 0 1 1 1 1 1 1 1

                                      40

                                      Logic Design amp Switching Theory 1 Lab Session 08 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                      41

                                      CTIVITY

                                      Cascade the following two 74148 8 x 3 Priority Encoders to form 16 x 4 Priority

                                      A 1

                                      Encoder

                                      Logic Design amp Switching Theory 1 Lab Session 09 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering `

                                      Lab Session 09 OBJECT

                                      Designing an Odd Parity Generator and Checker for a 3-bit Data COMPONENTS AND APPARATUS REQUIRED

                                      1 Following ICs and their Datasheets

                                      bull 7486 Quad 2-input Exclusive-OR Gates bull 7404 Hex Inverter

                                      2 Digital Trainer DT-01 or the following components Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches

                                      THEORY

                                      Parity Generator When binary data is transmitted and processed it is ndash as are all electrical signals ndash susceptible to noise that can either alter or distort its contents 1s may be effectively changed to 0s and 0s to 1s To overcome this problem one or more bits are often added to the data as an aid in detecting errors caused by noise The most common of these is a Parity bit that signifies whether the total number of 1s in a code group is odd or even In an Odd Parity system the parity bit is made 0 or 1 as necessary to make the total number 1s odd (counting the parity bit itself) In an Even Parity system the parity bit is chosen to make the total number of 1s even Table 91 shows how parity bits would be added to BCD code group in both systems

                                      Decimal BCD Value Parity Bit ABCD Odd Parity Even Parity

                                      0 0000 1 0 1 0001 0 1 2 0010 0 1 3 0011 1 0 4 0100 0 1 5 0101 1 0 6 0110 1 0 7 0111 0 1 8 1000 0 1 9 1001 1 0

                                      Table 91 Odd and Even Parity in BCD

                                      When digital data is received a parity checking circuit generates an error signal if the total number of 1s is odd in an even parity system or if it is even in an odd parity system Parity check always detects a single error (one bit change from 0 to 1 or 1 to 0) but may not detect

                                      42

                                      Logic Design amp Switching Theory 1 Lab Session 09 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering ` two or more errors Odd parity is used more often than even parity because even parity does not detect a situation where all 0s are created due to short circuit or other fault condition DESIGN OF A 3-BIT ODD PARITY GENERATOR AND CHECKER Let x y and z be the three bits that constitute the message and are the input to the Odd Parity Generator Circuit Since it is an odd parity system the bit P is generated so as to make the total number of 1s odd (including P) The function P can be expressed as follows P = x oplus y Ο z or P = x Ο y oplus z Since the IC available is 7486 which is quad 2input XOR IC therefore we will convert XNOR also to XOR

                                      P = x oplus y Ο z

                                      P = ( x oplus y ) Ο z Since for even number of variables ______

                                      XOR = XNOR Therefore ___________ _________

                                      P = ( x oplus y ) oplus z = x oplus y oplus z This logical expression can be implemented with two XOR gates and an inverter (see figure 91)

                                      Figure 91 Circuit Diagram for a 3-bit Parity Generator

                                      The 3-bit message and the parity bit are transmitted to their destination where they are applied to a Parity Checker Circuit An error occurs during transmission if the parity of the four bits received is even since the binary information transmitted was originally odd The output C of the parity checker should be a 1 when an error occurs ie when the number of 1s in the four inputs is even Therefore the function C can be expressed as

                                      C = x Ο y Ο z Ο P

                                      Using the same logic applied for the conversion of the equation of P

                                      PzyxC oplusoplusoplus= This logical expression can be implemented with three XOR gates and an inverter (see figure 92)

                                      43

                                      Logic Design amp Switching Theory 1 Lab Session 09 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering `

                                      44

                                      Figure 92 Circuit Diagram for a 3-bit Parity Checker Implementation and Observations Implement the 3-bit Parity Generator and Checker circuits (figure 91 and 92) on a bread board (prepare the pin diagram (use appendix A) and refer to laboratory session 01 for implementation procedure) and record the observations in the following table

                                      x y z P x y z P C x y z P C 0 0 0 0 0 0 0 1 0 0 0 0 0 1 0 0 0 1 1 0 0 1 0 1 0 0 0 1 0 1 0 1 0 0 1 1 0 0 1 1 1 0 1 1 1 0 0 0 1 0 0 1 1 0 0 1 0 1 0 1 0 1 1 1 0 1 1 1 0 0 1 1 0 1 1 1 0 1 1 1 0 1 1 1 1 1 1 1

                                      Odd Parity Generation Odd Parity Check ACTIVITY 1 Try using the parity checker of figure 92 as 3-bit parity generator Write the details here

                                      _____________________________________________________________________________________________________________________________________________________________________________________________________________________ ______________________________________________________________________________________________________________________________________________ _______________________________________________________________________ ______________________________________________________________________________________________________________________________________________

                                      Logic Design amp Switching Theory 1 Lab Session 10 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                      Lab Session 10 OBJECT

                                      Driving a seven segment display using 7447 7448 driver IC COMPONENTS AND APPARATUS REQUIRED

                                      1 Following ICs and their Datasheets

                                      bull Seven Segment Displays (Common Anode Common Cathode) bull 7447 7448 BCD to Seven Segment Driver

                                      2 Digital Trainer DT-01 or the following components Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches

                                      THEORY Seven Segment Displays A Seven Segment Display consists of seven light-emitting segments The segments are designated by letters a through g (see figure 101) By illuminating various combinations of segments the numerals 0 through 9 can be displayed Seven Segment Displays are commonly constructed with light-emitting diodes (LEDs) and with liquid-crystal displays (LCDs) LEDs generally provide greater illumination levels but require much greater power than LCDs An LED display can be a common-anode type or common cathode type In common anode type a high voltage is applied at the common terminal of the display and low voltage is applied at a segmentrsquos terminal for illumination In the common-cathode type a low voltage is applied at the common terminal of the display and high voltage is applied at a segmentrsquos terminal for illumination

                                      Figure 101 Seven Segment Display

                                      a f b g

                                      e c d

                                      7447 7448 BCD to Seven Segment Driver 7447 7448 IC is particularly used to drive Seven Segment Its input is a BCD number and output drives a seven segment display 7447 is used to drive common-anode displays whereas 7448 is used to drive common cathode displays 7447 7448 is a 16 pin IC Function of various pins of these ICs is described below

                                      bull A B C D Inputs representing BCD digits (D being the MSB)

                                      45

                                      Logic Design amp Switching Theory 1 Lab Session 10 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering bull OA through OG Outputs to drive segments a through g of the display (Active low

                                      in 7447 and active high in 7448) bull RBI Ripple Blanking Input Turns off all the segments if kept low provided that LT

                                      is kept high and all other inputs (A B C D BI) are kept low Should be kept high otherwise

                                      bull BI RBO Wire-AND logic serving as a Blanking Input and or Ripple Blanking Output

                                      o BI Turns off all the segments if low o RBO Goes to a low level (response condition) along with other outputs when

                                      RBI and inputs A B C and D are low with LT input at high level bull LT Lamp Test input Tests whether all segments are working or not Illuminates all

                                      segments if kept low provided that BI is kept high Should be kept high otherwise bull VCC and GND Supply connections lines CIRCUIT DIAGRAM

                                      Figure 102 Circuit diagram for 7447driving a common-anode display

                                      IMPLEMENTATION AND OBSERVATIONS

                                      bull Make connections as shown in the circuit diagram (refer to laboratory session 01 for implementation procedure)

                                      bull Apply different combinations of 1s and 0s at data inputs bull Observe the output and record your observations in the following table

                                      46

                                      Logic Design amp Switching Theory 1 Lab Session 10 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                      47

                                      Decimal Digit

                                      BCD Inputs Seven Segment Outputs D C B A a b c d e f g

                                      0 0 0 0 0 1 0 0 0 1 2 0 0 1 0 3 0 0 1 1 4 0 1 0 0 5 0 1 0 1 6 0 1 1 0 7 0 1 1 1 8 1 0 0 0 9 1 0 0 1

                                      ACTIVITY 1 Perform the Lamp Test for the designed circuit and write your observations

                                      ____________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________

                                      2 How can you use 7447 IC to drive a common-cathode display

                                      ____________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________

                                      3 What symbols appear in the seven segment display if inputs DCBA are

                                      DCBA Symbol

                                      1010

                                      1011

                                      1100

                                      1101

                                      1110

                                      1111

                                      Logic Design amp Switching Theory 1 Lab Session 11 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                      48

                                      Lab Session 11 OBJECT

                                      Testing different modes of JK-FF COMPONENTS AND APPARATUS REQUIRED 1 Following ICs and their Datasheets

                                      bull 7473 7476 JK Flip-Flop 2 Digital Trainer DT-01 or the following components

                                      Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches

                                      THEORY

                                      Flip-Flop A flip-flop circuit can maintain a binary state indefinitely (as long as the power is delivered to the circuit) until directed by an input signal to switch states The major differences among various types of flip-flops are in the number of inputs they possess and in the manner in which the inputs affect the binary state

                                      JK Flip-Flop JK flip flop is an edge triggered device A typical JK flip flop has three inputs J K and a clock input The flip-flop can be either positive or negative edge triggered The output Q is available in complemented form as well Beside the usual inputs and output most of the flip-flop IC also possess two asynchronous inputs namely Preset and Clear These inputs are usually active low If used Preset and Clear inputs keep the flip-flop in set and reset state respectively irrespective of the other inputs Both of these inputs cannot be used simultaneously otherwise they will bring the flip-flop in unstable state

                                      Figure 111 Symbol for JK flip-flop

                                      (a) positive-edge triggering (b) active low Preset (PR) and Clear (CLR) with positive-edge triggering

                                      (c) active low Preset (PR) and Clear (CLR) with negative-edge triggering

                                      Logic Design amp Switching Theory 1 Lab Session 11 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                      49

                                      TESTING OF 7473 7476 DUAL JK FLIP-FLOP

                                      Both the ICs 7473 and 7476 are similar in functionality except for one difference The flip-flops in 7473 have only one type of active low asynchronous input which is the Clear input whereas the flip-flops in 7476 have both Preset and Clear inputs Both these ICs have negative edge triggered flip-flops

                                      Circuit Diagram

                                      Figure 112 Pin connections of 7476

                                      Testing Procedure

                                      bull Make connections as shown in the circuit diagram (figure 112) bull Apply different combinations of 1s and 0s at J and K inputs bull Observe the output and record your observations in the following table

                                      Observations

                                      J

                                      K Q

                                      0 0 0 1 1 0 1 1

                                      ACTIVITY

                                      1 Observe the output Q of JK flip-flop if the clock input is connected to VCC or GND instead of a clock source Write your observations here __________________________________________________________________________________________________________________________________________ _______________________________________________________________________________________________________________________________________________________________________________________________________________

                                      Logic Design amp Switching Theory 1 Lab Session 12 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                      50

                                      Lab Session 12 OBJECT

                                      Designing sequential circuit for the given state diagram using D flip-flop GIVEN STATE DIAGRAM

                                      00

                                      11

                                      Figure 121 State Diagram COMPONENTS AND APPARATUS REQUIRED 1 Following ICs and their Datasheets

                                      bull 7474 D Flip-Flop bull ICs of basic gates (AND OR NOT XOR etc) as required

                                      2 Digital Trainer DT-01 or the following components Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches

                                      THEORY

                                      Sequential Circuits In Sequential Circuits the output not only depends on the present inputs but also on previous states of the circuit These circuits use memory elements (latches flip-flops) and the binary information stored in the memory elements at any given time defines the state of the sequential circuit Analysis of a Sequential Circuit The behavior of a sequential circuit is determined from the inputs the outputs and the states of its flip-flops Both the outputs and next state are a function of the inputs and the

                                      10

                                      01

                                      00 11 10

                                      00

                                      00 11 10 00

                                      Logic Design amp Switching Theory 1 Lab Session 12 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                      51

                                      present state The analysis of a sequential circuit form a state diagram comprises of the following bull Selecting a particular flip-flop to design the circuit bull Obtaining state table from the state diagram bull Finding input equations for the selected flip-flop bull Finding state equations (not required for the construction of circuit) bull Implementing the circuit using selected flip-flops and their input equations ANALYZING THE GIVEN STATE DIAGRAM D Flip-Flop D flip-flop is also called transparent flip-flop as it simply transfers the input data to the output For our design we require the graphical symbol and excitation table of D flip-flop (see figure 122)

                                      Qt Qt+1 T 0 0 0 0 1 1 1 0 0 1 1 1

                                      (b) Excitation table of D Flip-Flop

                                      (a) Graphical Symbol

                                      Figure 122 Characteristic equation of D flip-flop is Q(t+1) = D State Table The given state diagram has four states so we will need two D flip-flops (FF-0 FF-1) Form state table form the given state diagram and record the results in the following table

                                      Present State Input Next State Output Input to FF-0 D0

                                      Input to FF-1 D1 Q1t Q0t x Q1(t+1) Q0(t+1) z

                                      Logic Design amp Switching Theory 1 Lab Session 12 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                      52

                                      Input Equations Using Karnaugh map the input equations D0 and D1 for the two flip-flops can be found

                                      D0 D1 Q0x

                                      Q1

                                      _ _ Q0x

                                      _ Q0x

                                      Q0x

                                      _ Q0x

                                      Q0x

                                      Q1

                                      _ _ Q0x

                                      _ Q0x

                                      Q0x

                                      _ Q0x

                                      _ Q1

                                      _ Q1

                                      Q1

                                      Q1

                                      D0 = _________________ D1 = _________________

                                      State Equations Using the characteristic equation of D flip-flop we can find the state equations Q0(t+1) and Q1(t+1) for the to flip flops Q0(t+1) = _______________________ Q1(t+1) = _______________________ _______________________ _______________________ _______________________ _______________________ Circuit Diagram

                                      Logic Design amp Switching Theory 1 Lab Session 12 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                      53

                                      Implementation Procedure and Observations

                                      1 Implement the circuit using digital ICs on a bread board (prepare the pin diagram (use appendix A) and refer to laboratory session 01 for procedure)

                                      2 Make the clear inputs of the flip-flops low (to clear the flip-flops) The flip-flops will remain in clear state as long as the clear inputs are connected to low level

                                      3 Connect output Q0 and the clock pulse to an oscilloscope 4 Apply 0 to the input x 5 Now make the clear inputs to high 6 Observe the waveform for the first 5 clock pulses and record it 7 Repeat steps 2 to 6 keeping x=1 in step 4 this time 8 Repeat steps 2 to 7 this time connecting Q1 instead of Q0 to the oscilloscope in step

                                      3 Record your observations (Keep frequency of the clock pulse low (eg1Hz) so that the output waveforms can be observed easily)

                                      1 2 3 4 5 Clock Pulse

                                      Output Waveform for Q0 when x=0

                                      Output Waveform for Q0 when x=1

                                      Output Waveform for Q1 when x=0

                                      Output Waveform for Q1 when x=1

                                      Logic Design amp Switching Theory 1 Lab Session 13 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                      Lab Session 13 OBJECT

                                      Designing a modulo-5 asynchronous up-counter using JK-FF COMPONENTS AND APPARATUS REQUIRED

                                      1 Following ICs and their Datasheets

                                      bull 7400 Quad 2-input or 7410 Triple 3-input NAND Gates bull 7476 7473 JK Flip-Flop

                                      2 Digital Trainer DT-01 or the following components Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches

                                      THEORY

                                      Digital Counters A digital counter is a set of flip-flops whose states change in response to pulses applied at the input to the counter The flip-flops are interconnected so that their combined state at any time is the binary equivalent of the total number of pulses that have occurred up to that time Every counter resets after a certain number of clock pulses Thus as it name implies a counter is used to count pulses An n stage counter can count up to a maximum of 2n states n is equal to the number of flip-flops required for the construction of counter

                                      Modulus Counters The number of input pulses that causes a counter to reset to its initial count is called the modulus of the counter Thus the modulus equals to total number of distinct states (counts) including zero that a counter can store A binary counter with n stages is a modulo-2n (or mod-2n) counter The largest count a mod-N counter can achieve is N-1 ie a mod-N counter never reaches the binary number equal to its modulus N is always equal to or less than 2n Counters can be classified as bull Synchronous Counters which are clock driven All the flip-flops are driven by a

                                      single clock bull Asynchronous Counters which are event driven Clock input is given to the first

                                      flip-flop only Rest of the flip-flops are driven by their preceding flip-flops

                                      DESIGN OF A MOD-5 ASYNCHRONOUS UP COUNTER The number of flip-flops required to construct a mod-5 counter is 3 because 5 should be less than or equal to 2n This counter will count from 0 to 4 a total of 5 distinct states Since a 3-stage counter can count up to 8 states at maximum a NAND gate is used to reset it after 5 clock pulses Figure 131 shows the logic diagram

                                      54

                                      Logic Design amp Switching Theory 1 Lab Session 13 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                      55

                                      Figure 131 A Mod-5 Asynchronous Up Counter

                                      Implementation and Observations

                                      Implement the mod-5 counter circuit (figure 131) on a bread board (prepare the pin diagram (use appendix A) and refer to laboratory session 01 for implementation procedure) and record the observations in the following table

                                      Clock Pulse Q2 Q1 Q0

                                      0 1 2 3 4 5 6 7

                                      ACTIVITY

                                      Draw the timing diagram for mod-5 counter designed in this laboratory session

                                      Logic Design amp Switching Theory 1 Lab Session 14 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                      Lab Session 14 OBJECT

                                      Experimenting with 74194 4-bit bidirectional universal shift register COMPONENTS AND APPARATUS REQUIRED

                                      1 Following ICs and their Datasheets

                                      bull 74194 4-bit bidirectional universal shift register 2 Digital Trainer DT-01 or the following components

                                      Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches

                                      THEORY

                                      Shift Registers

                                      A Register is a set of flip-flops used to store binary data A register which is capable of shifting its binary information either to the right or left is called a shift register The logical configuration of a register consists of a chain of flip-flops connected in cascade with the output of one flip-flop connected to the input of next flip-flop All flip-flops receive a common clock pulse which causes the shift from one stage to the next

                                      Bidirectional Shift Registers A bi-directional shift register is one whose bits can be shifted from left to right or from right to left

                                      Universal Shift Registers A universal shift register is a bi-directional register whose input can be in either serial or parallel form and whose output can be in either serial or parallel form

                                      74194 4-BIT BIDIRECTIONAL UNIVERSAL SHIFT REGISTER

                                      The 74194 register provides parallel as well as serial loading in both directions Function of various pins of this IC is described below

                                      bull A B C and D Active high inputs for parallel loading bull QA QB QC and QD Active high outputs bull S0 and S1 Active high mode control inputs The following table shows combinations

                                      of S1 and S0 to enable various modes

                                      S1 S0 Clock Action 0 0 x No change 0 1 uarr Shift right 1 0 uarr Shift left 1 1 uarr Parallel load

                                      uarr shows the rising edge of the clock pulse

                                      56

                                      Logic Design amp Switching Theory 1 Lab Session 14 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering bull SR Active high serial input for right shifting bull SL Active high serial input for left shifting bull CLR Active low input Clears all the flip-flops of the register if set to 0 should be

                                      kept high otherwise bull CLK Clock input bull VCC and GND Supply connections lines Thus A B C and D are inputs for parallel loading whereas SR and SL are inputs for serial loading with right or left shifting respectively S1 and S0 are used to select the loading mode Circuit Diagram

                                      Figure 141 Pin connections of 74194 Testing Procedure

                                      bull Make connections as shown in the circuit diagram bull Observe the output for the input combinations given in the following table

                                      57

                                      Logic Design amp Switching Theory 1 Lab Session 14 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                      58

                                      Observations

                                      S1 S0 SL SR A B C D QA QB QC QD 0 0 0 1 0 0 0 0 0 1 1 0 0 0 0 1 1 0 0 0 0 0 1 0 1 1 0 0 0 0 1 1 0 0 1 1 0 1 0 0 0 1 1 1 0 1 0 1 1 0 1 0 0 1 1 0 1 1 1 0 0 1 1 1 1 1 0 0 1 1 1 1

                                      ACTIVITY 1 Show connections of 74194 to convert it into a ring counter with right shifting

                                      Logic Design amp Switching Theory 1 Lab Session 15 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                      Lab Session 15

                                      OBJECT

                                      Experimenting with 74245 octal bus transceivers using parallel port PC interfacing COMPONENTS AND APPARATUS REQUIRED 1 Parallel Port Connectors (DB-25) with Cable 2 Personal Computer with Windows 98 and TurboC Compiler Installed 3 Following ICs and their Datasheets

                                      bull 74245 Octal Bus Transceivers with 3-State Outputs 4 Digital Trainer DT-01 or the following components

                                      Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches

                                      THEORY

                                      3-State Logic Sometimes it is necessary to isolate one part of circuit from the other part For this purpose some TTL ICs are designed with 3-state logic Such devices have three possible output states high low and high impedance The device can be put into high impedance state by a control signal applied to an appropriate pin When such a device is in high impedance state there is very high impedance at its output effectively isolating the device from whatever circuitry the output normally drives 74245 Octal Bus Transceivers A bus is any conducting path or set of paths having electrical connections to one or more devices 74245 octal bus transceivers are mainly used to control connectivity between two devices or circuits It also provides direction control for signal flow Function of various pin of this IC is given below

                                      bull A1 through A8 Bus A bull B1 through B8 Bus B bull G΄ Active low enable input When high sets all the bus pins to high impedance state bull DIR Direction control for signal flow When set to high logic level transfers bus A

                                      data to B bus When set to low logic level transfers bus B data to A bus bull VCC and GND Supply connections lines Serial and Parallel Port Connectors A Parallel Port can consist of only 25 pin port adapter called a DB-25 and a serial port can consist of either a 25 pin port adapter called a DB-25 or 9 pin adapter called a DB-9 port adapter Whether the port is a 9 pin or 25 pin it can accomplish all of the same tasks that serial port communications have been designed for

                                      59

                                      Logic Design amp Switching Theory 1 Lab Session 15 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                      60

                                      Each adapter can be a male type connector with pins or a female type adapter with tiny holes Generally a PRINTER port (called LPT1) on the back of a computer is female type adapter and we need to use MALE DB-25 pin cable on it for PRINTER connection or for parallel LAPLINK cable And a COM port on the back of a computer is male for the serial ports but it may not necessarily be Parallel Port Connector ndash DB-25 The DB-25 connector (named for its B-size D-shaped shell and 25 pins) is practically ubiquitous in the electronics industry The DB-25 connector is used for a variety of purposes Two common applications are RS-232EIA-232 (serial) connections and the parallel printer interface on the IBM PC The DB-25 connector is also used for SCSI connections Normally the parallel port is used for output to a printer or other device It sends data 8-bits or one byte at a time in parallel The other lines available on the DB-25 connector are a combination of status lines control lines and ground lines The status and control lines are used for handshaking commands and feedback when we are talking to a printer

                                      Figure 152 DB-25 Female Figure 151 DB-25 Male

                                      Figure 153 Pin Layout for DB-25 As can be seen form figure 153 there are four types of pins in this connector

                                      bull Data pins (8 pins - D0 to D7) Active high bidirectional lines

                                      Logic Design amp Switching Theory 1 Lab Session 15 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering bull Control pins (4 pins - C0 to C3) C0 C1 and C3 are active low whereas C2 is active

                                      high These lines also are bidirectional bull Status pins (5 pins ndash S3 to S7) Only S7 is active low rest are active high input lines bull Ground pins (8 pins) Used as a reference signal for the low (below 05 volts) charge

                                      Parallel Port Addresses A DB-25 connector at a parallel port has three address one for each kind of pins register data status and control The first or base address generally refers to data register Second address is for status register and the third one is for control register In Windows 98 the base address is usually found to be 278H 378H or 3BCH Now if 378H is the base address then it refers to the data register whereas addresses for status and control register are respectively 379H and 37AH For Windows 98 the base address can be found as follows 1 On your Desktop right-click on My Computer and select Properties 2 Click on the Device Manager tab and find LPT1 under Plug and Play BIOS 3 After selecting LPT1 click the Properties button 4 Next select the Resources tab and the address should then appear next to InputOutput

                                      Range Accessing parallel port through C Language Programming There are multiple functions in C Language for accessing external ports The most commonly used are listed below

                                      bull unsigned char inportb(int portid) inportb reads a byte from a hardware port

                                      bull int inport(int portid) reads a word from a hardware port

                                      bull void outportb(int portid unsigned char value) outputs a byte to a hardware port

                                      bull void outport(int portid int value) outputs a word to a hardware port

                                      portid refers to the port address whereas value refers to the data to be sent TESTING 74245 USING PARALLEL PORT PC INTERFACING At one end the parallel port connector will be connected to the PC via parallel port cable and another connector (to be plugged into the PC parallel port slot) At the other end it will be connected to the buffer IC 74245 Data lines of the connector will be used to transfer 8-bit data between the PC and the buffer Out of the 8-bits of 74245 4-bits will be used to enter data which will be displayed at the monitor through a C language

                                      61

                                      Logic Design amp Switching Theory 1 Lab Session 15 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering program The remaining 4-bits will receive data from PC as entered by the user via keyboard

                                      Circuit Diagram

                                      Figure 154 Interface of 74245 to PC via Parallel Port

                                      Procedure

                                      1 Connect the DB-25 connector to the PC at one end and solder it to the circuit board at the other end

                                      2 Connect various pins of the connector and 74245 according to the circuit diagram shown in figure 152

                                      3 Using the functions listed in the previous section write a program in C language to operate various pins of the buffer The user interface of the program should provide option to the user whether to send or receive data from the port

                                      4 Set DIR switch to 1 5 Try sending some data bits to the port The result should be displayed at the LEDs 6 Set DIR switch to 0 7 Set some binary 4-bit value through the switches Try reading it via parallel port

                                      C Language Program

                                      A program to access parallel port for data transfers

                                      use header file include ltstdiohgt main program void main() define variable

                                      62

                                      Logic Design amp Switching Theory 1 Lab Session 15 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering unsigned int data=0 char choice while(1) printing option menu clrscr() printf(This program will send or receive a BCD digit from the parallel portn) printf(nPress your choice numbern) printf(n1 Send Data) printf(n2 Receive Data) printf(n3 Exitn) choice = getch() sending entered digit to the port if(choice == 1) input BCD digit printf(nEnter BCD digit to be sent to the port) data = getche() masking the first four bits data = data amp 0x0f sending to the port outportb(0x378data) printf(nThe BCD digit c has been sent to the port data) printing on screen the data received from the port else if(choice == 2) receiving data from the port data = inportb(0x378) masking the last four bits data = data amp 0xf0 shifting first four bits to make them the last four bits datagtgt=4 printf(nThe BCD digit set at the port is c data) exit else if(choice == 3) break key pressed is not in the menu else printf(nEnter valid choice number) printf(nnPress any key to continue) getch()

                                      63

                                      Logic Design amp Switching Theory 1 Lab Session 15 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                      ACTIVITY 1 In the above circuit DIR and G΄ inputs are hardwired Connect them to status or

                                      control pins of the parallel port connector and control their function through your software program Circuit Diagram Program Code ______________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________

                                      ___________________________________________________________________________________________________________________________________________________

                                      64

                                      Logic Design amp Switching Theory 1 Lab Session 15 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                      65

                                      _____________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ _____________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ _______________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ _________________________________________________ _________________________________________________

                                      Logic Design amp Switching Theory 1 Appendix A NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                      Appendix A

                                      PIN DIAGRAMS OF THE ICS REQUIRED FOR THE LABORATORY SESSIONS Consult the TTLIC data book for internal diagrams and electrical characteristics of these ICs 7400 Quad 2-Input NAND 7402 Quad 2-Input NOR

                                      7404 Hex Inverter 7408 Quad 2-Input AND

                                      7410 Triple 3-Input NAND 7411 Triple 3-Input AND

                                      7421 Dual 4-Input AND 7432 Quad 2-Input OR

                                      66

                                      Logic Design amp Switching Theory 1 Appendix A NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                      BCD-to-Seven Segm 7448 BCD-to-Seven Segment 7447 ent

                                      Decoder (15V OC) Decoder (2kΩ pull-up output)

                                      7473 Dual JK Flip-Flop 7474 Dual D-Type Flip-Flop

                                      7476 Dual JK Flop-Flop -Bit Binary Full Adder 7483 4 with Fast Carry

                                      86 Quad 2-Inpu 74138 3-to-8 Line 74 t Exclusive OR Decoder Demultiplexer

                                      67

                                      Logic Design amp Switching Theory 1 Appendix A NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                      68

                                      74148 8-to-3 Line 16-to-1 Line Data

                                      Priority Encoder 74150 Selector Multiplexer

                                      74245 Oct nsceivers Universal Shift Register (PIPO) (3-State)

                                      74194 4-Bit Bidirectional al Bus Tra

                                      Logic Design amp Switching Theory 1 Appendix B NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                      Appendix B

                                      DEBOUNCING CIRCUITRY FOR MECHANICAL SWITCHES Mechanical switches form the interface between human beings and computers or other digital systems For example a keyboard is a matrix of switches used to supply alphanumeric data to a computer Whatever the switch design it is a potential source of problems due to contact bounce The contact bounce creates a sense of narrow pulses when a switch is opened or closed An example of device whose operation would be adversely affected by contact bounce is a digital counter used to count the number of times a switch is depressed Eliminating the effects of contact bounce is called debouncing When data is entered into a computer via a keyboard a software debounce is often used This type of debouncing is a program that causes the computer to sample the switch terminal (ie to input data from it) many times in succession during the interval of time that contact bounce occurs If the data is sensed to be 1s (or 0s) for a specific number of consecutive samples then it is assumed that contact bounce has ended and the last value sensed is valid Hardware debouncing is the use of electronic circuitry to eliminate the effects of contact bounce There are numerous versions of such circuitry including those that use monostable multivibrators (one-shots) but the most straightforward is simply an RS latch Figure B1 shows the circuit When the switch is in position 1 R = 0 and S = 1 so the latch is set and the output (Q) is 1 When the switch is in position 0 R = 1and S = 0 so the latch is reset and the output is 0 When the switch is moved form one position to the other the latch changes state and bouncing occurs at either the R or the S input The bouncing does not affect the latch after it has change state An RS latch will remain set for example when its R input is 0 and its S input is alternately changed form 1 to 0

                                      Figure B1 Use of RS latch to debounce a mechanical switch

                                      69

                                      • 01-ldst-Outer title
                                        • Practical Workbook
                                        • Logic Design amp Switching Theory I
                                          • Dept of Computer amp Information Systems Engineering
                                            • NED University of Engineering amp Technology
                                            • Karachi ndash 75270 Pakistan
                                              • 02-ldst-inner Title
                                                • Practical Workbook
                                                • Logic Design amp Switching Theory I
                                                  • Dept of Computer amp Information Systems Engineering
                                                    • NED University of Engineering amp Technology
                                                    • Karachi ndash 75270 Pakistan
                                                      • 03-ldst-general info
                                                      • 04-ldst-introduction
                                                      • 05-Table of Contents
                                                        • CONTENTS
                                                          • Lab Session No Object Page No
                                                          • 1
                                                          • Also implementing and testing the given circuit on a bread board
                                                            • Working with Electronics Workbench
                                                              • Driving a seven segment display using 7447 7448 driver IC
                                                                • Designing a modulus-5 asynchronous up-counter using JK-FF
                                                                  • Experimenting with 74194 4-bit bidirectional universal shift register
                                                                      • 13
                                                                          • 06-ldst-Exp01
                                                                            • Lab Session 01
                                                                            • OBJECT
                                                                              • 1 Bread board
                                                                              • 2 5 V - power supply
                                                                              • 3 Multimeter
                                                                              • 4 Logic probe
                                                                              • 5 LEDs with resistors
                                                                              • 6 Connecting wires
                                                                              • 8 Following ICs and their datasheets
                                                                                • THEORY
                                                                                  • Logic Gates
                                                                                  • 1 The AND Gate ndash An AND gatersquos output is 1 if and only if all its inputs are 1 If A and B are two inputs to an AND gate then output F of the gate is given as F = AB
                                                                                  • 2 The OR Gate - An OR gatersquos output is 1 if at least one of its input is 1 If A and B are two inputs to an OR gate then output F of the gate is given as F = A+B
                                                                                  • 3 The NOT Gate (Inverter) ndash Its output is 1 when its input is 0 and its output is 0 when the input is 1 ie it complements a digital variable If A is the input to a NOT gate then output F of the gate is given as
                                                                                  • 4 The NAND Gate ndash Its output is 1 if at least one of its input is 0 This gate performs the same logic as an AND gate followed by an inverter If A and B are two inputs to a NAND gate then output F of the gate is given as
                                                                                    • 5 The NOR Gate - The output of a NOR gate is 1 if and only if all its inputs are 0 This gate performs the same logic function as an OR gate followed by an inverter If A and B are two inputs to a NAND gate then output F of the gate is given as
                                                                                        • DATA SHEETS
                                                                                          • Logic expression for the given logic diagram __________________________________
                                                                                              • 07-ldst-exp02
                                                                                                • Working with Electronics Workbench
                                                                                                  • 08-ldst-exp03
                                                                                                    • Designing Half and Full Adder Circuits
                                                                                                      • COMPONENTS AND APPARATUS REQUIRED
                                                                                                        • 1 Following ICs and their Datasheets
                                                                                                        • 7408 Quad 2-input AND Gate
                                                                                                        • 2 Digital Trainer DT-01 or the following components
                                                                                                          • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                          • Connecting wires Switches
                                                                                                            • THEORY
                                                                                                                • IMPLEMENTATION AND OBSERVATIONS
                                                                                                                  • 09-ldst-Exp04
                                                                                                                    • Lab Session 04
                                                                                                                    • 1 Digital ICs and their Datasheets
                                                                                                                    • 7408 Quad 2-input AND Gate
                                                                                                                    • 2 Digital Trainer DT-01 or the following components
                                                                                                                      • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                      • Connecting wires Switches
                                                                                                                      • PROCEDURE
                                                                                                                      • REDUCTION OF LOGIC EXPRESSION USING KARNAUGH MAP
                                                                                                                      • OBSERVATIONS
                                                                                                                      • RESULT
                                                                                                                          • 10-ldst-Exp05
                                                                                                                            • Lab Session 05
                                                                                                                            • 1 Following ICs and their Datasheets
                                                                                                                            • 7408 Quad 2-input AND Gate
                                                                                                                            • 2 Digital Trainer DT-01 or the following components
                                                                                                                              • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                              • (100 Ω) Connecting wires Switches
                                                                                                                              • THEORY
                                                                                                                                • IMPLEMENTATION AND OBSERVATIONS
                                                                                                                                  • 11-ldst-Exp06
                                                                                                                                    • OBJECT
                                                                                                                                    • 1 Following ICs and their Datasheets
                                                                                                                                    • 7408 Quad 2-input AND Gates or 7411 Triple 3-input AND Gates
                                                                                                                                    • 2 Digital Trainer DT-01 or the following components
                                                                                                                                      • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                      • Connecting wires Switches
                                                                                                                                        • Figure 62 Circuit Diagram for 4 x 1 Multiplexer
                                                                                                                                        • Implementation and Observations
                                                                                                                                          • Circuit Diagram
                                                                                                                                            • ACTIVITY
                                                                                                                                              • 12-ldst-exp07
                                                                                                                                                • 1 Following ICs and their Datasheets
                                                                                                                                                • 7408 Quad 2-input or 7411 Triple 3-input AND Gates
                                                                                                                                                • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                  • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                  • Connecting wires Switches
                                                                                                                                                    • THEORY
                                                                                                                                                        • Figure 72 Circuit Diagram for 2 x 4 Decoder 1 x 4 Demultiplexer
                                                                                                                                                        • Implementation and Observations
                                                                                                                                                          • Circuit Diagram
                                                                                                                                                            • ACTIVITY
                                                                                                                                                              • 13-ldst-Exp08
                                                                                                                                                                • OBJECT
                                                                                                                                                                • 1 Following ICs and their Datasheets
                                                                                                                                                                • 7408 Quad 2-input or 7421 Dual 4-input AND Gates
                                                                                                                                                                • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                  • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                  • Connecting wires Switches
                                                                                                                                                                    • THEORY
                                                                                                                                                                        • Figure 81 Circuit Diagram for 4 x 2 Priority Encoder
                                                                                                                                                                        • Implementation and Observations
                                                                                                                                                                          • Therefore if GS A2 A1 and A0 are all low then it shows that line 0 is selected and if E0 A2 A1 and A0 are all low then it shows that none of the inputs selected E0 and GS cannot be in the same state provided that E1 is enabled
                                                                                                                                                                          • Circuit Diagram
                                                                                                                                                                            • ACTIVITY
                                                                                                                                                                              • 14-ldst-exp09
                                                                                                                                                                                • OBJECT
                                                                                                                                                                                • 1 Following ICs and their Datasheets
                                                                                                                                                                                • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                  • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                  • Connecting wires Switches
                                                                                                                                                                                    • THEORY
                                                                                                                                                                                      • Parity Generator
                                                                                                                                                                                        • Let x y and z be the three bits that constitute the message and are the input to the Odd Parity Generator Circuit Since it is an odd parity system the bit P is generated so as to make the total number of 1s odd (including P) The function P can be expressed as follows
                                                                                                                                                                                        • Figure 91 Circuit Diagram for a 3-bit Parity Generator
                                                                                                                                                                                          • C = x Ο y Ο z Ο P
                                                                                                                                                                                            • Implementation and Observations
                                                                                                                                                                                              • ACTIVITY
                                                                                                                                                                                                  • 15-ldst-exp10
                                                                                                                                                                                                    • Driving a seven segment display using 7447 7448 driver IC
                                                                                                                                                                                                    • COMPONENTS AND APPARATUS REQUIRED
                                                                                                                                                                                                    • 1 Following ICs and their Datasheets
                                                                                                                                                                                                    • 7447 7448 BCD to Seven Segment Driver
                                                                                                                                                                                                    • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                      • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches
                                                                                                                                                                                                        • THEORY
                                                                                                                                                                                                        • Seven Segment Displays
                                                                                                                                                                                                        • CIRCUIT DIAGRAM
                                                                                                                                                                                                        • Figure 102 Circuit diagram for 7447driving a common-anode display
                                                                                                                                                                                                            • IMPLEMENTATION AND OBSERVATIONS
                                                                                                                                                                                                              • Decimal Digit
                                                                                                                                                                                                              • BCD Inputs
                                                                                                                                                                                                              • Seven Segment Outputs
                                                                                                                                                                                                              • D
                                                                                                                                                                                                              • C
                                                                                                                                                                                                              • B
                                                                                                                                                                                                              • A
                                                                                                                                                                                                              • a
                                                                                                                                                                                                              • b
                                                                                                                                                                                                              • c
                                                                                                                                                                                                              • d
                                                                                                                                                                                                              • e
                                                                                                                                                                                                              • f
                                                                                                                                                                                                              • g
                                                                                                                                                                                                              • 0
                                                                                                                                                                                                              • 0
                                                                                                                                                                                                              • 0
                                                                                                                                                                                                              • 0
                                                                                                                                                                                                              • 0
                                                                                                                                                                                                              • 1
                                                                                                                                                                                                              • 0
                                                                                                                                                                                                              • 0
                                                                                                                                                                                                              • 0
                                                                                                                                                                                                              • 1
                                                                                                                                                                                                              • 2
                                                                                                                                                                                                              • 0
                                                                                                                                                                                                              • 0
                                                                                                                                                                                                              • 1
                                                                                                                                                                                                              • 0
                                                                                                                                                                                                              • 3
                                                                                                                                                                                                              • 0
                                                                                                                                                                                                              • 0
                                                                                                                                                                                                              • 1
                                                                                                                                                                                                              • 1
                                                                                                                                                                                                              • 4
                                                                                                                                                                                                              • 0
                                                                                                                                                                                                              • 1
                                                                                                                                                                                                              • 0
                                                                                                                                                                                                              • 0
                                                                                                                                                                                                              • 5
                                                                                                                                                                                                              • 0
                                                                                                                                                                                                              • 1
                                                                                                                                                                                                              • 0
                                                                                                                                                                                                              • 1
                                                                                                                                                                                                              • 6
                                                                                                                                                                                                              • 0
                                                                                                                                                                                                              • 1
                                                                                                                                                                                                              • 1
                                                                                                                                                                                                              • 0
                                                                                                                                                                                                              • 7
                                                                                                                                                                                                              • 0
                                                                                                                                                                                                              • 1
                                                                                                                                                                                                              • 1
                                                                                                                                                                                                              • 1
                                                                                                                                                                                                              • 8
                                                                                                                                                                                                              • 1
                                                                                                                                                                                                              • 0
                                                                                                                                                                                                              • 0
                                                                                                                                                                                                              • 0
                                                                                                                                                                                                              • 9
                                                                                                                                                                                                              • 1
                                                                                                                                                                                                              • 0
                                                                                                                                                                                                              • 0
                                                                                                                                                                                                              • 1
                                                                                                                                                                                                                • ACTIVITY
                                                                                                                                                                                                                  • 16-ldst-exp11
                                                                                                                                                                                                                    • Lab Session 11
                                                                                                                                                                                                                      • OBJECT
                                                                                                                                                                                                                      • COMPONENTS AND APPARATUS REQUIRED
                                                                                                                                                                                                                        • 1 Following ICs and their Datasheets
                                                                                                                                                                                                                        • 7473 7476 JK Flip-Flop
                                                                                                                                                                                                                        • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                          • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                                          • Connecting wires Switches
                                                                                                                                                                                                                            • THEORY
                                                                                                                                                                                                                                • Flip-Flop
                                                                                                                                                                                                                                • JK Flip-Flop
                                                                                                                                                                                                                                  • Circuit Diagram
                                                                                                                                                                                                                                    • Observations
                                                                                                                                                                                                                                      • ACTIVITY
                                                                                                                                                                                                                                          • 17-ldst-exp12
                                                                                                                                                                                                                                            • Lab Session 12
                                                                                                                                                                                                                                              • OBJECT
                                                                                                                                                                                                                                              • GIVEN STATE DIAGRAM
                                                                                                                                                                                                                                              • Figure 121 State Diagram
                                                                                                                                                                                                                                              • COMPONENTS AND APPARATUS REQUIRED
                                                                                                                                                                                                                                                • 1 Following ICs and their Datasheets
                                                                                                                                                                                                                                                • 7474 D Flip-Flop
                                                                                                                                                                                                                                                • ICs of basic gates (AND OR NOT XOR etc) as required
                                                                                                                                                                                                                                                • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                                                  • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                                                                  • Connecting wires Switches
                                                                                                                                                                                                                                                    • THEORY
                                                                                                                                                                                                                                                        • Sequential Circuits
                                                                                                                                                                                                                                                          • 18-ldst-exp13
                                                                                                                                                                                                                                                            • Lab Session 13
                                                                                                                                                                                                                                                              • Designing a modulo-5 asynchronous up-counter using JK-FF
                                                                                                                                                                                                                                                                • 1 Following ICs and their Datasheets
                                                                                                                                                                                                                                                                • 7400 Quad 2-input or 7410 Triple 3-input NAND Gates
                                                                                                                                                                                                                                                                • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                                                                  • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                                                                                  • Connecting wires Switches
                                                                                                                                                                                                                                                                    • THEORY
                                                                                                                                                                                                                                                                        • Figure 131 A Mod-5 Asynchronous Up Counter
                                                                                                                                                                                                                                                                        • Implementation and Observations
                                                                                                                                                                                                                                                                          • ACTIVITY
                                                                                                                                                                                                                                                                              • 19-ldst-exp14
                                                                                                                                                                                                                                                                                • Experimenting with 74194 4-bit bidirectional universal shift register
                                                                                                                                                                                                                                                                                • 1 Following ICs and their Datasheets
                                                                                                                                                                                                                                                                                • 74194 4-bit bidirectional universal shift register
                                                                                                                                                                                                                                                                                • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                                                                                  • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                                                                                                  • Connecting wires Switches
                                                                                                                                                                                                                                                                                    • THEORY
                                                                                                                                                                                                                                                                                      • Shift Registers
                                                                                                                                                                                                                                                                                      • Bidirectional Shift Registers
                                                                                                                                                                                                                                                                                      • Universal Shift Registers
                                                                                                                                                                                                                                                                                        • S1
                                                                                                                                                                                                                                                                                          • Circuit Diagram
                                                                                                                                                                                                                                                                                          • ACTIVITY
                                                                                                                                                                                                                                                                                              • 20-ldst-exp15
                                                                                                                                                                                                                                                                                                • COMPONENTS AND APPARATUS REQUIRED
                                                                                                                                                                                                                                                                                                • 1 Parallel Port Connectors (DB-25) with Cable
                                                                                                                                                                                                                                                                                                • 2 Personal Computer with Windows 98 and TurboC Compiler Installed
                                                                                                                                                                                                                                                                                                • 3 Following ICs and their Datasheets
                                                                                                                                                                                                                                                                                                • 74245 Octal Bus Transceivers with 3-State Outputs
                                                                                                                                                                                                                                                                                                • 4 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                                                                                                  • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                                                                                                                    • Connecting wires Switches
                                                                                                                                                                                                                                                                                                      • THEORY
                                                                                                                                                                                                                                                                                                      • 3-State Logic
                                                                                                                                                                                                                                                                                                        • Serial and Parallel Port Connectors
                                                                                                                                                                                                                                                                                                        • Parallel Port Connector ndash DB-25
                                                                                                                                                                                                                                                                                                          • Accessing parallel port through C Language Programming
                                                                                                                                                                                                                                                                                                              • 21-ldst-appendixA
                                                                                                                                                                                                                                                                                                              • 22-ldst-appendixB
                                                                                                                                                                                                                                                                                                                • DEBOUNCING CIRCUITRY FOR MECHANICAL SWITCHES

                                        Logic Design amp Switching Theory 1 Lab Session 04 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                        Lab Session 04 OBJECT

                                        Use of Karnaugh Map (SOP-Expression) method GIVEN LOGIC EXPRESSION

                                        F (A B C D) = sum ( 0 1 2 4 5 6 8 9 12 13 14 ) COMPONENTS AND APPARATUS REQUIRED 1 Digital ICs and their Datasheets

                                        bull 7408 Quad 2-input AND Gate bull 7432 Quad 2-input OR Gate bull 7404 Hex Inverter

                                        2 Digital Trainer DT-01 or the following components Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches PROCEDURE 1 Use Karnaugh map to reduce the given function 2 Draw the circuit diagram for the obtained reduced function 3 Implement the reduced circuit using digital ICs on a bread board (prepare the pin

                                        diagram (use appendix A) and refer to laboratory session 01 for procedure) and record the observations

                                        REDUCTION OF LOGIC EXPRESSION USING KARNAUGH MAP F

                                        CD

                                        AB DC

                                        DC DC

                                        DC

                                        BA0 1 3 2

                                        BA4 5 7 6

                                        BA12 13 15 14

                                        BA8 9 11 10

                                        Reduced form of the given logic expression is __________________________________

                                        22

                                        Logic Design amp Switching Theory 1 Lab Session 04 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                        LOGIC DIAGRAM (REDUCED FORM) OBSERVATIONS

                                        A B C D Output 0 0 0 0 0 0 0 1 0 0 1 0 0 0 1 1 0 1 0 0 0 1 0 1 0 1 1 0 0 1 1 1 1 0 0 0 1 0 0 1 1 0 1 0 1 0 1 1 1 1 0 0 1 1 0 1 1 1 1 0 1 1 1 1

                                        RESULT The reduced form (SOP Expression) of the given logic function is

                                        ____________________________________________________________

                                        The observation table reflects the given logic function

                                        23

                                        Logic Design amp Switching Theory 1 Lab Session 04 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                        ACTIVITY 1 Using Electronics Workbench derive a truth table and logic circuit for the following logic expression

                                        BAAF +=

                                        Procedure 1 From the Instruments Parts Bin drag and drop Logic Converter on the design area 2 Double click the Logic Converter to reveal Logic Converter dialog box This dialog

                                        box shows various conversion options between truth table logic expression and logic circuit

                                        3 Enter the given logic expression in the edit box found at the end of the dialog box Use lsquo to represent invert of a variable For example A is written as Arsquo

                                        4 Click the Boolean Expression to Truth Table button The truth table appears in the logic converters display

                                        5 Now click the Boolean Expression to Circuit button This creates the logic circuit for the given expression in the design area Label the diagram if needed

                                        Resulting Logic Circuit For the given expression the final circuit will look like

                                        Figure 41

                                        24

                                        Logic Design amp Switching Theory 1 Lab Session 04 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                        ACTIVITY 2

                                        Using Electronics Workbench find a simplified logic expression and circuit for the following truth table

                                        A B C Output 0 0 0 1 0 0 1 1 0 1 0 0 0 1 1 1 1 0 0 0 1 0 1 0 1 1 0 0 1 1 1 1

                                        Procedure 1 Click three input channels from A to H across the top of the logic converter The

                                        display area below the terminals fills up with the necessary combinations of ones and zeros to fulfill the input conditions The values in the output column on the right are initially set to 0

                                        2 Edit the output column to specify the desired output for each input condition To change an output value select it and type a new value 1 0 or x An x indicates a donrsquot care condition

                                        3 To convert this truth table to a Boolean expression click the Truth Table to Boolean Expression button The Boolean expression will be displayed at the bottom of the logic converter

                                        4 Simplify the expression by clicking the Simplify button 5 Now click the Boolean Expression to Circuit button This creates the logic circuit for

                                        the given expression in the design area Resulting Logic Circuit For the given truth table the final simplified circuit will look like

                                        Figure 42

                                        25

                                        Logic Design amp Switching Theory 1 Lab Session 04 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                        ACTIVITY 3

                                        Using Electronics Workbench find the logic expression and truth table for the following logic circuit

                                        Figure 43

                                        Procedure 1 Attach the input terminals of the logic converter to up to four input points in the

                                        circuit 2 Connect the single output of the circuit to the output terminal on the logic converter

                                        icon 3 Click the Circuit to Truth Table button The truth table appears in the logic

                                        converters display 4 To convert this truth table to a Boolean expression click the Truth Table to Boolean

                                        Expression button The Boolean expression will be displayed at the bottom of the logic converter

                                        Resulting Logic Expression Logic Expression for the given circuit is found to be _____________________________

                                        26

                                        Logic Design amp Switching Theory 1 Lab Session 04 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                        27

                                        For activities 1 2 and 3 attach hardcopy of the output (truth table logic expression and logic circuit) form electronic workbench here

                                        Logic Design amp Switching Theory 1 Lab Session 05 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                        Lab Session 05 Lab Session 05 OBJECT OBJECT

                                        Designing a BCD Adder Designing a BCD Adder COMPONENTS AND APPARATUS REQUIRED COMPONENTS AND APPARATUS REQUIRED

                                        1 Following ICs and their Datasheets 1 Following ICs and their Datasheets bull 7408 Quad 2-input AND Gate bull 7408 Quad 2-input AND Gate bull 7432 Quad 2-input OR Gate bull 7432 Quad 2-input OR Gate bull 7483 4-bit Binary Adder bull 7483 4-bit Binary Adder

                                        2 Digital Trainer DT-01 or the following components 2 Digital Trainer DT-01 or the following components Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors (100 Ω) Connecting wires Switches (100 Ω) Connecting wires Switches

                                        THEORY THEORY

                                        A BCD Adder is a combinational circuit that adds two BCD digits in parallel and produces a sum digit also in BCD A BCD Adder is a combinational circuit that adds two BCD digits in parallel and produces a sum digit also in BCD

                                        A4 A3 A2 A1 B4 B3 B2 B1

                                        7483-BCD ADDER

                                        Cout (C4 ) Z4 Z3 Z2 Z1 Cin(C0)

                                        A4 A3 A2 A1 B4 B3 B2 B1

                                        7483-BCD ADDER

                                        Cout

                                        (C4 ) Z4 Z3 Z2 Z1 Cin(C0)

                                        Figure 51 BCD Adder Circuit

                                        28

                                        Logic Design amp Switching Theory 1 Lab Session 05 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                        29

                                        A BCD adder must include the correction logic in its internal construction The two BCD digits together with the input carry are first added using a 4-bit binary adder to produce the binary sum If no output carry is generated and the binary sum is less than or equal to 9 then the corresponding BCD sum is identical and therefore no conversion is needed When the output carry is equal to 1 or the binary sum is greater than 9 then a binary 0110 is added to the binary sum through another 4-bit binary adder If Cout is the carry output and Z4Z3Z2Z1 is the binary sum form the first 4-bit binary adder then the following equation indicates the condition when a binary 0110 is to be added

                                        C = COUT + Z4Z2 + Z4Z3 IMPLEMENTATION AND OBSERVATIONS Implement the BCD adder circuit according to figure 51 on a bread board (prepare the pin diagram (use appendix A) and refer to laboratory session 01 for procedure) A BCD adder has nine input bits (two BCD digits and a carry bit) which can result in a total of 512 combinations of which 312 inputs are donrsquot care Since it is a very lengthy procedure to record results for 200 valid input combinations therefore for simplicity just record results for any eight combinations in the following table

                                        Input Carry

                                        BCD Digit 1 BCD Digit 2 Carry Output

                                        BCD Sum A4 A3 A2 A1 B4 B3 B2 B1 Z4 Z3 Z2 Z1

                                        Logic Design amp Switching Theory 1 lab Session 06 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                        Lab Session 06

                                        OBJECT

                                        bull Designing of a 4 x 1 Multiplexer bull Experimenting with 74150 IC

                                        COMPONENTS AND APPARATUS REQUIRED 1 Following ICs and their Datasheets

                                        bull 7408 Quad 2-input AND Gates or 7411 Triple 3-input AND Gates bull 7432 Quad 2-input OR Gates bull 7404 Hex Inverter bull 74150 16 x 1 MUX

                                        2 Digital Trainer DT-01 or the following components Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches THEORY

                                        Multiplexers A digital data Multiplexer (MUX) is a combinational circuit having several data inputs and a single output A set of data-select inputs is used to control which of the data inputs is routed to the single output A multiplexer is also called a data selector because of this ability to select which data input is connected o the output Normally there are 2n input lines and n selection lines whose bit combination determine which input is selected DESIGN OF A 4 x 1 MULTIPLEXER A 4 x 1 multiplexer is capable of selecting one of four data inputs (see figure 61) The 2-bit binary number at the data select inputs S1 and S0 specifies which of the four data inputs is to be routed to the output Since there are two data select inputs therefore they can select 22 = 4 different data inputs lines

                                        S0 S1 D0 D1

                                        D2 D3

                                        Data-select Inputs Output

                                        Data Inputs

                                        Figure 61 Block Diagram of a 4 x1 Multiplexer

                                        30

                                        Logic Design amp Switching Theory 1 lab Session 06 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                        Figure 62 Circuit Diagram for 4 x 1 Multiplexer

                                        Implementation and Observations

                                        Implement the 4 x 1 Multiplexer circuit (figure 62) on a bread board (prepare the pin diagram (use appendix A) and refer to laboratory session 01 for implementation procedure) and record the observations in the following table For each data select combination specify the switch number as well as the binary value present on that selected switch

                                        S1 S0 Output 0 0 0 1 1 0 1 1

                                        TESTING OF 74150 - 16 x 1 MUX

                                        The 74150 IC has sixteen data inputs and four data-selection lines Function of various pins of this IC is described below

                                        bull E0 through E15 Data input lines

                                        31

                                        Logic Design amp Switching Theory 1 lab Session 06 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering bull A B C D Data select lines with D being the MSB bull W Active low output line bull Grsquo Active low enable line bull VCC and GND Supply connections lines

                                        Circuit Diagram

                                        Figure 63 Pin connections of 74150 for selecting E0

                                        Testing Procedure

                                        bull Make connections as shown in the circuit diagram bull Apply different data (1 or 0) at data inputs that are labeled as E0 to E15 Only

                                        connection for E0 is shown is the figure for simplicity bull Select the data input E0 with the help of data selectors A B C and D bull Observe the output which shows the complement of the data from E0 bull Select all the sixteen data inputs one by one and record your observations in the

                                        following table

                                        32

                                        Logic Design amp Switching Theory 1 lab Session 06 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                        33

                                        Observations

                                        Grsquo D C B A W Grsquo D C B A W 0 0 0 0 0 0 1 0 0 0 0 0 0 0 1 0 1 0 0 1 0 0 0 1 0 0 1 0 1 0 0 0 0 1 1 0 1 0 1 1 0 0 1 0 0 0 1 1 0 0 0 0 1 0 1 0 1 1 0 1 0 0 1 1 0 0 1 1 1 0 0 0 1 1 1 0 1 1 1 1

                                        ACTIVITY 1 Consider 4x1 Multiplexer Draw the output wave-form for the following data inputs

                                        (E0 E1 E2 E3) and select lines A B (B being the MSB) Output is W

                                        E3 E2 E1 E0 A B

                                        W

                                        2 Using the 4 x 1 MUX designed in this laboratory session implement the following logical function F (A B C) = Σ (0147)

                                        Show your working and input connections in the following block diagram according to the circuit you have implemented

                                        4 x 1 MUX

                                        S0 S1

                                        Output D0

                                        D1

                                        D2

                                        D3

                                        Logic Design amp Switching Theory 1 Lab Session 07 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                        Lab Session 07

                                        OBJECT

                                        bull Designing of a 2 x 4 Decoder 1 x 4 Demultiplexer bull Experimenting with 74138 IC

                                        COMPONENTS AND APPARATUS REQUIRED 1 Following ICs and their Datasheets

                                        bull 7408 Quad 2-input or 7411 Triple 3-input AND Gates bull 7404 Hex Inverter bull 74138 3 x 8 Decoder

                                        2 Digital Trainer DT-01 or the following components Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches THEORY

                                        Decoder A Decoder is a combinational circuit that converts binary information form n input lines to a maximum of 2n unique output lines In practical applications decoders are often used for selecting one of several devices

                                        Demultiplexer A decoder with an enable input can function as a Demultiplexer A Demultiplexer (DMUX) id a circuit that receives information on a single line and transmits this information on one of 2n possible output lines The selection of a specific output line is controlled by the bit values of n selection lines DESIGN OF A 2 x 4 DECODER 1 x 4 DEMULTIPLEXER A 2 x 4 decoder is capable of selecting one of four output lines (see figure 71 (a)) The 2-bit binary number at the data inputs S1 and S0 specifies which of the four data inputs is to be selected If we add an enable pin and use it as an input line then this decoder can be converted to a 1 x 4 Demultiplexer where S1 and S0 will select a line to which data input is to be routed (see figure 71 (b))

                                        Select S0 S0 Inputs

                                        S1 D0 D1

                                        D2

                                        D3

                                        Enable (a) Block Diagram of a 2 x 4 Decoder

                                        Figure 71

                                        S1 D0 D1

                                        D2

                                        D3

                                        Inputs

                                        Data Input (b) Block Diagram of a 1 x 4 Demulptiplexer

                                        34

                                        Logic Design amp Switching Theory 1 Lab Session 07 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                        Figure 72 Circuit Diagram for 2 x 4 Decoder 1 x 4 Demultiplexer

                                        Implementation and Observations Implement the 2 x 4 Decoder 1 x 4 Demultiplexer circuit (figure 72) on a bread board (prepare the pin diagram (use appendix A) and refer to laboratory session 01 for implementation procedure) and record the observations in the following table

                                        Enable Data Input S1 S0 D0 D1 D2 D3

                                        0 0 0 0 0 1 0 1 0 0 1 1 1 0 0 1 0 1 1 1 0 1 1 1

                                        TESTING OF 74138 3 x 8 Decoder The 74138 IC has three inputs and eight output lines It has three enable inputs and for the IC to function all three inputs need to be enabled Function of various pins of this IC is described below

                                        35

                                        Logic Design amp Switching Theory 1 Lab Session 07 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                        bull Y0 through Y7 Active low data outputs bull A B C Input select lines with C being the MSB bull G1 Active high enable Input bull G2Arsquo and G2Brsquo Active low enable Inputs bull VCC and GND Supply connections lines Circuit Diagram

                                        Figure 73 Pin connections of 74138

                                        Testing Procedure

                                        bull Make connections as shown in the circuit diagram bull Apply different combinations of 1s and 0s at data inputs bull Observe the output and record your observations in the following table

                                        Observations

                                        C B A Y0 Y1 Y2 Y3 Y4 Y5 Y6 Y7 0 0 0 0 0 1 0 1 0 0 1 1 1 0 0 1 0 1 1 1 0 1 1 1

                                        36

                                        Logic Design amp Switching Theory 1 Lab Session 07 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                        37

                                        ACTIVITY ACTIVITY 1 What will be the binary values at the outputs Y0 through Y7 of 74138 if 1 What will be the binary values at the outputs Y0 through Y7 of 74138 if

                                        bull All three enable pins are connected to ground bull All three enable pins are connected to ground __________________________________________________________________________________________________________________________________________ __________________________________________________________________________________________________________________________________________ _____________________________________________________________________ _____________________________________________________________________

                                        bull All three enable pins are connected to VCC bull All three enable pins are connected to VCC _______________________________________________________________________________________________________________________________________________________________________________________________________________

                                        _______________________________________________________________________________________________________________________________________________________________________________________________________________

                                        2 Show connections for 74138 in order to use it as a 1 x 8 Demultiplexer 2 Show connections for 74138 in order to use it as a 1 x 8 Demultiplexer

                                        3 Consider a 2 x 4 Decoder with two enable inputs (one active high - G and one active low ndash Grsquo) Draw the output wave-forms for D0 D1 D2 and D3 if the two select inputs are A and B (B being the MSB) All outputs are active low

                                        Grsquo

                                        G

                                        A B

                                        D0 D1 D2

                                        D3

                                        Logic Design amp Switching Theory 1 Lab Session 08 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                        Lab Session 08 OBJECT

                                        bull Designing of a 4 x 2 Priority Encoder bull Experimenting with 74148 IC

                                        COMPONENTS AND APPARATUS REQUIRED

                                        1 Following ICs and their Datasheets

                                        bull 7408 Quad 2-input or 7421 Dual 4-input AND Gates bull 7432 Quad 2-input OR Gates bull 7404 Hex Inverter bull 74148 Encoder

                                        2 Digital Trainer DT-01 or the following components Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches

                                        THEORY

                                        Encoder An Encoder is a digital function that produces a reverse operation from that of a decoder An Encoder has 2n (or less) input lines and n output lines The output lines generate the binary code for the 2n input variables Priority Encoder

                                        A simple encoder may produce an erroneous output if more than one of its inputs is high A Priority Encoder is one that responds to just one input among those that may be simultaneously high in accordance with some priority system The most common priority system is based on the relative magnitudes of the inputs whichever decimal input is largest is the one that is encoded

                                        DESIGN OF A 4 x 2 Priority Encoder

                                        The following equations represent the outputs of a 4 x 2 priority encoder 32 DDA +=

                                        321 DDDB += As can be seen from the equations that input D0 which has a binary code 00 is not used in any equation A binary code 00 at the output indicates two conditions Either D0 is selected or no input is selected In order to differentiate these two conditions we will provide an additional output Z to indicate if at least one of the inputs is a 1 The equation for Z will be

                                        4321 DDDDZ = If Z is 0 then the binary code 00 at the output indicates that D0 is selected and if Z is 1 then it indicates that no input line is selected

                                        38

                                        Logic Design amp Switching Theory 1 Lab Session 08 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                        Figure 81 Circuit Diagram for 4 x 2 Priority Encoder

                                        it (figure 81) on a bread board (prepare the to laboratory session 01 for implementation

                                        Implementation a Implement the 4 x 2 Priority Encoder circu

                                        ram (use appendix A) and refer

                                        nd Observations

                                        pin diagprocedure) and record the observations in the following table

                                        D3 D2 D1 D0 A B 0 0 0 1 0 0 1 x 0 1 x x 1 x x x

                                        TESTING OF 74148 8 x 3 Octal Priority Encoder

                                        imal digits There are nine of which three represents

                                        ing any of the inputs is high

                                        then it shows that line 0 is selected and if e inputs selected E0 and GS

                                        cannot be in the same state provided that E1 is enabled

                                        The 74148 is a priority encoder with active-Low input for dec

                                        input) and five output linesinputs lines (including an enablethe binary code for the octal digit Function of various pins of this IC is described below

                                        bull 0 through 7 Active low data inputs representing the octal digits A2 A1 A0 Active low output lines representing the binary code bullbull E1 Active low enable Input bull E0 Active low output indicating none of the inputs is high bull GS Active low output indicatbull VCC and GND Supply connections lines Therefore if GS A2 A1 and A0 are all low

                                        then it shows that none of thE0 A2 A1 and A0 are all low

                                        39

                                        Logic Design amp Switching Theory 1 Lab Session 08 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                        Circuit Diagram

                                        Figure 82 Pin connections of 74148

                                        Testing Procedure bull Make connections as sho

                                        binations of 1s and 0s at data inputs d record your observations in the following table

                                        GS E0

                                        wn in the circuit diagram bull Apply different combull Observe the output an Observations

                                        0 1 2 3 4 5 6 7 A2 A1 A0 1 1 1 1 1 1 1 1 x x x x x x x 0 x x x x x x 0 1 x x x x x 0 1 1 x x x x 0 1 1 1 x x x 0 1 1 1 1 x x 0 1 1 1 1 1 x 0 1 1 1 1 1 1 0 1 1 1 1 1 1 1

                                        40

                                        Logic Design amp Switching Theory 1 Lab Session 08 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                        41

                                        CTIVITY

                                        Cascade the following two 74148 8 x 3 Priority Encoders to form 16 x 4 Priority

                                        A 1

                                        Encoder

                                        Logic Design amp Switching Theory 1 Lab Session 09 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering `

                                        Lab Session 09 OBJECT

                                        Designing an Odd Parity Generator and Checker for a 3-bit Data COMPONENTS AND APPARATUS REQUIRED

                                        1 Following ICs and their Datasheets

                                        bull 7486 Quad 2-input Exclusive-OR Gates bull 7404 Hex Inverter

                                        2 Digital Trainer DT-01 or the following components Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches

                                        THEORY

                                        Parity Generator When binary data is transmitted and processed it is ndash as are all electrical signals ndash susceptible to noise that can either alter or distort its contents 1s may be effectively changed to 0s and 0s to 1s To overcome this problem one or more bits are often added to the data as an aid in detecting errors caused by noise The most common of these is a Parity bit that signifies whether the total number of 1s in a code group is odd or even In an Odd Parity system the parity bit is made 0 or 1 as necessary to make the total number 1s odd (counting the parity bit itself) In an Even Parity system the parity bit is chosen to make the total number of 1s even Table 91 shows how parity bits would be added to BCD code group in both systems

                                        Decimal BCD Value Parity Bit ABCD Odd Parity Even Parity

                                        0 0000 1 0 1 0001 0 1 2 0010 0 1 3 0011 1 0 4 0100 0 1 5 0101 1 0 6 0110 1 0 7 0111 0 1 8 1000 0 1 9 1001 1 0

                                        Table 91 Odd and Even Parity in BCD

                                        When digital data is received a parity checking circuit generates an error signal if the total number of 1s is odd in an even parity system or if it is even in an odd parity system Parity check always detects a single error (one bit change from 0 to 1 or 1 to 0) but may not detect

                                        42

                                        Logic Design amp Switching Theory 1 Lab Session 09 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering ` two or more errors Odd parity is used more often than even parity because even parity does not detect a situation where all 0s are created due to short circuit or other fault condition DESIGN OF A 3-BIT ODD PARITY GENERATOR AND CHECKER Let x y and z be the three bits that constitute the message and are the input to the Odd Parity Generator Circuit Since it is an odd parity system the bit P is generated so as to make the total number of 1s odd (including P) The function P can be expressed as follows P = x oplus y Ο z or P = x Ο y oplus z Since the IC available is 7486 which is quad 2input XOR IC therefore we will convert XNOR also to XOR

                                        P = x oplus y Ο z

                                        P = ( x oplus y ) Ο z Since for even number of variables ______

                                        XOR = XNOR Therefore ___________ _________

                                        P = ( x oplus y ) oplus z = x oplus y oplus z This logical expression can be implemented with two XOR gates and an inverter (see figure 91)

                                        Figure 91 Circuit Diagram for a 3-bit Parity Generator

                                        The 3-bit message and the parity bit are transmitted to their destination where they are applied to a Parity Checker Circuit An error occurs during transmission if the parity of the four bits received is even since the binary information transmitted was originally odd The output C of the parity checker should be a 1 when an error occurs ie when the number of 1s in the four inputs is even Therefore the function C can be expressed as

                                        C = x Ο y Ο z Ο P

                                        Using the same logic applied for the conversion of the equation of P

                                        PzyxC oplusoplusoplus= This logical expression can be implemented with three XOR gates and an inverter (see figure 92)

                                        43

                                        Logic Design amp Switching Theory 1 Lab Session 09 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering `

                                        44

                                        Figure 92 Circuit Diagram for a 3-bit Parity Checker Implementation and Observations Implement the 3-bit Parity Generator and Checker circuits (figure 91 and 92) on a bread board (prepare the pin diagram (use appendix A) and refer to laboratory session 01 for implementation procedure) and record the observations in the following table

                                        x y z P x y z P C x y z P C 0 0 0 0 0 0 0 1 0 0 0 0 0 1 0 0 0 1 1 0 0 1 0 1 0 0 0 1 0 1 0 1 0 0 1 1 0 0 1 1 1 0 1 1 1 0 0 0 1 0 0 1 1 0 0 1 0 1 0 1 0 1 1 1 0 1 1 1 0 0 1 1 0 1 1 1 0 1 1 1 0 1 1 1 1 1 1 1

                                        Odd Parity Generation Odd Parity Check ACTIVITY 1 Try using the parity checker of figure 92 as 3-bit parity generator Write the details here

                                        _____________________________________________________________________________________________________________________________________________________________________________________________________________________ ______________________________________________________________________________________________________________________________________________ _______________________________________________________________________ ______________________________________________________________________________________________________________________________________________

                                        Logic Design amp Switching Theory 1 Lab Session 10 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                        Lab Session 10 OBJECT

                                        Driving a seven segment display using 7447 7448 driver IC COMPONENTS AND APPARATUS REQUIRED

                                        1 Following ICs and their Datasheets

                                        bull Seven Segment Displays (Common Anode Common Cathode) bull 7447 7448 BCD to Seven Segment Driver

                                        2 Digital Trainer DT-01 or the following components Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches

                                        THEORY Seven Segment Displays A Seven Segment Display consists of seven light-emitting segments The segments are designated by letters a through g (see figure 101) By illuminating various combinations of segments the numerals 0 through 9 can be displayed Seven Segment Displays are commonly constructed with light-emitting diodes (LEDs) and with liquid-crystal displays (LCDs) LEDs generally provide greater illumination levels but require much greater power than LCDs An LED display can be a common-anode type or common cathode type In common anode type a high voltage is applied at the common terminal of the display and low voltage is applied at a segmentrsquos terminal for illumination In the common-cathode type a low voltage is applied at the common terminal of the display and high voltage is applied at a segmentrsquos terminal for illumination

                                        Figure 101 Seven Segment Display

                                        a f b g

                                        e c d

                                        7447 7448 BCD to Seven Segment Driver 7447 7448 IC is particularly used to drive Seven Segment Its input is a BCD number and output drives a seven segment display 7447 is used to drive common-anode displays whereas 7448 is used to drive common cathode displays 7447 7448 is a 16 pin IC Function of various pins of these ICs is described below

                                        bull A B C D Inputs representing BCD digits (D being the MSB)

                                        45

                                        Logic Design amp Switching Theory 1 Lab Session 10 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering bull OA through OG Outputs to drive segments a through g of the display (Active low

                                        in 7447 and active high in 7448) bull RBI Ripple Blanking Input Turns off all the segments if kept low provided that LT

                                        is kept high and all other inputs (A B C D BI) are kept low Should be kept high otherwise

                                        bull BI RBO Wire-AND logic serving as a Blanking Input and or Ripple Blanking Output

                                        o BI Turns off all the segments if low o RBO Goes to a low level (response condition) along with other outputs when

                                        RBI and inputs A B C and D are low with LT input at high level bull LT Lamp Test input Tests whether all segments are working or not Illuminates all

                                        segments if kept low provided that BI is kept high Should be kept high otherwise bull VCC and GND Supply connections lines CIRCUIT DIAGRAM

                                        Figure 102 Circuit diagram for 7447driving a common-anode display

                                        IMPLEMENTATION AND OBSERVATIONS

                                        bull Make connections as shown in the circuit diagram (refer to laboratory session 01 for implementation procedure)

                                        bull Apply different combinations of 1s and 0s at data inputs bull Observe the output and record your observations in the following table

                                        46

                                        Logic Design amp Switching Theory 1 Lab Session 10 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                        47

                                        Decimal Digit

                                        BCD Inputs Seven Segment Outputs D C B A a b c d e f g

                                        0 0 0 0 0 1 0 0 0 1 2 0 0 1 0 3 0 0 1 1 4 0 1 0 0 5 0 1 0 1 6 0 1 1 0 7 0 1 1 1 8 1 0 0 0 9 1 0 0 1

                                        ACTIVITY 1 Perform the Lamp Test for the designed circuit and write your observations

                                        ____________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________

                                        2 How can you use 7447 IC to drive a common-cathode display

                                        ____________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________

                                        3 What symbols appear in the seven segment display if inputs DCBA are

                                        DCBA Symbol

                                        1010

                                        1011

                                        1100

                                        1101

                                        1110

                                        1111

                                        Logic Design amp Switching Theory 1 Lab Session 11 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                        48

                                        Lab Session 11 OBJECT

                                        Testing different modes of JK-FF COMPONENTS AND APPARATUS REQUIRED 1 Following ICs and their Datasheets

                                        bull 7473 7476 JK Flip-Flop 2 Digital Trainer DT-01 or the following components

                                        Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches

                                        THEORY

                                        Flip-Flop A flip-flop circuit can maintain a binary state indefinitely (as long as the power is delivered to the circuit) until directed by an input signal to switch states The major differences among various types of flip-flops are in the number of inputs they possess and in the manner in which the inputs affect the binary state

                                        JK Flip-Flop JK flip flop is an edge triggered device A typical JK flip flop has three inputs J K and a clock input The flip-flop can be either positive or negative edge triggered The output Q is available in complemented form as well Beside the usual inputs and output most of the flip-flop IC also possess two asynchronous inputs namely Preset and Clear These inputs are usually active low If used Preset and Clear inputs keep the flip-flop in set and reset state respectively irrespective of the other inputs Both of these inputs cannot be used simultaneously otherwise they will bring the flip-flop in unstable state

                                        Figure 111 Symbol for JK flip-flop

                                        (a) positive-edge triggering (b) active low Preset (PR) and Clear (CLR) with positive-edge triggering

                                        (c) active low Preset (PR) and Clear (CLR) with negative-edge triggering

                                        Logic Design amp Switching Theory 1 Lab Session 11 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                        49

                                        TESTING OF 7473 7476 DUAL JK FLIP-FLOP

                                        Both the ICs 7473 and 7476 are similar in functionality except for one difference The flip-flops in 7473 have only one type of active low asynchronous input which is the Clear input whereas the flip-flops in 7476 have both Preset and Clear inputs Both these ICs have negative edge triggered flip-flops

                                        Circuit Diagram

                                        Figure 112 Pin connections of 7476

                                        Testing Procedure

                                        bull Make connections as shown in the circuit diagram (figure 112) bull Apply different combinations of 1s and 0s at J and K inputs bull Observe the output and record your observations in the following table

                                        Observations

                                        J

                                        K Q

                                        0 0 0 1 1 0 1 1

                                        ACTIVITY

                                        1 Observe the output Q of JK flip-flop if the clock input is connected to VCC or GND instead of a clock source Write your observations here __________________________________________________________________________________________________________________________________________ _______________________________________________________________________________________________________________________________________________________________________________________________________________

                                        Logic Design amp Switching Theory 1 Lab Session 12 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                        50

                                        Lab Session 12 OBJECT

                                        Designing sequential circuit for the given state diagram using D flip-flop GIVEN STATE DIAGRAM

                                        00

                                        11

                                        Figure 121 State Diagram COMPONENTS AND APPARATUS REQUIRED 1 Following ICs and their Datasheets

                                        bull 7474 D Flip-Flop bull ICs of basic gates (AND OR NOT XOR etc) as required

                                        2 Digital Trainer DT-01 or the following components Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches

                                        THEORY

                                        Sequential Circuits In Sequential Circuits the output not only depends on the present inputs but also on previous states of the circuit These circuits use memory elements (latches flip-flops) and the binary information stored in the memory elements at any given time defines the state of the sequential circuit Analysis of a Sequential Circuit The behavior of a sequential circuit is determined from the inputs the outputs and the states of its flip-flops Both the outputs and next state are a function of the inputs and the

                                        10

                                        01

                                        00 11 10

                                        00

                                        00 11 10 00

                                        Logic Design amp Switching Theory 1 Lab Session 12 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                        51

                                        present state The analysis of a sequential circuit form a state diagram comprises of the following bull Selecting a particular flip-flop to design the circuit bull Obtaining state table from the state diagram bull Finding input equations for the selected flip-flop bull Finding state equations (not required for the construction of circuit) bull Implementing the circuit using selected flip-flops and their input equations ANALYZING THE GIVEN STATE DIAGRAM D Flip-Flop D flip-flop is also called transparent flip-flop as it simply transfers the input data to the output For our design we require the graphical symbol and excitation table of D flip-flop (see figure 122)

                                        Qt Qt+1 T 0 0 0 0 1 1 1 0 0 1 1 1

                                        (b) Excitation table of D Flip-Flop

                                        (a) Graphical Symbol

                                        Figure 122 Characteristic equation of D flip-flop is Q(t+1) = D State Table The given state diagram has four states so we will need two D flip-flops (FF-0 FF-1) Form state table form the given state diagram and record the results in the following table

                                        Present State Input Next State Output Input to FF-0 D0

                                        Input to FF-1 D1 Q1t Q0t x Q1(t+1) Q0(t+1) z

                                        Logic Design amp Switching Theory 1 Lab Session 12 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                        52

                                        Input Equations Using Karnaugh map the input equations D0 and D1 for the two flip-flops can be found

                                        D0 D1 Q0x

                                        Q1

                                        _ _ Q0x

                                        _ Q0x

                                        Q0x

                                        _ Q0x

                                        Q0x

                                        Q1

                                        _ _ Q0x

                                        _ Q0x

                                        Q0x

                                        _ Q0x

                                        _ Q1

                                        _ Q1

                                        Q1

                                        Q1

                                        D0 = _________________ D1 = _________________

                                        State Equations Using the characteristic equation of D flip-flop we can find the state equations Q0(t+1) and Q1(t+1) for the to flip flops Q0(t+1) = _______________________ Q1(t+1) = _______________________ _______________________ _______________________ _______________________ _______________________ Circuit Diagram

                                        Logic Design amp Switching Theory 1 Lab Session 12 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                        53

                                        Implementation Procedure and Observations

                                        1 Implement the circuit using digital ICs on a bread board (prepare the pin diagram (use appendix A) and refer to laboratory session 01 for procedure)

                                        2 Make the clear inputs of the flip-flops low (to clear the flip-flops) The flip-flops will remain in clear state as long as the clear inputs are connected to low level

                                        3 Connect output Q0 and the clock pulse to an oscilloscope 4 Apply 0 to the input x 5 Now make the clear inputs to high 6 Observe the waveform for the first 5 clock pulses and record it 7 Repeat steps 2 to 6 keeping x=1 in step 4 this time 8 Repeat steps 2 to 7 this time connecting Q1 instead of Q0 to the oscilloscope in step

                                        3 Record your observations (Keep frequency of the clock pulse low (eg1Hz) so that the output waveforms can be observed easily)

                                        1 2 3 4 5 Clock Pulse

                                        Output Waveform for Q0 when x=0

                                        Output Waveform for Q0 when x=1

                                        Output Waveform for Q1 when x=0

                                        Output Waveform for Q1 when x=1

                                        Logic Design amp Switching Theory 1 Lab Session 13 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                        Lab Session 13 OBJECT

                                        Designing a modulo-5 asynchronous up-counter using JK-FF COMPONENTS AND APPARATUS REQUIRED

                                        1 Following ICs and their Datasheets

                                        bull 7400 Quad 2-input or 7410 Triple 3-input NAND Gates bull 7476 7473 JK Flip-Flop

                                        2 Digital Trainer DT-01 or the following components Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches

                                        THEORY

                                        Digital Counters A digital counter is a set of flip-flops whose states change in response to pulses applied at the input to the counter The flip-flops are interconnected so that their combined state at any time is the binary equivalent of the total number of pulses that have occurred up to that time Every counter resets after a certain number of clock pulses Thus as it name implies a counter is used to count pulses An n stage counter can count up to a maximum of 2n states n is equal to the number of flip-flops required for the construction of counter

                                        Modulus Counters The number of input pulses that causes a counter to reset to its initial count is called the modulus of the counter Thus the modulus equals to total number of distinct states (counts) including zero that a counter can store A binary counter with n stages is a modulo-2n (or mod-2n) counter The largest count a mod-N counter can achieve is N-1 ie a mod-N counter never reaches the binary number equal to its modulus N is always equal to or less than 2n Counters can be classified as bull Synchronous Counters which are clock driven All the flip-flops are driven by a

                                        single clock bull Asynchronous Counters which are event driven Clock input is given to the first

                                        flip-flop only Rest of the flip-flops are driven by their preceding flip-flops

                                        DESIGN OF A MOD-5 ASYNCHRONOUS UP COUNTER The number of flip-flops required to construct a mod-5 counter is 3 because 5 should be less than or equal to 2n This counter will count from 0 to 4 a total of 5 distinct states Since a 3-stage counter can count up to 8 states at maximum a NAND gate is used to reset it after 5 clock pulses Figure 131 shows the logic diagram

                                        54

                                        Logic Design amp Switching Theory 1 Lab Session 13 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                        55

                                        Figure 131 A Mod-5 Asynchronous Up Counter

                                        Implementation and Observations

                                        Implement the mod-5 counter circuit (figure 131) on a bread board (prepare the pin diagram (use appendix A) and refer to laboratory session 01 for implementation procedure) and record the observations in the following table

                                        Clock Pulse Q2 Q1 Q0

                                        0 1 2 3 4 5 6 7

                                        ACTIVITY

                                        Draw the timing diagram for mod-5 counter designed in this laboratory session

                                        Logic Design amp Switching Theory 1 Lab Session 14 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                        Lab Session 14 OBJECT

                                        Experimenting with 74194 4-bit bidirectional universal shift register COMPONENTS AND APPARATUS REQUIRED

                                        1 Following ICs and their Datasheets

                                        bull 74194 4-bit bidirectional universal shift register 2 Digital Trainer DT-01 or the following components

                                        Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches

                                        THEORY

                                        Shift Registers

                                        A Register is a set of flip-flops used to store binary data A register which is capable of shifting its binary information either to the right or left is called a shift register The logical configuration of a register consists of a chain of flip-flops connected in cascade with the output of one flip-flop connected to the input of next flip-flop All flip-flops receive a common clock pulse which causes the shift from one stage to the next

                                        Bidirectional Shift Registers A bi-directional shift register is one whose bits can be shifted from left to right or from right to left

                                        Universal Shift Registers A universal shift register is a bi-directional register whose input can be in either serial or parallel form and whose output can be in either serial or parallel form

                                        74194 4-BIT BIDIRECTIONAL UNIVERSAL SHIFT REGISTER

                                        The 74194 register provides parallel as well as serial loading in both directions Function of various pins of this IC is described below

                                        bull A B C and D Active high inputs for parallel loading bull QA QB QC and QD Active high outputs bull S0 and S1 Active high mode control inputs The following table shows combinations

                                        of S1 and S0 to enable various modes

                                        S1 S0 Clock Action 0 0 x No change 0 1 uarr Shift right 1 0 uarr Shift left 1 1 uarr Parallel load

                                        uarr shows the rising edge of the clock pulse

                                        56

                                        Logic Design amp Switching Theory 1 Lab Session 14 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering bull SR Active high serial input for right shifting bull SL Active high serial input for left shifting bull CLR Active low input Clears all the flip-flops of the register if set to 0 should be

                                        kept high otherwise bull CLK Clock input bull VCC and GND Supply connections lines Thus A B C and D are inputs for parallel loading whereas SR and SL are inputs for serial loading with right or left shifting respectively S1 and S0 are used to select the loading mode Circuit Diagram

                                        Figure 141 Pin connections of 74194 Testing Procedure

                                        bull Make connections as shown in the circuit diagram bull Observe the output for the input combinations given in the following table

                                        57

                                        Logic Design amp Switching Theory 1 Lab Session 14 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                        58

                                        Observations

                                        S1 S0 SL SR A B C D QA QB QC QD 0 0 0 1 0 0 0 0 0 1 1 0 0 0 0 1 1 0 0 0 0 0 1 0 1 1 0 0 0 0 1 1 0 0 1 1 0 1 0 0 0 1 1 1 0 1 0 1 1 0 1 0 0 1 1 0 1 1 1 0 0 1 1 1 1 1 0 0 1 1 1 1

                                        ACTIVITY 1 Show connections of 74194 to convert it into a ring counter with right shifting

                                        Logic Design amp Switching Theory 1 Lab Session 15 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                        Lab Session 15

                                        OBJECT

                                        Experimenting with 74245 octal bus transceivers using parallel port PC interfacing COMPONENTS AND APPARATUS REQUIRED 1 Parallel Port Connectors (DB-25) with Cable 2 Personal Computer with Windows 98 and TurboC Compiler Installed 3 Following ICs and their Datasheets

                                        bull 74245 Octal Bus Transceivers with 3-State Outputs 4 Digital Trainer DT-01 or the following components

                                        Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches

                                        THEORY

                                        3-State Logic Sometimes it is necessary to isolate one part of circuit from the other part For this purpose some TTL ICs are designed with 3-state logic Such devices have three possible output states high low and high impedance The device can be put into high impedance state by a control signal applied to an appropriate pin When such a device is in high impedance state there is very high impedance at its output effectively isolating the device from whatever circuitry the output normally drives 74245 Octal Bus Transceivers A bus is any conducting path or set of paths having electrical connections to one or more devices 74245 octal bus transceivers are mainly used to control connectivity between two devices or circuits It also provides direction control for signal flow Function of various pin of this IC is given below

                                        bull A1 through A8 Bus A bull B1 through B8 Bus B bull G΄ Active low enable input When high sets all the bus pins to high impedance state bull DIR Direction control for signal flow When set to high logic level transfers bus A

                                        data to B bus When set to low logic level transfers bus B data to A bus bull VCC and GND Supply connections lines Serial and Parallel Port Connectors A Parallel Port can consist of only 25 pin port adapter called a DB-25 and a serial port can consist of either a 25 pin port adapter called a DB-25 or 9 pin adapter called a DB-9 port adapter Whether the port is a 9 pin or 25 pin it can accomplish all of the same tasks that serial port communications have been designed for

                                        59

                                        Logic Design amp Switching Theory 1 Lab Session 15 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                        60

                                        Each adapter can be a male type connector with pins or a female type adapter with tiny holes Generally a PRINTER port (called LPT1) on the back of a computer is female type adapter and we need to use MALE DB-25 pin cable on it for PRINTER connection or for parallel LAPLINK cable And a COM port on the back of a computer is male for the serial ports but it may not necessarily be Parallel Port Connector ndash DB-25 The DB-25 connector (named for its B-size D-shaped shell and 25 pins) is practically ubiquitous in the electronics industry The DB-25 connector is used for a variety of purposes Two common applications are RS-232EIA-232 (serial) connections and the parallel printer interface on the IBM PC The DB-25 connector is also used for SCSI connections Normally the parallel port is used for output to a printer or other device It sends data 8-bits or one byte at a time in parallel The other lines available on the DB-25 connector are a combination of status lines control lines and ground lines The status and control lines are used for handshaking commands and feedback when we are talking to a printer

                                        Figure 152 DB-25 Female Figure 151 DB-25 Male

                                        Figure 153 Pin Layout for DB-25 As can be seen form figure 153 there are four types of pins in this connector

                                        bull Data pins (8 pins - D0 to D7) Active high bidirectional lines

                                        Logic Design amp Switching Theory 1 Lab Session 15 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering bull Control pins (4 pins - C0 to C3) C0 C1 and C3 are active low whereas C2 is active

                                        high These lines also are bidirectional bull Status pins (5 pins ndash S3 to S7) Only S7 is active low rest are active high input lines bull Ground pins (8 pins) Used as a reference signal for the low (below 05 volts) charge

                                        Parallel Port Addresses A DB-25 connector at a parallel port has three address one for each kind of pins register data status and control The first or base address generally refers to data register Second address is for status register and the third one is for control register In Windows 98 the base address is usually found to be 278H 378H or 3BCH Now if 378H is the base address then it refers to the data register whereas addresses for status and control register are respectively 379H and 37AH For Windows 98 the base address can be found as follows 1 On your Desktop right-click on My Computer and select Properties 2 Click on the Device Manager tab and find LPT1 under Plug and Play BIOS 3 After selecting LPT1 click the Properties button 4 Next select the Resources tab and the address should then appear next to InputOutput

                                        Range Accessing parallel port through C Language Programming There are multiple functions in C Language for accessing external ports The most commonly used are listed below

                                        bull unsigned char inportb(int portid) inportb reads a byte from a hardware port

                                        bull int inport(int portid) reads a word from a hardware port

                                        bull void outportb(int portid unsigned char value) outputs a byte to a hardware port

                                        bull void outport(int portid int value) outputs a word to a hardware port

                                        portid refers to the port address whereas value refers to the data to be sent TESTING 74245 USING PARALLEL PORT PC INTERFACING At one end the parallel port connector will be connected to the PC via parallel port cable and another connector (to be plugged into the PC parallel port slot) At the other end it will be connected to the buffer IC 74245 Data lines of the connector will be used to transfer 8-bit data between the PC and the buffer Out of the 8-bits of 74245 4-bits will be used to enter data which will be displayed at the monitor through a C language

                                        61

                                        Logic Design amp Switching Theory 1 Lab Session 15 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering program The remaining 4-bits will receive data from PC as entered by the user via keyboard

                                        Circuit Diagram

                                        Figure 154 Interface of 74245 to PC via Parallel Port

                                        Procedure

                                        1 Connect the DB-25 connector to the PC at one end and solder it to the circuit board at the other end

                                        2 Connect various pins of the connector and 74245 according to the circuit diagram shown in figure 152

                                        3 Using the functions listed in the previous section write a program in C language to operate various pins of the buffer The user interface of the program should provide option to the user whether to send or receive data from the port

                                        4 Set DIR switch to 1 5 Try sending some data bits to the port The result should be displayed at the LEDs 6 Set DIR switch to 0 7 Set some binary 4-bit value through the switches Try reading it via parallel port

                                        C Language Program

                                        A program to access parallel port for data transfers

                                        use header file include ltstdiohgt main program void main() define variable

                                        62

                                        Logic Design amp Switching Theory 1 Lab Session 15 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering unsigned int data=0 char choice while(1) printing option menu clrscr() printf(This program will send or receive a BCD digit from the parallel portn) printf(nPress your choice numbern) printf(n1 Send Data) printf(n2 Receive Data) printf(n3 Exitn) choice = getch() sending entered digit to the port if(choice == 1) input BCD digit printf(nEnter BCD digit to be sent to the port) data = getche() masking the first four bits data = data amp 0x0f sending to the port outportb(0x378data) printf(nThe BCD digit c has been sent to the port data) printing on screen the data received from the port else if(choice == 2) receiving data from the port data = inportb(0x378) masking the last four bits data = data amp 0xf0 shifting first four bits to make them the last four bits datagtgt=4 printf(nThe BCD digit set at the port is c data) exit else if(choice == 3) break key pressed is not in the menu else printf(nEnter valid choice number) printf(nnPress any key to continue) getch()

                                        63

                                        Logic Design amp Switching Theory 1 Lab Session 15 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                        ACTIVITY 1 In the above circuit DIR and G΄ inputs are hardwired Connect them to status or

                                        control pins of the parallel port connector and control their function through your software program Circuit Diagram Program Code ______________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________

                                        ___________________________________________________________________________________________________________________________________________________

                                        64

                                        Logic Design amp Switching Theory 1 Lab Session 15 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                        65

                                        _____________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ _____________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ _______________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ _________________________________________________ _________________________________________________

                                        Logic Design amp Switching Theory 1 Appendix A NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                        Appendix A

                                        PIN DIAGRAMS OF THE ICS REQUIRED FOR THE LABORATORY SESSIONS Consult the TTLIC data book for internal diagrams and electrical characteristics of these ICs 7400 Quad 2-Input NAND 7402 Quad 2-Input NOR

                                        7404 Hex Inverter 7408 Quad 2-Input AND

                                        7410 Triple 3-Input NAND 7411 Triple 3-Input AND

                                        7421 Dual 4-Input AND 7432 Quad 2-Input OR

                                        66

                                        Logic Design amp Switching Theory 1 Appendix A NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                        BCD-to-Seven Segm 7448 BCD-to-Seven Segment 7447 ent

                                        Decoder (15V OC) Decoder (2kΩ pull-up output)

                                        7473 Dual JK Flip-Flop 7474 Dual D-Type Flip-Flop

                                        7476 Dual JK Flop-Flop -Bit Binary Full Adder 7483 4 with Fast Carry

                                        86 Quad 2-Inpu 74138 3-to-8 Line 74 t Exclusive OR Decoder Demultiplexer

                                        67

                                        Logic Design amp Switching Theory 1 Appendix A NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                        68

                                        74148 8-to-3 Line 16-to-1 Line Data

                                        Priority Encoder 74150 Selector Multiplexer

                                        74245 Oct nsceivers Universal Shift Register (PIPO) (3-State)

                                        74194 4-Bit Bidirectional al Bus Tra

                                        Logic Design amp Switching Theory 1 Appendix B NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                        Appendix B

                                        DEBOUNCING CIRCUITRY FOR MECHANICAL SWITCHES Mechanical switches form the interface between human beings and computers or other digital systems For example a keyboard is a matrix of switches used to supply alphanumeric data to a computer Whatever the switch design it is a potential source of problems due to contact bounce The contact bounce creates a sense of narrow pulses when a switch is opened or closed An example of device whose operation would be adversely affected by contact bounce is a digital counter used to count the number of times a switch is depressed Eliminating the effects of contact bounce is called debouncing When data is entered into a computer via a keyboard a software debounce is often used This type of debouncing is a program that causes the computer to sample the switch terminal (ie to input data from it) many times in succession during the interval of time that contact bounce occurs If the data is sensed to be 1s (or 0s) for a specific number of consecutive samples then it is assumed that contact bounce has ended and the last value sensed is valid Hardware debouncing is the use of electronic circuitry to eliminate the effects of contact bounce There are numerous versions of such circuitry including those that use monostable multivibrators (one-shots) but the most straightforward is simply an RS latch Figure B1 shows the circuit When the switch is in position 1 R = 0 and S = 1 so the latch is set and the output (Q) is 1 When the switch is in position 0 R = 1and S = 0 so the latch is reset and the output is 0 When the switch is moved form one position to the other the latch changes state and bouncing occurs at either the R or the S input The bouncing does not affect the latch after it has change state An RS latch will remain set for example when its R input is 0 and its S input is alternately changed form 1 to 0

                                        Figure B1 Use of RS latch to debounce a mechanical switch

                                        69

                                        • 01-ldst-Outer title
                                          • Practical Workbook
                                          • Logic Design amp Switching Theory I
                                            • Dept of Computer amp Information Systems Engineering
                                              • NED University of Engineering amp Technology
                                              • Karachi ndash 75270 Pakistan
                                                • 02-ldst-inner Title
                                                  • Practical Workbook
                                                  • Logic Design amp Switching Theory I
                                                    • Dept of Computer amp Information Systems Engineering
                                                      • NED University of Engineering amp Technology
                                                      • Karachi ndash 75270 Pakistan
                                                        • 03-ldst-general info
                                                        • 04-ldst-introduction
                                                        • 05-Table of Contents
                                                          • CONTENTS
                                                            • Lab Session No Object Page No
                                                            • 1
                                                            • Also implementing and testing the given circuit on a bread board
                                                              • Working with Electronics Workbench
                                                                • Driving a seven segment display using 7447 7448 driver IC
                                                                  • Designing a modulus-5 asynchronous up-counter using JK-FF
                                                                    • Experimenting with 74194 4-bit bidirectional universal shift register
                                                                        • 13
                                                                            • 06-ldst-Exp01
                                                                              • Lab Session 01
                                                                              • OBJECT
                                                                                • 1 Bread board
                                                                                • 2 5 V - power supply
                                                                                • 3 Multimeter
                                                                                • 4 Logic probe
                                                                                • 5 LEDs with resistors
                                                                                • 6 Connecting wires
                                                                                • 8 Following ICs and their datasheets
                                                                                  • THEORY
                                                                                    • Logic Gates
                                                                                    • 1 The AND Gate ndash An AND gatersquos output is 1 if and only if all its inputs are 1 If A and B are two inputs to an AND gate then output F of the gate is given as F = AB
                                                                                    • 2 The OR Gate - An OR gatersquos output is 1 if at least one of its input is 1 If A and B are two inputs to an OR gate then output F of the gate is given as F = A+B
                                                                                    • 3 The NOT Gate (Inverter) ndash Its output is 1 when its input is 0 and its output is 0 when the input is 1 ie it complements a digital variable If A is the input to a NOT gate then output F of the gate is given as
                                                                                    • 4 The NAND Gate ndash Its output is 1 if at least one of its input is 0 This gate performs the same logic as an AND gate followed by an inverter If A and B are two inputs to a NAND gate then output F of the gate is given as
                                                                                      • 5 The NOR Gate - The output of a NOR gate is 1 if and only if all its inputs are 0 This gate performs the same logic function as an OR gate followed by an inverter If A and B are two inputs to a NAND gate then output F of the gate is given as
                                                                                          • DATA SHEETS
                                                                                            • Logic expression for the given logic diagram __________________________________
                                                                                                • 07-ldst-exp02
                                                                                                  • Working with Electronics Workbench
                                                                                                    • 08-ldst-exp03
                                                                                                      • Designing Half and Full Adder Circuits
                                                                                                        • COMPONENTS AND APPARATUS REQUIRED
                                                                                                          • 1 Following ICs and their Datasheets
                                                                                                          • 7408 Quad 2-input AND Gate
                                                                                                          • 2 Digital Trainer DT-01 or the following components
                                                                                                            • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                            • Connecting wires Switches
                                                                                                              • THEORY
                                                                                                                  • IMPLEMENTATION AND OBSERVATIONS
                                                                                                                    • 09-ldst-Exp04
                                                                                                                      • Lab Session 04
                                                                                                                      • 1 Digital ICs and their Datasheets
                                                                                                                      • 7408 Quad 2-input AND Gate
                                                                                                                      • 2 Digital Trainer DT-01 or the following components
                                                                                                                        • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                        • Connecting wires Switches
                                                                                                                        • PROCEDURE
                                                                                                                        • REDUCTION OF LOGIC EXPRESSION USING KARNAUGH MAP
                                                                                                                        • OBSERVATIONS
                                                                                                                        • RESULT
                                                                                                                            • 10-ldst-Exp05
                                                                                                                              • Lab Session 05
                                                                                                                              • 1 Following ICs and their Datasheets
                                                                                                                              • 7408 Quad 2-input AND Gate
                                                                                                                              • 2 Digital Trainer DT-01 or the following components
                                                                                                                                • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                • (100 Ω) Connecting wires Switches
                                                                                                                                • THEORY
                                                                                                                                  • IMPLEMENTATION AND OBSERVATIONS
                                                                                                                                    • 11-ldst-Exp06
                                                                                                                                      • OBJECT
                                                                                                                                      • 1 Following ICs and their Datasheets
                                                                                                                                      • 7408 Quad 2-input AND Gates or 7411 Triple 3-input AND Gates
                                                                                                                                      • 2 Digital Trainer DT-01 or the following components
                                                                                                                                        • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                        • Connecting wires Switches
                                                                                                                                          • Figure 62 Circuit Diagram for 4 x 1 Multiplexer
                                                                                                                                          • Implementation and Observations
                                                                                                                                            • Circuit Diagram
                                                                                                                                              • ACTIVITY
                                                                                                                                                • 12-ldst-exp07
                                                                                                                                                  • 1 Following ICs and their Datasheets
                                                                                                                                                  • 7408 Quad 2-input or 7411 Triple 3-input AND Gates
                                                                                                                                                  • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                    • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                    • Connecting wires Switches
                                                                                                                                                      • THEORY
                                                                                                                                                          • Figure 72 Circuit Diagram for 2 x 4 Decoder 1 x 4 Demultiplexer
                                                                                                                                                          • Implementation and Observations
                                                                                                                                                            • Circuit Diagram
                                                                                                                                                              • ACTIVITY
                                                                                                                                                                • 13-ldst-Exp08
                                                                                                                                                                  • OBJECT
                                                                                                                                                                  • 1 Following ICs and their Datasheets
                                                                                                                                                                  • 7408 Quad 2-input or 7421 Dual 4-input AND Gates
                                                                                                                                                                  • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                    • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                    • Connecting wires Switches
                                                                                                                                                                      • THEORY
                                                                                                                                                                          • Figure 81 Circuit Diagram for 4 x 2 Priority Encoder
                                                                                                                                                                          • Implementation and Observations
                                                                                                                                                                            • Therefore if GS A2 A1 and A0 are all low then it shows that line 0 is selected and if E0 A2 A1 and A0 are all low then it shows that none of the inputs selected E0 and GS cannot be in the same state provided that E1 is enabled
                                                                                                                                                                            • Circuit Diagram
                                                                                                                                                                              • ACTIVITY
                                                                                                                                                                                • 14-ldst-exp09
                                                                                                                                                                                  • OBJECT
                                                                                                                                                                                  • 1 Following ICs and their Datasheets
                                                                                                                                                                                  • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                    • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                    • Connecting wires Switches
                                                                                                                                                                                      • THEORY
                                                                                                                                                                                        • Parity Generator
                                                                                                                                                                                          • Let x y and z be the three bits that constitute the message and are the input to the Odd Parity Generator Circuit Since it is an odd parity system the bit P is generated so as to make the total number of 1s odd (including P) The function P can be expressed as follows
                                                                                                                                                                                          • Figure 91 Circuit Diagram for a 3-bit Parity Generator
                                                                                                                                                                                            • C = x Ο y Ο z Ο P
                                                                                                                                                                                              • Implementation and Observations
                                                                                                                                                                                                • ACTIVITY
                                                                                                                                                                                                    • 15-ldst-exp10
                                                                                                                                                                                                      • Driving a seven segment display using 7447 7448 driver IC
                                                                                                                                                                                                      • COMPONENTS AND APPARATUS REQUIRED
                                                                                                                                                                                                      • 1 Following ICs and their Datasheets
                                                                                                                                                                                                      • 7447 7448 BCD to Seven Segment Driver
                                                                                                                                                                                                      • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                        • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches
                                                                                                                                                                                                          • THEORY
                                                                                                                                                                                                          • Seven Segment Displays
                                                                                                                                                                                                          • CIRCUIT DIAGRAM
                                                                                                                                                                                                          • Figure 102 Circuit diagram for 7447driving a common-anode display
                                                                                                                                                                                                              • IMPLEMENTATION AND OBSERVATIONS
                                                                                                                                                                                                                • Decimal Digit
                                                                                                                                                                                                                • BCD Inputs
                                                                                                                                                                                                                • Seven Segment Outputs
                                                                                                                                                                                                                • D
                                                                                                                                                                                                                • C
                                                                                                                                                                                                                • B
                                                                                                                                                                                                                • A
                                                                                                                                                                                                                • a
                                                                                                                                                                                                                • b
                                                                                                                                                                                                                • c
                                                                                                                                                                                                                • d
                                                                                                                                                                                                                • e
                                                                                                                                                                                                                • f
                                                                                                                                                                                                                • g
                                                                                                                                                                                                                • 0
                                                                                                                                                                                                                • 0
                                                                                                                                                                                                                • 0
                                                                                                                                                                                                                • 0
                                                                                                                                                                                                                • 0
                                                                                                                                                                                                                • 1
                                                                                                                                                                                                                • 0
                                                                                                                                                                                                                • 0
                                                                                                                                                                                                                • 0
                                                                                                                                                                                                                • 1
                                                                                                                                                                                                                • 2
                                                                                                                                                                                                                • 0
                                                                                                                                                                                                                • 0
                                                                                                                                                                                                                • 1
                                                                                                                                                                                                                • 0
                                                                                                                                                                                                                • 3
                                                                                                                                                                                                                • 0
                                                                                                                                                                                                                • 0
                                                                                                                                                                                                                • 1
                                                                                                                                                                                                                • 1
                                                                                                                                                                                                                • 4
                                                                                                                                                                                                                • 0
                                                                                                                                                                                                                • 1
                                                                                                                                                                                                                • 0
                                                                                                                                                                                                                • 0
                                                                                                                                                                                                                • 5
                                                                                                                                                                                                                • 0
                                                                                                                                                                                                                • 1
                                                                                                                                                                                                                • 0
                                                                                                                                                                                                                • 1
                                                                                                                                                                                                                • 6
                                                                                                                                                                                                                • 0
                                                                                                                                                                                                                • 1
                                                                                                                                                                                                                • 1
                                                                                                                                                                                                                • 0
                                                                                                                                                                                                                • 7
                                                                                                                                                                                                                • 0
                                                                                                                                                                                                                • 1
                                                                                                                                                                                                                • 1
                                                                                                                                                                                                                • 1
                                                                                                                                                                                                                • 8
                                                                                                                                                                                                                • 1
                                                                                                                                                                                                                • 0
                                                                                                                                                                                                                • 0
                                                                                                                                                                                                                • 0
                                                                                                                                                                                                                • 9
                                                                                                                                                                                                                • 1
                                                                                                                                                                                                                • 0
                                                                                                                                                                                                                • 0
                                                                                                                                                                                                                • 1
                                                                                                                                                                                                                  • ACTIVITY
                                                                                                                                                                                                                    • 16-ldst-exp11
                                                                                                                                                                                                                      • Lab Session 11
                                                                                                                                                                                                                        • OBJECT
                                                                                                                                                                                                                        • COMPONENTS AND APPARATUS REQUIRED
                                                                                                                                                                                                                          • 1 Following ICs and their Datasheets
                                                                                                                                                                                                                          • 7473 7476 JK Flip-Flop
                                                                                                                                                                                                                          • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                            • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                                            • Connecting wires Switches
                                                                                                                                                                                                                              • THEORY
                                                                                                                                                                                                                                  • Flip-Flop
                                                                                                                                                                                                                                  • JK Flip-Flop
                                                                                                                                                                                                                                    • Circuit Diagram
                                                                                                                                                                                                                                      • Observations
                                                                                                                                                                                                                                        • ACTIVITY
                                                                                                                                                                                                                                            • 17-ldst-exp12
                                                                                                                                                                                                                                              • Lab Session 12
                                                                                                                                                                                                                                                • OBJECT
                                                                                                                                                                                                                                                • GIVEN STATE DIAGRAM
                                                                                                                                                                                                                                                • Figure 121 State Diagram
                                                                                                                                                                                                                                                • COMPONENTS AND APPARATUS REQUIRED
                                                                                                                                                                                                                                                  • 1 Following ICs and their Datasheets
                                                                                                                                                                                                                                                  • 7474 D Flip-Flop
                                                                                                                                                                                                                                                  • ICs of basic gates (AND OR NOT XOR etc) as required
                                                                                                                                                                                                                                                  • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                                                    • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                                                                    • Connecting wires Switches
                                                                                                                                                                                                                                                      • THEORY
                                                                                                                                                                                                                                                          • Sequential Circuits
                                                                                                                                                                                                                                                            • 18-ldst-exp13
                                                                                                                                                                                                                                                              • Lab Session 13
                                                                                                                                                                                                                                                                • Designing a modulo-5 asynchronous up-counter using JK-FF
                                                                                                                                                                                                                                                                  • 1 Following ICs and their Datasheets
                                                                                                                                                                                                                                                                  • 7400 Quad 2-input or 7410 Triple 3-input NAND Gates
                                                                                                                                                                                                                                                                  • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                                                                    • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                                                                                    • Connecting wires Switches
                                                                                                                                                                                                                                                                      • THEORY
                                                                                                                                                                                                                                                                          • Figure 131 A Mod-5 Asynchronous Up Counter
                                                                                                                                                                                                                                                                          • Implementation and Observations
                                                                                                                                                                                                                                                                            • ACTIVITY
                                                                                                                                                                                                                                                                                • 19-ldst-exp14
                                                                                                                                                                                                                                                                                  • Experimenting with 74194 4-bit bidirectional universal shift register
                                                                                                                                                                                                                                                                                  • 1 Following ICs and their Datasheets
                                                                                                                                                                                                                                                                                  • 74194 4-bit bidirectional universal shift register
                                                                                                                                                                                                                                                                                  • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                                                                                    • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                                                                                                    • Connecting wires Switches
                                                                                                                                                                                                                                                                                      • THEORY
                                                                                                                                                                                                                                                                                        • Shift Registers
                                                                                                                                                                                                                                                                                        • Bidirectional Shift Registers
                                                                                                                                                                                                                                                                                        • Universal Shift Registers
                                                                                                                                                                                                                                                                                          • S1
                                                                                                                                                                                                                                                                                            • Circuit Diagram
                                                                                                                                                                                                                                                                                            • ACTIVITY
                                                                                                                                                                                                                                                                                                • 20-ldst-exp15
                                                                                                                                                                                                                                                                                                  • COMPONENTS AND APPARATUS REQUIRED
                                                                                                                                                                                                                                                                                                  • 1 Parallel Port Connectors (DB-25) with Cable
                                                                                                                                                                                                                                                                                                  • 2 Personal Computer with Windows 98 and TurboC Compiler Installed
                                                                                                                                                                                                                                                                                                  • 3 Following ICs and their Datasheets
                                                                                                                                                                                                                                                                                                  • 74245 Octal Bus Transceivers with 3-State Outputs
                                                                                                                                                                                                                                                                                                  • 4 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                                                                                                    • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                                                                                                                      • Connecting wires Switches
                                                                                                                                                                                                                                                                                                        • THEORY
                                                                                                                                                                                                                                                                                                        • 3-State Logic
                                                                                                                                                                                                                                                                                                          • Serial and Parallel Port Connectors
                                                                                                                                                                                                                                                                                                          • Parallel Port Connector ndash DB-25
                                                                                                                                                                                                                                                                                                            • Accessing parallel port through C Language Programming
                                                                                                                                                                                                                                                                                                                • 21-ldst-appendixA
                                                                                                                                                                                                                                                                                                                • 22-ldst-appendixB
                                                                                                                                                                                                                                                                                                                  • DEBOUNCING CIRCUITRY FOR MECHANICAL SWITCHES

                                          Logic Design amp Switching Theory 1 Lab Session 04 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                          LOGIC DIAGRAM (REDUCED FORM) OBSERVATIONS

                                          A B C D Output 0 0 0 0 0 0 0 1 0 0 1 0 0 0 1 1 0 1 0 0 0 1 0 1 0 1 1 0 0 1 1 1 1 0 0 0 1 0 0 1 1 0 1 0 1 0 1 1 1 1 0 0 1 1 0 1 1 1 1 0 1 1 1 1

                                          RESULT The reduced form (SOP Expression) of the given logic function is

                                          ____________________________________________________________

                                          The observation table reflects the given logic function

                                          23

                                          Logic Design amp Switching Theory 1 Lab Session 04 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                          ACTIVITY 1 Using Electronics Workbench derive a truth table and logic circuit for the following logic expression

                                          BAAF +=

                                          Procedure 1 From the Instruments Parts Bin drag and drop Logic Converter on the design area 2 Double click the Logic Converter to reveal Logic Converter dialog box This dialog

                                          box shows various conversion options between truth table logic expression and logic circuit

                                          3 Enter the given logic expression in the edit box found at the end of the dialog box Use lsquo to represent invert of a variable For example A is written as Arsquo

                                          4 Click the Boolean Expression to Truth Table button The truth table appears in the logic converters display

                                          5 Now click the Boolean Expression to Circuit button This creates the logic circuit for the given expression in the design area Label the diagram if needed

                                          Resulting Logic Circuit For the given expression the final circuit will look like

                                          Figure 41

                                          24

                                          Logic Design amp Switching Theory 1 Lab Session 04 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                          ACTIVITY 2

                                          Using Electronics Workbench find a simplified logic expression and circuit for the following truth table

                                          A B C Output 0 0 0 1 0 0 1 1 0 1 0 0 0 1 1 1 1 0 0 0 1 0 1 0 1 1 0 0 1 1 1 1

                                          Procedure 1 Click three input channels from A to H across the top of the logic converter The

                                          display area below the terminals fills up with the necessary combinations of ones and zeros to fulfill the input conditions The values in the output column on the right are initially set to 0

                                          2 Edit the output column to specify the desired output for each input condition To change an output value select it and type a new value 1 0 or x An x indicates a donrsquot care condition

                                          3 To convert this truth table to a Boolean expression click the Truth Table to Boolean Expression button The Boolean expression will be displayed at the bottom of the logic converter

                                          4 Simplify the expression by clicking the Simplify button 5 Now click the Boolean Expression to Circuit button This creates the logic circuit for

                                          the given expression in the design area Resulting Logic Circuit For the given truth table the final simplified circuit will look like

                                          Figure 42

                                          25

                                          Logic Design amp Switching Theory 1 Lab Session 04 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                          ACTIVITY 3

                                          Using Electronics Workbench find the logic expression and truth table for the following logic circuit

                                          Figure 43

                                          Procedure 1 Attach the input terminals of the logic converter to up to four input points in the

                                          circuit 2 Connect the single output of the circuit to the output terminal on the logic converter

                                          icon 3 Click the Circuit to Truth Table button The truth table appears in the logic

                                          converters display 4 To convert this truth table to a Boolean expression click the Truth Table to Boolean

                                          Expression button The Boolean expression will be displayed at the bottom of the logic converter

                                          Resulting Logic Expression Logic Expression for the given circuit is found to be _____________________________

                                          26

                                          Logic Design amp Switching Theory 1 Lab Session 04 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                          27

                                          For activities 1 2 and 3 attach hardcopy of the output (truth table logic expression and logic circuit) form electronic workbench here

                                          Logic Design amp Switching Theory 1 Lab Session 05 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                          Lab Session 05 Lab Session 05 OBJECT OBJECT

                                          Designing a BCD Adder Designing a BCD Adder COMPONENTS AND APPARATUS REQUIRED COMPONENTS AND APPARATUS REQUIRED

                                          1 Following ICs and their Datasheets 1 Following ICs and their Datasheets bull 7408 Quad 2-input AND Gate bull 7408 Quad 2-input AND Gate bull 7432 Quad 2-input OR Gate bull 7432 Quad 2-input OR Gate bull 7483 4-bit Binary Adder bull 7483 4-bit Binary Adder

                                          2 Digital Trainer DT-01 or the following components 2 Digital Trainer DT-01 or the following components Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors (100 Ω) Connecting wires Switches (100 Ω) Connecting wires Switches

                                          THEORY THEORY

                                          A BCD Adder is a combinational circuit that adds two BCD digits in parallel and produces a sum digit also in BCD A BCD Adder is a combinational circuit that adds two BCD digits in parallel and produces a sum digit also in BCD

                                          A4 A3 A2 A1 B4 B3 B2 B1

                                          7483-BCD ADDER

                                          Cout (C4 ) Z4 Z3 Z2 Z1 Cin(C0)

                                          A4 A3 A2 A1 B4 B3 B2 B1

                                          7483-BCD ADDER

                                          Cout

                                          (C4 ) Z4 Z3 Z2 Z1 Cin(C0)

                                          Figure 51 BCD Adder Circuit

                                          28

                                          Logic Design amp Switching Theory 1 Lab Session 05 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                          29

                                          A BCD adder must include the correction logic in its internal construction The two BCD digits together with the input carry are first added using a 4-bit binary adder to produce the binary sum If no output carry is generated and the binary sum is less than or equal to 9 then the corresponding BCD sum is identical and therefore no conversion is needed When the output carry is equal to 1 or the binary sum is greater than 9 then a binary 0110 is added to the binary sum through another 4-bit binary adder If Cout is the carry output and Z4Z3Z2Z1 is the binary sum form the first 4-bit binary adder then the following equation indicates the condition when a binary 0110 is to be added

                                          C = COUT + Z4Z2 + Z4Z3 IMPLEMENTATION AND OBSERVATIONS Implement the BCD adder circuit according to figure 51 on a bread board (prepare the pin diagram (use appendix A) and refer to laboratory session 01 for procedure) A BCD adder has nine input bits (two BCD digits and a carry bit) which can result in a total of 512 combinations of which 312 inputs are donrsquot care Since it is a very lengthy procedure to record results for 200 valid input combinations therefore for simplicity just record results for any eight combinations in the following table

                                          Input Carry

                                          BCD Digit 1 BCD Digit 2 Carry Output

                                          BCD Sum A4 A3 A2 A1 B4 B3 B2 B1 Z4 Z3 Z2 Z1

                                          Logic Design amp Switching Theory 1 lab Session 06 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                          Lab Session 06

                                          OBJECT

                                          bull Designing of a 4 x 1 Multiplexer bull Experimenting with 74150 IC

                                          COMPONENTS AND APPARATUS REQUIRED 1 Following ICs and their Datasheets

                                          bull 7408 Quad 2-input AND Gates or 7411 Triple 3-input AND Gates bull 7432 Quad 2-input OR Gates bull 7404 Hex Inverter bull 74150 16 x 1 MUX

                                          2 Digital Trainer DT-01 or the following components Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches THEORY

                                          Multiplexers A digital data Multiplexer (MUX) is a combinational circuit having several data inputs and a single output A set of data-select inputs is used to control which of the data inputs is routed to the single output A multiplexer is also called a data selector because of this ability to select which data input is connected o the output Normally there are 2n input lines and n selection lines whose bit combination determine which input is selected DESIGN OF A 4 x 1 MULTIPLEXER A 4 x 1 multiplexer is capable of selecting one of four data inputs (see figure 61) The 2-bit binary number at the data select inputs S1 and S0 specifies which of the four data inputs is to be routed to the output Since there are two data select inputs therefore they can select 22 = 4 different data inputs lines

                                          S0 S1 D0 D1

                                          D2 D3

                                          Data-select Inputs Output

                                          Data Inputs

                                          Figure 61 Block Diagram of a 4 x1 Multiplexer

                                          30

                                          Logic Design amp Switching Theory 1 lab Session 06 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                          Figure 62 Circuit Diagram for 4 x 1 Multiplexer

                                          Implementation and Observations

                                          Implement the 4 x 1 Multiplexer circuit (figure 62) on a bread board (prepare the pin diagram (use appendix A) and refer to laboratory session 01 for implementation procedure) and record the observations in the following table For each data select combination specify the switch number as well as the binary value present on that selected switch

                                          S1 S0 Output 0 0 0 1 1 0 1 1

                                          TESTING OF 74150 - 16 x 1 MUX

                                          The 74150 IC has sixteen data inputs and four data-selection lines Function of various pins of this IC is described below

                                          bull E0 through E15 Data input lines

                                          31

                                          Logic Design amp Switching Theory 1 lab Session 06 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering bull A B C D Data select lines with D being the MSB bull W Active low output line bull Grsquo Active low enable line bull VCC and GND Supply connections lines

                                          Circuit Diagram

                                          Figure 63 Pin connections of 74150 for selecting E0

                                          Testing Procedure

                                          bull Make connections as shown in the circuit diagram bull Apply different data (1 or 0) at data inputs that are labeled as E0 to E15 Only

                                          connection for E0 is shown is the figure for simplicity bull Select the data input E0 with the help of data selectors A B C and D bull Observe the output which shows the complement of the data from E0 bull Select all the sixteen data inputs one by one and record your observations in the

                                          following table

                                          32

                                          Logic Design amp Switching Theory 1 lab Session 06 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                          33

                                          Observations

                                          Grsquo D C B A W Grsquo D C B A W 0 0 0 0 0 0 1 0 0 0 0 0 0 0 1 0 1 0 0 1 0 0 0 1 0 0 1 0 1 0 0 0 0 1 1 0 1 0 1 1 0 0 1 0 0 0 1 1 0 0 0 0 1 0 1 0 1 1 0 1 0 0 1 1 0 0 1 1 1 0 0 0 1 1 1 0 1 1 1 1

                                          ACTIVITY 1 Consider 4x1 Multiplexer Draw the output wave-form for the following data inputs

                                          (E0 E1 E2 E3) and select lines A B (B being the MSB) Output is W

                                          E3 E2 E1 E0 A B

                                          W

                                          2 Using the 4 x 1 MUX designed in this laboratory session implement the following logical function F (A B C) = Σ (0147)

                                          Show your working and input connections in the following block diagram according to the circuit you have implemented

                                          4 x 1 MUX

                                          S0 S1

                                          Output D0

                                          D1

                                          D2

                                          D3

                                          Logic Design amp Switching Theory 1 Lab Session 07 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                          Lab Session 07

                                          OBJECT

                                          bull Designing of a 2 x 4 Decoder 1 x 4 Demultiplexer bull Experimenting with 74138 IC

                                          COMPONENTS AND APPARATUS REQUIRED 1 Following ICs and their Datasheets

                                          bull 7408 Quad 2-input or 7411 Triple 3-input AND Gates bull 7404 Hex Inverter bull 74138 3 x 8 Decoder

                                          2 Digital Trainer DT-01 or the following components Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches THEORY

                                          Decoder A Decoder is a combinational circuit that converts binary information form n input lines to a maximum of 2n unique output lines In practical applications decoders are often used for selecting one of several devices

                                          Demultiplexer A decoder with an enable input can function as a Demultiplexer A Demultiplexer (DMUX) id a circuit that receives information on a single line and transmits this information on one of 2n possible output lines The selection of a specific output line is controlled by the bit values of n selection lines DESIGN OF A 2 x 4 DECODER 1 x 4 DEMULTIPLEXER A 2 x 4 decoder is capable of selecting one of four output lines (see figure 71 (a)) The 2-bit binary number at the data inputs S1 and S0 specifies which of the four data inputs is to be selected If we add an enable pin and use it as an input line then this decoder can be converted to a 1 x 4 Demultiplexer where S1 and S0 will select a line to which data input is to be routed (see figure 71 (b))

                                          Select S0 S0 Inputs

                                          S1 D0 D1

                                          D2

                                          D3

                                          Enable (a) Block Diagram of a 2 x 4 Decoder

                                          Figure 71

                                          S1 D0 D1

                                          D2

                                          D3

                                          Inputs

                                          Data Input (b) Block Diagram of a 1 x 4 Demulptiplexer

                                          34

                                          Logic Design amp Switching Theory 1 Lab Session 07 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                          Figure 72 Circuit Diagram for 2 x 4 Decoder 1 x 4 Demultiplexer

                                          Implementation and Observations Implement the 2 x 4 Decoder 1 x 4 Demultiplexer circuit (figure 72) on a bread board (prepare the pin diagram (use appendix A) and refer to laboratory session 01 for implementation procedure) and record the observations in the following table

                                          Enable Data Input S1 S0 D0 D1 D2 D3

                                          0 0 0 0 0 1 0 1 0 0 1 1 1 0 0 1 0 1 1 1 0 1 1 1

                                          TESTING OF 74138 3 x 8 Decoder The 74138 IC has three inputs and eight output lines It has three enable inputs and for the IC to function all three inputs need to be enabled Function of various pins of this IC is described below

                                          35

                                          Logic Design amp Switching Theory 1 Lab Session 07 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                          bull Y0 through Y7 Active low data outputs bull A B C Input select lines with C being the MSB bull G1 Active high enable Input bull G2Arsquo and G2Brsquo Active low enable Inputs bull VCC and GND Supply connections lines Circuit Diagram

                                          Figure 73 Pin connections of 74138

                                          Testing Procedure

                                          bull Make connections as shown in the circuit diagram bull Apply different combinations of 1s and 0s at data inputs bull Observe the output and record your observations in the following table

                                          Observations

                                          C B A Y0 Y1 Y2 Y3 Y4 Y5 Y6 Y7 0 0 0 0 0 1 0 1 0 0 1 1 1 0 0 1 0 1 1 1 0 1 1 1

                                          36

                                          Logic Design amp Switching Theory 1 Lab Session 07 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                          37

                                          ACTIVITY ACTIVITY 1 What will be the binary values at the outputs Y0 through Y7 of 74138 if 1 What will be the binary values at the outputs Y0 through Y7 of 74138 if

                                          bull All three enable pins are connected to ground bull All three enable pins are connected to ground __________________________________________________________________________________________________________________________________________ __________________________________________________________________________________________________________________________________________ _____________________________________________________________________ _____________________________________________________________________

                                          bull All three enable pins are connected to VCC bull All three enable pins are connected to VCC _______________________________________________________________________________________________________________________________________________________________________________________________________________

                                          _______________________________________________________________________________________________________________________________________________________________________________________________________________

                                          2 Show connections for 74138 in order to use it as a 1 x 8 Demultiplexer 2 Show connections for 74138 in order to use it as a 1 x 8 Demultiplexer

                                          3 Consider a 2 x 4 Decoder with two enable inputs (one active high - G and one active low ndash Grsquo) Draw the output wave-forms for D0 D1 D2 and D3 if the two select inputs are A and B (B being the MSB) All outputs are active low

                                          Grsquo

                                          G

                                          A B

                                          D0 D1 D2

                                          D3

                                          Logic Design amp Switching Theory 1 Lab Session 08 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                          Lab Session 08 OBJECT

                                          bull Designing of a 4 x 2 Priority Encoder bull Experimenting with 74148 IC

                                          COMPONENTS AND APPARATUS REQUIRED

                                          1 Following ICs and their Datasheets

                                          bull 7408 Quad 2-input or 7421 Dual 4-input AND Gates bull 7432 Quad 2-input OR Gates bull 7404 Hex Inverter bull 74148 Encoder

                                          2 Digital Trainer DT-01 or the following components Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches

                                          THEORY

                                          Encoder An Encoder is a digital function that produces a reverse operation from that of a decoder An Encoder has 2n (or less) input lines and n output lines The output lines generate the binary code for the 2n input variables Priority Encoder

                                          A simple encoder may produce an erroneous output if more than one of its inputs is high A Priority Encoder is one that responds to just one input among those that may be simultaneously high in accordance with some priority system The most common priority system is based on the relative magnitudes of the inputs whichever decimal input is largest is the one that is encoded

                                          DESIGN OF A 4 x 2 Priority Encoder

                                          The following equations represent the outputs of a 4 x 2 priority encoder 32 DDA +=

                                          321 DDDB += As can be seen from the equations that input D0 which has a binary code 00 is not used in any equation A binary code 00 at the output indicates two conditions Either D0 is selected or no input is selected In order to differentiate these two conditions we will provide an additional output Z to indicate if at least one of the inputs is a 1 The equation for Z will be

                                          4321 DDDDZ = If Z is 0 then the binary code 00 at the output indicates that D0 is selected and if Z is 1 then it indicates that no input line is selected

                                          38

                                          Logic Design amp Switching Theory 1 Lab Session 08 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                          Figure 81 Circuit Diagram for 4 x 2 Priority Encoder

                                          it (figure 81) on a bread board (prepare the to laboratory session 01 for implementation

                                          Implementation a Implement the 4 x 2 Priority Encoder circu

                                          ram (use appendix A) and refer

                                          nd Observations

                                          pin diagprocedure) and record the observations in the following table

                                          D3 D2 D1 D0 A B 0 0 0 1 0 0 1 x 0 1 x x 1 x x x

                                          TESTING OF 74148 8 x 3 Octal Priority Encoder

                                          imal digits There are nine of which three represents

                                          ing any of the inputs is high

                                          then it shows that line 0 is selected and if e inputs selected E0 and GS

                                          cannot be in the same state provided that E1 is enabled

                                          The 74148 is a priority encoder with active-Low input for dec

                                          input) and five output linesinputs lines (including an enablethe binary code for the octal digit Function of various pins of this IC is described below

                                          bull 0 through 7 Active low data inputs representing the octal digits A2 A1 A0 Active low output lines representing the binary code bullbull E1 Active low enable Input bull E0 Active low output indicating none of the inputs is high bull GS Active low output indicatbull VCC and GND Supply connections lines Therefore if GS A2 A1 and A0 are all low

                                          then it shows that none of thE0 A2 A1 and A0 are all low

                                          39

                                          Logic Design amp Switching Theory 1 Lab Session 08 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                          Circuit Diagram

                                          Figure 82 Pin connections of 74148

                                          Testing Procedure bull Make connections as sho

                                          binations of 1s and 0s at data inputs d record your observations in the following table

                                          GS E0

                                          wn in the circuit diagram bull Apply different combull Observe the output an Observations

                                          0 1 2 3 4 5 6 7 A2 A1 A0 1 1 1 1 1 1 1 1 x x x x x x x 0 x x x x x x 0 1 x x x x x 0 1 1 x x x x 0 1 1 1 x x x 0 1 1 1 1 x x 0 1 1 1 1 1 x 0 1 1 1 1 1 1 0 1 1 1 1 1 1 1

                                          40

                                          Logic Design amp Switching Theory 1 Lab Session 08 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                          41

                                          CTIVITY

                                          Cascade the following two 74148 8 x 3 Priority Encoders to form 16 x 4 Priority

                                          A 1

                                          Encoder

                                          Logic Design amp Switching Theory 1 Lab Session 09 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering `

                                          Lab Session 09 OBJECT

                                          Designing an Odd Parity Generator and Checker for a 3-bit Data COMPONENTS AND APPARATUS REQUIRED

                                          1 Following ICs and their Datasheets

                                          bull 7486 Quad 2-input Exclusive-OR Gates bull 7404 Hex Inverter

                                          2 Digital Trainer DT-01 or the following components Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches

                                          THEORY

                                          Parity Generator When binary data is transmitted and processed it is ndash as are all electrical signals ndash susceptible to noise that can either alter or distort its contents 1s may be effectively changed to 0s and 0s to 1s To overcome this problem one or more bits are often added to the data as an aid in detecting errors caused by noise The most common of these is a Parity bit that signifies whether the total number of 1s in a code group is odd or even In an Odd Parity system the parity bit is made 0 or 1 as necessary to make the total number 1s odd (counting the parity bit itself) In an Even Parity system the parity bit is chosen to make the total number of 1s even Table 91 shows how parity bits would be added to BCD code group in both systems

                                          Decimal BCD Value Parity Bit ABCD Odd Parity Even Parity

                                          0 0000 1 0 1 0001 0 1 2 0010 0 1 3 0011 1 0 4 0100 0 1 5 0101 1 0 6 0110 1 0 7 0111 0 1 8 1000 0 1 9 1001 1 0

                                          Table 91 Odd and Even Parity in BCD

                                          When digital data is received a parity checking circuit generates an error signal if the total number of 1s is odd in an even parity system or if it is even in an odd parity system Parity check always detects a single error (one bit change from 0 to 1 or 1 to 0) but may not detect

                                          42

                                          Logic Design amp Switching Theory 1 Lab Session 09 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering ` two or more errors Odd parity is used more often than even parity because even parity does not detect a situation where all 0s are created due to short circuit or other fault condition DESIGN OF A 3-BIT ODD PARITY GENERATOR AND CHECKER Let x y and z be the three bits that constitute the message and are the input to the Odd Parity Generator Circuit Since it is an odd parity system the bit P is generated so as to make the total number of 1s odd (including P) The function P can be expressed as follows P = x oplus y Ο z or P = x Ο y oplus z Since the IC available is 7486 which is quad 2input XOR IC therefore we will convert XNOR also to XOR

                                          P = x oplus y Ο z

                                          P = ( x oplus y ) Ο z Since for even number of variables ______

                                          XOR = XNOR Therefore ___________ _________

                                          P = ( x oplus y ) oplus z = x oplus y oplus z This logical expression can be implemented with two XOR gates and an inverter (see figure 91)

                                          Figure 91 Circuit Diagram for a 3-bit Parity Generator

                                          The 3-bit message and the parity bit are transmitted to their destination where they are applied to a Parity Checker Circuit An error occurs during transmission if the parity of the four bits received is even since the binary information transmitted was originally odd The output C of the parity checker should be a 1 when an error occurs ie when the number of 1s in the four inputs is even Therefore the function C can be expressed as

                                          C = x Ο y Ο z Ο P

                                          Using the same logic applied for the conversion of the equation of P

                                          PzyxC oplusoplusoplus= This logical expression can be implemented with three XOR gates and an inverter (see figure 92)

                                          43

                                          Logic Design amp Switching Theory 1 Lab Session 09 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering `

                                          44

                                          Figure 92 Circuit Diagram for a 3-bit Parity Checker Implementation and Observations Implement the 3-bit Parity Generator and Checker circuits (figure 91 and 92) on a bread board (prepare the pin diagram (use appendix A) and refer to laboratory session 01 for implementation procedure) and record the observations in the following table

                                          x y z P x y z P C x y z P C 0 0 0 0 0 0 0 1 0 0 0 0 0 1 0 0 0 1 1 0 0 1 0 1 0 0 0 1 0 1 0 1 0 0 1 1 0 0 1 1 1 0 1 1 1 0 0 0 1 0 0 1 1 0 0 1 0 1 0 1 0 1 1 1 0 1 1 1 0 0 1 1 0 1 1 1 0 1 1 1 0 1 1 1 1 1 1 1

                                          Odd Parity Generation Odd Parity Check ACTIVITY 1 Try using the parity checker of figure 92 as 3-bit parity generator Write the details here

                                          _____________________________________________________________________________________________________________________________________________________________________________________________________________________ ______________________________________________________________________________________________________________________________________________ _______________________________________________________________________ ______________________________________________________________________________________________________________________________________________

                                          Logic Design amp Switching Theory 1 Lab Session 10 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                          Lab Session 10 OBJECT

                                          Driving a seven segment display using 7447 7448 driver IC COMPONENTS AND APPARATUS REQUIRED

                                          1 Following ICs and their Datasheets

                                          bull Seven Segment Displays (Common Anode Common Cathode) bull 7447 7448 BCD to Seven Segment Driver

                                          2 Digital Trainer DT-01 or the following components Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches

                                          THEORY Seven Segment Displays A Seven Segment Display consists of seven light-emitting segments The segments are designated by letters a through g (see figure 101) By illuminating various combinations of segments the numerals 0 through 9 can be displayed Seven Segment Displays are commonly constructed with light-emitting diodes (LEDs) and with liquid-crystal displays (LCDs) LEDs generally provide greater illumination levels but require much greater power than LCDs An LED display can be a common-anode type or common cathode type In common anode type a high voltage is applied at the common terminal of the display and low voltage is applied at a segmentrsquos terminal for illumination In the common-cathode type a low voltage is applied at the common terminal of the display and high voltage is applied at a segmentrsquos terminal for illumination

                                          Figure 101 Seven Segment Display

                                          a f b g

                                          e c d

                                          7447 7448 BCD to Seven Segment Driver 7447 7448 IC is particularly used to drive Seven Segment Its input is a BCD number and output drives a seven segment display 7447 is used to drive common-anode displays whereas 7448 is used to drive common cathode displays 7447 7448 is a 16 pin IC Function of various pins of these ICs is described below

                                          bull A B C D Inputs representing BCD digits (D being the MSB)

                                          45

                                          Logic Design amp Switching Theory 1 Lab Session 10 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering bull OA through OG Outputs to drive segments a through g of the display (Active low

                                          in 7447 and active high in 7448) bull RBI Ripple Blanking Input Turns off all the segments if kept low provided that LT

                                          is kept high and all other inputs (A B C D BI) are kept low Should be kept high otherwise

                                          bull BI RBO Wire-AND logic serving as a Blanking Input and or Ripple Blanking Output

                                          o BI Turns off all the segments if low o RBO Goes to a low level (response condition) along with other outputs when

                                          RBI and inputs A B C and D are low with LT input at high level bull LT Lamp Test input Tests whether all segments are working or not Illuminates all

                                          segments if kept low provided that BI is kept high Should be kept high otherwise bull VCC and GND Supply connections lines CIRCUIT DIAGRAM

                                          Figure 102 Circuit diagram for 7447driving a common-anode display

                                          IMPLEMENTATION AND OBSERVATIONS

                                          bull Make connections as shown in the circuit diagram (refer to laboratory session 01 for implementation procedure)

                                          bull Apply different combinations of 1s and 0s at data inputs bull Observe the output and record your observations in the following table

                                          46

                                          Logic Design amp Switching Theory 1 Lab Session 10 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                          47

                                          Decimal Digit

                                          BCD Inputs Seven Segment Outputs D C B A a b c d e f g

                                          0 0 0 0 0 1 0 0 0 1 2 0 0 1 0 3 0 0 1 1 4 0 1 0 0 5 0 1 0 1 6 0 1 1 0 7 0 1 1 1 8 1 0 0 0 9 1 0 0 1

                                          ACTIVITY 1 Perform the Lamp Test for the designed circuit and write your observations

                                          ____________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________

                                          2 How can you use 7447 IC to drive a common-cathode display

                                          ____________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________

                                          3 What symbols appear in the seven segment display if inputs DCBA are

                                          DCBA Symbol

                                          1010

                                          1011

                                          1100

                                          1101

                                          1110

                                          1111

                                          Logic Design amp Switching Theory 1 Lab Session 11 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                          48

                                          Lab Session 11 OBJECT

                                          Testing different modes of JK-FF COMPONENTS AND APPARATUS REQUIRED 1 Following ICs and their Datasheets

                                          bull 7473 7476 JK Flip-Flop 2 Digital Trainer DT-01 or the following components

                                          Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches

                                          THEORY

                                          Flip-Flop A flip-flop circuit can maintain a binary state indefinitely (as long as the power is delivered to the circuit) until directed by an input signal to switch states The major differences among various types of flip-flops are in the number of inputs they possess and in the manner in which the inputs affect the binary state

                                          JK Flip-Flop JK flip flop is an edge triggered device A typical JK flip flop has three inputs J K and a clock input The flip-flop can be either positive or negative edge triggered The output Q is available in complemented form as well Beside the usual inputs and output most of the flip-flop IC also possess two asynchronous inputs namely Preset and Clear These inputs are usually active low If used Preset and Clear inputs keep the flip-flop in set and reset state respectively irrespective of the other inputs Both of these inputs cannot be used simultaneously otherwise they will bring the flip-flop in unstable state

                                          Figure 111 Symbol for JK flip-flop

                                          (a) positive-edge triggering (b) active low Preset (PR) and Clear (CLR) with positive-edge triggering

                                          (c) active low Preset (PR) and Clear (CLR) with negative-edge triggering

                                          Logic Design amp Switching Theory 1 Lab Session 11 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                          49

                                          TESTING OF 7473 7476 DUAL JK FLIP-FLOP

                                          Both the ICs 7473 and 7476 are similar in functionality except for one difference The flip-flops in 7473 have only one type of active low asynchronous input which is the Clear input whereas the flip-flops in 7476 have both Preset and Clear inputs Both these ICs have negative edge triggered flip-flops

                                          Circuit Diagram

                                          Figure 112 Pin connections of 7476

                                          Testing Procedure

                                          bull Make connections as shown in the circuit diagram (figure 112) bull Apply different combinations of 1s and 0s at J and K inputs bull Observe the output and record your observations in the following table

                                          Observations

                                          J

                                          K Q

                                          0 0 0 1 1 0 1 1

                                          ACTIVITY

                                          1 Observe the output Q of JK flip-flop if the clock input is connected to VCC or GND instead of a clock source Write your observations here __________________________________________________________________________________________________________________________________________ _______________________________________________________________________________________________________________________________________________________________________________________________________________

                                          Logic Design amp Switching Theory 1 Lab Session 12 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                          50

                                          Lab Session 12 OBJECT

                                          Designing sequential circuit for the given state diagram using D flip-flop GIVEN STATE DIAGRAM

                                          00

                                          11

                                          Figure 121 State Diagram COMPONENTS AND APPARATUS REQUIRED 1 Following ICs and their Datasheets

                                          bull 7474 D Flip-Flop bull ICs of basic gates (AND OR NOT XOR etc) as required

                                          2 Digital Trainer DT-01 or the following components Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches

                                          THEORY

                                          Sequential Circuits In Sequential Circuits the output not only depends on the present inputs but also on previous states of the circuit These circuits use memory elements (latches flip-flops) and the binary information stored in the memory elements at any given time defines the state of the sequential circuit Analysis of a Sequential Circuit The behavior of a sequential circuit is determined from the inputs the outputs and the states of its flip-flops Both the outputs and next state are a function of the inputs and the

                                          10

                                          01

                                          00 11 10

                                          00

                                          00 11 10 00

                                          Logic Design amp Switching Theory 1 Lab Session 12 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                          51

                                          present state The analysis of a sequential circuit form a state diagram comprises of the following bull Selecting a particular flip-flop to design the circuit bull Obtaining state table from the state diagram bull Finding input equations for the selected flip-flop bull Finding state equations (not required for the construction of circuit) bull Implementing the circuit using selected flip-flops and their input equations ANALYZING THE GIVEN STATE DIAGRAM D Flip-Flop D flip-flop is also called transparent flip-flop as it simply transfers the input data to the output For our design we require the graphical symbol and excitation table of D flip-flop (see figure 122)

                                          Qt Qt+1 T 0 0 0 0 1 1 1 0 0 1 1 1

                                          (b) Excitation table of D Flip-Flop

                                          (a) Graphical Symbol

                                          Figure 122 Characteristic equation of D flip-flop is Q(t+1) = D State Table The given state diagram has four states so we will need two D flip-flops (FF-0 FF-1) Form state table form the given state diagram and record the results in the following table

                                          Present State Input Next State Output Input to FF-0 D0

                                          Input to FF-1 D1 Q1t Q0t x Q1(t+1) Q0(t+1) z

                                          Logic Design amp Switching Theory 1 Lab Session 12 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                          52

                                          Input Equations Using Karnaugh map the input equations D0 and D1 for the two flip-flops can be found

                                          D0 D1 Q0x

                                          Q1

                                          _ _ Q0x

                                          _ Q0x

                                          Q0x

                                          _ Q0x

                                          Q0x

                                          Q1

                                          _ _ Q0x

                                          _ Q0x

                                          Q0x

                                          _ Q0x

                                          _ Q1

                                          _ Q1

                                          Q1

                                          Q1

                                          D0 = _________________ D1 = _________________

                                          State Equations Using the characteristic equation of D flip-flop we can find the state equations Q0(t+1) and Q1(t+1) for the to flip flops Q0(t+1) = _______________________ Q1(t+1) = _______________________ _______________________ _______________________ _______________________ _______________________ Circuit Diagram

                                          Logic Design amp Switching Theory 1 Lab Session 12 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                          53

                                          Implementation Procedure and Observations

                                          1 Implement the circuit using digital ICs on a bread board (prepare the pin diagram (use appendix A) and refer to laboratory session 01 for procedure)

                                          2 Make the clear inputs of the flip-flops low (to clear the flip-flops) The flip-flops will remain in clear state as long as the clear inputs are connected to low level

                                          3 Connect output Q0 and the clock pulse to an oscilloscope 4 Apply 0 to the input x 5 Now make the clear inputs to high 6 Observe the waveform for the first 5 clock pulses and record it 7 Repeat steps 2 to 6 keeping x=1 in step 4 this time 8 Repeat steps 2 to 7 this time connecting Q1 instead of Q0 to the oscilloscope in step

                                          3 Record your observations (Keep frequency of the clock pulse low (eg1Hz) so that the output waveforms can be observed easily)

                                          1 2 3 4 5 Clock Pulse

                                          Output Waveform for Q0 when x=0

                                          Output Waveform for Q0 when x=1

                                          Output Waveform for Q1 when x=0

                                          Output Waveform for Q1 when x=1

                                          Logic Design amp Switching Theory 1 Lab Session 13 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                          Lab Session 13 OBJECT

                                          Designing a modulo-5 asynchronous up-counter using JK-FF COMPONENTS AND APPARATUS REQUIRED

                                          1 Following ICs and their Datasheets

                                          bull 7400 Quad 2-input or 7410 Triple 3-input NAND Gates bull 7476 7473 JK Flip-Flop

                                          2 Digital Trainer DT-01 or the following components Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches

                                          THEORY

                                          Digital Counters A digital counter is a set of flip-flops whose states change in response to pulses applied at the input to the counter The flip-flops are interconnected so that their combined state at any time is the binary equivalent of the total number of pulses that have occurred up to that time Every counter resets after a certain number of clock pulses Thus as it name implies a counter is used to count pulses An n stage counter can count up to a maximum of 2n states n is equal to the number of flip-flops required for the construction of counter

                                          Modulus Counters The number of input pulses that causes a counter to reset to its initial count is called the modulus of the counter Thus the modulus equals to total number of distinct states (counts) including zero that a counter can store A binary counter with n stages is a modulo-2n (or mod-2n) counter The largest count a mod-N counter can achieve is N-1 ie a mod-N counter never reaches the binary number equal to its modulus N is always equal to or less than 2n Counters can be classified as bull Synchronous Counters which are clock driven All the flip-flops are driven by a

                                          single clock bull Asynchronous Counters which are event driven Clock input is given to the first

                                          flip-flop only Rest of the flip-flops are driven by their preceding flip-flops

                                          DESIGN OF A MOD-5 ASYNCHRONOUS UP COUNTER The number of flip-flops required to construct a mod-5 counter is 3 because 5 should be less than or equal to 2n This counter will count from 0 to 4 a total of 5 distinct states Since a 3-stage counter can count up to 8 states at maximum a NAND gate is used to reset it after 5 clock pulses Figure 131 shows the logic diagram

                                          54

                                          Logic Design amp Switching Theory 1 Lab Session 13 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                          55

                                          Figure 131 A Mod-5 Asynchronous Up Counter

                                          Implementation and Observations

                                          Implement the mod-5 counter circuit (figure 131) on a bread board (prepare the pin diagram (use appendix A) and refer to laboratory session 01 for implementation procedure) and record the observations in the following table

                                          Clock Pulse Q2 Q1 Q0

                                          0 1 2 3 4 5 6 7

                                          ACTIVITY

                                          Draw the timing diagram for mod-5 counter designed in this laboratory session

                                          Logic Design amp Switching Theory 1 Lab Session 14 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                          Lab Session 14 OBJECT

                                          Experimenting with 74194 4-bit bidirectional universal shift register COMPONENTS AND APPARATUS REQUIRED

                                          1 Following ICs and their Datasheets

                                          bull 74194 4-bit bidirectional universal shift register 2 Digital Trainer DT-01 or the following components

                                          Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches

                                          THEORY

                                          Shift Registers

                                          A Register is a set of flip-flops used to store binary data A register which is capable of shifting its binary information either to the right or left is called a shift register The logical configuration of a register consists of a chain of flip-flops connected in cascade with the output of one flip-flop connected to the input of next flip-flop All flip-flops receive a common clock pulse which causes the shift from one stage to the next

                                          Bidirectional Shift Registers A bi-directional shift register is one whose bits can be shifted from left to right or from right to left

                                          Universal Shift Registers A universal shift register is a bi-directional register whose input can be in either serial or parallel form and whose output can be in either serial or parallel form

                                          74194 4-BIT BIDIRECTIONAL UNIVERSAL SHIFT REGISTER

                                          The 74194 register provides parallel as well as serial loading in both directions Function of various pins of this IC is described below

                                          bull A B C and D Active high inputs for parallel loading bull QA QB QC and QD Active high outputs bull S0 and S1 Active high mode control inputs The following table shows combinations

                                          of S1 and S0 to enable various modes

                                          S1 S0 Clock Action 0 0 x No change 0 1 uarr Shift right 1 0 uarr Shift left 1 1 uarr Parallel load

                                          uarr shows the rising edge of the clock pulse

                                          56

                                          Logic Design amp Switching Theory 1 Lab Session 14 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering bull SR Active high serial input for right shifting bull SL Active high serial input for left shifting bull CLR Active low input Clears all the flip-flops of the register if set to 0 should be

                                          kept high otherwise bull CLK Clock input bull VCC and GND Supply connections lines Thus A B C and D are inputs for parallel loading whereas SR and SL are inputs for serial loading with right or left shifting respectively S1 and S0 are used to select the loading mode Circuit Diagram

                                          Figure 141 Pin connections of 74194 Testing Procedure

                                          bull Make connections as shown in the circuit diagram bull Observe the output for the input combinations given in the following table

                                          57

                                          Logic Design amp Switching Theory 1 Lab Session 14 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                          58

                                          Observations

                                          S1 S0 SL SR A B C D QA QB QC QD 0 0 0 1 0 0 0 0 0 1 1 0 0 0 0 1 1 0 0 0 0 0 1 0 1 1 0 0 0 0 1 1 0 0 1 1 0 1 0 0 0 1 1 1 0 1 0 1 1 0 1 0 0 1 1 0 1 1 1 0 0 1 1 1 1 1 0 0 1 1 1 1

                                          ACTIVITY 1 Show connections of 74194 to convert it into a ring counter with right shifting

                                          Logic Design amp Switching Theory 1 Lab Session 15 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                          Lab Session 15

                                          OBJECT

                                          Experimenting with 74245 octal bus transceivers using parallel port PC interfacing COMPONENTS AND APPARATUS REQUIRED 1 Parallel Port Connectors (DB-25) with Cable 2 Personal Computer with Windows 98 and TurboC Compiler Installed 3 Following ICs and their Datasheets

                                          bull 74245 Octal Bus Transceivers with 3-State Outputs 4 Digital Trainer DT-01 or the following components

                                          Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches

                                          THEORY

                                          3-State Logic Sometimes it is necessary to isolate one part of circuit from the other part For this purpose some TTL ICs are designed with 3-state logic Such devices have three possible output states high low and high impedance The device can be put into high impedance state by a control signal applied to an appropriate pin When such a device is in high impedance state there is very high impedance at its output effectively isolating the device from whatever circuitry the output normally drives 74245 Octal Bus Transceivers A bus is any conducting path or set of paths having electrical connections to one or more devices 74245 octal bus transceivers are mainly used to control connectivity between two devices or circuits It also provides direction control for signal flow Function of various pin of this IC is given below

                                          bull A1 through A8 Bus A bull B1 through B8 Bus B bull G΄ Active low enable input When high sets all the bus pins to high impedance state bull DIR Direction control for signal flow When set to high logic level transfers bus A

                                          data to B bus When set to low logic level transfers bus B data to A bus bull VCC and GND Supply connections lines Serial and Parallel Port Connectors A Parallel Port can consist of only 25 pin port adapter called a DB-25 and a serial port can consist of either a 25 pin port adapter called a DB-25 or 9 pin adapter called a DB-9 port adapter Whether the port is a 9 pin or 25 pin it can accomplish all of the same tasks that serial port communications have been designed for

                                          59

                                          Logic Design amp Switching Theory 1 Lab Session 15 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                          60

                                          Each adapter can be a male type connector with pins or a female type adapter with tiny holes Generally a PRINTER port (called LPT1) on the back of a computer is female type adapter and we need to use MALE DB-25 pin cable on it for PRINTER connection or for parallel LAPLINK cable And a COM port on the back of a computer is male for the serial ports but it may not necessarily be Parallel Port Connector ndash DB-25 The DB-25 connector (named for its B-size D-shaped shell and 25 pins) is practically ubiquitous in the electronics industry The DB-25 connector is used for a variety of purposes Two common applications are RS-232EIA-232 (serial) connections and the parallel printer interface on the IBM PC The DB-25 connector is also used for SCSI connections Normally the parallel port is used for output to a printer or other device It sends data 8-bits or one byte at a time in parallel The other lines available on the DB-25 connector are a combination of status lines control lines and ground lines The status and control lines are used for handshaking commands and feedback when we are talking to a printer

                                          Figure 152 DB-25 Female Figure 151 DB-25 Male

                                          Figure 153 Pin Layout for DB-25 As can be seen form figure 153 there are four types of pins in this connector

                                          bull Data pins (8 pins - D0 to D7) Active high bidirectional lines

                                          Logic Design amp Switching Theory 1 Lab Session 15 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering bull Control pins (4 pins - C0 to C3) C0 C1 and C3 are active low whereas C2 is active

                                          high These lines also are bidirectional bull Status pins (5 pins ndash S3 to S7) Only S7 is active low rest are active high input lines bull Ground pins (8 pins) Used as a reference signal for the low (below 05 volts) charge

                                          Parallel Port Addresses A DB-25 connector at a parallel port has three address one for each kind of pins register data status and control The first or base address generally refers to data register Second address is for status register and the third one is for control register In Windows 98 the base address is usually found to be 278H 378H or 3BCH Now if 378H is the base address then it refers to the data register whereas addresses for status and control register are respectively 379H and 37AH For Windows 98 the base address can be found as follows 1 On your Desktop right-click on My Computer and select Properties 2 Click on the Device Manager tab and find LPT1 under Plug and Play BIOS 3 After selecting LPT1 click the Properties button 4 Next select the Resources tab and the address should then appear next to InputOutput

                                          Range Accessing parallel port through C Language Programming There are multiple functions in C Language for accessing external ports The most commonly used are listed below

                                          bull unsigned char inportb(int portid) inportb reads a byte from a hardware port

                                          bull int inport(int portid) reads a word from a hardware port

                                          bull void outportb(int portid unsigned char value) outputs a byte to a hardware port

                                          bull void outport(int portid int value) outputs a word to a hardware port

                                          portid refers to the port address whereas value refers to the data to be sent TESTING 74245 USING PARALLEL PORT PC INTERFACING At one end the parallel port connector will be connected to the PC via parallel port cable and another connector (to be plugged into the PC parallel port slot) At the other end it will be connected to the buffer IC 74245 Data lines of the connector will be used to transfer 8-bit data between the PC and the buffer Out of the 8-bits of 74245 4-bits will be used to enter data which will be displayed at the monitor through a C language

                                          61

                                          Logic Design amp Switching Theory 1 Lab Session 15 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering program The remaining 4-bits will receive data from PC as entered by the user via keyboard

                                          Circuit Diagram

                                          Figure 154 Interface of 74245 to PC via Parallel Port

                                          Procedure

                                          1 Connect the DB-25 connector to the PC at one end and solder it to the circuit board at the other end

                                          2 Connect various pins of the connector and 74245 according to the circuit diagram shown in figure 152

                                          3 Using the functions listed in the previous section write a program in C language to operate various pins of the buffer The user interface of the program should provide option to the user whether to send or receive data from the port

                                          4 Set DIR switch to 1 5 Try sending some data bits to the port The result should be displayed at the LEDs 6 Set DIR switch to 0 7 Set some binary 4-bit value through the switches Try reading it via parallel port

                                          C Language Program

                                          A program to access parallel port for data transfers

                                          use header file include ltstdiohgt main program void main() define variable

                                          62

                                          Logic Design amp Switching Theory 1 Lab Session 15 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering unsigned int data=0 char choice while(1) printing option menu clrscr() printf(This program will send or receive a BCD digit from the parallel portn) printf(nPress your choice numbern) printf(n1 Send Data) printf(n2 Receive Data) printf(n3 Exitn) choice = getch() sending entered digit to the port if(choice == 1) input BCD digit printf(nEnter BCD digit to be sent to the port) data = getche() masking the first four bits data = data amp 0x0f sending to the port outportb(0x378data) printf(nThe BCD digit c has been sent to the port data) printing on screen the data received from the port else if(choice == 2) receiving data from the port data = inportb(0x378) masking the last four bits data = data amp 0xf0 shifting first four bits to make them the last four bits datagtgt=4 printf(nThe BCD digit set at the port is c data) exit else if(choice == 3) break key pressed is not in the menu else printf(nEnter valid choice number) printf(nnPress any key to continue) getch()

                                          63

                                          Logic Design amp Switching Theory 1 Lab Session 15 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                          ACTIVITY 1 In the above circuit DIR and G΄ inputs are hardwired Connect them to status or

                                          control pins of the parallel port connector and control their function through your software program Circuit Diagram Program Code ______________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________

                                          ___________________________________________________________________________________________________________________________________________________

                                          64

                                          Logic Design amp Switching Theory 1 Lab Session 15 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                          65

                                          _____________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ _____________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ _______________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ _________________________________________________ _________________________________________________

                                          Logic Design amp Switching Theory 1 Appendix A NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                          Appendix A

                                          PIN DIAGRAMS OF THE ICS REQUIRED FOR THE LABORATORY SESSIONS Consult the TTLIC data book for internal diagrams and electrical characteristics of these ICs 7400 Quad 2-Input NAND 7402 Quad 2-Input NOR

                                          7404 Hex Inverter 7408 Quad 2-Input AND

                                          7410 Triple 3-Input NAND 7411 Triple 3-Input AND

                                          7421 Dual 4-Input AND 7432 Quad 2-Input OR

                                          66

                                          Logic Design amp Switching Theory 1 Appendix A NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                          BCD-to-Seven Segm 7448 BCD-to-Seven Segment 7447 ent

                                          Decoder (15V OC) Decoder (2kΩ pull-up output)

                                          7473 Dual JK Flip-Flop 7474 Dual D-Type Flip-Flop

                                          7476 Dual JK Flop-Flop -Bit Binary Full Adder 7483 4 with Fast Carry

                                          86 Quad 2-Inpu 74138 3-to-8 Line 74 t Exclusive OR Decoder Demultiplexer

                                          67

                                          Logic Design amp Switching Theory 1 Appendix A NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                          68

                                          74148 8-to-3 Line 16-to-1 Line Data

                                          Priority Encoder 74150 Selector Multiplexer

                                          74245 Oct nsceivers Universal Shift Register (PIPO) (3-State)

                                          74194 4-Bit Bidirectional al Bus Tra

                                          Logic Design amp Switching Theory 1 Appendix B NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                          Appendix B

                                          DEBOUNCING CIRCUITRY FOR MECHANICAL SWITCHES Mechanical switches form the interface between human beings and computers or other digital systems For example a keyboard is a matrix of switches used to supply alphanumeric data to a computer Whatever the switch design it is a potential source of problems due to contact bounce The contact bounce creates a sense of narrow pulses when a switch is opened or closed An example of device whose operation would be adversely affected by contact bounce is a digital counter used to count the number of times a switch is depressed Eliminating the effects of contact bounce is called debouncing When data is entered into a computer via a keyboard a software debounce is often used This type of debouncing is a program that causes the computer to sample the switch terminal (ie to input data from it) many times in succession during the interval of time that contact bounce occurs If the data is sensed to be 1s (or 0s) for a specific number of consecutive samples then it is assumed that contact bounce has ended and the last value sensed is valid Hardware debouncing is the use of electronic circuitry to eliminate the effects of contact bounce There are numerous versions of such circuitry including those that use monostable multivibrators (one-shots) but the most straightforward is simply an RS latch Figure B1 shows the circuit When the switch is in position 1 R = 0 and S = 1 so the latch is set and the output (Q) is 1 When the switch is in position 0 R = 1and S = 0 so the latch is reset and the output is 0 When the switch is moved form one position to the other the latch changes state and bouncing occurs at either the R or the S input The bouncing does not affect the latch after it has change state An RS latch will remain set for example when its R input is 0 and its S input is alternately changed form 1 to 0

                                          Figure B1 Use of RS latch to debounce a mechanical switch

                                          69

                                          • 01-ldst-Outer title
                                            • Practical Workbook
                                            • Logic Design amp Switching Theory I
                                              • Dept of Computer amp Information Systems Engineering
                                                • NED University of Engineering amp Technology
                                                • Karachi ndash 75270 Pakistan
                                                  • 02-ldst-inner Title
                                                    • Practical Workbook
                                                    • Logic Design amp Switching Theory I
                                                      • Dept of Computer amp Information Systems Engineering
                                                        • NED University of Engineering amp Technology
                                                        • Karachi ndash 75270 Pakistan
                                                          • 03-ldst-general info
                                                          • 04-ldst-introduction
                                                          • 05-Table of Contents
                                                            • CONTENTS
                                                              • Lab Session No Object Page No
                                                              • 1
                                                              • Also implementing and testing the given circuit on a bread board
                                                                • Working with Electronics Workbench
                                                                  • Driving a seven segment display using 7447 7448 driver IC
                                                                    • Designing a modulus-5 asynchronous up-counter using JK-FF
                                                                      • Experimenting with 74194 4-bit bidirectional universal shift register
                                                                          • 13
                                                                              • 06-ldst-Exp01
                                                                                • Lab Session 01
                                                                                • OBJECT
                                                                                  • 1 Bread board
                                                                                  • 2 5 V - power supply
                                                                                  • 3 Multimeter
                                                                                  • 4 Logic probe
                                                                                  • 5 LEDs with resistors
                                                                                  • 6 Connecting wires
                                                                                  • 8 Following ICs and their datasheets
                                                                                    • THEORY
                                                                                      • Logic Gates
                                                                                      • 1 The AND Gate ndash An AND gatersquos output is 1 if and only if all its inputs are 1 If A and B are two inputs to an AND gate then output F of the gate is given as F = AB
                                                                                      • 2 The OR Gate - An OR gatersquos output is 1 if at least one of its input is 1 If A and B are two inputs to an OR gate then output F of the gate is given as F = A+B
                                                                                      • 3 The NOT Gate (Inverter) ndash Its output is 1 when its input is 0 and its output is 0 when the input is 1 ie it complements a digital variable If A is the input to a NOT gate then output F of the gate is given as
                                                                                      • 4 The NAND Gate ndash Its output is 1 if at least one of its input is 0 This gate performs the same logic as an AND gate followed by an inverter If A and B are two inputs to a NAND gate then output F of the gate is given as
                                                                                        • 5 The NOR Gate - The output of a NOR gate is 1 if and only if all its inputs are 0 This gate performs the same logic function as an OR gate followed by an inverter If A and B are two inputs to a NAND gate then output F of the gate is given as
                                                                                            • DATA SHEETS
                                                                                              • Logic expression for the given logic diagram __________________________________
                                                                                                  • 07-ldst-exp02
                                                                                                    • Working with Electronics Workbench
                                                                                                      • 08-ldst-exp03
                                                                                                        • Designing Half and Full Adder Circuits
                                                                                                          • COMPONENTS AND APPARATUS REQUIRED
                                                                                                            • 1 Following ICs and their Datasheets
                                                                                                            • 7408 Quad 2-input AND Gate
                                                                                                            • 2 Digital Trainer DT-01 or the following components
                                                                                                              • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                              • Connecting wires Switches
                                                                                                                • THEORY
                                                                                                                    • IMPLEMENTATION AND OBSERVATIONS
                                                                                                                      • 09-ldst-Exp04
                                                                                                                        • Lab Session 04
                                                                                                                        • 1 Digital ICs and their Datasheets
                                                                                                                        • 7408 Quad 2-input AND Gate
                                                                                                                        • 2 Digital Trainer DT-01 or the following components
                                                                                                                          • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                          • Connecting wires Switches
                                                                                                                          • PROCEDURE
                                                                                                                          • REDUCTION OF LOGIC EXPRESSION USING KARNAUGH MAP
                                                                                                                          • OBSERVATIONS
                                                                                                                          • RESULT
                                                                                                                              • 10-ldst-Exp05
                                                                                                                                • Lab Session 05
                                                                                                                                • 1 Following ICs and their Datasheets
                                                                                                                                • 7408 Quad 2-input AND Gate
                                                                                                                                • 2 Digital Trainer DT-01 or the following components
                                                                                                                                  • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                  • (100 Ω) Connecting wires Switches
                                                                                                                                  • THEORY
                                                                                                                                    • IMPLEMENTATION AND OBSERVATIONS
                                                                                                                                      • 11-ldst-Exp06
                                                                                                                                        • OBJECT
                                                                                                                                        • 1 Following ICs and their Datasheets
                                                                                                                                        • 7408 Quad 2-input AND Gates or 7411 Triple 3-input AND Gates
                                                                                                                                        • 2 Digital Trainer DT-01 or the following components
                                                                                                                                          • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                          • Connecting wires Switches
                                                                                                                                            • Figure 62 Circuit Diagram for 4 x 1 Multiplexer
                                                                                                                                            • Implementation and Observations
                                                                                                                                              • Circuit Diagram
                                                                                                                                                • ACTIVITY
                                                                                                                                                  • 12-ldst-exp07
                                                                                                                                                    • 1 Following ICs and their Datasheets
                                                                                                                                                    • 7408 Quad 2-input or 7411 Triple 3-input AND Gates
                                                                                                                                                    • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                      • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                      • Connecting wires Switches
                                                                                                                                                        • THEORY
                                                                                                                                                            • Figure 72 Circuit Diagram for 2 x 4 Decoder 1 x 4 Demultiplexer
                                                                                                                                                            • Implementation and Observations
                                                                                                                                                              • Circuit Diagram
                                                                                                                                                                • ACTIVITY
                                                                                                                                                                  • 13-ldst-Exp08
                                                                                                                                                                    • OBJECT
                                                                                                                                                                    • 1 Following ICs and their Datasheets
                                                                                                                                                                    • 7408 Quad 2-input or 7421 Dual 4-input AND Gates
                                                                                                                                                                    • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                      • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                      • Connecting wires Switches
                                                                                                                                                                        • THEORY
                                                                                                                                                                            • Figure 81 Circuit Diagram for 4 x 2 Priority Encoder
                                                                                                                                                                            • Implementation and Observations
                                                                                                                                                                              • Therefore if GS A2 A1 and A0 are all low then it shows that line 0 is selected and if E0 A2 A1 and A0 are all low then it shows that none of the inputs selected E0 and GS cannot be in the same state provided that E1 is enabled
                                                                                                                                                                              • Circuit Diagram
                                                                                                                                                                                • ACTIVITY
                                                                                                                                                                                  • 14-ldst-exp09
                                                                                                                                                                                    • OBJECT
                                                                                                                                                                                    • 1 Following ICs and their Datasheets
                                                                                                                                                                                    • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                      • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                      • Connecting wires Switches
                                                                                                                                                                                        • THEORY
                                                                                                                                                                                          • Parity Generator
                                                                                                                                                                                            • Let x y and z be the three bits that constitute the message and are the input to the Odd Parity Generator Circuit Since it is an odd parity system the bit P is generated so as to make the total number of 1s odd (including P) The function P can be expressed as follows
                                                                                                                                                                                            • Figure 91 Circuit Diagram for a 3-bit Parity Generator
                                                                                                                                                                                              • C = x Ο y Ο z Ο P
                                                                                                                                                                                                • Implementation and Observations
                                                                                                                                                                                                  • ACTIVITY
                                                                                                                                                                                                      • 15-ldst-exp10
                                                                                                                                                                                                        • Driving a seven segment display using 7447 7448 driver IC
                                                                                                                                                                                                        • COMPONENTS AND APPARATUS REQUIRED
                                                                                                                                                                                                        • 1 Following ICs and their Datasheets
                                                                                                                                                                                                        • 7447 7448 BCD to Seven Segment Driver
                                                                                                                                                                                                        • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                          • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches
                                                                                                                                                                                                            • THEORY
                                                                                                                                                                                                            • Seven Segment Displays
                                                                                                                                                                                                            • CIRCUIT DIAGRAM
                                                                                                                                                                                                            • Figure 102 Circuit diagram for 7447driving a common-anode display
                                                                                                                                                                                                                • IMPLEMENTATION AND OBSERVATIONS
                                                                                                                                                                                                                  • Decimal Digit
                                                                                                                                                                                                                  • BCD Inputs
                                                                                                                                                                                                                  • Seven Segment Outputs
                                                                                                                                                                                                                  • D
                                                                                                                                                                                                                  • C
                                                                                                                                                                                                                  • B
                                                                                                                                                                                                                  • A
                                                                                                                                                                                                                  • a
                                                                                                                                                                                                                  • b
                                                                                                                                                                                                                  • c
                                                                                                                                                                                                                  • d
                                                                                                                                                                                                                  • e
                                                                                                                                                                                                                  • f
                                                                                                                                                                                                                  • g
                                                                                                                                                                                                                  • 0
                                                                                                                                                                                                                  • 0
                                                                                                                                                                                                                  • 0
                                                                                                                                                                                                                  • 0
                                                                                                                                                                                                                  • 0
                                                                                                                                                                                                                  • 1
                                                                                                                                                                                                                  • 0
                                                                                                                                                                                                                  • 0
                                                                                                                                                                                                                  • 0
                                                                                                                                                                                                                  • 1
                                                                                                                                                                                                                  • 2
                                                                                                                                                                                                                  • 0
                                                                                                                                                                                                                  • 0
                                                                                                                                                                                                                  • 1
                                                                                                                                                                                                                  • 0
                                                                                                                                                                                                                  • 3
                                                                                                                                                                                                                  • 0
                                                                                                                                                                                                                  • 0
                                                                                                                                                                                                                  • 1
                                                                                                                                                                                                                  • 1
                                                                                                                                                                                                                  • 4
                                                                                                                                                                                                                  • 0
                                                                                                                                                                                                                  • 1
                                                                                                                                                                                                                  • 0
                                                                                                                                                                                                                  • 0
                                                                                                                                                                                                                  • 5
                                                                                                                                                                                                                  • 0
                                                                                                                                                                                                                  • 1
                                                                                                                                                                                                                  • 0
                                                                                                                                                                                                                  • 1
                                                                                                                                                                                                                  • 6
                                                                                                                                                                                                                  • 0
                                                                                                                                                                                                                  • 1
                                                                                                                                                                                                                  • 1
                                                                                                                                                                                                                  • 0
                                                                                                                                                                                                                  • 7
                                                                                                                                                                                                                  • 0
                                                                                                                                                                                                                  • 1
                                                                                                                                                                                                                  • 1
                                                                                                                                                                                                                  • 1
                                                                                                                                                                                                                  • 8
                                                                                                                                                                                                                  • 1
                                                                                                                                                                                                                  • 0
                                                                                                                                                                                                                  • 0
                                                                                                                                                                                                                  • 0
                                                                                                                                                                                                                  • 9
                                                                                                                                                                                                                  • 1
                                                                                                                                                                                                                  • 0
                                                                                                                                                                                                                  • 0
                                                                                                                                                                                                                  • 1
                                                                                                                                                                                                                    • ACTIVITY
                                                                                                                                                                                                                      • 16-ldst-exp11
                                                                                                                                                                                                                        • Lab Session 11
                                                                                                                                                                                                                          • OBJECT
                                                                                                                                                                                                                          • COMPONENTS AND APPARATUS REQUIRED
                                                                                                                                                                                                                            • 1 Following ICs and their Datasheets
                                                                                                                                                                                                                            • 7473 7476 JK Flip-Flop
                                                                                                                                                                                                                            • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                              • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                                              • Connecting wires Switches
                                                                                                                                                                                                                                • THEORY
                                                                                                                                                                                                                                    • Flip-Flop
                                                                                                                                                                                                                                    • JK Flip-Flop
                                                                                                                                                                                                                                      • Circuit Diagram
                                                                                                                                                                                                                                        • Observations
                                                                                                                                                                                                                                          • ACTIVITY
                                                                                                                                                                                                                                              • 17-ldst-exp12
                                                                                                                                                                                                                                                • Lab Session 12
                                                                                                                                                                                                                                                  • OBJECT
                                                                                                                                                                                                                                                  • GIVEN STATE DIAGRAM
                                                                                                                                                                                                                                                  • Figure 121 State Diagram
                                                                                                                                                                                                                                                  • COMPONENTS AND APPARATUS REQUIRED
                                                                                                                                                                                                                                                    • 1 Following ICs and their Datasheets
                                                                                                                                                                                                                                                    • 7474 D Flip-Flop
                                                                                                                                                                                                                                                    • ICs of basic gates (AND OR NOT XOR etc) as required
                                                                                                                                                                                                                                                    • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                                                      • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                                                                      • Connecting wires Switches
                                                                                                                                                                                                                                                        • THEORY
                                                                                                                                                                                                                                                            • Sequential Circuits
                                                                                                                                                                                                                                                              • 18-ldst-exp13
                                                                                                                                                                                                                                                                • Lab Session 13
                                                                                                                                                                                                                                                                  • Designing a modulo-5 asynchronous up-counter using JK-FF
                                                                                                                                                                                                                                                                    • 1 Following ICs and their Datasheets
                                                                                                                                                                                                                                                                    • 7400 Quad 2-input or 7410 Triple 3-input NAND Gates
                                                                                                                                                                                                                                                                    • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                                                                      • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                                                                                      • Connecting wires Switches
                                                                                                                                                                                                                                                                        • THEORY
                                                                                                                                                                                                                                                                            • Figure 131 A Mod-5 Asynchronous Up Counter
                                                                                                                                                                                                                                                                            • Implementation and Observations
                                                                                                                                                                                                                                                                              • ACTIVITY
                                                                                                                                                                                                                                                                                  • 19-ldst-exp14
                                                                                                                                                                                                                                                                                    • Experimenting with 74194 4-bit bidirectional universal shift register
                                                                                                                                                                                                                                                                                    • 1 Following ICs and their Datasheets
                                                                                                                                                                                                                                                                                    • 74194 4-bit bidirectional universal shift register
                                                                                                                                                                                                                                                                                    • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                                                                                      • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                                                                                                      • Connecting wires Switches
                                                                                                                                                                                                                                                                                        • THEORY
                                                                                                                                                                                                                                                                                          • Shift Registers
                                                                                                                                                                                                                                                                                          • Bidirectional Shift Registers
                                                                                                                                                                                                                                                                                          • Universal Shift Registers
                                                                                                                                                                                                                                                                                            • S1
                                                                                                                                                                                                                                                                                              • Circuit Diagram
                                                                                                                                                                                                                                                                                              • ACTIVITY
                                                                                                                                                                                                                                                                                                  • 20-ldst-exp15
                                                                                                                                                                                                                                                                                                    • COMPONENTS AND APPARATUS REQUIRED
                                                                                                                                                                                                                                                                                                    • 1 Parallel Port Connectors (DB-25) with Cable
                                                                                                                                                                                                                                                                                                    • 2 Personal Computer with Windows 98 and TurboC Compiler Installed
                                                                                                                                                                                                                                                                                                    • 3 Following ICs and their Datasheets
                                                                                                                                                                                                                                                                                                    • 74245 Octal Bus Transceivers with 3-State Outputs
                                                                                                                                                                                                                                                                                                    • 4 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                                                                                                      • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                                                                                                                        • Connecting wires Switches
                                                                                                                                                                                                                                                                                                          • THEORY
                                                                                                                                                                                                                                                                                                          • 3-State Logic
                                                                                                                                                                                                                                                                                                            • Serial and Parallel Port Connectors
                                                                                                                                                                                                                                                                                                            • Parallel Port Connector ndash DB-25
                                                                                                                                                                                                                                                                                                              • Accessing parallel port through C Language Programming
                                                                                                                                                                                                                                                                                                                  • 21-ldst-appendixA
                                                                                                                                                                                                                                                                                                                  • 22-ldst-appendixB
                                                                                                                                                                                                                                                                                                                    • DEBOUNCING CIRCUITRY FOR MECHANICAL SWITCHES

                                            Logic Design amp Switching Theory 1 Lab Session 04 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                            ACTIVITY 1 Using Electronics Workbench derive a truth table and logic circuit for the following logic expression

                                            BAAF +=

                                            Procedure 1 From the Instruments Parts Bin drag and drop Logic Converter on the design area 2 Double click the Logic Converter to reveal Logic Converter dialog box This dialog

                                            box shows various conversion options between truth table logic expression and logic circuit

                                            3 Enter the given logic expression in the edit box found at the end of the dialog box Use lsquo to represent invert of a variable For example A is written as Arsquo

                                            4 Click the Boolean Expression to Truth Table button The truth table appears in the logic converters display

                                            5 Now click the Boolean Expression to Circuit button This creates the logic circuit for the given expression in the design area Label the diagram if needed

                                            Resulting Logic Circuit For the given expression the final circuit will look like

                                            Figure 41

                                            24

                                            Logic Design amp Switching Theory 1 Lab Session 04 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                            ACTIVITY 2

                                            Using Electronics Workbench find a simplified logic expression and circuit for the following truth table

                                            A B C Output 0 0 0 1 0 0 1 1 0 1 0 0 0 1 1 1 1 0 0 0 1 0 1 0 1 1 0 0 1 1 1 1

                                            Procedure 1 Click three input channels from A to H across the top of the logic converter The

                                            display area below the terminals fills up with the necessary combinations of ones and zeros to fulfill the input conditions The values in the output column on the right are initially set to 0

                                            2 Edit the output column to specify the desired output for each input condition To change an output value select it and type a new value 1 0 or x An x indicates a donrsquot care condition

                                            3 To convert this truth table to a Boolean expression click the Truth Table to Boolean Expression button The Boolean expression will be displayed at the bottom of the logic converter

                                            4 Simplify the expression by clicking the Simplify button 5 Now click the Boolean Expression to Circuit button This creates the logic circuit for

                                            the given expression in the design area Resulting Logic Circuit For the given truth table the final simplified circuit will look like

                                            Figure 42

                                            25

                                            Logic Design amp Switching Theory 1 Lab Session 04 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                            ACTIVITY 3

                                            Using Electronics Workbench find the logic expression and truth table for the following logic circuit

                                            Figure 43

                                            Procedure 1 Attach the input terminals of the logic converter to up to four input points in the

                                            circuit 2 Connect the single output of the circuit to the output terminal on the logic converter

                                            icon 3 Click the Circuit to Truth Table button The truth table appears in the logic

                                            converters display 4 To convert this truth table to a Boolean expression click the Truth Table to Boolean

                                            Expression button The Boolean expression will be displayed at the bottom of the logic converter

                                            Resulting Logic Expression Logic Expression for the given circuit is found to be _____________________________

                                            26

                                            Logic Design amp Switching Theory 1 Lab Session 04 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                            27

                                            For activities 1 2 and 3 attach hardcopy of the output (truth table logic expression and logic circuit) form electronic workbench here

                                            Logic Design amp Switching Theory 1 Lab Session 05 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                            Lab Session 05 Lab Session 05 OBJECT OBJECT

                                            Designing a BCD Adder Designing a BCD Adder COMPONENTS AND APPARATUS REQUIRED COMPONENTS AND APPARATUS REQUIRED

                                            1 Following ICs and their Datasheets 1 Following ICs and their Datasheets bull 7408 Quad 2-input AND Gate bull 7408 Quad 2-input AND Gate bull 7432 Quad 2-input OR Gate bull 7432 Quad 2-input OR Gate bull 7483 4-bit Binary Adder bull 7483 4-bit Binary Adder

                                            2 Digital Trainer DT-01 or the following components 2 Digital Trainer DT-01 or the following components Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors (100 Ω) Connecting wires Switches (100 Ω) Connecting wires Switches

                                            THEORY THEORY

                                            A BCD Adder is a combinational circuit that adds two BCD digits in parallel and produces a sum digit also in BCD A BCD Adder is a combinational circuit that adds two BCD digits in parallel and produces a sum digit also in BCD

                                            A4 A3 A2 A1 B4 B3 B2 B1

                                            7483-BCD ADDER

                                            Cout (C4 ) Z4 Z3 Z2 Z1 Cin(C0)

                                            A4 A3 A2 A1 B4 B3 B2 B1

                                            7483-BCD ADDER

                                            Cout

                                            (C4 ) Z4 Z3 Z2 Z1 Cin(C0)

                                            Figure 51 BCD Adder Circuit

                                            28

                                            Logic Design amp Switching Theory 1 Lab Session 05 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                            29

                                            A BCD adder must include the correction logic in its internal construction The two BCD digits together with the input carry are first added using a 4-bit binary adder to produce the binary sum If no output carry is generated and the binary sum is less than or equal to 9 then the corresponding BCD sum is identical and therefore no conversion is needed When the output carry is equal to 1 or the binary sum is greater than 9 then a binary 0110 is added to the binary sum through another 4-bit binary adder If Cout is the carry output and Z4Z3Z2Z1 is the binary sum form the first 4-bit binary adder then the following equation indicates the condition when a binary 0110 is to be added

                                            C = COUT + Z4Z2 + Z4Z3 IMPLEMENTATION AND OBSERVATIONS Implement the BCD adder circuit according to figure 51 on a bread board (prepare the pin diagram (use appendix A) and refer to laboratory session 01 for procedure) A BCD adder has nine input bits (two BCD digits and a carry bit) which can result in a total of 512 combinations of which 312 inputs are donrsquot care Since it is a very lengthy procedure to record results for 200 valid input combinations therefore for simplicity just record results for any eight combinations in the following table

                                            Input Carry

                                            BCD Digit 1 BCD Digit 2 Carry Output

                                            BCD Sum A4 A3 A2 A1 B4 B3 B2 B1 Z4 Z3 Z2 Z1

                                            Logic Design amp Switching Theory 1 lab Session 06 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                            Lab Session 06

                                            OBJECT

                                            bull Designing of a 4 x 1 Multiplexer bull Experimenting with 74150 IC

                                            COMPONENTS AND APPARATUS REQUIRED 1 Following ICs and their Datasheets

                                            bull 7408 Quad 2-input AND Gates or 7411 Triple 3-input AND Gates bull 7432 Quad 2-input OR Gates bull 7404 Hex Inverter bull 74150 16 x 1 MUX

                                            2 Digital Trainer DT-01 or the following components Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches THEORY

                                            Multiplexers A digital data Multiplexer (MUX) is a combinational circuit having several data inputs and a single output A set of data-select inputs is used to control which of the data inputs is routed to the single output A multiplexer is also called a data selector because of this ability to select which data input is connected o the output Normally there are 2n input lines and n selection lines whose bit combination determine which input is selected DESIGN OF A 4 x 1 MULTIPLEXER A 4 x 1 multiplexer is capable of selecting one of four data inputs (see figure 61) The 2-bit binary number at the data select inputs S1 and S0 specifies which of the four data inputs is to be routed to the output Since there are two data select inputs therefore they can select 22 = 4 different data inputs lines

                                            S0 S1 D0 D1

                                            D2 D3

                                            Data-select Inputs Output

                                            Data Inputs

                                            Figure 61 Block Diagram of a 4 x1 Multiplexer

                                            30

                                            Logic Design amp Switching Theory 1 lab Session 06 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                            Figure 62 Circuit Diagram for 4 x 1 Multiplexer

                                            Implementation and Observations

                                            Implement the 4 x 1 Multiplexer circuit (figure 62) on a bread board (prepare the pin diagram (use appendix A) and refer to laboratory session 01 for implementation procedure) and record the observations in the following table For each data select combination specify the switch number as well as the binary value present on that selected switch

                                            S1 S0 Output 0 0 0 1 1 0 1 1

                                            TESTING OF 74150 - 16 x 1 MUX

                                            The 74150 IC has sixteen data inputs and four data-selection lines Function of various pins of this IC is described below

                                            bull E0 through E15 Data input lines

                                            31

                                            Logic Design amp Switching Theory 1 lab Session 06 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering bull A B C D Data select lines with D being the MSB bull W Active low output line bull Grsquo Active low enable line bull VCC and GND Supply connections lines

                                            Circuit Diagram

                                            Figure 63 Pin connections of 74150 for selecting E0

                                            Testing Procedure

                                            bull Make connections as shown in the circuit diagram bull Apply different data (1 or 0) at data inputs that are labeled as E0 to E15 Only

                                            connection for E0 is shown is the figure for simplicity bull Select the data input E0 with the help of data selectors A B C and D bull Observe the output which shows the complement of the data from E0 bull Select all the sixteen data inputs one by one and record your observations in the

                                            following table

                                            32

                                            Logic Design amp Switching Theory 1 lab Session 06 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                            33

                                            Observations

                                            Grsquo D C B A W Grsquo D C B A W 0 0 0 0 0 0 1 0 0 0 0 0 0 0 1 0 1 0 0 1 0 0 0 1 0 0 1 0 1 0 0 0 0 1 1 0 1 0 1 1 0 0 1 0 0 0 1 1 0 0 0 0 1 0 1 0 1 1 0 1 0 0 1 1 0 0 1 1 1 0 0 0 1 1 1 0 1 1 1 1

                                            ACTIVITY 1 Consider 4x1 Multiplexer Draw the output wave-form for the following data inputs

                                            (E0 E1 E2 E3) and select lines A B (B being the MSB) Output is W

                                            E3 E2 E1 E0 A B

                                            W

                                            2 Using the 4 x 1 MUX designed in this laboratory session implement the following logical function F (A B C) = Σ (0147)

                                            Show your working and input connections in the following block diagram according to the circuit you have implemented

                                            4 x 1 MUX

                                            S0 S1

                                            Output D0

                                            D1

                                            D2

                                            D3

                                            Logic Design amp Switching Theory 1 Lab Session 07 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                            Lab Session 07

                                            OBJECT

                                            bull Designing of a 2 x 4 Decoder 1 x 4 Demultiplexer bull Experimenting with 74138 IC

                                            COMPONENTS AND APPARATUS REQUIRED 1 Following ICs and their Datasheets

                                            bull 7408 Quad 2-input or 7411 Triple 3-input AND Gates bull 7404 Hex Inverter bull 74138 3 x 8 Decoder

                                            2 Digital Trainer DT-01 or the following components Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches THEORY

                                            Decoder A Decoder is a combinational circuit that converts binary information form n input lines to a maximum of 2n unique output lines In practical applications decoders are often used for selecting one of several devices

                                            Demultiplexer A decoder with an enable input can function as a Demultiplexer A Demultiplexer (DMUX) id a circuit that receives information on a single line and transmits this information on one of 2n possible output lines The selection of a specific output line is controlled by the bit values of n selection lines DESIGN OF A 2 x 4 DECODER 1 x 4 DEMULTIPLEXER A 2 x 4 decoder is capable of selecting one of four output lines (see figure 71 (a)) The 2-bit binary number at the data inputs S1 and S0 specifies which of the four data inputs is to be selected If we add an enable pin and use it as an input line then this decoder can be converted to a 1 x 4 Demultiplexer where S1 and S0 will select a line to which data input is to be routed (see figure 71 (b))

                                            Select S0 S0 Inputs

                                            S1 D0 D1

                                            D2

                                            D3

                                            Enable (a) Block Diagram of a 2 x 4 Decoder

                                            Figure 71

                                            S1 D0 D1

                                            D2

                                            D3

                                            Inputs

                                            Data Input (b) Block Diagram of a 1 x 4 Demulptiplexer

                                            34

                                            Logic Design amp Switching Theory 1 Lab Session 07 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                            Figure 72 Circuit Diagram for 2 x 4 Decoder 1 x 4 Demultiplexer

                                            Implementation and Observations Implement the 2 x 4 Decoder 1 x 4 Demultiplexer circuit (figure 72) on a bread board (prepare the pin diagram (use appendix A) and refer to laboratory session 01 for implementation procedure) and record the observations in the following table

                                            Enable Data Input S1 S0 D0 D1 D2 D3

                                            0 0 0 0 0 1 0 1 0 0 1 1 1 0 0 1 0 1 1 1 0 1 1 1

                                            TESTING OF 74138 3 x 8 Decoder The 74138 IC has three inputs and eight output lines It has three enable inputs and for the IC to function all three inputs need to be enabled Function of various pins of this IC is described below

                                            35

                                            Logic Design amp Switching Theory 1 Lab Session 07 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                            bull Y0 through Y7 Active low data outputs bull A B C Input select lines with C being the MSB bull G1 Active high enable Input bull G2Arsquo and G2Brsquo Active low enable Inputs bull VCC and GND Supply connections lines Circuit Diagram

                                            Figure 73 Pin connections of 74138

                                            Testing Procedure

                                            bull Make connections as shown in the circuit diagram bull Apply different combinations of 1s and 0s at data inputs bull Observe the output and record your observations in the following table

                                            Observations

                                            C B A Y0 Y1 Y2 Y3 Y4 Y5 Y6 Y7 0 0 0 0 0 1 0 1 0 0 1 1 1 0 0 1 0 1 1 1 0 1 1 1

                                            36

                                            Logic Design amp Switching Theory 1 Lab Session 07 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                            37

                                            ACTIVITY ACTIVITY 1 What will be the binary values at the outputs Y0 through Y7 of 74138 if 1 What will be the binary values at the outputs Y0 through Y7 of 74138 if

                                            bull All three enable pins are connected to ground bull All three enable pins are connected to ground __________________________________________________________________________________________________________________________________________ __________________________________________________________________________________________________________________________________________ _____________________________________________________________________ _____________________________________________________________________

                                            bull All three enable pins are connected to VCC bull All three enable pins are connected to VCC _______________________________________________________________________________________________________________________________________________________________________________________________________________

                                            _______________________________________________________________________________________________________________________________________________________________________________________________________________

                                            2 Show connections for 74138 in order to use it as a 1 x 8 Demultiplexer 2 Show connections for 74138 in order to use it as a 1 x 8 Demultiplexer

                                            3 Consider a 2 x 4 Decoder with two enable inputs (one active high - G and one active low ndash Grsquo) Draw the output wave-forms for D0 D1 D2 and D3 if the two select inputs are A and B (B being the MSB) All outputs are active low

                                            Grsquo

                                            G

                                            A B

                                            D0 D1 D2

                                            D3

                                            Logic Design amp Switching Theory 1 Lab Session 08 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                            Lab Session 08 OBJECT

                                            bull Designing of a 4 x 2 Priority Encoder bull Experimenting with 74148 IC

                                            COMPONENTS AND APPARATUS REQUIRED

                                            1 Following ICs and their Datasheets

                                            bull 7408 Quad 2-input or 7421 Dual 4-input AND Gates bull 7432 Quad 2-input OR Gates bull 7404 Hex Inverter bull 74148 Encoder

                                            2 Digital Trainer DT-01 or the following components Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches

                                            THEORY

                                            Encoder An Encoder is a digital function that produces a reverse operation from that of a decoder An Encoder has 2n (or less) input lines and n output lines The output lines generate the binary code for the 2n input variables Priority Encoder

                                            A simple encoder may produce an erroneous output if more than one of its inputs is high A Priority Encoder is one that responds to just one input among those that may be simultaneously high in accordance with some priority system The most common priority system is based on the relative magnitudes of the inputs whichever decimal input is largest is the one that is encoded

                                            DESIGN OF A 4 x 2 Priority Encoder

                                            The following equations represent the outputs of a 4 x 2 priority encoder 32 DDA +=

                                            321 DDDB += As can be seen from the equations that input D0 which has a binary code 00 is not used in any equation A binary code 00 at the output indicates two conditions Either D0 is selected or no input is selected In order to differentiate these two conditions we will provide an additional output Z to indicate if at least one of the inputs is a 1 The equation for Z will be

                                            4321 DDDDZ = If Z is 0 then the binary code 00 at the output indicates that D0 is selected and if Z is 1 then it indicates that no input line is selected

                                            38

                                            Logic Design amp Switching Theory 1 Lab Session 08 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                            Figure 81 Circuit Diagram for 4 x 2 Priority Encoder

                                            it (figure 81) on a bread board (prepare the to laboratory session 01 for implementation

                                            Implementation a Implement the 4 x 2 Priority Encoder circu

                                            ram (use appendix A) and refer

                                            nd Observations

                                            pin diagprocedure) and record the observations in the following table

                                            D3 D2 D1 D0 A B 0 0 0 1 0 0 1 x 0 1 x x 1 x x x

                                            TESTING OF 74148 8 x 3 Octal Priority Encoder

                                            imal digits There are nine of which three represents

                                            ing any of the inputs is high

                                            then it shows that line 0 is selected and if e inputs selected E0 and GS

                                            cannot be in the same state provided that E1 is enabled

                                            The 74148 is a priority encoder with active-Low input for dec

                                            input) and five output linesinputs lines (including an enablethe binary code for the octal digit Function of various pins of this IC is described below

                                            bull 0 through 7 Active low data inputs representing the octal digits A2 A1 A0 Active low output lines representing the binary code bullbull E1 Active low enable Input bull E0 Active low output indicating none of the inputs is high bull GS Active low output indicatbull VCC and GND Supply connections lines Therefore if GS A2 A1 and A0 are all low

                                            then it shows that none of thE0 A2 A1 and A0 are all low

                                            39

                                            Logic Design amp Switching Theory 1 Lab Session 08 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                            Circuit Diagram

                                            Figure 82 Pin connections of 74148

                                            Testing Procedure bull Make connections as sho

                                            binations of 1s and 0s at data inputs d record your observations in the following table

                                            GS E0

                                            wn in the circuit diagram bull Apply different combull Observe the output an Observations

                                            0 1 2 3 4 5 6 7 A2 A1 A0 1 1 1 1 1 1 1 1 x x x x x x x 0 x x x x x x 0 1 x x x x x 0 1 1 x x x x 0 1 1 1 x x x 0 1 1 1 1 x x 0 1 1 1 1 1 x 0 1 1 1 1 1 1 0 1 1 1 1 1 1 1

                                            40

                                            Logic Design amp Switching Theory 1 Lab Session 08 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                            41

                                            CTIVITY

                                            Cascade the following two 74148 8 x 3 Priority Encoders to form 16 x 4 Priority

                                            A 1

                                            Encoder

                                            Logic Design amp Switching Theory 1 Lab Session 09 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering `

                                            Lab Session 09 OBJECT

                                            Designing an Odd Parity Generator and Checker for a 3-bit Data COMPONENTS AND APPARATUS REQUIRED

                                            1 Following ICs and their Datasheets

                                            bull 7486 Quad 2-input Exclusive-OR Gates bull 7404 Hex Inverter

                                            2 Digital Trainer DT-01 or the following components Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches

                                            THEORY

                                            Parity Generator When binary data is transmitted and processed it is ndash as are all electrical signals ndash susceptible to noise that can either alter or distort its contents 1s may be effectively changed to 0s and 0s to 1s To overcome this problem one or more bits are often added to the data as an aid in detecting errors caused by noise The most common of these is a Parity bit that signifies whether the total number of 1s in a code group is odd or even In an Odd Parity system the parity bit is made 0 or 1 as necessary to make the total number 1s odd (counting the parity bit itself) In an Even Parity system the parity bit is chosen to make the total number of 1s even Table 91 shows how parity bits would be added to BCD code group in both systems

                                            Decimal BCD Value Parity Bit ABCD Odd Parity Even Parity

                                            0 0000 1 0 1 0001 0 1 2 0010 0 1 3 0011 1 0 4 0100 0 1 5 0101 1 0 6 0110 1 0 7 0111 0 1 8 1000 0 1 9 1001 1 0

                                            Table 91 Odd and Even Parity in BCD

                                            When digital data is received a parity checking circuit generates an error signal if the total number of 1s is odd in an even parity system or if it is even in an odd parity system Parity check always detects a single error (one bit change from 0 to 1 or 1 to 0) but may not detect

                                            42

                                            Logic Design amp Switching Theory 1 Lab Session 09 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering ` two or more errors Odd parity is used more often than even parity because even parity does not detect a situation where all 0s are created due to short circuit or other fault condition DESIGN OF A 3-BIT ODD PARITY GENERATOR AND CHECKER Let x y and z be the three bits that constitute the message and are the input to the Odd Parity Generator Circuit Since it is an odd parity system the bit P is generated so as to make the total number of 1s odd (including P) The function P can be expressed as follows P = x oplus y Ο z or P = x Ο y oplus z Since the IC available is 7486 which is quad 2input XOR IC therefore we will convert XNOR also to XOR

                                            P = x oplus y Ο z

                                            P = ( x oplus y ) Ο z Since for even number of variables ______

                                            XOR = XNOR Therefore ___________ _________

                                            P = ( x oplus y ) oplus z = x oplus y oplus z This logical expression can be implemented with two XOR gates and an inverter (see figure 91)

                                            Figure 91 Circuit Diagram for a 3-bit Parity Generator

                                            The 3-bit message and the parity bit are transmitted to their destination where they are applied to a Parity Checker Circuit An error occurs during transmission if the parity of the four bits received is even since the binary information transmitted was originally odd The output C of the parity checker should be a 1 when an error occurs ie when the number of 1s in the four inputs is even Therefore the function C can be expressed as

                                            C = x Ο y Ο z Ο P

                                            Using the same logic applied for the conversion of the equation of P

                                            PzyxC oplusoplusoplus= This logical expression can be implemented with three XOR gates and an inverter (see figure 92)

                                            43

                                            Logic Design amp Switching Theory 1 Lab Session 09 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering `

                                            44

                                            Figure 92 Circuit Diagram for a 3-bit Parity Checker Implementation and Observations Implement the 3-bit Parity Generator and Checker circuits (figure 91 and 92) on a bread board (prepare the pin diagram (use appendix A) and refer to laboratory session 01 for implementation procedure) and record the observations in the following table

                                            x y z P x y z P C x y z P C 0 0 0 0 0 0 0 1 0 0 0 0 0 1 0 0 0 1 1 0 0 1 0 1 0 0 0 1 0 1 0 1 0 0 1 1 0 0 1 1 1 0 1 1 1 0 0 0 1 0 0 1 1 0 0 1 0 1 0 1 0 1 1 1 0 1 1 1 0 0 1 1 0 1 1 1 0 1 1 1 0 1 1 1 1 1 1 1

                                            Odd Parity Generation Odd Parity Check ACTIVITY 1 Try using the parity checker of figure 92 as 3-bit parity generator Write the details here

                                            _____________________________________________________________________________________________________________________________________________________________________________________________________________________ ______________________________________________________________________________________________________________________________________________ _______________________________________________________________________ ______________________________________________________________________________________________________________________________________________

                                            Logic Design amp Switching Theory 1 Lab Session 10 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                            Lab Session 10 OBJECT

                                            Driving a seven segment display using 7447 7448 driver IC COMPONENTS AND APPARATUS REQUIRED

                                            1 Following ICs and their Datasheets

                                            bull Seven Segment Displays (Common Anode Common Cathode) bull 7447 7448 BCD to Seven Segment Driver

                                            2 Digital Trainer DT-01 or the following components Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches

                                            THEORY Seven Segment Displays A Seven Segment Display consists of seven light-emitting segments The segments are designated by letters a through g (see figure 101) By illuminating various combinations of segments the numerals 0 through 9 can be displayed Seven Segment Displays are commonly constructed with light-emitting diodes (LEDs) and with liquid-crystal displays (LCDs) LEDs generally provide greater illumination levels but require much greater power than LCDs An LED display can be a common-anode type or common cathode type In common anode type a high voltage is applied at the common terminal of the display and low voltage is applied at a segmentrsquos terminal for illumination In the common-cathode type a low voltage is applied at the common terminal of the display and high voltage is applied at a segmentrsquos terminal for illumination

                                            Figure 101 Seven Segment Display

                                            a f b g

                                            e c d

                                            7447 7448 BCD to Seven Segment Driver 7447 7448 IC is particularly used to drive Seven Segment Its input is a BCD number and output drives a seven segment display 7447 is used to drive common-anode displays whereas 7448 is used to drive common cathode displays 7447 7448 is a 16 pin IC Function of various pins of these ICs is described below

                                            bull A B C D Inputs representing BCD digits (D being the MSB)

                                            45

                                            Logic Design amp Switching Theory 1 Lab Session 10 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering bull OA through OG Outputs to drive segments a through g of the display (Active low

                                            in 7447 and active high in 7448) bull RBI Ripple Blanking Input Turns off all the segments if kept low provided that LT

                                            is kept high and all other inputs (A B C D BI) are kept low Should be kept high otherwise

                                            bull BI RBO Wire-AND logic serving as a Blanking Input and or Ripple Blanking Output

                                            o BI Turns off all the segments if low o RBO Goes to a low level (response condition) along with other outputs when

                                            RBI and inputs A B C and D are low with LT input at high level bull LT Lamp Test input Tests whether all segments are working or not Illuminates all

                                            segments if kept low provided that BI is kept high Should be kept high otherwise bull VCC and GND Supply connections lines CIRCUIT DIAGRAM

                                            Figure 102 Circuit diagram for 7447driving a common-anode display

                                            IMPLEMENTATION AND OBSERVATIONS

                                            bull Make connections as shown in the circuit diagram (refer to laboratory session 01 for implementation procedure)

                                            bull Apply different combinations of 1s and 0s at data inputs bull Observe the output and record your observations in the following table

                                            46

                                            Logic Design amp Switching Theory 1 Lab Session 10 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                            47

                                            Decimal Digit

                                            BCD Inputs Seven Segment Outputs D C B A a b c d e f g

                                            0 0 0 0 0 1 0 0 0 1 2 0 0 1 0 3 0 0 1 1 4 0 1 0 0 5 0 1 0 1 6 0 1 1 0 7 0 1 1 1 8 1 0 0 0 9 1 0 0 1

                                            ACTIVITY 1 Perform the Lamp Test for the designed circuit and write your observations

                                            ____________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________

                                            2 How can you use 7447 IC to drive a common-cathode display

                                            ____________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________

                                            3 What symbols appear in the seven segment display if inputs DCBA are

                                            DCBA Symbol

                                            1010

                                            1011

                                            1100

                                            1101

                                            1110

                                            1111

                                            Logic Design amp Switching Theory 1 Lab Session 11 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                            48

                                            Lab Session 11 OBJECT

                                            Testing different modes of JK-FF COMPONENTS AND APPARATUS REQUIRED 1 Following ICs and their Datasheets

                                            bull 7473 7476 JK Flip-Flop 2 Digital Trainer DT-01 or the following components

                                            Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches

                                            THEORY

                                            Flip-Flop A flip-flop circuit can maintain a binary state indefinitely (as long as the power is delivered to the circuit) until directed by an input signal to switch states The major differences among various types of flip-flops are in the number of inputs they possess and in the manner in which the inputs affect the binary state

                                            JK Flip-Flop JK flip flop is an edge triggered device A typical JK flip flop has three inputs J K and a clock input The flip-flop can be either positive or negative edge triggered The output Q is available in complemented form as well Beside the usual inputs and output most of the flip-flop IC also possess two asynchronous inputs namely Preset and Clear These inputs are usually active low If used Preset and Clear inputs keep the flip-flop in set and reset state respectively irrespective of the other inputs Both of these inputs cannot be used simultaneously otherwise they will bring the flip-flop in unstable state

                                            Figure 111 Symbol for JK flip-flop

                                            (a) positive-edge triggering (b) active low Preset (PR) and Clear (CLR) with positive-edge triggering

                                            (c) active low Preset (PR) and Clear (CLR) with negative-edge triggering

                                            Logic Design amp Switching Theory 1 Lab Session 11 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                            49

                                            TESTING OF 7473 7476 DUAL JK FLIP-FLOP

                                            Both the ICs 7473 and 7476 are similar in functionality except for one difference The flip-flops in 7473 have only one type of active low asynchronous input which is the Clear input whereas the flip-flops in 7476 have both Preset and Clear inputs Both these ICs have negative edge triggered flip-flops

                                            Circuit Diagram

                                            Figure 112 Pin connections of 7476

                                            Testing Procedure

                                            bull Make connections as shown in the circuit diagram (figure 112) bull Apply different combinations of 1s and 0s at J and K inputs bull Observe the output and record your observations in the following table

                                            Observations

                                            J

                                            K Q

                                            0 0 0 1 1 0 1 1

                                            ACTIVITY

                                            1 Observe the output Q of JK flip-flop if the clock input is connected to VCC or GND instead of a clock source Write your observations here __________________________________________________________________________________________________________________________________________ _______________________________________________________________________________________________________________________________________________________________________________________________________________

                                            Logic Design amp Switching Theory 1 Lab Session 12 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                            50

                                            Lab Session 12 OBJECT

                                            Designing sequential circuit for the given state diagram using D flip-flop GIVEN STATE DIAGRAM

                                            00

                                            11

                                            Figure 121 State Diagram COMPONENTS AND APPARATUS REQUIRED 1 Following ICs and their Datasheets

                                            bull 7474 D Flip-Flop bull ICs of basic gates (AND OR NOT XOR etc) as required

                                            2 Digital Trainer DT-01 or the following components Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches

                                            THEORY

                                            Sequential Circuits In Sequential Circuits the output not only depends on the present inputs but also on previous states of the circuit These circuits use memory elements (latches flip-flops) and the binary information stored in the memory elements at any given time defines the state of the sequential circuit Analysis of a Sequential Circuit The behavior of a sequential circuit is determined from the inputs the outputs and the states of its flip-flops Both the outputs and next state are a function of the inputs and the

                                            10

                                            01

                                            00 11 10

                                            00

                                            00 11 10 00

                                            Logic Design amp Switching Theory 1 Lab Session 12 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                            51

                                            present state The analysis of a sequential circuit form a state diagram comprises of the following bull Selecting a particular flip-flop to design the circuit bull Obtaining state table from the state diagram bull Finding input equations for the selected flip-flop bull Finding state equations (not required for the construction of circuit) bull Implementing the circuit using selected flip-flops and their input equations ANALYZING THE GIVEN STATE DIAGRAM D Flip-Flop D flip-flop is also called transparent flip-flop as it simply transfers the input data to the output For our design we require the graphical symbol and excitation table of D flip-flop (see figure 122)

                                            Qt Qt+1 T 0 0 0 0 1 1 1 0 0 1 1 1

                                            (b) Excitation table of D Flip-Flop

                                            (a) Graphical Symbol

                                            Figure 122 Characteristic equation of D flip-flop is Q(t+1) = D State Table The given state diagram has four states so we will need two D flip-flops (FF-0 FF-1) Form state table form the given state diagram and record the results in the following table

                                            Present State Input Next State Output Input to FF-0 D0

                                            Input to FF-1 D1 Q1t Q0t x Q1(t+1) Q0(t+1) z

                                            Logic Design amp Switching Theory 1 Lab Session 12 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                            52

                                            Input Equations Using Karnaugh map the input equations D0 and D1 for the two flip-flops can be found

                                            D0 D1 Q0x

                                            Q1

                                            _ _ Q0x

                                            _ Q0x

                                            Q0x

                                            _ Q0x

                                            Q0x

                                            Q1

                                            _ _ Q0x

                                            _ Q0x

                                            Q0x

                                            _ Q0x

                                            _ Q1

                                            _ Q1

                                            Q1

                                            Q1

                                            D0 = _________________ D1 = _________________

                                            State Equations Using the characteristic equation of D flip-flop we can find the state equations Q0(t+1) and Q1(t+1) for the to flip flops Q0(t+1) = _______________________ Q1(t+1) = _______________________ _______________________ _______________________ _______________________ _______________________ Circuit Diagram

                                            Logic Design amp Switching Theory 1 Lab Session 12 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                            53

                                            Implementation Procedure and Observations

                                            1 Implement the circuit using digital ICs on a bread board (prepare the pin diagram (use appendix A) and refer to laboratory session 01 for procedure)

                                            2 Make the clear inputs of the flip-flops low (to clear the flip-flops) The flip-flops will remain in clear state as long as the clear inputs are connected to low level

                                            3 Connect output Q0 and the clock pulse to an oscilloscope 4 Apply 0 to the input x 5 Now make the clear inputs to high 6 Observe the waveform for the first 5 clock pulses and record it 7 Repeat steps 2 to 6 keeping x=1 in step 4 this time 8 Repeat steps 2 to 7 this time connecting Q1 instead of Q0 to the oscilloscope in step

                                            3 Record your observations (Keep frequency of the clock pulse low (eg1Hz) so that the output waveforms can be observed easily)

                                            1 2 3 4 5 Clock Pulse

                                            Output Waveform for Q0 when x=0

                                            Output Waveform for Q0 when x=1

                                            Output Waveform for Q1 when x=0

                                            Output Waveform for Q1 when x=1

                                            Logic Design amp Switching Theory 1 Lab Session 13 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                            Lab Session 13 OBJECT

                                            Designing a modulo-5 asynchronous up-counter using JK-FF COMPONENTS AND APPARATUS REQUIRED

                                            1 Following ICs and their Datasheets

                                            bull 7400 Quad 2-input or 7410 Triple 3-input NAND Gates bull 7476 7473 JK Flip-Flop

                                            2 Digital Trainer DT-01 or the following components Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches

                                            THEORY

                                            Digital Counters A digital counter is a set of flip-flops whose states change in response to pulses applied at the input to the counter The flip-flops are interconnected so that their combined state at any time is the binary equivalent of the total number of pulses that have occurred up to that time Every counter resets after a certain number of clock pulses Thus as it name implies a counter is used to count pulses An n stage counter can count up to a maximum of 2n states n is equal to the number of flip-flops required for the construction of counter

                                            Modulus Counters The number of input pulses that causes a counter to reset to its initial count is called the modulus of the counter Thus the modulus equals to total number of distinct states (counts) including zero that a counter can store A binary counter with n stages is a modulo-2n (or mod-2n) counter The largest count a mod-N counter can achieve is N-1 ie a mod-N counter never reaches the binary number equal to its modulus N is always equal to or less than 2n Counters can be classified as bull Synchronous Counters which are clock driven All the flip-flops are driven by a

                                            single clock bull Asynchronous Counters which are event driven Clock input is given to the first

                                            flip-flop only Rest of the flip-flops are driven by their preceding flip-flops

                                            DESIGN OF A MOD-5 ASYNCHRONOUS UP COUNTER The number of flip-flops required to construct a mod-5 counter is 3 because 5 should be less than or equal to 2n This counter will count from 0 to 4 a total of 5 distinct states Since a 3-stage counter can count up to 8 states at maximum a NAND gate is used to reset it after 5 clock pulses Figure 131 shows the logic diagram

                                            54

                                            Logic Design amp Switching Theory 1 Lab Session 13 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                            55

                                            Figure 131 A Mod-5 Asynchronous Up Counter

                                            Implementation and Observations

                                            Implement the mod-5 counter circuit (figure 131) on a bread board (prepare the pin diagram (use appendix A) and refer to laboratory session 01 for implementation procedure) and record the observations in the following table

                                            Clock Pulse Q2 Q1 Q0

                                            0 1 2 3 4 5 6 7

                                            ACTIVITY

                                            Draw the timing diagram for mod-5 counter designed in this laboratory session

                                            Logic Design amp Switching Theory 1 Lab Session 14 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                            Lab Session 14 OBJECT

                                            Experimenting with 74194 4-bit bidirectional universal shift register COMPONENTS AND APPARATUS REQUIRED

                                            1 Following ICs and their Datasheets

                                            bull 74194 4-bit bidirectional universal shift register 2 Digital Trainer DT-01 or the following components

                                            Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches

                                            THEORY

                                            Shift Registers

                                            A Register is a set of flip-flops used to store binary data A register which is capable of shifting its binary information either to the right or left is called a shift register The logical configuration of a register consists of a chain of flip-flops connected in cascade with the output of one flip-flop connected to the input of next flip-flop All flip-flops receive a common clock pulse which causes the shift from one stage to the next

                                            Bidirectional Shift Registers A bi-directional shift register is one whose bits can be shifted from left to right or from right to left

                                            Universal Shift Registers A universal shift register is a bi-directional register whose input can be in either serial or parallel form and whose output can be in either serial or parallel form

                                            74194 4-BIT BIDIRECTIONAL UNIVERSAL SHIFT REGISTER

                                            The 74194 register provides parallel as well as serial loading in both directions Function of various pins of this IC is described below

                                            bull A B C and D Active high inputs for parallel loading bull QA QB QC and QD Active high outputs bull S0 and S1 Active high mode control inputs The following table shows combinations

                                            of S1 and S0 to enable various modes

                                            S1 S0 Clock Action 0 0 x No change 0 1 uarr Shift right 1 0 uarr Shift left 1 1 uarr Parallel load

                                            uarr shows the rising edge of the clock pulse

                                            56

                                            Logic Design amp Switching Theory 1 Lab Session 14 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering bull SR Active high serial input for right shifting bull SL Active high serial input for left shifting bull CLR Active low input Clears all the flip-flops of the register if set to 0 should be

                                            kept high otherwise bull CLK Clock input bull VCC and GND Supply connections lines Thus A B C and D are inputs for parallel loading whereas SR and SL are inputs for serial loading with right or left shifting respectively S1 and S0 are used to select the loading mode Circuit Diagram

                                            Figure 141 Pin connections of 74194 Testing Procedure

                                            bull Make connections as shown in the circuit diagram bull Observe the output for the input combinations given in the following table

                                            57

                                            Logic Design amp Switching Theory 1 Lab Session 14 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                            58

                                            Observations

                                            S1 S0 SL SR A B C D QA QB QC QD 0 0 0 1 0 0 0 0 0 1 1 0 0 0 0 1 1 0 0 0 0 0 1 0 1 1 0 0 0 0 1 1 0 0 1 1 0 1 0 0 0 1 1 1 0 1 0 1 1 0 1 0 0 1 1 0 1 1 1 0 0 1 1 1 1 1 0 0 1 1 1 1

                                            ACTIVITY 1 Show connections of 74194 to convert it into a ring counter with right shifting

                                            Logic Design amp Switching Theory 1 Lab Session 15 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                            Lab Session 15

                                            OBJECT

                                            Experimenting with 74245 octal bus transceivers using parallel port PC interfacing COMPONENTS AND APPARATUS REQUIRED 1 Parallel Port Connectors (DB-25) with Cable 2 Personal Computer with Windows 98 and TurboC Compiler Installed 3 Following ICs and their Datasheets

                                            bull 74245 Octal Bus Transceivers with 3-State Outputs 4 Digital Trainer DT-01 or the following components

                                            Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches

                                            THEORY

                                            3-State Logic Sometimes it is necessary to isolate one part of circuit from the other part For this purpose some TTL ICs are designed with 3-state logic Such devices have three possible output states high low and high impedance The device can be put into high impedance state by a control signal applied to an appropriate pin When such a device is in high impedance state there is very high impedance at its output effectively isolating the device from whatever circuitry the output normally drives 74245 Octal Bus Transceivers A bus is any conducting path or set of paths having electrical connections to one or more devices 74245 octal bus transceivers are mainly used to control connectivity between two devices or circuits It also provides direction control for signal flow Function of various pin of this IC is given below

                                            bull A1 through A8 Bus A bull B1 through B8 Bus B bull G΄ Active low enable input When high sets all the bus pins to high impedance state bull DIR Direction control for signal flow When set to high logic level transfers bus A

                                            data to B bus When set to low logic level transfers bus B data to A bus bull VCC and GND Supply connections lines Serial and Parallel Port Connectors A Parallel Port can consist of only 25 pin port adapter called a DB-25 and a serial port can consist of either a 25 pin port adapter called a DB-25 or 9 pin adapter called a DB-9 port adapter Whether the port is a 9 pin or 25 pin it can accomplish all of the same tasks that serial port communications have been designed for

                                            59

                                            Logic Design amp Switching Theory 1 Lab Session 15 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                            60

                                            Each adapter can be a male type connector with pins or a female type adapter with tiny holes Generally a PRINTER port (called LPT1) on the back of a computer is female type adapter and we need to use MALE DB-25 pin cable on it for PRINTER connection or for parallel LAPLINK cable And a COM port on the back of a computer is male for the serial ports but it may not necessarily be Parallel Port Connector ndash DB-25 The DB-25 connector (named for its B-size D-shaped shell and 25 pins) is practically ubiquitous in the electronics industry The DB-25 connector is used for a variety of purposes Two common applications are RS-232EIA-232 (serial) connections and the parallel printer interface on the IBM PC The DB-25 connector is also used for SCSI connections Normally the parallel port is used for output to a printer or other device It sends data 8-bits or one byte at a time in parallel The other lines available on the DB-25 connector are a combination of status lines control lines and ground lines The status and control lines are used for handshaking commands and feedback when we are talking to a printer

                                            Figure 152 DB-25 Female Figure 151 DB-25 Male

                                            Figure 153 Pin Layout for DB-25 As can be seen form figure 153 there are four types of pins in this connector

                                            bull Data pins (8 pins - D0 to D7) Active high bidirectional lines

                                            Logic Design amp Switching Theory 1 Lab Session 15 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering bull Control pins (4 pins - C0 to C3) C0 C1 and C3 are active low whereas C2 is active

                                            high These lines also are bidirectional bull Status pins (5 pins ndash S3 to S7) Only S7 is active low rest are active high input lines bull Ground pins (8 pins) Used as a reference signal for the low (below 05 volts) charge

                                            Parallel Port Addresses A DB-25 connector at a parallel port has three address one for each kind of pins register data status and control The first or base address generally refers to data register Second address is for status register and the third one is for control register In Windows 98 the base address is usually found to be 278H 378H or 3BCH Now if 378H is the base address then it refers to the data register whereas addresses for status and control register are respectively 379H and 37AH For Windows 98 the base address can be found as follows 1 On your Desktop right-click on My Computer and select Properties 2 Click on the Device Manager tab and find LPT1 under Plug and Play BIOS 3 After selecting LPT1 click the Properties button 4 Next select the Resources tab and the address should then appear next to InputOutput

                                            Range Accessing parallel port through C Language Programming There are multiple functions in C Language for accessing external ports The most commonly used are listed below

                                            bull unsigned char inportb(int portid) inportb reads a byte from a hardware port

                                            bull int inport(int portid) reads a word from a hardware port

                                            bull void outportb(int portid unsigned char value) outputs a byte to a hardware port

                                            bull void outport(int portid int value) outputs a word to a hardware port

                                            portid refers to the port address whereas value refers to the data to be sent TESTING 74245 USING PARALLEL PORT PC INTERFACING At one end the parallel port connector will be connected to the PC via parallel port cable and another connector (to be plugged into the PC parallel port slot) At the other end it will be connected to the buffer IC 74245 Data lines of the connector will be used to transfer 8-bit data between the PC and the buffer Out of the 8-bits of 74245 4-bits will be used to enter data which will be displayed at the monitor through a C language

                                            61

                                            Logic Design amp Switching Theory 1 Lab Session 15 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering program The remaining 4-bits will receive data from PC as entered by the user via keyboard

                                            Circuit Diagram

                                            Figure 154 Interface of 74245 to PC via Parallel Port

                                            Procedure

                                            1 Connect the DB-25 connector to the PC at one end and solder it to the circuit board at the other end

                                            2 Connect various pins of the connector and 74245 according to the circuit diagram shown in figure 152

                                            3 Using the functions listed in the previous section write a program in C language to operate various pins of the buffer The user interface of the program should provide option to the user whether to send or receive data from the port

                                            4 Set DIR switch to 1 5 Try sending some data bits to the port The result should be displayed at the LEDs 6 Set DIR switch to 0 7 Set some binary 4-bit value through the switches Try reading it via parallel port

                                            C Language Program

                                            A program to access parallel port for data transfers

                                            use header file include ltstdiohgt main program void main() define variable

                                            62

                                            Logic Design amp Switching Theory 1 Lab Session 15 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering unsigned int data=0 char choice while(1) printing option menu clrscr() printf(This program will send or receive a BCD digit from the parallel portn) printf(nPress your choice numbern) printf(n1 Send Data) printf(n2 Receive Data) printf(n3 Exitn) choice = getch() sending entered digit to the port if(choice == 1) input BCD digit printf(nEnter BCD digit to be sent to the port) data = getche() masking the first four bits data = data amp 0x0f sending to the port outportb(0x378data) printf(nThe BCD digit c has been sent to the port data) printing on screen the data received from the port else if(choice == 2) receiving data from the port data = inportb(0x378) masking the last four bits data = data amp 0xf0 shifting first four bits to make them the last four bits datagtgt=4 printf(nThe BCD digit set at the port is c data) exit else if(choice == 3) break key pressed is not in the menu else printf(nEnter valid choice number) printf(nnPress any key to continue) getch()

                                            63

                                            Logic Design amp Switching Theory 1 Lab Session 15 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                            ACTIVITY 1 In the above circuit DIR and G΄ inputs are hardwired Connect them to status or

                                            control pins of the parallel port connector and control their function through your software program Circuit Diagram Program Code ______________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________

                                            ___________________________________________________________________________________________________________________________________________________

                                            64

                                            Logic Design amp Switching Theory 1 Lab Session 15 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                            65

                                            _____________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ _____________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ _______________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ _________________________________________________ _________________________________________________

                                            Logic Design amp Switching Theory 1 Appendix A NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                            Appendix A

                                            PIN DIAGRAMS OF THE ICS REQUIRED FOR THE LABORATORY SESSIONS Consult the TTLIC data book for internal diagrams and electrical characteristics of these ICs 7400 Quad 2-Input NAND 7402 Quad 2-Input NOR

                                            7404 Hex Inverter 7408 Quad 2-Input AND

                                            7410 Triple 3-Input NAND 7411 Triple 3-Input AND

                                            7421 Dual 4-Input AND 7432 Quad 2-Input OR

                                            66

                                            Logic Design amp Switching Theory 1 Appendix A NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                            BCD-to-Seven Segm 7448 BCD-to-Seven Segment 7447 ent

                                            Decoder (15V OC) Decoder (2kΩ pull-up output)

                                            7473 Dual JK Flip-Flop 7474 Dual D-Type Flip-Flop

                                            7476 Dual JK Flop-Flop -Bit Binary Full Adder 7483 4 with Fast Carry

                                            86 Quad 2-Inpu 74138 3-to-8 Line 74 t Exclusive OR Decoder Demultiplexer

                                            67

                                            Logic Design amp Switching Theory 1 Appendix A NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                            68

                                            74148 8-to-3 Line 16-to-1 Line Data

                                            Priority Encoder 74150 Selector Multiplexer

                                            74245 Oct nsceivers Universal Shift Register (PIPO) (3-State)

                                            74194 4-Bit Bidirectional al Bus Tra

                                            Logic Design amp Switching Theory 1 Appendix B NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                            Appendix B

                                            DEBOUNCING CIRCUITRY FOR MECHANICAL SWITCHES Mechanical switches form the interface between human beings and computers or other digital systems For example a keyboard is a matrix of switches used to supply alphanumeric data to a computer Whatever the switch design it is a potential source of problems due to contact bounce The contact bounce creates a sense of narrow pulses when a switch is opened or closed An example of device whose operation would be adversely affected by contact bounce is a digital counter used to count the number of times a switch is depressed Eliminating the effects of contact bounce is called debouncing When data is entered into a computer via a keyboard a software debounce is often used This type of debouncing is a program that causes the computer to sample the switch terminal (ie to input data from it) many times in succession during the interval of time that contact bounce occurs If the data is sensed to be 1s (or 0s) for a specific number of consecutive samples then it is assumed that contact bounce has ended and the last value sensed is valid Hardware debouncing is the use of electronic circuitry to eliminate the effects of contact bounce There are numerous versions of such circuitry including those that use monostable multivibrators (one-shots) but the most straightforward is simply an RS latch Figure B1 shows the circuit When the switch is in position 1 R = 0 and S = 1 so the latch is set and the output (Q) is 1 When the switch is in position 0 R = 1and S = 0 so the latch is reset and the output is 0 When the switch is moved form one position to the other the latch changes state and bouncing occurs at either the R or the S input The bouncing does not affect the latch after it has change state An RS latch will remain set for example when its R input is 0 and its S input is alternately changed form 1 to 0

                                            Figure B1 Use of RS latch to debounce a mechanical switch

                                            69

                                            • 01-ldst-Outer title
                                              • Practical Workbook
                                              • Logic Design amp Switching Theory I
                                                • Dept of Computer amp Information Systems Engineering
                                                  • NED University of Engineering amp Technology
                                                  • Karachi ndash 75270 Pakistan
                                                    • 02-ldst-inner Title
                                                      • Practical Workbook
                                                      • Logic Design amp Switching Theory I
                                                        • Dept of Computer amp Information Systems Engineering
                                                          • NED University of Engineering amp Technology
                                                          • Karachi ndash 75270 Pakistan
                                                            • 03-ldst-general info
                                                            • 04-ldst-introduction
                                                            • 05-Table of Contents
                                                              • CONTENTS
                                                                • Lab Session No Object Page No
                                                                • 1
                                                                • Also implementing and testing the given circuit on a bread board
                                                                  • Working with Electronics Workbench
                                                                    • Driving a seven segment display using 7447 7448 driver IC
                                                                      • Designing a modulus-5 asynchronous up-counter using JK-FF
                                                                        • Experimenting with 74194 4-bit bidirectional universal shift register
                                                                            • 13
                                                                                • 06-ldst-Exp01
                                                                                  • Lab Session 01
                                                                                  • OBJECT
                                                                                    • 1 Bread board
                                                                                    • 2 5 V - power supply
                                                                                    • 3 Multimeter
                                                                                    • 4 Logic probe
                                                                                    • 5 LEDs with resistors
                                                                                    • 6 Connecting wires
                                                                                    • 8 Following ICs and their datasheets
                                                                                      • THEORY
                                                                                        • Logic Gates
                                                                                        • 1 The AND Gate ndash An AND gatersquos output is 1 if and only if all its inputs are 1 If A and B are two inputs to an AND gate then output F of the gate is given as F = AB
                                                                                        • 2 The OR Gate - An OR gatersquos output is 1 if at least one of its input is 1 If A and B are two inputs to an OR gate then output F of the gate is given as F = A+B
                                                                                        • 3 The NOT Gate (Inverter) ndash Its output is 1 when its input is 0 and its output is 0 when the input is 1 ie it complements a digital variable If A is the input to a NOT gate then output F of the gate is given as
                                                                                        • 4 The NAND Gate ndash Its output is 1 if at least one of its input is 0 This gate performs the same logic as an AND gate followed by an inverter If A and B are two inputs to a NAND gate then output F of the gate is given as
                                                                                          • 5 The NOR Gate - The output of a NOR gate is 1 if and only if all its inputs are 0 This gate performs the same logic function as an OR gate followed by an inverter If A and B are two inputs to a NAND gate then output F of the gate is given as
                                                                                              • DATA SHEETS
                                                                                                • Logic expression for the given logic diagram __________________________________
                                                                                                    • 07-ldst-exp02
                                                                                                      • Working with Electronics Workbench
                                                                                                        • 08-ldst-exp03
                                                                                                          • Designing Half and Full Adder Circuits
                                                                                                            • COMPONENTS AND APPARATUS REQUIRED
                                                                                                              • 1 Following ICs and their Datasheets
                                                                                                              • 7408 Quad 2-input AND Gate
                                                                                                              • 2 Digital Trainer DT-01 or the following components
                                                                                                                • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                • Connecting wires Switches
                                                                                                                  • THEORY
                                                                                                                      • IMPLEMENTATION AND OBSERVATIONS
                                                                                                                        • 09-ldst-Exp04
                                                                                                                          • Lab Session 04
                                                                                                                          • 1 Digital ICs and their Datasheets
                                                                                                                          • 7408 Quad 2-input AND Gate
                                                                                                                          • 2 Digital Trainer DT-01 or the following components
                                                                                                                            • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                            • Connecting wires Switches
                                                                                                                            • PROCEDURE
                                                                                                                            • REDUCTION OF LOGIC EXPRESSION USING KARNAUGH MAP
                                                                                                                            • OBSERVATIONS
                                                                                                                            • RESULT
                                                                                                                                • 10-ldst-Exp05
                                                                                                                                  • Lab Session 05
                                                                                                                                  • 1 Following ICs and their Datasheets
                                                                                                                                  • 7408 Quad 2-input AND Gate
                                                                                                                                  • 2 Digital Trainer DT-01 or the following components
                                                                                                                                    • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                    • (100 Ω) Connecting wires Switches
                                                                                                                                    • THEORY
                                                                                                                                      • IMPLEMENTATION AND OBSERVATIONS
                                                                                                                                        • 11-ldst-Exp06
                                                                                                                                          • OBJECT
                                                                                                                                          • 1 Following ICs and their Datasheets
                                                                                                                                          • 7408 Quad 2-input AND Gates or 7411 Triple 3-input AND Gates
                                                                                                                                          • 2 Digital Trainer DT-01 or the following components
                                                                                                                                            • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                            • Connecting wires Switches
                                                                                                                                              • Figure 62 Circuit Diagram for 4 x 1 Multiplexer
                                                                                                                                              • Implementation and Observations
                                                                                                                                                • Circuit Diagram
                                                                                                                                                  • ACTIVITY
                                                                                                                                                    • 12-ldst-exp07
                                                                                                                                                      • 1 Following ICs and their Datasheets
                                                                                                                                                      • 7408 Quad 2-input or 7411 Triple 3-input AND Gates
                                                                                                                                                      • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                        • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                        • Connecting wires Switches
                                                                                                                                                          • THEORY
                                                                                                                                                              • Figure 72 Circuit Diagram for 2 x 4 Decoder 1 x 4 Demultiplexer
                                                                                                                                                              • Implementation and Observations
                                                                                                                                                                • Circuit Diagram
                                                                                                                                                                  • ACTIVITY
                                                                                                                                                                    • 13-ldst-Exp08
                                                                                                                                                                      • OBJECT
                                                                                                                                                                      • 1 Following ICs and their Datasheets
                                                                                                                                                                      • 7408 Quad 2-input or 7421 Dual 4-input AND Gates
                                                                                                                                                                      • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                        • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                        • Connecting wires Switches
                                                                                                                                                                          • THEORY
                                                                                                                                                                              • Figure 81 Circuit Diagram for 4 x 2 Priority Encoder
                                                                                                                                                                              • Implementation and Observations
                                                                                                                                                                                • Therefore if GS A2 A1 and A0 are all low then it shows that line 0 is selected and if E0 A2 A1 and A0 are all low then it shows that none of the inputs selected E0 and GS cannot be in the same state provided that E1 is enabled
                                                                                                                                                                                • Circuit Diagram
                                                                                                                                                                                  • ACTIVITY
                                                                                                                                                                                    • 14-ldst-exp09
                                                                                                                                                                                      • OBJECT
                                                                                                                                                                                      • 1 Following ICs and their Datasheets
                                                                                                                                                                                      • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                        • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                        • Connecting wires Switches
                                                                                                                                                                                          • THEORY
                                                                                                                                                                                            • Parity Generator
                                                                                                                                                                                              • Let x y and z be the three bits that constitute the message and are the input to the Odd Parity Generator Circuit Since it is an odd parity system the bit P is generated so as to make the total number of 1s odd (including P) The function P can be expressed as follows
                                                                                                                                                                                              • Figure 91 Circuit Diagram for a 3-bit Parity Generator
                                                                                                                                                                                                • C = x Ο y Ο z Ο P
                                                                                                                                                                                                  • Implementation and Observations
                                                                                                                                                                                                    • ACTIVITY
                                                                                                                                                                                                        • 15-ldst-exp10
                                                                                                                                                                                                          • Driving a seven segment display using 7447 7448 driver IC
                                                                                                                                                                                                          • COMPONENTS AND APPARATUS REQUIRED
                                                                                                                                                                                                          • 1 Following ICs and their Datasheets
                                                                                                                                                                                                          • 7447 7448 BCD to Seven Segment Driver
                                                                                                                                                                                                          • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                            • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches
                                                                                                                                                                                                              • THEORY
                                                                                                                                                                                                              • Seven Segment Displays
                                                                                                                                                                                                              • CIRCUIT DIAGRAM
                                                                                                                                                                                                              • Figure 102 Circuit diagram for 7447driving a common-anode display
                                                                                                                                                                                                                  • IMPLEMENTATION AND OBSERVATIONS
                                                                                                                                                                                                                    • Decimal Digit
                                                                                                                                                                                                                    • BCD Inputs
                                                                                                                                                                                                                    • Seven Segment Outputs
                                                                                                                                                                                                                    • D
                                                                                                                                                                                                                    • C
                                                                                                                                                                                                                    • B
                                                                                                                                                                                                                    • A
                                                                                                                                                                                                                    • a
                                                                                                                                                                                                                    • b
                                                                                                                                                                                                                    • c
                                                                                                                                                                                                                    • d
                                                                                                                                                                                                                    • e
                                                                                                                                                                                                                    • f
                                                                                                                                                                                                                    • g
                                                                                                                                                                                                                    • 0
                                                                                                                                                                                                                    • 0
                                                                                                                                                                                                                    • 0
                                                                                                                                                                                                                    • 0
                                                                                                                                                                                                                    • 0
                                                                                                                                                                                                                    • 1
                                                                                                                                                                                                                    • 0
                                                                                                                                                                                                                    • 0
                                                                                                                                                                                                                    • 0
                                                                                                                                                                                                                    • 1
                                                                                                                                                                                                                    • 2
                                                                                                                                                                                                                    • 0
                                                                                                                                                                                                                    • 0
                                                                                                                                                                                                                    • 1
                                                                                                                                                                                                                    • 0
                                                                                                                                                                                                                    • 3
                                                                                                                                                                                                                    • 0
                                                                                                                                                                                                                    • 0
                                                                                                                                                                                                                    • 1
                                                                                                                                                                                                                    • 1
                                                                                                                                                                                                                    • 4
                                                                                                                                                                                                                    • 0
                                                                                                                                                                                                                    • 1
                                                                                                                                                                                                                    • 0
                                                                                                                                                                                                                    • 0
                                                                                                                                                                                                                    • 5
                                                                                                                                                                                                                    • 0
                                                                                                                                                                                                                    • 1
                                                                                                                                                                                                                    • 0
                                                                                                                                                                                                                    • 1
                                                                                                                                                                                                                    • 6
                                                                                                                                                                                                                    • 0
                                                                                                                                                                                                                    • 1
                                                                                                                                                                                                                    • 1
                                                                                                                                                                                                                    • 0
                                                                                                                                                                                                                    • 7
                                                                                                                                                                                                                    • 0
                                                                                                                                                                                                                    • 1
                                                                                                                                                                                                                    • 1
                                                                                                                                                                                                                    • 1
                                                                                                                                                                                                                    • 8
                                                                                                                                                                                                                    • 1
                                                                                                                                                                                                                    • 0
                                                                                                                                                                                                                    • 0
                                                                                                                                                                                                                    • 0
                                                                                                                                                                                                                    • 9
                                                                                                                                                                                                                    • 1
                                                                                                                                                                                                                    • 0
                                                                                                                                                                                                                    • 0
                                                                                                                                                                                                                    • 1
                                                                                                                                                                                                                      • ACTIVITY
                                                                                                                                                                                                                        • 16-ldst-exp11
                                                                                                                                                                                                                          • Lab Session 11
                                                                                                                                                                                                                            • OBJECT
                                                                                                                                                                                                                            • COMPONENTS AND APPARATUS REQUIRED
                                                                                                                                                                                                                              • 1 Following ICs and their Datasheets
                                                                                                                                                                                                                              • 7473 7476 JK Flip-Flop
                                                                                                                                                                                                                              • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                                • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                                                • Connecting wires Switches
                                                                                                                                                                                                                                  • THEORY
                                                                                                                                                                                                                                      • Flip-Flop
                                                                                                                                                                                                                                      • JK Flip-Flop
                                                                                                                                                                                                                                        • Circuit Diagram
                                                                                                                                                                                                                                          • Observations
                                                                                                                                                                                                                                            • ACTIVITY
                                                                                                                                                                                                                                                • 17-ldst-exp12
                                                                                                                                                                                                                                                  • Lab Session 12
                                                                                                                                                                                                                                                    • OBJECT
                                                                                                                                                                                                                                                    • GIVEN STATE DIAGRAM
                                                                                                                                                                                                                                                    • Figure 121 State Diagram
                                                                                                                                                                                                                                                    • COMPONENTS AND APPARATUS REQUIRED
                                                                                                                                                                                                                                                      • 1 Following ICs and their Datasheets
                                                                                                                                                                                                                                                      • 7474 D Flip-Flop
                                                                                                                                                                                                                                                      • ICs of basic gates (AND OR NOT XOR etc) as required
                                                                                                                                                                                                                                                      • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                                                        • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                                                                        • Connecting wires Switches
                                                                                                                                                                                                                                                          • THEORY
                                                                                                                                                                                                                                                              • Sequential Circuits
                                                                                                                                                                                                                                                                • 18-ldst-exp13
                                                                                                                                                                                                                                                                  • Lab Session 13
                                                                                                                                                                                                                                                                    • Designing a modulo-5 asynchronous up-counter using JK-FF
                                                                                                                                                                                                                                                                      • 1 Following ICs and their Datasheets
                                                                                                                                                                                                                                                                      • 7400 Quad 2-input or 7410 Triple 3-input NAND Gates
                                                                                                                                                                                                                                                                      • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                                                                        • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                                                                                        • Connecting wires Switches
                                                                                                                                                                                                                                                                          • THEORY
                                                                                                                                                                                                                                                                              • Figure 131 A Mod-5 Asynchronous Up Counter
                                                                                                                                                                                                                                                                              • Implementation and Observations
                                                                                                                                                                                                                                                                                • ACTIVITY
                                                                                                                                                                                                                                                                                    • 19-ldst-exp14
                                                                                                                                                                                                                                                                                      • Experimenting with 74194 4-bit bidirectional universal shift register
                                                                                                                                                                                                                                                                                      • 1 Following ICs and their Datasheets
                                                                                                                                                                                                                                                                                      • 74194 4-bit bidirectional universal shift register
                                                                                                                                                                                                                                                                                      • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                                                                                        • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                                                                                                        • Connecting wires Switches
                                                                                                                                                                                                                                                                                          • THEORY
                                                                                                                                                                                                                                                                                            • Shift Registers
                                                                                                                                                                                                                                                                                            • Bidirectional Shift Registers
                                                                                                                                                                                                                                                                                            • Universal Shift Registers
                                                                                                                                                                                                                                                                                              • S1
                                                                                                                                                                                                                                                                                                • Circuit Diagram
                                                                                                                                                                                                                                                                                                • ACTIVITY
                                                                                                                                                                                                                                                                                                    • 20-ldst-exp15
                                                                                                                                                                                                                                                                                                      • COMPONENTS AND APPARATUS REQUIRED
                                                                                                                                                                                                                                                                                                      • 1 Parallel Port Connectors (DB-25) with Cable
                                                                                                                                                                                                                                                                                                      • 2 Personal Computer with Windows 98 and TurboC Compiler Installed
                                                                                                                                                                                                                                                                                                      • 3 Following ICs and their Datasheets
                                                                                                                                                                                                                                                                                                      • 74245 Octal Bus Transceivers with 3-State Outputs
                                                                                                                                                                                                                                                                                                      • 4 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                                                                                                        • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                                                                                                                          • Connecting wires Switches
                                                                                                                                                                                                                                                                                                            • THEORY
                                                                                                                                                                                                                                                                                                            • 3-State Logic
                                                                                                                                                                                                                                                                                                              • Serial and Parallel Port Connectors
                                                                                                                                                                                                                                                                                                              • Parallel Port Connector ndash DB-25
                                                                                                                                                                                                                                                                                                                • Accessing parallel port through C Language Programming
                                                                                                                                                                                                                                                                                                                    • 21-ldst-appendixA
                                                                                                                                                                                                                                                                                                                    • 22-ldst-appendixB
                                                                                                                                                                                                                                                                                                                      • DEBOUNCING CIRCUITRY FOR MECHANICAL SWITCHES

                                              Logic Design amp Switching Theory 1 Lab Session 04 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                              ACTIVITY 2

                                              Using Electronics Workbench find a simplified logic expression and circuit for the following truth table

                                              A B C Output 0 0 0 1 0 0 1 1 0 1 0 0 0 1 1 1 1 0 0 0 1 0 1 0 1 1 0 0 1 1 1 1

                                              Procedure 1 Click three input channels from A to H across the top of the logic converter The

                                              display area below the terminals fills up with the necessary combinations of ones and zeros to fulfill the input conditions The values in the output column on the right are initially set to 0

                                              2 Edit the output column to specify the desired output for each input condition To change an output value select it and type a new value 1 0 or x An x indicates a donrsquot care condition

                                              3 To convert this truth table to a Boolean expression click the Truth Table to Boolean Expression button The Boolean expression will be displayed at the bottom of the logic converter

                                              4 Simplify the expression by clicking the Simplify button 5 Now click the Boolean Expression to Circuit button This creates the logic circuit for

                                              the given expression in the design area Resulting Logic Circuit For the given truth table the final simplified circuit will look like

                                              Figure 42

                                              25

                                              Logic Design amp Switching Theory 1 Lab Session 04 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                              ACTIVITY 3

                                              Using Electronics Workbench find the logic expression and truth table for the following logic circuit

                                              Figure 43

                                              Procedure 1 Attach the input terminals of the logic converter to up to four input points in the

                                              circuit 2 Connect the single output of the circuit to the output terminal on the logic converter

                                              icon 3 Click the Circuit to Truth Table button The truth table appears in the logic

                                              converters display 4 To convert this truth table to a Boolean expression click the Truth Table to Boolean

                                              Expression button The Boolean expression will be displayed at the bottom of the logic converter

                                              Resulting Logic Expression Logic Expression for the given circuit is found to be _____________________________

                                              26

                                              Logic Design amp Switching Theory 1 Lab Session 04 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                              27

                                              For activities 1 2 and 3 attach hardcopy of the output (truth table logic expression and logic circuit) form electronic workbench here

                                              Logic Design amp Switching Theory 1 Lab Session 05 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                              Lab Session 05 Lab Session 05 OBJECT OBJECT

                                              Designing a BCD Adder Designing a BCD Adder COMPONENTS AND APPARATUS REQUIRED COMPONENTS AND APPARATUS REQUIRED

                                              1 Following ICs and their Datasheets 1 Following ICs and their Datasheets bull 7408 Quad 2-input AND Gate bull 7408 Quad 2-input AND Gate bull 7432 Quad 2-input OR Gate bull 7432 Quad 2-input OR Gate bull 7483 4-bit Binary Adder bull 7483 4-bit Binary Adder

                                              2 Digital Trainer DT-01 or the following components 2 Digital Trainer DT-01 or the following components Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors (100 Ω) Connecting wires Switches (100 Ω) Connecting wires Switches

                                              THEORY THEORY

                                              A BCD Adder is a combinational circuit that adds two BCD digits in parallel and produces a sum digit also in BCD A BCD Adder is a combinational circuit that adds two BCD digits in parallel and produces a sum digit also in BCD

                                              A4 A3 A2 A1 B4 B3 B2 B1

                                              7483-BCD ADDER

                                              Cout (C4 ) Z4 Z3 Z2 Z1 Cin(C0)

                                              A4 A3 A2 A1 B4 B3 B2 B1

                                              7483-BCD ADDER

                                              Cout

                                              (C4 ) Z4 Z3 Z2 Z1 Cin(C0)

                                              Figure 51 BCD Adder Circuit

                                              28

                                              Logic Design amp Switching Theory 1 Lab Session 05 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                              29

                                              A BCD adder must include the correction logic in its internal construction The two BCD digits together with the input carry are first added using a 4-bit binary adder to produce the binary sum If no output carry is generated and the binary sum is less than or equal to 9 then the corresponding BCD sum is identical and therefore no conversion is needed When the output carry is equal to 1 or the binary sum is greater than 9 then a binary 0110 is added to the binary sum through another 4-bit binary adder If Cout is the carry output and Z4Z3Z2Z1 is the binary sum form the first 4-bit binary adder then the following equation indicates the condition when a binary 0110 is to be added

                                              C = COUT + Z4Z2 + Z4Z3 IMPLEMENTATION AND OBSERVATIONS Implement the BCD adder circuit according to figure 51 on a bread board (prepare the pin diagram (use appendix A) and refer to laboratory session 01 for procedure) A BCD adder has nine input bits (two BCD digits and a carry bit) which can result in a total of 512 combinations of which 312 inputs are donrsquot care Since it is a very lengthy procedure to record results for 200 valid input combinations therefore for simplicity just record results for any eight combinations in the following table

                                              Input Carry

                                              BCD Digit 1 BCD Digit 2 Carry Output

                                              BCD Sum A4 A3 A2 A1 B4 B3 B2 B1 Z4 Z3 Z2 Z1

                                              Logic Design amp Switching Theory 1 lab Session 06 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                              Lab Session 06

                                              OBJECT

                                              bull Designing of a 4 x 1 Multiplexer bull Experimenting with 74150 IC

                                              COMPONENTS AND APPARATUS REQUIRED 1 Following ICs and their Datasheets

                                              bull 7408 Quad 2-input AND Gates or 7411 Triple 3-input AND Gates bull 7432 Quad 2-input OR Gates bull 7404 Hex Inverter bull 74150 16 x 1 MUX

                                              2 Digital Trainer DT-01 or the following components Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches THEORY

                                              Multiplexers A digital data Multiplexer (MUX) is a combinational circuit having several data inputs and a single output A set of data-select inputs is used to control which of the data inputs is routed to the single output A multiplexer is also called a data selector because of this ability to select which data input is connected o the output Normally there are 2n input lines and n selection lines whose bit combination determine which input is selected DESIGN OF A 4 x 1 MULTIPLEXER A 4 x 1 multiplexer is capable of selecting one of four data inputs (see figure 61) The 2-bit binary number at the data select inputs S1 and S0 specifies which of the four data inputs is to be routed to the output Since there are two data select inputs therefore they can select 22 = 4 different data inputs lines

                                              S0 S1 D0 D1

                                              D2 D3

                                              Data-select Inputs Output

                                              Data Inputs

                                              Figure 61 Block Diagram of a 4 x1 Multiplexer

                                              30

                                              Logic Design amp Switching Theory 1 lab Session 06 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                              Figure 62 Circuit Diagram for 4 x 1 Multiplexer

                                              Implementation and Observations

                                              Implement the 4 x 1 Multiplexer circuit (figure 62) on a bread board (prepare the pin diagram (use appendix A) and refer to laboratory session 01 for implementation procedure) and record the observations in the following table For each data select combination specify the switch number as well as the binary value present on that selected switch

                                              S1 S0 Output 0 0 0 1 1 0 1 1

                                              TESTING OF 74150 - 16 x 1 MUX

                                              The 74150 IC has sixteen data inputs and four data-selection lines Function of various pins of this IC is described below

                                              bull E0 through E15 Data input lines

                                              31

                                              Logic Design amp Switching Theory 1 lab Session 06 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering bull A B C D Data select lines with D being the MSB bull W Active low output line bull Grsquo Active low enable line bull VCC and GND Supply connections lines

                                              Circuit Diagram

                                              Figure 63 Pin connections of 74150 for selecting E0

                                              Testing Procedure

                                              bull Make connections as shown in the circuit diagram bull Apply different data (1 or 0) at data inputs that are labeled as E0 to E15 Only

                                              connection for E0 is shown is the figure for simplicity bull Select the data input E0 with the help of data selectors A B C and D bull Observe the output which shows the complement of the data from E0 bull Select all the sixteen data inputs one by one and record your observations in the

                                              following table

                                              32

                                              Logic Design amp Switching Theory 1 lab Session 06 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                              33

                                              Observations

                                              Grsquo D C B A W Grsquo D C B A W 0 0 0 0 0 0 1 0 0 0 0 0 0 0 1 0 1 0 0 1 0 0 0 1 0 0 1 0 1 0 0 0 0 1 1 0 1 0 1 1 0 0 1 0 0 0 1 1 0 0 0 0 1 0 1 0 1 1 0 1 0 0 1 1 0 0 1 1 1 0 0 0 1 1 1 0 1 1 1 1

                                              ACTIVITY 1 Consider 4x1 Multiplexer Draw the output wave-form for the following data inputs

                                              (E0 E1 E2 E3) and select lines A B (B being the MSB) Output is W

                                              E3 E2 E1 E0 A B

                                              W

                                              2 Using the 4 x 1 MUX designed in this laboratory session implement the following logical function F (A B C) = Σ (0147)

                                              Show your working and input connections in the following block diagram according to the circuit you have implemented

                                              4 x 1 MUX

                                              S0 S1

                                              Output D0

                                              D1

                                              D2

                                              D3

                                              Logic Design amp Switching Theory 1 Lab Session 07 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                              Lab Session 07

                                              OBJECT

                                              bull Designing of a 2 x 4 Decoder 1 x 4 Demultiplexer bull Experimenting with 74138 IC

                                              COMPONENTS AND APPARATUS REQUIRED 1 Following ICs and their Datasheets

                                              bull 7408 Quad 2-input or 7411 Triple 3-input AND Gates bull 7404 Hex Inverter bull 74138 3 x 8 Decoder

                                              2 Digital Trainer DT-01 or the following components Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches THEORY

                                              Decoder A Decoder is a combinational circuit that converts binary information form n input lines to a maximum of 2n unique output lines In practical applications decoders are often used for selecting one of several devices

                                              Demultiplexer A decoder with an enable input can function as a Demultiplexer A Demultiplexer (DMUX) id a circuit that receives information on a single line and transmits this information on one of 2n possible output lines The selection of a specific output line is controlled by the bit values of n selection lines DESIGN OF A 2 x 4 DECODER 1 x 4 DEMULTIPLEXER A 2 x 4 decoder is capable of selecting one of four output lines (see figure 71 (a)) The 2-bit binary number at the data inputs S1 and S0 specifies which of the four data inputs is to be selected If we add an enable pin and use it as an input line then this decoder can be converted to a 1 x 4 Demultiplexer where S1 and S0 will select a line to which data input is to be routed (see figure 71 (b))

                                              Select S0 S0 Inputs

                                              S1 D0 D1

                                              D2

                                              D3

                                              Enable (a) Block Diagram of a 2 x 4 Decoder

                                              Figure 71

                                              S1 D0 D1

                                              D2

                                              D3

                                              Inputs

                                              Data Input (b) Block Diagram of a 1 x 4 Demulptiplexer

                                              34

                                              Logic Design amp Switching Theory 1 Lab Session 07 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                              Figure 72 Circuit Diagram for 2 x 4 Decoder 1 x 4 Demultiplexer

                                              Implementation and Observations Implement the 2 x 4 Decoder 1 x 4 Demultiplexer circuit (figure 72) on a bread board (prepare the pin diagram (use appendix A) and refer to laboratory session 01 for implementation procedure) and record the observations in the following table

                                              Enable Data Input S1 S0 D0 D1 D2 D3

                                              0 0 0 0 0 1 0 1 0 0 1 1 1 0 0 1 0 1 1 1 0 1 1 1

                                              TESTING OF 74138 3 x 8 Decoder The 74138 IC has three inputs and eight output lines It has three enable inputs and for the IC to function all three inputs need to be enabled Function of various pins of this IC is described below

                                              35

                                              Logic Design amp Switching Theory 1 Lab Session 07 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                              bull Y0 through Y7 Active low data outputs bull A B C Input select lines with C being the MSB bull G1 Active high enable Input bull G2Arsquo and G2Brsquo Active low enable Inputs bull VCC and GND Supply connections lines Circuit Diagram

                                              Figure 73 Pin connections of 74138

                                              Testing Procedure

                                              bull Make connections as shown in the circuit diagram bull Apply different combinations of 1s and 0s at data inputs bull Observe the output and record your observations in the following table

                                              Observations

                                              C B A Y0 Y1 Y2 Y3 Y4 Y5 Y6 Y7 0 0 0 0 0 1 0 1 0 0 1 1 1 0 0 1 0 1 1 1 0 1 1 1

                                              36

                                              Logic Design amp Switching Theory 1 Lab Session 07 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                              37

                                              ACTIVITY ACTIVITY 1 What will be the binary values at the outputs Y0 through Y7 of 74138 if 1 What will be the binary values at the outputs Y0 through Y7 of 74138 if

                                              bull All three enable pins are connected to ground bull All three enable pins are connected to ground __________________________________________________________________________________________________________________________________________ __________________________________________________________________________________________________________________________________________ _____________________________________________________________________ _____________________________________________________________________

                                              bull All three enable pins are connected to VCC bull All three enable pins are connected to VCC _______________________________________________________________________________________________________________________________________________________________________________________________________________

                                              _______________________________________________________________________________________________________________________________________________________________________________________________________________

                                              2 Show connections for 74138 in order to use it as a 1 x 8 Demultiplexer 2 Show connections for 74138 in order to use it as a 1 x 8 Demultiplexer

                                              3 Consider a 2 x 4 Decoder with two enable inputs (one active high - G and one active low ndash Grsquo) Draw the output wave-forms for D0 D1 D2 and D3 if the two select inputs are A and B (B being the MSB) All outputs are active low

                                              Grsquo

                                              G

                                              A B

                                              D0 D1 D2

                                              D3

                                              Logic Design amp Switching Theory 1 Lab Session 08 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                              Lab Session 08 OBJECT

                                              bull Designing of a 4 x 2 Priority Encoder bull Experimenting with 74148 IC

                                              COMPONENTS AND APPARATUS REQUIRED

                                              1 Following ICs and their Datasheets

                                              bull 7408 Quad 2-input or 7421 Dual 4-input AND Gates bull 7432 Quad 2-input OR Gates bull 7404 Hex Inverter bull 74148 Encoder

                                              2 Digital Trainer DT-01 or the following components Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches

                                              THEORY

                                              Encoder An Encoder is a digital function that produces a reverse operation from that of a decoder An Encoder has 2n (or less) input lines and n output lines The output lines generate the binary code for the 2n input variables Priority Encoder

                                              A simple encoder may produce an erroneous output if more than one of its inputs is high A Priority Encoder is one that responds to just one input among those that may be simultaneously high in accordance with some priority system The most common priority system is based on the relative magnitudes of the inputs whichever decimal input is largest is the one that is encoded

                                              DESIGN OF A 4 x 2 Priority Encoder

                                              The following equations represent the outputs of a 4 x 2 priority encoder 32 DDA +=

                                              321 DDDB += As can be seen from the equations that input D0 which has a binary code 00 is not used in any equation A binary code 00 at the output indicates two conditions Either D0 is selected or no input is selected In order to differentiate these two conditions we will provide an additional output Z to indicate if at least one of the inputs is a 1 The equation for Z will be

                                              4321 DDDDZ = If Z is 0 then the binary code 00 at the output indicates that D0 is selected and if Z is 1 then it indicates that no input line is selected

                                              38

                                              Logic Design amp Switching Theory 1 Lab Session 08 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                              Figure 81 Circuit Diagram for 4 x 2 Priority Encoder

                                              it (figure 81) on a bread board (prepare the to laboratory session 01 for implementation

                                              Implementation a Implement the 4 x 2 Priority Encoder circu

                                              ram (use appendix A) and refer

                                              nd Observations

                                              pin diagprocedure) and record the observations in the following table

                                              D3 D2 D1 D0 A B 0 0 0 1 0 0 1 x 0 1 x x 1 x x x

                                              TESTING OF 74148 8 x 3 Octal Priority Encoder

                                              imal digits There are nine of which three represents

                                              ing any of the inputs is high

                                              then it shows that line 0 is selected and if e inputs selected E0 and GS

                                              cannot be in the same state provided that E1 is enabled

                                              The 74148 is a priority encoder with active-Low input for dec

                                              input) and five output linesinputs lines (including an enablethe binary code for the octal digit Function of various pins of this IC is described below

                                              bull 0 through 7 Active low data inputs representing the octal digits A2 A1 A0 Active low output lines representing the binary code bullbull E1 Active low enable Input bull E0 Active low output indicating none of the inputs is high bull GS Active low output indicatbull VCC and GND Supply connections lines Therefore if GS A2 A1 and A0 are all low

                                              then it shows that none of thE0 A2 A1 and A0 are all low

                                              39

                                              Logic Design amp Switching Theory 1 Lab Session 08 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                              Circuit Diagram

                                              Figure 82 Pin connections of 74148

                                              Testing Procedure bull Make connections as sho

                                              binations of 1s and 0s at data inputs d record your observations in the following table

                                              GS E0

                                              wn in the circuit diagram bull Apply different combull Observe the output an Observations

                                              0 1 2 3 4 5 6 7 A2 A1 A0 1 1 1 1 1 1 1 1 x x x x x x x 0 x x x x x x 0 1 x x x x x 0 1 1 x x x x 0 1 1 1 x x x 0 1 1 1 1 x x 0 1 1 1 1 1 x 0 1 1 1 1 1 1 0 1 1 1 1 1 1 1

                                              40

                                              Logic Design amp Switching Theory 1 Lab Session 08 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                              41

                                              CTIVITY

                                              Cascade the following two 74148 8 x 3 Priority Encoders to form 16 x 4 Priority

                                              A 1

                                              Encoder

                                              Logic Design amp Switching Theory 1 Lab Session 09 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering `

                                              Lab Session 09 OBJECT

                                              Designing an Odd Parity Generator and Checker for a 3-bit Data COMPONENTS AND APPARATUS REQUIRED

                                              1 Following ICs and their Datasheets

                                              bull 7486 Quad 2-input Exclusive-OR Gates bull 7404 Hex Inverter

                                              2 Digital Trainer DT-01 or the following components Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches

                                              THEORY

                                              Parity Generator When binary data is transmitted and processed it is ndash as are all electrical signals ndash susceptible to noise that can either alter or distort its contents 1s may be effectively changed to 0s and 0s to 1s To overcome this problem one or more bits are often added to the data as an aid in detecting errors caused by noise The most common of these is a Parity bit that signifies whether the total number of 1s in a code group is odd or even In an Odd Parity system the parity bit is made 0 or 1 as necessary to make the total number 1s odd (counting the parity bit itself) In an Even Parity system the parity bit is chosen to make the total number of 1s even Table 91 shows how parity bits would be added to BCD code group in both systems

                                              Decimal BCD Value Parity Bit ABCD Odd Parity Even Parity

                                              0 0000 1 0 1 0001 0 1 2 0010 0 1 3 0011 1 0 4 0100 0 1 5 0101 1 0 6 0110 1 0 7 0111 0 1 8 1000 0 1 9 1001 1 0

                                              Table 91 Odd and Even Parity in BCD

                                              When digital data is received a parity checking circuit generates an error signal if the total number of 1s is odd in an even parity system or if it is even in an odd parity system Parity check always detects a single error (one bit change from 0 to 1 or 1 to 0) but may not detect

                                              42

                                              Logic Design amp Switching Theory 1 Lab Session 09 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering ` two or more errors Odd parity is used more often than even parity because even parity does not detect a situation where all 0s are created due to short circuit or other fault condition DESIGN OF A 3-BIT ODD PARITY GENERATOR AND CHECKER Let x y and z be the three bits that constitute the message and are the input to the Odd Parity Generator Circuit Since it is an odd parity system the bit P is generated so as to make the total number of 1s odd (including P) The function P can be expressed as follows P = x oplus y Ο z or P = x Ο y oplus z Since the IC available is 7486 which is quad 2input XOR IC therefore we will convert XNOR also to XOR

                                              P = x oplus y Ο z

                                              P = ( x oplus y ) Ο z Since for even number of variables ______

                                              XOR = XNOR Therefore ___________ _________

                                              P = ( x oplus y ) oplus z = x oplus y oplus z This logical expression can be implemented with two XOR gates and an inverter (see figure 91)

                                              Figure 91 Circuit Diagram for a 3-bit Parity Generator

                                              The 3-bit message and the parity bit are transmitted to their destination where they are applied to a Parity Checker Circuit An error occurs during transmission if the parity of the four bits received is even since the binary information transmitted was originally odd The output C of the parity checker should be a 1 when an error occurs ie when the number of 1s in the four inputs is even Therefore the function C can be expressed as

                                              C = x Ο y Ο z Ο P

                                              Using the same logic applied for the conversion of the equation of P

                                              PzyxC oplusoplusoplus= This logical expression can be implemented with three XOR gates and an inverter (see figure 92)

                                              43

                                              Logic Design amp Switching Theory 1 Lab Session 09 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering `

                                              44

                                              Figure 92 Circuit Diagram for a 3-bit Parity Checker Implementation and Observations Implement the 3-bit Parity Generator and Checker circuits (figure 91 and 92) on a bread board (prepare the pin diagram (use appendix A) and refer to laboratory session 01 for implementation procedure) and record the observations in the following table

                                              x y z P x y z P C x y z P C 0 0 0 0 0 0 0 1 0 0 0 0 0 1 0 0 0 1 1 0 0 1 0 1 0 0 0 1 0 1 0 1 0 0 1 1 0 0 1 1 1 0 1 1 1 0 0 0 1 0 0 1 1 0 0 1 0 1 0 1 0 1 1 1 0 1 1 1 0 0 1 1 0 1 1 1 0 1 1 1 0 1 1 1 1 1 1 1

                                              Odd Parity Generation Odd Parity Check ACTIVITY 1 Try using the parity checker of figure 92 as 3-bit parity generator Write the details here

                                              _____________________________________________________________________________________________________________________________________________________________________________________________________________________ ______________________________________________________________________________________________________________________________________________ _______________________________________________________________________ ______________________________________________________________________________________________________________________________________________

                                              Logic Design amp Switching Theory 1 Lab Session 10 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                              Lab Session 10 OBJECT

                                              Driving a seven segment display using 7447 7448 driver IC COMPONENTS AND APPARATUS REQUIRED

                                              1 Following ICs and their Datasheets

                                              bull Seven Segment Displays (Common Anode Common Cathode) bull 7447 7448 BCD to Seven Segment Driver

                                              2 Digital Trainer DT-01 or the following components Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches

                                              THEORY Seven Segment Displays A Seven Segment Display consists of seven light-emitting segments The segments are designated by letters a through g (see figure 101) By illuminating various combinations of segments the numerals 0 through 9 can be displayed Seven Segment Displays are commonly constructed with light-emitting diodes (LEDs) and with liquid-crystal displays (LCDs) LEDs generally provide greater illumination levels but require much greater power than LCDs An LED display can be a common-anode type or common cathode type In common anode type a high voltage is applied at the common terminal of the display and low voltage is applied at a segmentrsquos terminal for illumination In the common-cathode type a low voltage is applied at the common terminal of the display and high voltage is applied at a segmentrsquos terminal for illumination

                                              Figure 101 Seven Segment Display

                                              a f b g

                                              e c d

                                              7447 7448 BCD to Seven Segment Driver 7447 7448 IC is particularly used to drive Seven Segment Its input is a BCD number and output drives a seven segment display 7447 is used to drive common-anode displays whereas 7448 is used to drive common cathode displays 7447 7448 is a 16 pin IC Function of various pins of these ICs is described below

                                              bull A B C D Inputs representing BCD digits (D being the MSB)

                                              45

                                              Logic Design amp Switching Theory 1 Lab Session 10 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering bull OA through OG Outputs to drive segments a through g of the display (Active low

                                              in 7447 and active high in 7448) bull RBI Ripple Blanking Input Turns off all the segments if kept low provided that LT

                                              is kept high and all other inputs (A B C D BI) are kept low Should be kept high otherwise

                                              bull BI RBO Wire-AND logic serving as a Blanking Input and or Ripple Blanking Output

                                              o BI Turns off all the segments if low o RBO Goes to a low level (response condition) along with other outputs when

                                              RBI and inputs A B C and D are low with LT input at high level bull LT Lamp Test input Tests whether all segments are working or not Illuminates all

                                              segments if kept low provided that BI is kept high Should be kept high otherwise bull VCC and GND Supply connections lines CIRCUIT DIAGRAM

                                              Figure 102 Circuit diagram for 7447driving a common-anode display

                                              IMPLEMENTATION AND OBSERVATIONS

                                              bull Make connections as shown in the circuit diagram (refer to laboratory session 01 for implementation procedure)

                                              bull Apply different combinations of 1s and 0s at data inputs bull Observe the output and record your observations in the following table

                                              46

                                              Logic Design amp Switching Theory 1 Lab Session 10 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                              47

                                              Decimal Digit

                                              BCD Inputs Seven Segment Outputs D C B A a b c d e f g

                                              0 0 0 0 0 1 0 0 0 1 2 0 0 1 0 3 0 0 1 1 4 0 1 0 0 5 0 1 0 1 6 0 1 1 0 7 0 1 1 1 8 1 0 0 0 9 1 0 0 1

                                              ACTIVITY 1 Perform the Lamp Test for the designed circuit and write your observations

                                              ____________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________

                                              2 How can you use 7447 IC to drive a common-cathode display

                                              ____________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________

                                              3 What symbols appear in the seven segment display if inputs DCBA are

                                              DCBA Symbol

                                              1010

                                              1011

                                              1100

                                              1101

                                              1110

                                              1111

                                              Logic Design amp Switching Theory 1 Lab Session 11 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                              48

                                              Lab Session 11 OBJECT

                                              Testing different modes of JK-FF COMPONENTS AND APPARATUS REQUIRED 1 Following ICs and their Datasheets

                                              bull 7473 7476 JK Flip-Flop 2 Digital Trainer DT-01 or the following components

                                              Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches

                                              THEORY

                                              Flip-Flop A flip-flop circuit can maintain a binary state indefinitely (as long as the power is delivered to the circuit) until directed by an input signal to switch states The major differences among various types of flip-flops are in the number of inputs they possess and in the manner in which the inputs affect the binary state

                                              JK Flip-Flop JK flip flop is an edge triggered device A typical JK flip flop has three inputs J K and a clock input The flip-flop can be either positive or negative edge triggered The output Q is available in complemented form as well Beside the usual inputs and output most of the flip-flop IC also possess two asynchronous inputs namely Preset and Clear These inputs are usually active low If used Preset and Clear inputs keep the flip-flop in set and reset state respectively irrespective of the other inputs Both of these inputs cannot be used simultaneously otherwise they will bring the flip-flop in unstable state

                                              Figure 111 Symbol for JK flip-flop

                                              (a) positive-edge triggering (b) active low Preset (PR) and Clear (CLR) with positive-edge triggering

                                              (c) active low Preset (PR) and Clear (CLR) with negative-edge triggering

                                              Logic Design amp Switching Theory 1 Lab Session 11 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                              49

                                              TESTING OF 7473 7476 DUAL JK FLIP-FLOP

                                              Both the ICs 7473 and 7476 are similar in functionality except for one difference The flip-flops in 7473 have only one type of active low asynchronous input which is the Clear input whereas the flip-flops in 7476 have both Preset and Clear inputs Both these ICs have negative edge triggered flip-flops

                                              Circuit Diagram

                                              Figure 112 Pin connections of 7476

                                              Testing Procedure

                                              bull Make connections as shown in the circuit diagram (figure 112) bull Apply different combinations of 1s and 0s at J and K inputs bull Observe the output and record your observations in the following table

                                              Observations

                                              J

                                              K Q

                                              0 0 0 1 1 0 1 1

                                              ACTIVITY

                                              1 Observe the output Q of JK flip-flop if the clock input is connected to VCC or GND instead of a clock source Write your observations here __________________________________________________________________________________________________________________________________________ _______________________________________________________________________________________________________________________________________________________________________________________________________________

                                              Logic Design amp Switching Theory 1 Lab Session 12 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                              50

                                              Lab Session 12 OBJECT

                                              Designing sequential circuit for the given state diagram using D flip-flop GIVEN STATE DIAGRAM

                                              00

                                              11

                                              Figure 121 State Diagram COMPONENTS AND APPARATUS REQUIRED 1 Following ICs and their Datasheets

                                              bull 7474 D Flip-Flop bull ICs of basic gates (AND OR NOT XOR etc) as required

                                              2 Digital Trainer DT-01 or the following components Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches

                                              THEORY

                                              Sequential Circuits In Sequential Circuits the output not only depends on the present inputs but also on previous states of the circuit These circuits use memory elements (latches flip-flops) and the binary information stored in the memory elements at any given time defines the state of the sequential circuit Analysis of a Sequential Circuit The behavior of a sequential circuit is determined from the inputs the outputs and the states of its flip-flops Both the outputs and next state are a function of the inputs and the

                                              10

                                              01

                                              00 11 10

                                              00

                                              00 11 10 00

                                              Logic Design amp Switching Theory 1 Lab Session 12 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                              51

                                              present state The analysis of a sequential circuit form a state diagram comprises of the following bull Selecting a particular flip-flop to design the circuit bull Obtaining state table from the state diagram bull Finding input equations for the selected flip-flop bull Finding state equations (not required for the construction of circuit) bull Implementing the circuit using selected flip-flops and their input equations ANALYZING THE GIVEN STATE DIAGRAM D Flip-Flop D flip-flop is also called transparent flip-flop as it simply transfers the input data to the output For our design we require the graphical symbol and excitation table of D flip-flop (see figure 122)

                                              Qt Qt+1 T 0 0 0 0 1 1 1 0 0 1 1 1

                                              (b) Excitation table of D Flip-Flop

                                              (a) Graphical Symbol

                                              Figure 122 Characteristic equation of D flip-flop is Q(t+1) = D State Table The given state diagram has four states so we will need two D flip-flops (FF-0 FF-1) Form state table form the given state diagram and record the results in the following table

                                              Present State Input Next State Output Input to FF-0 D0

                                              Input to FF-1 D1 Q1t Q0t x Q1(t+1) Q0(t+1) z

                                              Logic Design amp Switching Theory 1 Lab Session 12 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                              52

                                              Input Equations Using Karnaugh map the input equations D0 and D1 for the two flip-flops can be found

                                              D0 D1 Q0x

                                              Q1

                                              _ _ Q0x

                                              _ Q0x

                                              Q0x

                                              _ Q0x

                                              Q0x

                                              Q1

                                              _ _ Q0x

                                              _ Q0x

                                              Q0x

                                              _ Q0x

                                              _ Q1

                                              _ Q1

                                              Q1

                                              Q1

                                              D0 = _________________ D1 = _________________

                                              State Equations Using the characteristic equation of D flip-flop we can find the state equations Q0(t+1) and Q1(t+1) for the to flip flops Q0(t+1) = _______________________ Q1(t+1) = _______________________ _______________________ _______________________ _______________________ _______________________ Circuit Diagram

                                              Logic Design amp Switching Theory 1 Lab Session 12 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                              53

                                              Implementation Procedure and Observations

                                              1 Implement the circuit using digital ICs on a bread board (prepare the pin diagram (use appendix A) and refer to laboratory session 01 for procedure)

                                              2 Make the clear inputs of the flip-flops low (to clear the flip-flops) The flip-flops will remain in clear state as long as the clear inputs are connected to low level

                                              3 Connect output Q0 and the clock pulse to an oscilloscope 4 Apply 0 to the input x 5 Now make the clear inputs to high 6 Observe the waveform for the first 5 clock pulses and record it 7 Repeat steps 2 to 6 keeping x=1 in step 4 this time 8 Repeat steps 2 to 7 this time connecting Q1 instead of Q0 to the oscilloscope in step

                                              3 Record your observations (Keep frequency of the clock pulse low (eg1Hz) so that the output waveforms can be observed easily)

                                              1 2 3 4 5 Clock Pulse

                                              Output Waveform for Q0 when x=0

                                              Output Waveform for Q0 when x=1

                                              Output Waveform for Q1 when x=0

                                              Output Waveform for Q1 when x=1

                                              Logic Design amp Switching Theory 1 Lab Session 13 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                              Lab Session 13 OBJECT

                                              Designing a modulo-5 asynchronous up-counter using JK-FF COMPONENTS AND APPARATUS REQUIRED

                                              1 Following ICs and their Datasheets

                                              bull 7400 Quad 2-input or 7410 Triple 3-input NAND Gates bull 7476 7473 JK Flip-Flop

                                              2 Digital Trainer DT-01 or the following components Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches

                                              THEORY

                                              Digital Counters A digital counter is a set of flip-flops whose states change in response to pulses applied at the input to the counter The flip-flops are interconnected so that their combined state at any time is the binary equivalent of the total number of pulses that have occurred up to that time Every counter resets after a certain number of clock pulses Thus as it name implies a counter is used to count pulses An n stage counter can count up to a maximum of 2n states n is equal to the number of flip-flops required for the construction of counter

                                              Modulus Counters The number of input pulses that causes a counter to reset to its initial count is called the modulus of the counter Thus the modulus equals to total number of distinct states (counts) including zero that a counter can store A binary counter with n stages is a modulo-2n (or mod-2n) counter The largest count a mod-N counter can achieve is N-1 ie a mod-N counter never reaches the binary number equal to its modulus N is always equal to or less than 2n Counters can be classified as bull Synchronous Counters which are clock driven All the flip-flops are driven by a

                                              single clock bull Asynchronous Counters which are event driven Clock input is given to the first

                                              flip-flop only Rest of the flip-flops are driven by their preceding flip-flops

                                              DESIGN OF A MOD-5 ASYNCHRONOUS UP COUNTER The number of flip-flops required to construct a mod-5 counter is 3 because 5 should be less than or equal to 2n This counter will count from 0 to 4 a total of 5 distinct states Since a 3-stage counter can count up to 8 states at maximum a NAND gate is used to reset it after 5 clock pulses Figure 131 shows the logic diagram

                                              54

                                              Logic Design amp Switching Theory 1 Lab Session 13 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                              55

                                              Figure 131 A Mod-5 Asynchronous Up Counter

                                              Implementation and Observations

                                              Implement the mod-5 counter circuit (figure 131) on a bread board (prepare the pin diagram (use appendix A) and refer to laboratory session 01 for implementation procedure) and record the observations in the following table

                                              Clock Pulse Q2 Q1 Q0

                                              0 1 2 3 4 5 6 7

                                              ACTIVITY

                                              Draw the timing diagram for mod-5 counter designed in this laboratory session

                                              Logic Design amp Switching Theory 1 Lab Session 14 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                              Lab Session 14 OBJECT

                                              Experimenting with 74194 4-bit bidirectional universal shift register COMPONENTS AND APPARATUS REQUIRED

                                              1 Following ICs and their Datasheets

                                              bull 74194 4-bit bidirectional universal shift register 2 Digital Trainer DT-01 or the following components

                                              Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches

                                              THEORY

                                              Shift Registers

                                              A Register is a set of flip-flops used to store binary data A register which is capable of shifting its binary information either to the right or left is called a shift register The logical configuration of a register consists of a chain of flip-flops connected in cascade with the output of one flip-flop connected to the input of next flip-flop All flip-flops receive a common clock pulse which causes the shift from one stage to the next

                                              Bidirectional Shift Registers A bi-directional shift register is one whose bits can be shifted from left to right or from right to left

                                              Universal Shift Registers A universal shift register is a bi-directional register whose input can be in either serial or parallel form and whose output can be in either serial or parallel form

                                              74194 4-BIT BIDIRECTIONAL UNIVERSAL SHIFT REGISTER

                                              The 74194 register provides parallel as well as serial loading in both directions Function of various pins of this IC is described below

                                              bull A B C and D Active high inputs for parallel loading bull QA QB QC and QD Active high outputs bull S0 and S1 Active high mode control inputs The following table shows combinations

                                              of S1 and S0 to enable various modes

                                              S1 S0 Clock Action 0 0 x No change 0 1 uarr Shift right 1 0 uarr Shift left 1 1 uarr Parallel load

                                              uarr shows the rising edge of the clock pulse

                                              56

                                              Logic Design amp Switching Theory 1 Lab Session 14 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering bull SR Active high serial input for right shifting bull SL Active high serial input for left shifting bull CLR Active low input Clears all the flip-flops of the register if set to 0 should be

                                              kept high otherwise bull CLK Clock input bull VCC and GND Supply connections lines Thus A B C and D are inputs for parallel loading whereas SR and SL are inputs for serial loading with right or left shifting respectively S1 and S0 are used to select the loading mode Circuit Diagram

                                              Figure 141 Pin connections of 74194 Testing Procedure

                                              bull Make connections as shown in the circuit diagram bull Observe the output for the input combinations given in the following table

                                              57

                                              Logic Design amp Switching Theory 1 Lab Session 14 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                              58

                                              Observations

                                              S1 S0 SL SR A B C D QA QB QC QD 0 0 0 1 0 0 0 0 0 1 1 0 0 0 0 1 1 0 0 0 0 0 1 0 1 1 0 0 0 0 1 1 0 0 1 1 0 1 0 0 0 1 1 1 0 1 0 1 1 0 1 0 0 1 1 0 1 1 1 0 0 1 1 1 1 1 0 0 1 1 1 1

                                              ACTIVITY 1 Show connections of 74194 to convert it into a ring counter with right shifting

                                              Logic Design amp Switching Theory 1 Lab Session 15 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                              Lab Session 15

                                              OBJECT

                                              Experimenting with 74245 octal bus transceivers using parallel port PC interfacing COMPONENTS AND APPARATUS REQUIRED 1 Parallel Port Connectors (DB-25) with Cable 2 Personal Computer with Windows 98 and TurboC Compiler Installed 3 Following ICs and their Datasheets

                                              bull 74245 Octal Bus Transceivers with 3-State Outputs 4 Digital Trainer DT-01 or the following components

                                              Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches

                                              THEORY

                                              3-State Logic Sometimes it is necessary to isolate one part of circuit from the other part For this purpose some TTL ICs are designed with 3-state logic Such devices have three possible output states high low and high impedance The device can be put into high impedance state by a control signal applied to an appropriate pin When such a device is in high impedance state there is very high impedance at its output effectively isolating the device from whatever circuitry the output normally drives 74245 Octal Bus Transceivers A bus is any conducting path or set of paths having electrical connections to one or more devices 74245 octal bus transceivers are mainly used to control connectivity between two devices or circuits It also provides direction control for signal flow Function of various pin of this IC is given below

                                              bull A1 through A8 Bus A bull B1 through B8 Bus B bull G΄ Active low enable input When high sets all the bus pins to high impedance state bull DIR Direction control for signal flow When set to high logic level transfers bus A

                                              data to B bus When set to low logic level transfers bus B data to A bus bull VCC and GND Supply connections lines Serial and Parallel Port Connectors A Parallel Port can consist of only 25 pin port adapter called a DB-25 and a serial port can consist of either a 25 pin port adapter called a DB-25 or 9 pin adapter called a DB-9 port adapter Whether the port is a 9 pin or 25 pin it can accomplish all of the same tasks that serial port communications have been designed for

                                              59

                                              Logic Design amp Switching Theory 1 Lab Session 15 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                              60

                                              Each adapter can be a male type connector with pins or a female type adapter with tiny holes Generally a PRINTER port (called LPT1) on the back of a computer is female type adapter and we need to use MALE DB-25 pin cable on it for PRINTER connection or for parallel LAPLINK cable And a COM port on the back of a computer is male for the serial ports but it may not necessarily be Parallel Port Connector ndash DB-25 The DB-25 connector (named for its B-size D-shaped shell and 25 pins) is practically ubiquitous in the electronics industry The DB-25 connector is used for a variety of purposes Two common applications are RS-232EIA-232 (serial) connections and the parallel printer interface on the IBM PC The DB-25 connector is also used for SCSI connections Normally the parallel port is used for output to a printer or other device It sends data 8-bits or one byte at a time in parallel The other lines available on the DB-25 connector are a combination of status lines control lines and ground lines The status and control lines are used for handshaking commands and feedback when we are talking to a printer

                                              Figure 152 DB-25 Female Figure 151 DB-25 Male

                                              Figure 153 Pin Layout for DB-25 As can be seen form figure 153 there are four types of pins in this connector

                                              bull Data pins (8 pins - D0 to D7) Active high bidirectional lines

                                              Logic Design amp Switching Theory 1 Lab Session 15 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering bull Control pins (4 pins - C0 to C3) C0 C1 and C3 are active low whereas C2 is active

                                              high These lines also are bidirectional bull Status pins (5 pins ndash S3 to S7) Only S7 is active low rest are active high input lines bull Ground pins (8 pins) Used as a reference signal for the low (below 05 volts) charge

                                              Parallel Port Addresses A DB-25 connector at a parallel port has three address one for each kind of pins register data status and control The first or base address generally refers to data register Second address is for status register and the third one is for control register In Windows 98 the base address is usually found to be 278H 378H or 3BCH Now if 378H is the base address then it refers to the data register whereas addresses for status and control register are respectively 379H and 37AH For Windows 98 the base address can be found as follows 1 On your Desktop right-click on My Computer and select Properties 2 Click on the Device Manager tab and find LPT1 under Plug and Play BIOS 3 After selecting LPT1 click the Properties button 4 Next select the Resources tab and the address should then appear next to InputOutput

                                              Range Accessing parallel port through C Language Programming There are multiple functions in C Language for accessing external ports The most commonly used are listed below

                                              bull unsigned char inportb(int portid) inportb reads a byte from a hardware port

                                              bull int inport(int portid) reads a word from a hardware port

                                              bull void outportb(int portid unsigned char value) outputs a byte to a hardware port

                                              bull void outport(int portid int value) outputs a word to a hardware port

                                              portid refers to the port address whereas value refers to the data to be sent TESTING 74245 USING PARALLEL PORT PC INTERFACING At one end the parallel port connector will be connected to the PC via parallel port cable and another connector (to be plugged into the PC parallel port slot) At the other end it will be connected to the buffer IC 74245 Data lines of the connector will be used to transfer 8-bit data between the PC and the buffer Out of the 8-bits of 74245 4-bits will be used to enter data which will be displayed at the monitor through a C language

                                              61

                                              Logic Design amp Switching Theory 1 Lab Session 15 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering program The remaining 4-bits will receive data from PC as entered by the user via keyboard

                                              Circuit Diagram

                                              Figure 154 Interface of 74245 to PC via Parallel Port

                                              Procedure

                                              1 Connect the DB-25 connector to the PC at one end and solder it to the circuit board at the other end

                                              2 Connect various pins of the connector and 74245 according to the circuit diagram shown in figure 152

                                              3 Using the functions listed in the previous section write a program in C language to operate various pins of the buffer The user interface of the program should provide option to the user whether to send or receive data from the port

                                              4 Set DIR switch to 1 5 Try sending some data bits to the port The result should be displayed at the LEDs 6 Set DIR switch to 0 7 Set some binary 4-bit value through the switches Try reading it via parallel port

                                              C Language Program

                                              A program to access parallel port for data transfers

                                              use header file include ltstdiohgt main program void main() define variable

                                              62

                                              Logic Design amp Switching Theory 1 Lab Session 15 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering unsigned int data=0 char choice while(1) printing option menu clrscr() printf(This program will send or receive a BCD digit from the parallel portn) printf(nPress your choice numbern) printf(n1 Send Data) printf(n2 Receive Data) printf(n3 Exitn) choice = getch() sending entered digit to the port if(choice == 1) input BCD digit printf(nEnter BCD digit to be sent to the port) data = getche() masking the first four bits data = data amp 0x0f sending to the port outportb(0x378data) printf(nThe BCD digit c has been sent to the port data) printing on screen the data received from the port else if(choice == 2) receiving data from the port data = inportb(0x378) masking the last four bits data = data amp 0xf0 shifting first four bits to make them the last four bits datagtgt=4 printf(nThe BCD digit set at the port is c data) exit else if(choice == 3) break key pressed is not in the menu else printf(nEnter valid choice number) printf(nnPress any key to continue) getch()

                                              63

                                              Logic Design amp Switching Theory 1 Lab Session 15 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                              ACTIVITY 1 In the above circuit DIR and G΄ inputs are hardwired Connect them to status or

                                              control pins of the parallel port connector and control their function through your software program Circuit Diagram Program Code ______________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________

                                              ___________________________________________________________________________________________________________________________________________________

                                              64

                                              Logic Design amp Switching Theory 1 Lab Session 15 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                              65

                                              _____________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ _____________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ _______________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ _________________________________________________ _________________________________________________

                                              Logic Design amp Switching Theory 1 Appendix A NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                              Appendix A

                                              PIN DIAGRAMS OF THE ICS REQUIRED FOR THE LABORATORY SESSIONS Consult the TTLIC data book for internal diagrams and electrical characteristics of these ICs 7400 Quad 2-Input NAND 7402 Quad 2-Input NOR

                                              7404 Hex Inverter 7408 Quad 2-Input AND

                                              7410 Triple 3-Input NAND 7411 Triple 3-Input AND

                                              7421 Dual 4-Input AND 7432 Quad 2-Input OR

                                              66

                                              Logic Design amp Switching Theory 1 Appendix A NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                              BCD-to-Seven Segm 7448 BCD-to-Seven Segment 7447 ent

                                              Decoder (15V OC) Decoder (2kΩ pull-up output)

                                              7473 Dual JK Flip-Flop 7474 Dual D-Type Flip-Flop

                                              7476 Dual JK Flop-Flop -Bit Binary Full Adder 7483 4 with Fast Carry

                                              86 Quad 2-Inpu 74138 3-to-8 Line 74 t Exclusive OR Decoder Demultiplexer

                                              67

                                              Logic Design amp Switching Theory 1 Appendix A NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                              68

                                              74148 8-to-3 Line 16-to-1 Line Data

                                              Priority Encoder 74150 Selector Multiplexer

                                              74245 Oct nsceivers Universal Shift Register (PIPO) (3-State)

                                              74194 4-Bit Bidirectional al Bus Tra

                                              Logic Design amp Switching Theory 1 Appendix B NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                              Appendix B

                                              DEBOUNCING CIRCUITRY FOR MECHANICAL SWITCHES Mechanical switches form the interface between human beings and computers or other digital systems For example a keyboard is a matrix of switches used to supply alphanumeric data to a computer Whatever the switch design it is a potential source of problems due to contact bounce The contact bounce creates a sense of narrow pulses when a switch is opened or closed An example of device whose operation would be adversely affected by contact bounce is a digital counter used to count the number of times a switch is depressed Eliminating the effects of contact bounce is called debouncing When data is entered into a computer via a keyboard a software debounce is often used This type of debouncing is a program that causes the computer to sample the switch terminal (ie to input data from it) many times in succession during the interval of time that contact bounce occurs If the data is sensed to be 1s (or 0s) for a specific number of consecutive samples then it is assumed that contact bounce has ended and the last value sensed is valid Hardware debouncing is the use of electronic circuitry to eliminate the effects of contact bounce There are numerous versions of such circuitry including those that use monostable multivibrators (one-shots) but the most straightforward is simply an RS latch Figure B1 shows the circuit When the switch is in position 1 R = 0 and S = 1 so the latch is set and the output (Q) is 1 When the switch is in position 0 R = 1and S = 0 so the latch is reset and the output is 0 When the switch is moved form one position to the other the latch changes state and bouncing occurs at either the R or the S input The bouncing does not affect the latch after it has change state An RS latch will remain set for example when its R input is 0 and its S input is alternately changed form 1 to 0

                                              Figure B1 Use of RS latch to debounce a mechanical switch

                                              69

                                              • 01-ldst-Outer title
                                                • Practical Workbook
                                                • Logic Design amp Switching Theory I
                                                  • Dept of Computer amp Information Systems Engineering
                                                    • NED University of Engineering amp Technology
                                                    • Karachi ndash 75270 Pakistan
                                                      • 02-ldst-inner Title
                                                        • Practical Workbook
                                                        • Logic Design amp Switching Theory I
                                                          • Dept of Computer amp Information Systems Engineering
                                                            • NED University of Engineering amp Technology
                                                            • Karachi ndash 75270 Pakistan
                                                              • 03-ldst-general info
                                                              • 04-ldst-introduction
                                                              • 05-Table of Contents
                                                                • CONTENTS
                                                                  • Lab Session No Object Page No
                                                                  • 1
                                                                  • Also implementing and testing the given circuit on a bread board
                                                                    • Working with Electronics Workbench
                                                                      • Driving a seven segment display using 7447 7448 driver IC
                                                                        • Designing a modulus-5 asynchronous up-counter using JK-FF
                                                                          • Experimenting with 74194 4-bit bidirectional universal shift register
                                                                              • 13
                                                                                  • 06-ldst-Exp01
                                                                                    • Lab Session 01
                                                                                    • OBJECT
                                                                                      • 1 Bread board
                                                                                      • 2 5 V - power supply
                                                                                      • 3 Multimeter
                                                                                      • 4 Logic probe
                                                                                      • 5 LEDs with resistors
                                                                                      • 6 Connecting wires
                                                                                      • 8 Following ICs and their datasheets
                                                                                        • THEORY
                                                                                          • Logic Gates
                                                                                          • 1 The AND Gate ndash An AND gatersquos output is 1 if and only if all its inputs are 1 If A and B are two inputs to an AND gate then output F of the gate is given as F = AB
                                                                                          • 2 The OR Gate - An OR gatersquos output is 1 if at least one of its input is 1 If A and B are two inputs to an OR gate then output F of the gate is given as F = A+B
                                                                                          • 3 The NOT Gate (Inverter) ndash Its output is 1 when its input is 0 and its output is 0 when the input is 1 ie it complements a digital variable If A is the input to a NOT gate then output F of the gate is given as
                                                                                          • 4 The NAND Gate ndash Its output is 1 if at least one of its input is 0 This gate performs the same logic as an AND gate followed by an inverter If A and B are two inputs to a NAND gate then output F of the gate is given as
                                                                                            • 5 The NOR Gate - The output of a NOR gate is 1 if and only if all its inputs are 0 This gate performs the same logic function as an OR gate followed by an inverter If A and B are two inputs to a NAND gate then output F of the gate is given as
                                                                                                • DATA SHEETS
                                                                                                  • Logic expression for the given logic diagram __________________________________
                                                                                                      • 07-ldst-exp02
                                                                                                        • Working with Electronics Workbench
                                                                                                          • 08-ldst-exp03
                                                                                                            • Designing Half and Full Adder Circuits
                                                                                                              • COMPONENTS AND APPARATUS REQUIRED
                                                                                                                • 1 Following ICs and their Datasheets
                                                                                                                • 7408 Quad 2-input AND Gate
                                                                                                                • 2 Digital Trainer DT-01 or the following components
                                                                                                                  • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                  • Connecting wires Switches
                                                                                                                    • THEORY
                                                                                                                        • IMPLEMENTATION AND OBSERVATIONS
                                                                                                                          • 09-ldst-Exp04
                                                                                                                            • Lab Session 04
                                                                                                                            • 1 Digital ICs and their Datasheets
                                                                                                                            • 7408 Quad 2-input AND Gate
                                                                                                                            • 2 Digital Trainer DT-01 or the following components
                                                                                                                              • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                              • Connecting wires Switches
                                                                                                                              • PROCEDURE
                                                                                                                              • REDUCTION OF LOGIC EXPRESSION USING KARNAUGH MAP
                                                                                                                              • OBSERVATIONS
                                                                                                                              • RESULT
                                                                                                                                  • 10-ldst-Exp05
                                                                                                                                    • Lab Session 05
                                                                                                                                    • 1 Following ICs and their Datasheets
                                                                                                                                    • 7408 Quad 2-input AND Gate
                                                                                                                                    • 2 Digital Trainer DT-01 or the following components
                                                                                                                                      • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                      • (100 Ω) Connecting wires Switches
                                                                                                                                      • THEORY
                                                                                                                                        • IMPLEMENTATION AND OBSERVATIONS
                                                                                                                                          • 11-ldst-Exp06
                                                                                                                                            • OBJECT
                                                                                                                                            • 1 Following ICs and their Datasheets
                                                                                                                                            • 7408 Quad 2-input AND Gates or 7411 Triple 3-input AND Gates
                                                                                                                                            • 2 Digital Trainer DT-01 or the following components
                                                                                                                                              • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                              • Connecting wires Switches
                                                                                                                                                • Figure 62 Circuit Diagram for 4 x 1 Multiplexer
                                                                                                                                                • Implementation and Observations
                                                                                                                                                  • Circuit Diagram
                                                                                                                                                    • ACTIVITY
                                                                                                                                                      • 12-ldst-exp07
                                                                                                                                                        • 1 Following ICs and their Datasheets
                                                                                                                                                        • 7408 Quad 2-input or 7411 Triple 3-input AND Gates
                                                                                                                                                        • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                          • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                          • Connecting wires Switches
                                                                                                                                                            • THEORY
                                                                                                                                                                • Figure 72 Circuit Diagram for 2 x 4 Decoder 1 x 4 Demultiplexer
                                                                                                                                                                • Implementation and Observations
                                                                                                                                                                  • Circuit Diagram
                                                                                                                                                                    • ACTIVITY
                                                                                                                                                                      • 13-ldst-Exp08
                                                                                                                                                                        • OBJECT
                                                                                                                                                                        • 1 Following ICs and their Datasheets
                                                                                                                                                                        • 7408 Quad 2-input or 7421 Dual 4-input AND Gates
                                                                                                                                                                        • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                          • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                          • Connecting wires Switches
                                                                                                                                                                            • THEORY
                                                                                                                                                                                • Figure 81 Circuit Diagram for 4 x 2 Priority Encoder
                                                                                                                                                                                • Implementation and Observations
                                                                                                                                                                                  • Therefore if GS A2 A1 and A0 are all low then it shows that line 0 is selected and if E0 A2 A1 and A0 are all low then it shows that none of the inputs selected E0 and GS cannot be in the same state provided that E1 is enabled
                                                                                                                                                                                  • Circuit Diagram
                                                                                                                                                                                    • ACTIVITY
                                                                                                                                                                                      • 14-ldst-exp09
                                                                                                                                                                                        • OBJECT
                                                                                                                                                                                        • 1 Following ICs and their Datasheets
                                                                                                                                                                                        • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                          • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                          • Connecting wires Switches
                                                                                                                                                                                            • THEORY
                                                                                                                                                                                              • Parity Generator
                                                                                                                                                                                                • Let x y and z be the three bits that constitute the message and are the input to the Odd Parity Generator Circuit Since it is an odd parity system the bit P is generated so as to make the total number of 1s odd (including P) The function P can be expressed as follows
                                                                                                                                                                                                • Figure 91 Circuit Diagram for a 3-bit Parity Generator
                                                                                                                                                                                                  • C = x Ο y Ο z Ο P
                                                                                                                                                                                                    • Implementation and Observations
                                                                                                                                                                                                      • ACTIVITY
                                                                                                                                                                                                          • 15-ldst-exp10
                                                                                                                                                                                                            • Driving a seven segment display using 7447 7448 driver IC
                                                                                                                                                                                                            • COMPONENTS AND APPARATUS REQUIRED
                                                                                                                                                                                                            • 1 Following ICs and their Datasheets
                                                                                                                                                                                                            • 7447 7448 BCD to Seven Segment Driver
                                                                                                                                                                                                            • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                              • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches
                                                                                                                                                                                                                • THEORY
                                                                                                                                                                                                                • Seven Segment Displays
                                                                                                                                                                                                                • CIRCUIT DIAGRAM
                                                                                                                                                                                                                • Figure 102 Circuit diagram for 7447driving a common-anode display
                                                                                                                                                                                                                    • IMPLEMENTATION AND OBSERVATIONS
                                                                                                                                                                                                                      • Decimal Digit
                                                                                                                                                                                                                      • BCD Inputs
                                                                                                                                                                                                                      • Seven Segment Outputs
                                                                                                                                                                                                                      • D
                                                                                                                                                                                                                      • C
                                                                                                                                                                                                                      • B
                                                                                                                                                                                                                      • A
                                                                                                                                                                                                                      • a
                                                                                                                                                                                                                      • b
                                                                                                                                                                                                                      • c
                                                                                                                                                                                                                      • d
                                                                                                                                                                                                                      • e
                                                                                                                                                                                                                      • f
                                                                                                                                                                                                                      • g
                                                                                                                                                                                                                      • 0
                                                                                                                                                                                                                      • 0
                                                                                                                                                                                                                      • 0
                                                                                                                                                                                                                      • 0
                                                                                                                                                                                                                      • 0
                                                                                                                                                                                                                      • 1
                                                                                                                                                                                                                      • 0
                                                                                                                                                                                                                      • 0
                                                                                                                                                                                                                      • 0
                                                                                                                                                                                                                      • 1
                                                                                                                                                                                                                      • 2
                                                                                                                                                                                                                      • 0
                                                                                                                                                                                                                      • 0
                                                                                                                                                                                                                      • 1
                                                                                                                                                                                                                      • 0
                                                                                                                                                                                                                      • 3
                                                                                                                                                                                                                      • 0
                                                                                                                                                                                                                      • 0
                                                                                                                                                                                                                      • 1
                                                                                                                                                                                                                      • 1
                                                                                                                                                                                                                      • 4
                                                                                                                                                                                                                      • 0
                                                                                                                                                                                                                      • 1
                                                                                                                                                                                                                      • 0
                                                                                                                                                                                                                      • 0
                                                                                                                                                                                                                      • 5
                                                                                                                                                                                                                      • 0
                                                                                                                                                                                                                      • 1
                                                                                                                                                                                                                      • 0
                                                                                                                                                                                                                      • 1
                                                                                                                                                                                                                      • 6
                                                                                                                                                                                                                      • 0
                                                                                                                                                                                                                      • 1
                                                                                                                                                                                                                      • 1
                                                                                                                                                                                                                      • 0
                                                                                                                                                                                                                      • 7
                                                                                                                                                                                                                      • 0
                                                                                                                                                                                                                      • 1
                                                                                                                                                                                                                      • 1
                                                                                                                                                                                                                      • 1
                                                                                                                                                                                                                      • 8
                                                                                                                                                                                                                      • 1
                                                                                                                                                                                                                      • 0
                                                                                                                                                                                                                      • 0
                                                                                                                                                                                                                      • 0
                                                                                                                                                                                                                      • 9
                                                                                                                                                                                                                      • 1
                                                                                                                                                                                                                      • 0
                                                                                                                                                                                                                      • 0
                                                                                                                                                                                                                      • 1
                                                                                                                                                                                                                        • ACTIVITY
                                                                                                                                                                                                                          • 16-ldst-exp11
                                                                                                                                                                                                                            • Lab Session 11
                                                                                                                                                                                                                              • OBJECT
                                                                                                                                                                                                                              • COMPONENTS AND APPARATUS REQUIRED
                                                                                                                                                                                                                                • 1 Following ICs and their Datasheets
                                                                                                                                                                                                                                • 7473 7476 JK Flip-Flop
                                                                                                                                                                                                                                • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                                  • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                                                  • Connecting wires Switches
                                                                                                                                                                                                                                    • THEORY
                                                                                                                                                                                                                                        • Flip-Flop
                                                                                                                                                                                                                                        • JK Flip-Flop
                                                                                                                                                                                                                                          • Circuit Diagram
                                                                                                                                                                                                                                            • Observations
                                                                                                                                                                                                                                              • ACTIVITY
                                                                                                                                                                                                                                                  • 17-ldst-exp12
                                                                                                                                                                                                                                                    • Lab Session 12
                                                                                                                                                                                                                                                      • OBJECT
                                                                                                                                                                                                                                                      • GIVEN STATE DIAGRAM
                                                                                                                                                                                                                                                      • Figure 121 State Diagram
                                                                                                                                                                                                                                                      • COMPONENTS AND APPARATUS REQUIRED
                                                                                                                                                                                                                                                        • 1 Following ICs and their Datasheets
                                                                                                                                                                                                                                                        • 7474 D Flip-Flop
                                                                                                                                                                                                                                                        • ICs of basic gates (AND OR NOT XOR etc) as required
                                                                                                                                                                                                                                                        • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                                                          • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                                                                          • Connecting wires Switches
                                                                                                                                                                                                                                                            • THEORY
                                                                                                                                                                                                                                                                • Sequential Circuits
                                                                                                                                                                                                                                                                  • 18-ldst-exp13
                                                                                                                                                                                                                                                                    • Lab Session 13
                                                                                                                                                                                                                                                                      • Designing a modulo-5 asynchronous up-counter using JK-FF
                                                                                                                                                                                                                                                                        • 1 Following ICs and their Datasheets
                                                                                                                                                                                                                                                                        • 7400 Quad 2-input or 7410 Triple 3-input NAND Gates
                                                                                                                                                                                                                                                                        • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                                                                          • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                                                                                          • Connecting wires Switches
                                                                                                                                                                                                                                                                            • THEORY
                                                                                                                                                                                                                                                                                • Figure 131 A Mod-5 Asynchronous Up Counter
                                                                                                                                                                                                                                                                                • Implementation and Observations
                                                                                                                                                                                                                                                                                  • ACTIVITY
                                                                                                                                                                                                                                                                                      • 19-ldst-exp14
                                                                                                                                                                                                                                                                                        • Experimenting with 74194 4-bit bidirectional universal shift register
                                                                                                                                                                                                                                                                                        • 1 Following ICs and their Datasheets
                                                                                                                                                                                                                                                                                        • 74194 4-bit bidirectional universal shift register
                                                                                                                                                                                                                                                                                        • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                                                                                          • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                                                                                                          • Connecting wires Switches
                                                                                                                                                                                                                                                                                            • THEORY
                                                                                                                                                                                                                                                                                              • Shift Registers
                                                                                                                                                                                                                                                                                              • Bidirectional Shift Registers
                                                                                                                                                                                                                                                                                              • Universal Shift Registers
                                                                                                                                                                                                                                                                                                • S1
                                                                                                                                                                                                                                                                                                  • Circuit Diagram
                                                                                                                                                                                                                                                                                                  • ACTIVITY
                                                                                                                                                                                                                                                                                                      • 20-ldst-exp15
                                                                                                                                                                                                                                                                                                        • COMPONENTS AND APPARATUS REQUIRED
                                                                                                                                                                                                                                                                                                        • 1 Parallel Port Connectors (DB-25) with Cable
                                                                                                                                                                                                                                                                                                        • 2 Personal Computer with Windows 98 and TurboC Compiler Installed
                                                                                                                                                                                                                                                                                                        • 3 Following ICs and their Datasheets
                                                                                                                                                                                                                                                                                                        • 74245 Octal Bus Transceivers with 3-State Outputs
                                                                                                                                                                                                                                                                                                        • 4 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                                                                                                          • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                                                                                                                            • Connecting wires Switches
                                                                                                                                                                                                                                                                                                              • THEORY
                                                                                                                                                                                                                                                                                                              • 3-State Logic
                                                                                                                                                                                                                                                                                                                • Serial and Parallel Port Connectors
                                                                                                                                                                                                                                                                                                                • Parallel Port Connector ndash DB-25
                                                                                                                                                                                                                                                                                                                  • Accessing parallel port through C Language Programming
                                                                                                                                                                                                                                                                                                                      • 21-ldst-appendixA
                                                                                                                                                                                                                                                                                                                      • 22-ldst-appendixB
                                                                                                                                                                                                                                                                                                                        • DEBOUNCING CIRCUITRY FOR MECHANICAL SWITCHES

                                                Logic Design amp Switching Theory 1 Lab Session 04 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                ACTIVITY 3

                                                Using Electronics Workbench find the logic expression and truth table for the following logic circuit

                                                Figure 43

                                                Procedure 1 Attach the input terminals of the logic converter to up to four input points in the

                                                circuit 2 Connect the single output of the circuit to the output terminal on the logic converter

                                                icon 3 Click the Circuit to Truth Table button The truth table appears in the logic

                                                converters display 4 To convert this truth table to a Boolean expression click the Truth Table to Boolean

                                                Expression button The Boolean expression will be displayed at the bottom of the logic converter

                                                Resulting Logic Expression Logic Expression for the given circuit is found to be _____________________________

                                                26

                                                Logic Design amp Switching Theory 1 Lab Session 04 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                27

                                                For activities 1 2 and 3 attach hardcopy of the output (truth table logic expression and logic circuit) form electronic workbench here

                                                Logic Design amp Switching Theory 1 Lab Session 05 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                Lab Session 05 Lab Session 05 OBJECT OBJECT

                                                Designing a BCD Adder Designing a BCD Adder COMPONENTS AND APPARATUS REQUIRED COMPONENTS AND APPARATUS REQUIRED

                                                1 Following ICs and their Datasheets 1 Following ICs and their Datasheets bull 7408 Quad 2-input AND Gate bull 7408 Quad 2-input AND Gate bull 7432 Quad 2-input OR Gate bull 7432 Quad 2-input OR Gate bull 7483 4-bit Binary Adder bull 7483 4-bit Binary Adder

                                                2 Digital Trainer DT-01 or the following components 2 Digital Trainer DT-01 or the following components Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors (100 Ω) Connecting wires Switches (100 Ω) Connecting wires Switches

                                                THEORY THEORY

                                                A BCD Adder is a combinational circuit that adds two BCD digits in parallel and produces a sum digit also in BCD A BCD Adder is a combinational circuit that adds two BCD digits in parallel and produces a sum digit also in BCD

                                                A4 A3 A2 A1 B4 B3 B2 B1

                                                7483-BCD ADDER

                                                Cout (C4 ) Z4 Z3 Z2 Z1 Cin(C0)

                                                A4 A3 A2 A1 B4 B3 B2 B1

                                                7483-BCD ADDER

                                                Cout

                                                (C4 ) Z4 Z3 Z2 Z1 Cin(C0)

                                                Figure 51 BCD Adder Circuit

                                                28

                                                Logic Design amp Switching Theory 1 Lab Session 05 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                29

                                                A BCD adder must include the correction logic in its internal construction The two BCD digits together with the input carry are first added using a 4-bit binary adder to produce the binary sum If no output carry is generated and the binary sum is less than or equal to 9 then the corresponding BCD sum is identical and therefore no conversion is needed When the output carry is equal to 1 or the binary sum is greater than 9 then a binary 0110 is added to the binary sum through another 4-bit binary adder If Cout is the carry output and Z4Z3Z2Z1 is the binary sum form the first 4-bit binary adder then the following equation indicates the condition when a binary 0110 is to be added

                                                C = COUT + Z4Z2 + Z4Z3 IMPLEMENTATION AND OBSERVATIONS Implement the BCD adder circuit according to figure 51 on a bread board (prepare the pin diagram (use appendix A) and refer to laboratory session 01 for procedure) A BCD adder has nine input bits (two BCD digits and a carry bit) which can result in a total of 512 combinations of which 312 inputs are donrsquot care Since it is a very lengthy procedure to record results for 200 valid input combinations therefore for simplicity just record results for any eight combinations in the following table

                                                Input Carry

                                                BCD Digit 1 BCD Digit 2 Carry Output

                                                BCD Sum A4 A3 A2 A1 B4 B3 B2 B1 Z4 Z3 Z2 Z1

                                                Logic Design amp Switching Theory 1 lab Session 06 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                Lab Session 06

                                                OBJECT

                                                bull Designing of a 4 x 1 Multiplexer bull Experimenting with 74150 IC

                                                COMPONENTS AND APPARATUS REQUIRED 1 Following ICs and their Datasheets

                                                bull 7408 Quad 2-input AND Gates or 7411 Triple 3-input AND Gates bull 7432 Quad 2-input OR Gates bull 7404 Hex Inverter bull 74150 16 x 1 MUX

                                                2 Digital Trainer DT-01 or the following components Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches THEORY

                                                Multiplexers A digital data Multiplexer (MUX) is a combinational circuit having several data inputs and a single output A set of data-select inputs is used to control which of the data inputs is routed to the single output A multiplexer is also called a data selector because of this ability to select which data input is connected o the output Normally there are 2n input lines and n selection lines whose bit combination determine which input is selected DESIGN OF A 4 x 1 MULTIPLEXER A 4 x 1 multiplexer is capable of selecting one of four data inputs (see figure 61) The 2-bit binary number at the data select inputs S1 and S0 specifies which of the four data inputs is to be routed to the output Since there are two data select inputs therefore they can select 22 = 4 different data inputs lines

                                                S0 S1 D0 D1

                                                D2 D3

                                                Data-select Inputs Output

                                                Data Inputs

                                                Figure 61 Block Diagram of a 4 x1 Multiplexer

                                                30

                                                Logic Design amp Switching Theory 1 lab Session 06 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                Figure 62 Circuit Diagram for 4 x 1 Multiplexer

                                                Implementation and Observations

                                                Implement the 4 x 1 Multiplexer circuit (figure 62) on a bread board (prepare the pin diagram (use appendix A) and refer to laboratory session 01 for implementation procedure) and record the observations in the following table For each data select combination specify the switch number as well as the binary value present on that selected switch

                                                S1 S0 Output 0 0 0 1 1 0 1 1

                                                TESTING OF 74150 - 16 x 1 MUX

                                                The 74150 IC has sixteen data inputs and four data-selection lines Function of various pins of this IC is described below

                                                bull E0 through E15 Data input lines

                                                31

                                                Logic Design amp Switching Theory 1 lab Session 06 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering bull A B C D Data select lines with D being the MSB bull W Active low output line bull Grsquo Active low enable line bull VCC and GND Supply connections lines

                                                Circuit Diagram

                                                Figure 63 Pin connections of 74150 for selecting E0

                                                Testing Procedure

                                                bull Make connections as shown in the circuit diagram bull Apply different data (1 or 0) at data inputs that are labeled as E0 to E15 Only

                                                connection for E0 is shown is the figure for simplicity bull Select the data input E0 with the help of data selectors A B C and D bull Observe the output which shows the complement of the data from E0 bull Select all the sixteen data inputs one by one and record your observations in the

                                                following table

                                                32

                                                Logic Design amp Switching Theory 1 lab Session 06 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                33

                                                Observations

                                                Grsquo D C B A W Grsquo D C B A W 0 0 0 0 0 0 1 0 0 0 0 0 0 0 1 0 1 0 0 1 0 0 0 1 0 0 1 0 1 0 0 0 0 1 1 0 1 0 1 1 0 0 1 0 0 0 1 1 0 0 0 0 1 0 1 0 1 1 0 1 0 0 1 1 0 0 1 1 1 0 0 0 1 1 1 0 1 1 1 1

                                                ACTIVITY 1 Consider 4x1 Multiplexer Draw the output wave-form for the following data inputs

                                                (E0 E1 E2 E3) and select lines A B (B being the MSB) Output is W

                                                E3 E2 E1 E0 A B

                                                W

                                                2 Using the 4 x 1 MUX designed in this laboratory session implement the following logical function F (A B C) = Σ (0147)

                                                Show your working and input connections in the following block diagram according to the circuit you have implemented

                                                4 x 1 MUX

                                                S0 S1

                                                Output D0

                                                D1

                                                D2

                                                D3

                                                Logic Design amp Switching Theory 1 Lab Session 07 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                Lab Session 07

                                                OBJECT

                                                bull Designing of a 2 x 4 Decoder 1 x 4 Demultiplexer bull Experimenting with 74138 IC

                                                COMPONENTS AND APPARATUS REQUIRED 1 Following ICs and their Datasheets

                                                bull 7408 Quad 2-input or 7411 Triple 3-input AND Gates bull 7404 Hex Inverter bull 74138 3 x 8 Decoder

                                                2 Digital Trainer DT-01 or the following components Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches THEORY

                                                Decoder A Decoder is a combinational circuit that converts binary information form n input lines to a maximum of 2n unique output lines In practical applications decoders are often used for selecting one of several devices

                                                Demultiplexer A decoder with an enable input can function as a Demultiplexer A Demultiplexer (DMUX) id a circuit that receives information on a single line and transmits this information on one of 2n possible output lines The selection of a specific output line is controlled by the bit values of n selection lines DESIGN OF A 2 x 4 DECODER 1 x 4 DEMULTIPLEXER A 2 x 4 decoder is capable of selecting one of four output lines (see figure 71 (a)) The 2-bit binary number at the data inputs S1 and S0 specifies which of the four data inputs is to be selected If we add an enable pin and use it as an input line then this decoder can be converted to a 1 x 4 Demultiplexer where S1 and S0 will select a line to which data input is to be routed (see figure 71 (b))

                                                Select S0 S0 Inputs

                                                S1 D0 D1

                                                D2

                                                D3

                                                Enable (a) Block Diagram of a 2 x 4 Decoder

                                                Figure 71

                                                S1 D0 D1

                                                D2

                                                D3

                                                Inputs

                                                Data Input (b) Block Diagram of a 1 x 4 Demulptiplexer

                                                34

                                                Logic Design amp Switching Theory 1 Lab Session 07 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                Figure 72 Circuit Diagram for 2 x 4 Decoder 1 x 4 Demultiplexer

                                                Implementation and Observations Implement the 2 x 4 Decoder 1 x 4 Demultiplexer circuit (figure 72) on a bread board (prepare the pin diagram (use appendix A) and refer to laboratory session 01 for implementation procedure) and record the observations in the following table

                                                Enable Data Input S1 S0 D0 D1 D2 D3

                                                0 0 0 0 0 1 0 1 0 0 1 1 1 0 0 1 0 1 1 1 0 1 1 1

                                                TESTING OF 74138 3 x 8 Decoder The 74138 IC has three inputs and eight output lines It has three enable inputs and for the IC to function all three inputs need to be enabled Function of various pins of this IC is described below

                                                35

                                                Logic Design amp Switching Theory 1 Lab Session 07 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                bull Y0 through Y7 Active low data outputs bull A B C Input select lines with C being the MSB bull G1 Active high enable Input bull G2Arsquo and G2Brsquo Active low enable Inputs bull VCC and GND Supply connections lines Circuit Diagram

                                                Figure 73 Pin connections of 74138

                                                Testing Procedure

                                                bull Make connections as shown in the circuit diagram bull Apply different combinations of 1s and 0s at data inputs bull Observe the output and record your observations in the following table

                                                Observations

                                                C B A Y0 Y1 Y2 Y3 Y4 Y5 Y6 Y7 0 0 0 0 0 1 0 1 0 0 1 1 1 0 0 1 0 1 1 1 0 1 1 1

                                                36

                                                Logic Design amp Switching Theory 1 Lab Session 07 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                37

                                                ACTIVITY ACTIVITY 1 What will be the binary values at the outputs Y0 through Y7 of 74138 if 1 What will be the binary values at the outputs Y0 through Y7 of 74138 if

                                                bull All three enable pins are connected to ground bull All three enable pins are connected to ground __________________________________________________________________________________________________________________________________________ __________________________________________________________________________________________________________________________________________ _____________________________________________________________________ _____________________________________________________________________

                                                bull All three enable pins are connected to VCC bull All three enable pins are connected to VCC _______________________________________________________________________________________________________________________________________________________________________________________________________________

                                                _______________________________________________________________________________________________________________________________________________________________________________________________________________

                                                2 Show connections for 74138 in order to use it as a 1 x 8 Demultiplexer 2 Show connections for 74138 in order to use it as a 1 x 8 Demultiplexer

                                                3 Consider a 2 x 4 Decoder with two enable inputs (one active high - G and one active low ndash Grsquo) Draw the output wave-forms for D0 D1 D2 and D3 if the two select inputs are A and B (B being the MSB) All outputs are active low

                                                Grsquo

                                                G

                                                A B

                                                D0 D1 D2

                                                D3

                                                Logic Design amp Switching Theory 1 Lab Session 08 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                Lab Session 08 OBJECT

                                                bull Designing of a 4 x 2 Priority Encoder bull Experimenting with 74148 IC

                                                COMPONENTS AND APPARATUS REQUIRED

                                                1 Following ICs and their Datasheets

                                                bull 7408 Quad 2-input or 7421 Dual 4-input AND Gates bull 7432 Quad 2-input OR Gates bull 7404 Hex Inverter bull 74148 Encoder

                                                2 Digital Trainer DT-01 or the following components Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches

                                                THEORY

                                                Encoder An Encoder is a digital function that produces a reverse operation from that of a decoder An Encoder has 2n (or less) input lines and n output lines The output lines generate the binary code for the 2n input variables Priority Encoder

                                                A simple encoder may produce an erroneous output if more than one of its inputs is high A Priority Encoder is one that responds to just one input among those that may be simultaneously high in accordance with some priority system The most common priority system is based on the relative magnitudes of the inputs whichever decimal input is largest is the one that is encoded

                                                DESIGN OF A 4 x 2 Priority Encoder

                                                The following equations represent the outputs of a 4 x 2 priority encoder 32 DDA +=

                                                321 DDDB += As can be seen from the equations that input D0 which has a binary code 00 is not used in any equation A binary code 00 at the output indicates two conditions Either D0 is selected or no input is selected In order to differentiate these two conditions we will provide an additional output Z to indicate if at least one of the inputs is a 1 The equation for Z will be

                                                4321 DDDDZ = If Z is 0 then the binary code 00 at the output indicates that D0 is selected and if Z is 1 then it indicates that no input line is selected

                                                38

                                                Logic Design amp Switching Theory 1 Lab Session 08 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                Figure 81 Circuit Diagram for 4 x 2 Priority Encoder

                                                it (figure 81) on a bread board (prepare the to laboratory session 01 for implementation

                                                Implementation a Implement the 4 x 2 Priority Encoder circu

                                                ram (use appendix A) and refer

                                                nd Observations

                                                pin diagprocedure) and record the observations in the following table

                                                D3 D2 D1 D0 A B 0 0 0 1 0 0 1 x 0 1 x x 1 x x x

                                                TESTING OF 74148 8 x 3 Octal Priority Encoder

                                                imal digits There are nine of which three represents

                                                ing any of the inputs is high

                                                then it shows that line 0 is selected and if e inputs selected E0 and GS

                                                cannot be in the same state provided that E1 is enabled

                                                The 74148 is a priority encoder with active-Low input for dec

                                                input) and five output linesinputs lines (including an enablethe binary code for the octal digit Function of various pins of this IC is described below

                                                bull 0 through 7 Active low data inputs representing the octal digits A2 A1 A0 Active low output lines representing the binary code bullbull E1 Active low enable Input bull E0 Active low output indicating none of the inputs is high bull GS Active low output indicatbull VCC and GND Supply connections lines Therefore if GS A2 A1 and A0 are all low

                                                then it shows that none of thE0 A2 A1 and A0 are all low

                                                39

                                                Logic Design amp Switching Theory 1 Lab Session 08 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                Circuit Diagram

                                                Figure 82 Pin connections of 74148

                                                Testing Procedure bull Make connections as sho

                                                binations of 1s and 0s at data inputs d record your observations in the following table

                                                GS E0

                                                wn in the circuit diagram bull Apply different combull Observe the output an Observations

                                                0 1 2 3 4 5 6 7 A2 A1 A0 1 1 1 1 1 1 1 1 x x x x x x x 0 x x x x x x 0 1 x x x x x 0 1 1 x x x x 0 1 1 1 x x x 0 1 1 1 1 x x 0 1 1 1 1 1 x 0 1 1 1 1 1 1 0 1 1 1 1 1 1 1

                                                40

                                                Logic Design amp Switching Theory 1 Lab Session 08 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                41

                                                CTIVITY

                                                Cascade the following two 74148 8 x 3 Priority Encoders to form 16 x 4 Priority

                                                A 1

                                                Encoder

                                                Logic Design amp Switching Theory 1 Lab Session 09 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering `

                                                Lab Session 09 OBJECT

                                                Designing an Odd Parity Generator and Checker for a 3-bit Data COMPONENTS AND APPARATUS REQUIRED

                                                1 Following ICs and their Datasheets

                                                bull 7486 Quad 2-input Exclusive-OR Gates bull 7404 Hex Inverter

                                                2 Digital Trainer DT-01 or the following components Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches

                                                THEORY

                                                Parity Generator When binary data is transmitted and processed it is ndash as are all electrical signals ndash susceptible to noise that can either alter or distort its contents 1s may be effectively changed to 0s and 0s to 1s To overcome this problem one or more bits are often added to the data as an aid in detecting errors caused by noise The most common of these is a Parity bit that signifies whether the total number of 1s in a code group is odd or even In an Odd Parity system the parity bit is made 0 or 1 as necessary to make the total number 1s odd (counting the parity bit itself) In an Even Parity system the parity bit is chosen to make the total number of 1s even Table 91 shows how parity bits would be added to BCD code group in both systems

                                                Decimal BCD Value Parity Bit ABCD Odd Parity Even Parity

                                                0 0000 1 0 1 0001 0 1 2 0010 0 1 3 0011 1 0 4 0100 0 1 5 0101 1 0 6 0110 1 0 7 0111 0 1 8 1000 0 1 9 1001 1 0

                                                Table 91 Odd and Even Parity in BCD

                                                When digital data is received a parity checking circuit generates an error signal if the total number of 1s is odd in an even parity system or if it is even in an odd parity system Parity check always detects a single error (one bit change from 0 to 1 or 1 to 0) but may not detect

                                                42

                                                Logic Design amp Switching Theory 1 Lab Session 09 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering ` two or more errors Odd parity is used more often than even parity because even parity does not detect a situation where all 0s are created due to short circuit or other fault condition DESIGN OF A 3-BIT ODD PARITY GENERATOR AND CHECKER Let x y and z be the three bits that constitute the message and are the input to the Odd Parity Generator Circuit Since it is an odd parity system the bit P is generated so as to make the total number of 1s odd (including P) The function P can be expressed as follows P = x oplus y Ο z or P = x Ο y oplus z Since the IC available is 7486 which is quad 2input XOR IC therefore we will convert XNOR also to XOR

                                                P = x oplus y Ο z

                                                P = ( x oplus y ) Ο z Since for even number of variables ______

                                                XOR = XNOR Therefore ___________ _________

                                                P = ( x oplus y ) oplus z = x oplus y oplus z This logical expression can be implemented with two XOR gates and an inverter (see figure 91)

                                                Figure 91 Circuit Diagram for a 3-bit Parity Generator

                                                The 3-bit message and the parity bit are transmitted to their destination where they are applied to a Parity Checker Circuit An error occurs during transmission if the parity of the four bits received is even since the binary information transmitted was originally odd The output C of the parity checker should be a 1 when an error occurs ie when the number of 1s in the four inputs is even Therefore the function C can be expressed as

                                                C = x Ο y Ο z Ο P

                                                Using the same logic applied for the conversion of the equation of P

                                                PzyxC oplusoplusoplus= This logical expression can be implemented with three XOR gates and an inverter (see figure 92)

                                                43

                                                Logic Design amp Switching Theory 1 Lab Session 09 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering `

                                                44

                                                Figure 92 Circuit Diagram for a 3-bit Parity Checker Implementation and Observations Implement the 3-bit Parity Generator and Checker circuits (figure 91 and 92) on a bread board (prepare the pin diagram (use appendix A) and refer to laboratory session 01 for implementation procedure) and record the observations in the following table

                                                x y z P x y z P C x y z P C 0 0 0 0 0 0 0 1 0 0 0 0 0 1 0 0 0 1 1 0 0 1 0 1 0 0 0 1 0 1 0 1 0 0 1 1 0 0 1 1 1 0 1 1 1 0 0 0 1 0 0 1 1 0 0 1 0 1 0 1 0 1 1 1 0 1 1 1 0 0 1 1 0 1 1 1 0 1 1 1 0 1 1 1 1 1 1 1

                                                Odd Parity Generation Odd Parity Check ACTIVITY 1 Try using the parity checker of figure 92 as 3-bit parity generator Write the details here

                                                _____________________________________________________________________________________________________________________________________________________________________________________________________________________ ______________________________________________________________________________________________________________________________________________ _______________________________________________________________________ ______________________________________________________________________________________________________________________________________________

                                                Logic Design amp Switching Theory 1 Lab Session 10 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                Lab Session 10 OBJECT

                                                Driving a seven segment display using 7447 7448 driver IC COMPONENTS AND APPARATUS REQUIRED

                                                1 Following ICs and their Datasheets

                                                bull Seven Segment Displays (Common Anode Common Cathode) bull 7447 7448 BCD to Seven Segment Driver

                                                2 Digital Trainer DT-01 or the following components Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches

                                                THEORY Seven Segment Displays A Seven Segment Display consists of seven light-emitting segments The segments are designated by letters a through g (see figure 101) By illuminating various combinations of segments the numerals 0 through 9 can be displayed Seven Segment Displays are commonly constructed with light-emitting diodes (LEDs) and with liquid-crystal displays (LCDs) LEDs generally provide greater illumination levels but require much greater power than LCDs An LED display can be a common-anode type or common cathode type In common anode type a high voltage is applied at the common terminal of the display and low voltage is applied at a segmentrsquos terminal for illumination In the common-cathode type a low voltage is applied at the common terminal of the display and high voltage is applied at a segmentrsquos terminal for illumination

                                                Figure 101 Seven Segment Display

                                                a f b g

                                                e c d

                                                7447 7448 BCD to Seven Segment Driver 7447 7448 IC is particularly used to drive Seven Segment Its input is a BCD number and output drives a seven segment display 7447 is used to drive common-anode displays whereas 7448 is used to drive common cathode displays 7447 7448 is a 16 pin IC Function of various pins of these ICs is described below

                                                bull A B C D Inputs representing BCD digits (D being the MSB)

                                                45

                                                Logic Design amp Switching Theory 1 Lab Session 10 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering bull OA through OG Outputs to drive segments a through g of the display (Active low

                                                in 7447 and active high in 7448) bull RBI Ripple Blanking Input Turns off all the segments if kept low provided that LT

                                                is kept high and all other inputs (A B C D BI) are kept low Should be kept high otherwise

                                                bull BI RBO Wire-AND logic serving as a Blanking Input and or Ripple Blanking Output

                                                o BI Turns off all the segments if low o RBO Goes to a low level (response condition) along with other outputs when

                                                RBI and inputs A B C and D are low with LT input at high level bull LT Lamp Test input Tests whether all segments are working or not Illuminates all

                                                segments if kept low provided that BI is kept high Should be kept high otherwise bull VCC and GND Supply connections lines CIRCUIT DIAGRAM

                                                Figure 102 Circuit diagram for 7447driving a common-anode display

                                                IMPLEMENTATION AND OBSERVATIONS

                                                bull Make connections as shown in the circuit diagram (refer to laboratory session 01 for implementation procedure)

                                                bull Apply different combinations of 1s and 0s at data inputs bull Observe the output and record your observations in the following table

                                                46

                                                Logic Design amp Switching Theory 1 Lab Session 10 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                47

                                                Decimal Digit

                                                BCD Inputs Seven Segment Outputs D C B A a b c d e f g

                                                0 0 0 0 0 1 0 0 0 1 2 0 0 1 0 3 0 0 1 1 4 0 1 0 0 5 0 1 0 1 6 0 1 1 0 7 0 1 1 1 8 1 0 0 0 9 1 0 0 1

                                                ACTIVITY 1 Perform the Lamp Test for the designed circuit and write your observations

                                                ____________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________

                                                2 How can you use 7447 IC to drive a common-cathode display

                                                ____________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________

                                                3 What symbols appear in the seven segment display if inputs DCBA are

                                                DCBA Symbol

                                                1010

                                                1011

                                                1100

                                                1101

                                                1110

                                                1111

                                                Logic Design amp Switching Theory 1 Lab Session 11 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                48

                                                Lab Session 11 OBJECT

                                                Testing different modes of JK-FF COMPONENTS AND APPARATUS REQUIRED 1 Following ICs and their Datasheets

                                                bull 7473 7476 JK Flip-Flop 2 Digital Trainer DT-01 or the following components

                                                Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches

                                                THEORY

                                                Flip-Flop A flip-flop circuit can maintain a binary state indefinitely (as long as the power is delivered to the circuit) until directed by an input signal to switch states The major differences among various types of flip-flops are in the number of inputs they possess and in the manner in which the inputs affect the binary state

                                                JK Flip-Flop JK flip flop is an edge triggered device A typical JK flip flop has three inputs J K and a clock input The flip-flop can be either positive or negative edge triggered The output Q is available in complemented form as well Beside the usual inputs and output most of the flip-flop IC also possess two asynchronous inputs namely Preset and Clear These inputs are usually active low If used Preset and Clear inputs keep the flip-flop in set and reset state respectively irrespective of the other inputs Both of these inputs cannot be used simultaneously otherwise they will bring the flip-flop in unstable state

                                                Figure 111 Symbol for JK flip-flop

                                                (a) positive-edge triggering (b) active low Preset (PR) and Clear (CLR) with positive-edge triggering

                                                (c) active low Preset (PR) and Clear (CLR) with negative-edge triggering

                                                Logic Design amp Switching Theory 1 Lab Session 11 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                49

                                                TESTING OF 7473 7476 DUAL JK FLIP-FLOP

                                                Both the ICs 7473 and 7476 are similar in functionality except for one difference The flip-flops in 7473 have only one type of active low asynchronous input which is the Clear input whereas the flip-flops in 7476 have both Preset and Clear inputs Both these ICs have negative edge triggered flip-flops

                                                Circuit Diagram

                                                Figure 112 Pin connections of 7476

                                                Testing Procedure

                                                bull Make connections as shown in the circuit diagram (figure 112) bull Apply different combinations of 1s and 0s at J and K inputs bull Observe the output and record your observations in the following table

                                                Observations

                                                J

                                                K Q

                                                0 0 0 1 1 0 1 1

                                                ACTIVITY

                                                1 Observe the output Q of JK flip-flop if the clock input is connected to VCC or GND instead of a clock source Write your observations here __________________________________________________________________________________________________________________________________________ _______________________________________________________________________________________________________________________________________________________________________________________________________________

                                                Logic Design amp Switching Theory 1 Lab Session 12 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                50

                                                Lab Session 12 OBJECT

                                                Designing sequential circuit for the given state diagram using D flip-flop GIVEN STATE DIAGRAM

                                                00

                                                11

                                                Figure 121 State Diagram COMPONENTS AND APPARATUS REQUIRED 1 Following ICs and their Datasheets

                                                bull 7474 D Flip-Flop bull ICs of basic gates (AND OR NOT XOR etc) as required

                                                2 Digital Trainer DT-01 or the following components Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches

                                                THEORY

                                                Sequential Circuits In Sequential Circuits the output not only depends on the present inputs but also on previous states of the circuit These circuits use memory elements (latches flip-flops) and the binary information stored in the memory elements at any given time defines the state of the sequential circuit Analysis of a Sequential Circuit The behavior of a sequential circuit is determined from the inputs the outputs and the states of its flip-flops Both the outputs and next state are a function of the inputs and the

                                                10

                                                01

                                                00 11 10

                                                00

                                                00 11 10 00

                                                Logic Design amp Switching Theory 1 Lab Session 12 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                51

                                                present state The analysis of a sequential circuit form a state diagram comprises of the following bull Selecting a particular flip-flop to design the circuit bull Obtaining state table from the state diagram bull Finding input equations for the selected flip-flop bull Finding state equations (not required for the construction of circuit) bull Implementing the circuit using selected flip-flops and their input equations ANALYZING THE GIVEN STATE DIAGRAM D Flip-Flop D flip-flop is also called transparent flip-flop as it simply transfers the input data to the output For our design we require the graphical symbol and excitation table of D flip-flop (see figure 122)

                                                Qt Qt+1 T 0 0 0 0 1 1 1 0 0 1 1 1

                                                (b) Excitation table of D Flip-Flop

                                                (a) Graphical Symbol

                                                Figure 122 Characteristic equation of D flip-flop is Q(t+1) = D State Table The given state diagram has four states so we will need two D flip-flops (FF-0 FF-1) Form state table form the given state diagram and record the results in the following table

                                                Present State Input Next State Output Input to FF-0 D0

                                                Input to FF-1 D1 Q1t Q0t x Q1(t+1) Q0(t+1) z

                                                Logic Design amp Switching Theory 1 Lab Session 12 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                52

                                                Input Equations Using Karnaugh map the input equations D0 and D1 for the two flip-flops can be found

                                                D0 D1 Q0x

                                                Q1

                                                _ _ Q0x

                                                _ Q0x

                                                Q0x

                                                _ Q0x

                                                Q0x

                                                Q1

                                                _ _ Q0x

                                                _ Q0x

                                                Q0x

                                                _ Q0x

                                                _ Q1

                                                _ Q1

                                                Q1

                                                Q1

                                                D0 = _________________ D1 = _________________

                                                State Equations Using the characteristic equation of D flip-flop we can find the state equations Q0(t+1) and Q1(t+1) for the to flip flops Q0(t+1) = _______________________ Q1(t+1) = _______________________ _______________________ _______________________ _______________________ _______________________ Circuit Diagram

                                                Logic Design amp Switching Theory 1 Lab Session 12 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                53

                                                Implementation Procedure and Observations

                                                1 Implement the circuit using digital ICs on a bread board (prepare the pin diagram (use appendix A) and refer to laboratory session 01 for procedure)

                                                2 Make the clear inputs of the flip-flops low (to clear the flip-flops) The flip-flops will remain in clear state as long as the clear inputs are connected to low level

                                                3 Connect output Q0 and the clock pulse to an oscilloscope 4 Apply 0 to the input x 5 Now make the clear inputs to high 6 Observe the waveform for the first 5 clock pulses and record it 7 Repeat steps 2 to 6 keeping x=1 in step 4 this time 8 Repeat steps 2 to 7 this time connecting Q1 instead of Q0 to the oscilloscope in step

                                                3 Record your observations (Keep frequency of the clock pulse low (eg1Hz) so that the output waveforms can be observed easily)

                                                1 2 3 4 5 Clock Pulse

                                                Output Waveform for Q0 when x=0

                                                Output Waveform for Q0 when x=1

                                                Output Waveform for Q1 when x=0

                                                Output Waveform for Q1 when x=1

                                                Logic Design amp Switching Theory 1 Lab Session 13 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                Lab Session 13 OBJECT

                                                Designing a modulo-5 asynchronous up-counter using JK-FF COMPONENTS AND APPARATUS REQUIRED

                                                1 Following ICs and their Datasheets

                                                bull 7400 Quad 2-input or 7410 Triple 3-input NAND Gates bull 7476 7473 JK Flip-Flop

                                                2 Digital Trainer DT-01 or the following components Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches

                                                THEORY

                                                Digital Counters A digital counter is a set of flip-flops whose states change in response to pulses applied at the input to the counter The flip-flops are interconnected so that their combined state at any time is the binary equivalent of the total number of pulses that have occurred up to that time Every counter resets after a certain number of clock pulses Thus as it name implies a counter is used to count pulses An n stage counter can count up to a maximum of 2n states n is equal to the number of flip-flops required for the construction of counter

                                                Modulus Counters The number of input pulses that causes a counter to reset to its initial count is called the modulus of the counter Thus the modulus equals to total number of distinct states (counts) including zero that a counter can store A binary counter with n stages is a modulo-2n (or mod-2n) counter The largest count a mod-N counter can achieve is N-1 ie a mod-N counter never reaches the binary number equal to its modulus N is always equal to or less than 2n Counters can be classified as bull Synchronous Counters which are clock driven All the flip-flops are driven by a

                                                single clock bull Asynchronous Counters which are event driven Clock input is given to the first

                                                flip-flop only Rest of the flip-flops are driven by their preceding flip-flops

                                                DESIGN OF A MOD-5 ASYNCHRONOUS UP COUNTER The number of flip-flops required to construct a mod-5 counter is 3 because 5 should be less than or equal to 2n This counter will count from 0 to 4 a total of 5 distinct states Since a 3-stage counter can count up to 8 states at maximum a NAND gate is used to reset it after 5 clock pulses Figure 131 shows the logic diagram

                                                54

                                                Logic Design amp Switching Theory 1 Lab Session 13 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                55

                                                Figure 131 A Mod-5 Asynchronous Up Counter

                                                Implementation and Observations

                                                Implement the mod-5 counter circuit (figure 131) on a bread board (prepare the pin diagram (use appendix A) and refer to laboratory session 01 for implementation procedure) and record the observations in the following table

                                                Clock Pulse Q2 Q1 Q0

                                                0 1 2 3 4 5 6 7

                                                ACTIVITY

                                                Draw the timing diagram for mod-5 counter designed in this laboratory session

                                                Logic Design amp Switching Theory 1 Lab Session 14 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                Lab Session 14 OBJECT

                                                Experimenting with 74194 4-bit bidirectional universal shift register COMPONENTS AND APPARATUS REQUIRED

                                                1 Following ICs and their Datasheets

                                                bull 74194 4-bit bidirectional universal shift register 2 Digital Trainer DT-01 or the following components

                                                Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches

                                                THEORY

                                                Shift Registers

                                                A Register is a set of flip-flops used to store binary data A register which is capable of shifting its binary information either to the right or left is called a shift register The logical configuration of a register consists of a chain of flip-flops connected in cascade with the output of one flip-flop connected to the input of next flip-flop All flip-flops receive a common clock pulse which causes the shift from one stage to the next

                                                Bidirectional Shift Registers A bi-directional shift register is one whose bits can be shifted from left to right or from right to left

                                                Universal Shift Registers A universal shift register is a bi-directional register whose input can be in either serial or parallel form and whose output can be in either serial or parallel form

                                                74194 4-BIT BIDIRECTIONAL UNIVERSAL SHIFT REGISTER

                                                The 74194 register provides parallel as well as serial loading in both directions Function of various pins of this IC is described below

                                                bull A B C and D Active high inputs for parallel loading bull QA QB QC and QD Active high outputs bull S0 and S1 Active high mode control inputs The following table shows combinations

                                                of S1 and S0 to enable various modes

                                                S1 S0 Clock Action 0 0 x No change 0 1 uarr Shift right 1 0 uarr Shift left 1 1 uarr Parallel load

                                                uarr shows the rising edge of the clock pulse

                                                56

                                                Logic Design amp Switching Theory 1 Lab Session 14 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering bull SR Active high serial input for right shifting bull SL Active high serial input for left shifting bull CLR Active low input Clears all the flip-flops of the register if set to 0 should be

                                                kept high otherwise bull CLK Clock input bull VCC and GND Supply connections lines Thus A B C and D are inputs for parallel loading whereas SR and SL are inputs for serial loading with right or left shifting respectively S1 and S0 are used to select the loading mode Circuit Diagram

                                                Figure 141 Pin connections of 74194 Testing Procedure

                                                bull Make connections as shown in the circuit diagram bull Observe the output for the input combinations given in the following table

                                                57

                                                Logic Design amp Switching Theory 1 Lab Session 14 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                58

                                                Observations

                                                S1 S0 SL SR A B C D QA QB QC QD 0 0 0 1 0 0 0 0 0 1 1 0 0 0 0 1 1 0 0 0 0 0 1 0 1 1 0 0 0 0 1 1 0 0 1 1 0 1 0 0 0 1 1 1 0 1 0 1 1 0 1 0 0 1 1 0 1 1 1 0 0 1 1 1 1 1 0 0 1 1 1 1

                                                ACTIVITY 1 Show connections of 74194 to convert it into a ring counter with right shifting

                                                Logic Design amp Switching Theory 1 Lab Session 15 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                Lab Session 15

                                                OBJECT

                                                Experimenting with 74245 octal bus transceivers using parallel port PC interfacing COMPONENTS AND APPARATUS REQUIRED 1 Parallel Port Connectors (DB-25) with Cable 2 Personal Computer with Windows 98 and TurboC Compiler Installed 3 Following ICs and their Datasheets

                                                bull 74245 Octal Bus Transceivers with 3-State Outputs 4 Digital Trainer DT-01 or the following components

                                                Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches

                                                THEORY

                                                3-State Logic Sometimes it is necessary to isolate one part of circuit from the other part For this purpose some TTL ICs are designed with 3-state logic Such devices have three possible output states high low and high impedance The device can be put into high impedance state by a control signal applied to an appropriate pin When such a device is in high impedance state there is very high impedance at its output effectively isolating the device from whatever circuitry the output normally drives 74245 Octal Bus Transceivers A bus is any conducting path or set of paths having electrical connections to one or more devices 74245 octal bus transceivers are mainly used to control connectivity between two devices or circuits It also provides direction control for signal flow Function of various pin of this IC is given below

                                                bull A1 through A8 Bus A bull B1 through B8 Bus B bull G΄ Active low enable input When high sets all the bus pins to high impedance state bull DIR Direction control for signal flow When set to high logic level transfers bus A

                                                data to B bus When set to low logic level transfers bus B data to A bus bull VCC and GND Supply connections lines Serial and Parallel Port Connectors A Parallel Port can consist of only 25 pin port adapter called a DB-25 and a serial port can consist of either a 25 pin port adapter called a DB-25 or 9 pin adapter called a DB-9 port adapter Whether the port is a 9 pin or 25 pin it can accomplish all of the same tasks that serial port communications have been designed for

                                                59

                                                Logic Design amp Switching Theory 1 Lab Session 15 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                60

                                                Each adapter can be a male type connector with pins or a female type adapter with tiny holes Generally a PRINTER port (called LPT1) on the back of a computer is female type adapter and we need to use MALE DB-25 pin cable on it for PRINTER connection or for parallel LAPLINK cable And a COM port on the back of a computer is male for the serial ports but it may not necessarily be Parallel Port Connector ndash DB-25 The DB-25 connector (named for its B-size D-shaped shell and 25 pins) is practically ubiquitous in the electronics industry The DB-25 connector is used for a variety of purposes Two common applications are RS-232EIA-232 (serial) connections and the parallel printer interface on the IBM PC The DB-25 connector is also used for SCSI connections Normally the parallel port is used for output to a printer or other device It sends data 8-bits or one byte at a time in parallel The other lines available on the DB-25 connector are a combination of status lines control lines and ground lines The status and control lines are used for handshaking commands and feedback when we are talking to a printer

                                                Figure 152 DB-25 Female Figure 151 DB-25 Male

                                                Figure 153 Pin Layout for DB-25 As can be seen form figure 153 there are four types of pins in this connector

                                                bull Data pins (8 pins - D0 to D7) Active high bidirectional lines

                                                Logic Design amp Switching Theory 1 Lab Session 15 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering bull Control pins (4 pins - C0 to C3) C0 C1 and C3 are active low whereas C2 is active

                                                high These lines also are bidirectional bull Status pins (5 pins ndash S3 to S7) Only S7 is active low rest are active high input lines bull Ground pins (8 pins) Used as a reference signal for the low (below 05 volts) charge

                                                Parallel Port Addresses A DB-25 connector at a parallel port has three address one for each kind of pins register data status and control The first or base address generally refers to data register Second address is for status register and the third one is for control register In Windows 98 the base address is usually found to be 278H 378H or 3BCH Now if 378H is the base address then it refers to the data register whereas addresses for status and control register are respectively 379H and 37AH For Windows 98 the base address can be found as follows 1 On your Desktop right-click on My Computer and select Properties 2 Click on the Device Manager tab and find LPT1 under Plug and Play BIOS 3 After selecting LPT1 click the Properties button 4 Next select the Resources tab and the address should then appear next to InputOutput

                                                Range Accessing parallel port through C Language Programming There are multiple functions in C Language for accessing external ports The most commonly used are listed below

                                                bull unsigned char inportb(int portid) inportb reads a byte from a hardware port

                                                bull int inport(int portid) reads a word from a hardware port

                                                bull void outportb(int portid unsigned char value) outputs a byte to a hardware port

                                                bull void outport(int portid int value) outputs a word to a hardware port

                                                portid refers to the port address whereas value refers to the data to be sent TESTING 74245 USING PARALLEL PORT PC INTERFACING At one end the parallel port connector will be connected to the PC via parallel port cable and another connector (to be plugged into the PC parallel port slot) At the other end it will be connected to the buffer IC 74245 Data lines of the connector will be used to transfer 8-bit data between the PC and the buffer Out of the 8-bits of 74245 4-bits will be used to enter data which will be displayed at the monitor through a C language

                                                61

                                                Logic Design amp Switching Theory 1 Lab Session 15 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering program The remaining 4-bits will receive data from PC as entered by the user via keyboard

                                                Circuit Diagram

                                                Figure 154 Interface of 74245 to PC via Parallel Port

                                                Procedure

                                                1 Connect the DB-25 connector to the PC at one end and solder it to the circuit board at the other end

                                                2 Connect various pins of the connector and 74245 according to the circuit diagram shown in figure 152

                                                3 Using the functions listed in the previous section write a program in C language to operate various pins of the buffer The user interface of the program should provide option to the user whether to send or receive data from the port

                                                4 Set DIR switch to 1 5 Try sending some data bits to the port The result should be displayed at the LEDs 6 Set DIR switch to 0 7 Set some binary 4-bit value through the switches Try reading it via parallel port

                                                C Language Program

                                                A program to access parallel port for data transfers

                                                use header file include ltstdiohgt main program void main() define variable

                                                62

                                                Logic Design amp Switching Theory 1 Lab Session 15 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering unsigned int data=0 char choice while(1) printing option menu clrscr() printf(This program will send or receive a BCD digit from the parallel portn) printf(nPress your choice numbern) printf(n1 Send Data) printf(n2 Receive Data) printf(n3 Exitn) choice = getch() sending entered digit to the port if(choice == 1) input BCD digit printf(nEnter BCD digit to be sent to the port) data = getche() masking the first four bits data = data amp 0x0f sending to the port outportb(0x378data) printf(nThe BCD digit c has been sent to the port data) printing on screen the data received from the port else if(choice == 2) receiving data from the port data = inportb(0x378) masking the last four bits data = data amp 0xf0 shifting first four bits to make them the last four bits datagtgt=4 printf(nThe BCD digit set at the port is c data) exit else if(choice == 3) break key pressed is not in the menu else printf(nEnter valid choice number) printf(nnPress any key to continue) getch()

                                                63

                                                Logic Design amp Switching Theory 1 Lab Session 15 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                ACTIVITY 1 In the above circuit DIR and G΄ inputs are hardwired Connect them to status or

                                                control pins of the parallel port connector and control their function through your software program Circuit Diagram Program Code ______________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________

                                                ___________________________________________________________________________________________________________________________________________________

                                                64

                                                Logic Design amp Switching Theory 1 Lab Session 15 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                65

                                                _____________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ _____________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ _______________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ _________________________________________________ _________________________________________________

                                                Logic Design amp Switching Theory 1 Appendix A NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                Appendix A

                                                PIN DIAGRAMS OF THE ICS REQUIRED FOR THE LABORATORY SESSIONS Consult the TTLIC data book for internal diagrams and electrical characteristics of these ICs 7400 Quad 2-Input NAND 7402 Quad 2-Input NOR

                                                7404 Hex Inverter 7408 Quad 2-Input AND

                                                7410 Triple 3-Input NAND 7411 Triple 3-Input AND

                                                7421 Dual 4-Input AND 7432 Quad 2-Input OR

                                                66

                                                Logic Design amp Switching Theory 1 Appendix A NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                BCD-to-Seven Segm 7448 BCD-to-Seven Segment 7447 ent

                                                Decoder (15V OC) Decoder (2kΩ pull-up output)

                                                7473 Dual JK Flip-Flop 7474 Dual D-Type Flip-Flop

                                                7476 Dual JK Flop-Flop -Bit Binary Full Adder 7483 4 with Fast Carry

                                                86 Quad 2-Inpu 74138 3-to-8 Line 74 t Exclusive OR Decoder Demultiplexer

                                                67

                                                Logic Design amp Switching Theory 1 Appendix A NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                68

                                                74148 8-to-3 Line 16-to-1 Line Data

                                                Priority Encoder 74150 Selector Multiplexer

                                                74245 Oct nsceivers Universal Shift Register (PIPO) (3-State)

                                                74194 4-Bit Bidirectional al Bus Tra

                                                Logic Design amp Switching Theory 1 Appendix B NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                Appendix B

                                                DEBOUNCING CIRCUITRY FOR MECHANICAL SWITCHES Mechanical switches form the interface between human beings and computers or other digital systems For example a keyboard is a matrix of switches used to supply alphanumeric data to a computer Whatever the switch design it is a potential source of problems due to contact bounce The contact bounce creates a sense of narrow pulses when a switch is opened or closed An example of device whose operation would be adversely affected by contact bounce is a digital counter used to count the number of times a switch is depressed Eliminating the effects of contact bounce is called debouncing When data is entered into a computer via a keyboard a software debounce is often used This type of debouncing is a program that causes the computer to sample the switch terminal (ie to input data from it) many times in succession during the interval of time that contact bounce occurs If the data is sensed to be 1s (or 0s) for a specific number of consecutive samples then it is assumed that contact bounce has ended and the last value sensed is valid Hardware debouncing is the use of electronic circuitry to eliminate the effects of contact bounce There are numerous versions of such circuitry including those that use monostable multivibrators (one-shots) but the most straightforward is simply an RS latch Figure B1 shows the circuit When the switch is in position 1 R = 0 and S = 1 so the latch is set and the output (Q) is 1 When the switch is in position 0 R = 1and S = 0 so the latch is reset and the output is 0 When the switch is moved form one position to the other the latch changes state and bouncing occurs at either the R or the S input The bouncing does not affect the latch after it has change state An RS latch will remain set for example when its R input is 0 and its S input is alternately changed form 1 to 0

                                                Figure B1 Use of RS latch to debounce a mechanical switch

                                                69

                                                • 01-ldst-Outer title
                                                  • Practical Workbook
                                                  • Logic Design amp Switching Theory I
                                                    • Dept of Computer amp Information Systems Engineering
                                                      • NED University of Engineering amp Technology
                                                      • Karachi ndash 75270 Pakistan
                                                        • 02-ldst-inner Title
                                                          • Practical Workbook
                                                          • Logic Design amp Switching Theory I
                                                            • Dept of Computer amp Information Systems Engineering
                                                              • NED University of Engineering amp Technology
                                                              • Karachi ndash 75270 Pakistan
                                                                • 03-ldst-general info
                                                                • 04-ldst-introduction
                                                                • 05-Table of Contents
                                                                  • CONTENTS
                                                                    • Lab Session No Object Page No
                                                                    • 1
                                                                    • Also implementing and testing the given circuit on a bread board
                                                                      • Working with Electronics Workbench
                                                                        • Driving a seven segment display using 7447 7448 driver IC
                                                                          • Designing a modulus-5 asynchronous up-counter using JK-FF
                                                                            • Experimenting with 74194 4-bit bidirectional universal shift register
                                                                                • 13
                                                                                    • 06-ldst-Exp01
                                                                                      • Lab Session 01
                                                                                      • OBJECT
                                                                                        • 1 Bread board
                                                                                        • 2 5 V - power supply
                                                                                        • 3 Multimeter
                                                                                        • 4 Logic probe
                                                                                        • 5 LEDs with resistors
                                                                                        • 6 Connecting wires
                                                                                        • 8 Following ICs and their datasheets
                                                                                          • THEORY
                                                                                            • Logic Gates
                                                                                            • 1 The AND Gate ndash An AND gatersquos output is 1 if and only if all its inputs are 1 If A and B are two inputs to an AND gate then output F of the gate is given as F = AB
                                                                                            • 2 The OR Gate - An OR gatersquos output is 1 if at least one of its input is 1 If A and B are two inputs to an OR gate then output F of the gate is given as F = A+B
                                                                                            • 3 The NOT Gate (Inverter) ndash Its output is 1 when its input is 0 and its output is 0 when the input is 1 ie it complements a digital variable If A is the input to a NOT gate then output F of the gate is given as
                                                                                            • 4 The NAND Gate ndash Its output is 1 if at least one of its input is 0 This gate performs the same logic as an AND gate followed by an inverter If A and B are two inputs to a NAND gate then output F of the gate is given as
                                                                                              • 5 The NOR Gate - The output of a NOR gate is 1 if and only if all its inputs are 0 This gate performs the same logic function as an OR gate followed by an inverter If A and B are two inputs to a NAND gate then output F of the gate is given as
                                                                                                  • DATA SHEETS
                                                                                                    • Logic expression for the given logic diagram __________________________________
                                                                                                        • 07-ldst-exp02
                                                                                                          • Working with Electronics Workbench
                                                                                                            • 08-ldst-exp03
                                                                                                              • Designing Half and Full Adder Circuits
                                                                                                                • COMPONENTS AND APPARATUS REQUIRED
                                                                                                                  • 1 Following ICs and their Datasheets
                                                                                                                  • 7408 Quad 2-input AND Gate
                                                                                                                  • 2 Digital Trainer DT-01 or the following components
                                                                                                                    • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                    • Connecting wires Switches
                                                                                                                      • THEORY
                                                                                                                          • IMPLEMENTATION AND OBSERVATIONS
                                                                                                                            • 09-ldst-Exp04
                                                                                                                              • Lab Session 04
                                                                                                                              • 1 Digital ICs and their Datasheets
                                                                                                                              • 7408 Quad 2-input AND Gate
                                                                                                                              • 2 Digital Trainer DT-01 or the following components
                                                                                                                                • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                • Connecting wires Switches
                                                                                                                                • PROCEDURE
                                                                                                                                • REDUCTION OF LOGIC EXPRESSION USING KARNAUGH MAP
                                                                                                                                • OBSERVATIONS
                                                                                                                                • RESULT
                                                                                                                                    • 10-ldst-Exp05
                                                                                                                                      • Lab Session 05
                                                                                                                                      • 1 Following ICs and their Datasheets
                                                                                                                                      • 7408 Quad 2-input AND Gate
                                                                                                                                      • 2 Digital Trainer DT-01 or the following components
                                                                                                                                        • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                        • (100 Ω) Connecting wires Switches
                                                                                                                                        • THEORY
                                                                                                                                          • IMPLEMENTATION AND OBSERVATIONS
                                                                                                                                            • 11-ldst-Exp06
                                                                                                                                              • OBJECT
                                                                                                                                              • 1 Following ICs and their Datasheets
                                                                                                                                              • 7408 Quad 2-input AND Gates or 7411 Triple 3-input AND Gates
                                                                                                                                              • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                • Connecting wires Switches
                                                                                                                                                  • Figure 62 Circuit Diagram for 4 x 1 Multiplexer
                                                                                                                                                  • Implementation and Observations
                                                                                                                                                    • Circuit Diagram
                                                                                                                                                      • ACTIVITY
                                                                                                                                                        • 12-ldst-exp07
                                                                                                                                                          • 1 Following ICs and their Datasheets
                                                                                                                                                          • 7408 Quad 2-input or 7411 Triple 3-input AND Gates
                                                                                                                                                          • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                            • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                            • Connecting wires Switches
                                                                                                                                                              • THEORY
                                                                                                                                                                  • Figure 72 Circuit Diagram for 2 x 4 Decoder 1 x 4 Demultiplexer
                                                                                                                                                                  • Implementation and Observations
                                                                                                                                                                    • Circuit Diagram
                                                                                                                                                                      • ACTIVITY
                                                                                                                                                                        • 13-ldst-Exp08
                                                                                                                                                                          • OBJECT
                                                                                                                                                                          • 1 Following ICs and their Datasheets
                                                                                                                                                                          • 7408 Quad 2-input or 7421 Dual 4-input AND Gates
                                                                                                                                                                          • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                            • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                            • Connecting wires Switches
                                                                                                                                                                              • THEORY
                                                                                                                                                                                  • Figure 81 Circuit Diagram for 4 x 2 Priority Encoder
                                                                                                                                                                                  • Implementation and Observations
                                                                                                                                                                                    • Therefore if GS A2 A1 and A0 are all low then it shows that line 0 is selected and if E0 A2 A1 and A0 are all low then it shows that none of the inputs selected E0 and GS cannot be in the same state provided that E1 is enabled
                                                                                                                                                                                    • Circuit Diagram
                                                                                                                                                                                      • ACTIVITY
                                                                                                                                                                                        • 14-ldst-exp09
                                                                                                                                                                                          • OBJECT
                                                                                                                                                                                          • 1 Following ICs and their Datasheets
                                                                                                                                                                                          • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                            • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                            • Connecting wires Switches
                                                                                                                                                                                              • THEORY
                                                                                                                                                                                                • Parity Generator
                                                                                                                                                                                                  • Let x y and z be the three bits that constitute the message and are the input to the Odd Parity Generator Circuit Since it is an odd parity system the bit P is generated so as to make the total number of 1s odd (including P) The function P can be expressed as follows
                                                                                                                                                                                                  • Figure 91 Circuit Diagram for a 3-bit Parity Generator
                                                                                                                                                                                                    • C = x Ο y Ο z Ο P
                                                                                                                                                                                                      • Implementation and Observations
                                                                                                                                                                                                        • ACTIVITY
                                                                                                                                                                                                            • 15-ldst-exp10
                                                                                                                                                                                                              • Driving a seven segment display using 7447 7448 driver IC
                                                                                                                                                                                                              • COMPONENTS AND APPARATUS REQUIRED
                                                                                                                                                                                                              • 1 Following ICs and their Datasheets
                                                                                                                                                                                                              • 7447 7448 BCD to Seven Segment Driver
                                                                                                                                                                                                              • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches
                                                                                                                                                                                                                  • THEORY
                                                                                                                                                                                                                  • Seven Segment Displays
                                                                                                                                                                                                                  • CIRCUIT DIAGRAM
                                                                                                                                                                                                                  • Figure 102 Circuit diagram for 7447driving a common-anode display
                                                                                                                                                                                                                      • IMPLEMENTATION AND OBSERVATIONS
                                                                                                                                                                                                                        • Decimal Digit
                                                                                                                                                                                                                        • BCD Inputs
                                                                                                                                                                                                                        • Seven Segment Outputs
                                                                                                                                                                                                                        • D
                                                                                                                                                                                                                        • C
                                                                                                                                                                                                                        • B
                                                                                                                                                                                                                        • A
                                                                                                                                                                                                                        • a
                                                                                                                                                                                                                        • b
                                                                                                                                                                                                                        • c
                                                                                                                                                                                                                        • d
                                                                                                                                                                                                                        • e
                                                                                                                                                                                                                        • f
                                                                                                                                                                                                                        • g
                                                                                                                                                                                                                        • 0
                                                                                                                                                                                                                        • 0
                                                                                                                                                                                                                        • 0
                                                                                                                                                                                                                        • 0
                                                                                                                                                                                                                        • 0
                                                                                                                                                                                                                        • 1
                                                                                                                                                                                                                        • 0
                                                                                                                                                                                                                        • 0
                                                                                                                                                                                                                        • 0
                                                                                                                                                                                                                        • 1
                                                                                                                                                                                                                        • 2
                                                                                                                                                                                                                        • 0
                                                                                                                                                                                                                        • 0
                                                                                                                                                                                                                        • 1
                                                                                                                                                                                                                        • 0
                                                                                                                                                                                                                        • 3
                                                                                                                                                                                                                        • 0
                                                                                                                                                                                                                        • 0
                                                                                                                                                                                                                        • 1
                                                                                                                                                                                                                        • 1
                                                                                                                                                                                                                        • 4
                                                                                                                                                                                                                        • 0
                                                                                                                                                                                                                        • 1
                                                                                                                                                                                                                        • 0
                                                                                                                                                                                                                        • 0
                                                                                                                                                                                                                        • 5
                                                                                                                                                                                                                        • 0
                                                                                                                                                                                                                        • 1
                                                                                                                                                                                                                        • 0
                                                                                                                                                                                                                        • 1
                                                                                                                                                                                                                        • 6
                                                                                                                                                                                                                        • 0
                                                                                                                                                                                                                        • 1
                                                                                                                                                                                                                        • 1
                                                                                                                                                                                                                        • 0
                                                                                                                                                                                                                        • 7
                                                                                                                                                                                                                        • 0
                                                                                                                                                                                                                        • 1
                                                                                                                                                                                                                        • 1
                                                                                                                                                                                                                        • 1
                                                                                                                                                                                                                        • 8
                                                                                                                                                                                                                        • 1
                                                                                                                                                                                                                        • 0
                                                                                                                                                                                                                        • 0
                                                                                                                                                                                                                        • 0
                                                                                                                                                                                                                        • 9
                                                                                                                                                                                                                        • 1
                                                                                                                                                                                                                        • 0
                                                                                                                                                                                                                        • 0
                                                                                                                                                                                                                        • 1
                                                                                                                                                                                                                          • ACTIVITY
                                                                                                                                                                                                                            • 16-ldst-exp11
                                                                                                                                                                                                                              • Lab Session 11
                                                                                                                                                                                                                                • OBJECT
                                                                                                                                                                                                                                • COMPONENTS AND APPARATUS REQUIRED
                                                                                                                                                                                                                                  • 1 Following ICs and their Datasheets
                                                                                                                                                                                                                                  • 7473 7476 JK Flip-Flop
                                                                                                                                                                                                                                  • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                                    • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                                                    • Connecting wires Switches
                                                                                                                                                                                                                                      • THEORY
                                                                                                                                                                                                                                          • Flip-Flop
                                                                                                                                                                                                                                          • JK Flip-Flop
                                                                                                                                                                                                                                            • Circuit Diagram
                                                                                                                                                                                                                                              • Observations
                                                                                                                                                                                                                                                • ACTIVITY
                                                                                                                                                                                                                                                    • 17-ldst-exp12
                                                                                                                                                                                                                                                      • Lab Session 12
                                                                                                                                                                                                                                                        • OBJECT
                                                                                                                                                                                                                                                        • GIVEN STATE DIAGRAM
                                                                                                                                                                                                                                                        • Figure 121 State Diagram
                                                                                                                                                                                                                                                        • COMPONENTS AND APPARATUS REQUIRED
                                                                                                                                                                                                                                                          • 1 Following ICs and their Datasheets
                                                                                                                                                                                                                                                          • 7474 D Flip-Flop
                                                                                                                                                                                                                                                          • ICs of basic gates (AND OR NOT XOR etc) as required
                                                                                                                                                                                                                                                          • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                                                            • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                                                                            • Connecting wires Switches
                                                                                                                                                                                                                                                              • THEORY
                                                                                                                                                                                                                                                                  • Sequential Circuits
                                                                                                                                                                                                                                                                    • 18-ldst-exp13
                                                                                                                                                                                                                                                                      • Lab Session 13
                                                                                                                                                                                                                                                                        • Designing a modulo-5 asynchronous up-counter using JK-FF
                                                                                                                                                                                                                                                                          • 1 Following ICs and their Datasheets
                                                                                                                                                                                                                                                                          • 7400 Quad 2-input or 7410 Triple 3-input NAND Gates
                                                                                                                                                                                                                                                                          • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                                                                            • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                                                                                            • Connecting wires Switches
                                                                                                                                                                                                                                                                              • THEORY
                                                                                                                                                                                                                                                                                  • Figure 131 A Mod-5 Asynchronous Up Counter
                                                                                                                                                                                                                                                                                  • Implementation and Observations
                                                                                                                                                                                                                                                                                    • ACTIVITY
                                                                                                                                                                                                                                                                                        • 19-ldst-exp14
                                                                                                                                                                                                                                                                                          • Experimenting with 74194 4-bit bidirectional universal shift register
                                                                                                                                                                                                                                                                                          • 1 Following ICs and their Datasheets
                                                                                                                                                                                                                                                                                          • 74194 4-bit bidirectional universal shift register
                                                                                                                                                                                                                                                                                          • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                                                                                            • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                                                                                                            • Connecting wires Switches
                                                                                                                                                                                                                                                                                              • THEORY
                                                                                                                                                                                                                                                                                                • Shift Registers
                                                                                                                                                                                                                                                                                                • Bidirectional Shift Registers
                                                                                                                                                                                                                                                                                                • Universal Shift Registers
                                                                                                                                                                                                                                                                                                  • S1
                                                                                                                                                                                                                                                                                                    • Circuit Diagram
                                                                                                                                                                                                                                                                                                    • ACTIVITY
                                                                                                                                                                                                                                                                                                        • 20-ldst-exp15
                                                                                                                                                                                                                                                                                                          • COMPONENTS AND APPARATUS REQUIRED
                                                                                                                                                                                                                                                                                                          • 1 Parallel Port Connectors (DB-25) with Cable
                                                                                                                                                                                                                                                                                                          • 2 Personal Computer with Windows 98 and TurboC Compiler Installed
                                                                                                                                                                                                                                                                                                          • 3 Following ICs and their Datasheets
                                                                                                                                                                                                                                                                                                          • 74245 Octal Bus Transceivers with 3-State Outputs
                                                                                                                                                                                                                                                                                                          • 4 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                                                                                                            • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                                                                                                                              • Connecting wires Switches
                                                                                                                                                                                                                                                                                                                • THEORY
                                                                                                                                                                                                                                                                                                                • 3-State Logic
                                                                                                                                                                                                                                                                                                                  • Serial and Parallel Port Connectors
                                                                                                                                                                                                                                                                                                                  • Parallel Port Connector ndash DB-25
                                                                                                                                                                                                                                                                                                                    • Accessing parallel port through C Language Programming
                                                                                                                                                                                                                                                                                                                        • 21-ldst-appendixA
                                                                                                                                                                                                                                                                                                                        • 22-ldst-appendixB
                                                                                                                                                                                                                                                                                                                          • DEBOUNCING CIRCUITRY FOR MECHANICAL SWITCHES

                                                  Logic Design amp Switching Theory 1 Lab Session 04 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                  27

                                                  For activities 1 2 and 3 attach hardcopy of the output (truth table logic expression and logic circuit) form electronic workbench here

                                                  Logic Design amp Switching Theory 1 Lab Session 05 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                  Lab Session 05 Lab Session 05 OBJECT OBJECT

                                                  Designing a BCD Adder Designing a BCD Adder COMPONENTS AND APPARATUS REQUIRED COMPONENTS AND APPARATUS REQUIRED

                                                  1 Following ICs and their Datasheets 1 Following ICs and their Datasheets bull 7408 Quad 2-input AND Gate bull 7408 Quad 2-input AND Gate bull 7432 Quad 2-input OR Gate bull 7432 Quad 2-input OR Gate bull 7483 4-bit Binary Adder bull 7483 4-bit Binary Adder

                                                  2 Digital Trainer DT-01 or the following components 2 Digital Trainer DT-01 or the following components Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors (100 Ω) Connecting wires Switches (100 Ω) Connecting wires Switches

                                                  THEORY THEORY

                                                  A BCD Adder is a combinational circuit that adds two BCD digits in parallel and produces a sum digit also in BCD A BCD Adder is a combinational circuit that adds two BCD digits in parallel and produces a sum digit also in BCD

                                                  A4 A3 A2 A1 B4 B3 B2 B1

                                                  7483-BCD ADDER

                                                  Cout (C4 ) Z4 Z3 Z2 Z1 Cin(C0)

                                                  A4 A3 A2 A1 B4 B3 B2 B1

                                                  7483-BCD ADDER

                                                  Cout

                                                  (C4 ) Z4 Z3 Z2 Z1 Cin(C0)

                                                  Figure 51 BCD Adder Circuit

                                                  28

                                                  Logic Design amp Switching Theory 1 Lab Session 05 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                  29

                                                  A BCD adder must include the correction logic in its internal construction The two BCD digits together with the input carry are first added using a 4-bit binary adder to produce the binary sum If no output carry is generated and the binary sum is less than or equal to 9 then the corresponding BCD sum is identical and therefore no conversion is needed When the output carry is equal to 1 or the binary sum is greater than 9 then a binary 0110 is added to the binary sum through another 4-bit binary adder If Cout is the carry output and Z4Z3Z2Z1 is the binary sum form the first 4-bit binary adder then the following equation indicates the condition when a binary 0110 is to be added

                                                  C = COUT + Z4Z2 + Z4Z3 IMPLEMENTATION AND OBSERVATIONS Implement the BCD adder circuit according to figure 51 on a bread board (prepare the pin diagram (use appendix A) and refer to laboratory session 01 for procedure) A BCD adder has nine input bits (two BCD digits and a carry bit) which can result in a total of 512 combinations of which 312 inputs are donrsquot care Since it is a very lengthy procedure to record results for 200 valid input combinations therefore for simplicity just record results for any eight combinations in the following table

                                                  Input Carry

                                                  BCD Digit 1 BCD Digit 2 Carry Output

                                                  BCD Sum A4 A3 A2 A1 B4 B3 B2 B1 Z4 Z3 Z2 Z1

                                                  Logic Design amp Switching Theory 1 lab Session 06 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                  Lab Session 06

                                                  OBJECT

                                                  bull Designing of a 4 x 1 Multiplexer bull Experimenting with 74150 IC

                                                  COMPONENTS AND APPARATUS REQUIRED 1 Following ICs and their Datasheets

                                                  bull 7408 Quad 2-input AND Gates or 7411 Triple 3-input AND Gates bull 7432 Quad 2-input OR Gates bull 7404 Hex Inverter bull 74150 16 x 1 MUX

                                                  2 Digital Trainer DT-01 or the following components Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches THEORY

                                                  Multiplexers A digital data Multiplexer (MUX) is a combinational circuit having several data inputs and a single output A set of data-select inputs is used to control which of the data inputs is routed to the single output A multiplexer is also called a data selector because of this ability to select which data input is connected o the output Normally there are 2n input lines and n selection lines whose bit combination determine which input is selected DESIGN OF A 4 x 1 MULTIPLEXER A 4 x 1 multiplexer is capable of selecting one of four data inputs (see figure 61) The 2-bit binary number at the data select inputs S1 and S0 specifies which of the four data inputs is to be routed to the output Since there are two data select inputs therefore they can select 22 = 4 different data inputs lines

                                                  S0 S1 D0 D1

                                                  D2 D3

                                                  Data-select Inputs Output

                                                  Data Inputs

                                                  Figure 61 Block Diagram of a 4 x1 Multiplexer

                                                  30

                                                  Logic Design amp Switching Theory 1 lab Session 06 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                  Figure 62 Circuit Diagram for 4 x 1 Multiplexer

                                                  Implementation and Observations

                                                  Implement the 4 x 1 Multiplexer circuit (figure 62) on a bread board (prepare the pin diagram (use appendix A) and refer to laboratory session 01 for implementation procedure) and record the observations in the following table For each data select combination specify the switch number as well as the binary value present on that selected switch

                                                  S1 S0 Output 0 0 0 1 1 0 1 1

                                                  TESTING OF 74150 - 16 x 1 MUX

                                                  The 74150 IC has sixteen data inputs and four data-selection lines Function of various pins of this IC is described below

                                                  bull E0 through E15 Data input lines

                                                  31

                                                  Logic Design amp Switching Theory 1 lab Session 06 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering bull A B C D Data select lines with D being the MSB bull W Active low output line bull Grsquo Active low enable line bull VCC and GND Supply connections lines

                                                  Circuit Diagram

                                                  Figure 63 Pin connections of 74150 for selecting E0

                                                  Testing Procedure

                                                  bull Make connections as shown in the circuit diagram bull Apply different data (1 or 0) at data inputs that are labeled as E0 to E15 Only

                                                  connection for E0 is shown is the figure for simplicity bull Select the data input E0 with the help of data selectors A B C and D bull Observe the output which shows the complement of the data from E0 bull Select all the sixteen data inputs one by one and record your observations in the

                                                  following table

                                                  32

                                                  Logic Design amp Switching Theory 1 lab Session 06 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                  33

                                                  Observations

                                                  Grsquo D C B A W Grsquo D C B A W 0 0 0 0 0 0 1 0 0 0 0 0 0 0 1 0 1 0 0 1 0 0 0 1 0 0 1 0 1 0 0 0 0 1 1 0 1 0 1 1 0 0 1 0 0 0 1 1 0 0 0 0 1 0 1 0 1 1 0 1 0 0 1 1 0 0 1 1 1 0 0 0 1 1 1 0 1 1 1 1

                                                  ACTIVITY 1 Consider 4x1 Multiplexer Draw the output wave-form for the following data inputs

                                                  (E0 E1 E2 E3) and select lines A B (B being the MSB) Output is W

                                                  E3 E2 E1 E0 A B

                                                  W

                                                  2 Using the 4 x 1 MUX designed in this laboratory session implement the following logical function F (A B C) = Σ (0147)

                                                  Show your working and input connections in the following block diagram according to the circuit you have implemented

                                                  4 x 1 MUX

                                                  S0 S1

                                                  Output D0

                                                  D1

                                                  D2

                                                  D3

                                                  Logic Design amp Switching Theory 1 Lab Session 07 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                  Lab Session 07

                                                  OBJECT

                                                  bull Designing of a 2 x 4 Decoder 1 x 4 Demultiplexer bull Experimenting with 74138 IC

                                                  COMPONENTS AND APPARATUS REQUIRED 1 Following ICs and their Datasheets

                                                  bull 7408 Quad 2-input or 7411 Triple 3-input AND Gates bull 7404 Hex Inverter bull 74138 3 x 8 Decoder

                                                  2 Digital Trainer DT-01 or the following components Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches THEORY

                                                  Decoder A Decoder is a combinational circuit that converts binary information form n input lines to a maximum of 2n unique output lines In practical applications decoders are often used for selecting one of several devices

                                                  Demultiplexer A decoder with an enable input can function as a Demultiplexer A Demultiplexer (DMUX) id a circuit that receives information on a single line and transmits this information on one of 2n possible output lines The selection of a specific output line is controlled by the bit values of n selection lines DESIGN OF A 2 x 4 DECODER 1 x 4 DEMULTIPLEXER A 2 x 4 decoder is capable of selecting one of four output lines (see figure 71 (a)) The 2-bit binary number at the data inputs S1 and S0 specifies which of the four data inputs is to be selected If we add an enable pin and use it as an input line then this decoder can be converted to a 1 x 4 Demultiplexer where S1 and S0 will select a line to which data input is to be routed (see figure 71 (b))

                                                  Select S0 S0 Inputs

                                                  S1 D0 D1

                                                  D2

                                                  D3

                                                  Enable (a) Block Diagram of a 2 x 4 Decoder

                                                  Figure 71

                                                  S1 D0 D1

                                                  D2

                                                  D3

                                                  Inputs

                                                  Data Input (b) Block Diagram of a 1 x 4 Demulptiplexer

                                                  34

                                                  Logic Design amp Switching Theory 1 Lab Session 07 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                  Figure 72 Circuit Diagram for 2 x 4 Decoder 1 x 4 Demultiplexer

                                                  Implementation and Observations Implement the 2 x 4 Decoder 1 x 4 Demultiplexer circuit (figure 72) on a bread board (prepare the pin diagram (use appendix A) and refer to laboratory session 01 for implementation procedure) and record the observations in the following table

                                                  Enable Data Input S1 S0 D0 D1 D2 D3

                                                  0 0 0 0 0 1 0 1 0 0 1 1 1 0 0 1 0 1 1 1 0 1 1 1

                                                  TESTING OF 74138 3 x 8 Decoder The 74138 IC has three inputs and eight output lines It has three enable inputs and for the IC to function all three inputs need to be enabled Function of various pins of this IC is described below

                                                  35

                                                  Logic Design amp Switching Theory 1 Lab Session 07 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                  bull Y0 through Y7 Active low data outputs bull A B C Input select lines with C being the MSB bull G1 Active high enable Input bull G2Arsquo and G2Brsquo Active low enable Inputs bull VCC and GND Supply connections lines Circuit Diagram

                                                  Figure 73 Pin connections of 74138

                                                  Testing Procedure

                                                  bull Make connections as shown in the circuit diagram bull Apply different combinations of 1s and 0s at data inputs bull Observe the output and record your observations in the following table

                                                  Observations

                                                  C B A Y0 Y1 Y2 Y3 Y4 Y5 Y6 Y7 0 0 0 0 0 1 0 1 0 0 1 1 1 0 0 1 0 1 1 1 0 1 1 1

                                                  36

                                                  Logic Design amp Switching Theory 1 Lab Session 07 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                  37

                                                  ACTIVITY ACTIVITY 1 What will be the binary values at the outputs Y0 through Y7 of 74138 if 1 What will be the binary values at the outputs Y0 through Y7 of 74138 if

                                                  bull All three enable pins are connected to ground bull All three enable pins are connected to ground __________________________________________________________________________________________________________________________________________ __________________________________________________________________________________________________________________________________________ _____________________________________________________________________ _____________________________________________________________________

                                                  bull All three enable pins are connected to VCC bull All three enable pins are connected to VCC _______________________________________________________________________________________________________________________________________________________________________________________________________________

                                                  _______________________________________________________________________________________________________________________________________________________________________________________________________________

                                                  2 Show connections for 74138 in order to use it as a 1 x 8 Demultiplexer 2 Show connections for 74138 in order to use it as a 1 x 8 Demultiplexer

                                                  3 Consider a 2 x 4 Decoder with two enable inputs (one active high - G and one active low ndash Grsquo) Draw the output wave-forms for D0 D1 D2 and D3 if the two select inputs are A and B (B being the MSB) All outputs are active low

                                                  Grsquo

                                                  G

                                                  A B

                                                  D0 D1 D2

                                                  D3

                                                  Logic Design amp Switching Theory 1 Lab Session 08 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                  Lab Session 08 OBJECT

                                                  bull Designing of a 4 x 2 Priority Encoder bull Experimenting with 74148 IC

                                                  COMPONENTS AND APPARATUS REQUIRED

                                                  1 Following ICs and their Datasheets

                                                  bull 7408 Quad 2-input or 7421 Dual 4-input AND Gates bull 7432 Quad 2-input OR Gates bull 7404 Hex Inverter bull 74148 Encoder

                                                  2 Digital Trainer DT-01 or the following components Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches

                                                  THEORY

                                                  Encoder An Encoder is a digital function that produces a reverse operation from that of a decoder An Encoder has 2n (or less) input lines and n output lines The output lines generate the binary code for the 2n input variables Priority Encoder

                                                  A simple encoder may produce an erroneous output if more than one of its inputs is high A Priority Encoder is one that responds to just one input among those that may be simultaneously high in accordance with some priority system The most common priority system is based on the relative magnitudes of the inputs whichever decimal input is largest is the one that is encoded

                                                  DESIGN OF A 4 x 2 Priority Encoder

                                                  The following equations represent the outputs of a 4 x 2 priority encoder 32 DDA +=

                                                  321 DDDB += As can be seen from the equations that input D0 which has a binary code 00 is not used in any equation A binary code 00 at the output indicates two conditions Either D0 is selected or no input is selected In order to differentiate these two conditions we will provide an additional output Z to indicate if at least one of the inputs is a 1 The equation for Z will be

                                                  4321 DDDDZ = If Z is 0 then the binary code 00 at the output indicates that D0 is selected and if Z is 1 then it indicates that no input line is selected

                                                  38

                                                  Logic Design amp Switching Theory 1 Lab Session 08 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                  Figure 81 Circuit Diagram for 4 x 2 Priority Encoder

                                                  it (figure 81) on a bread board (prepare the to laboratory session 01 for implementation

                                                  Implementation a Implement the 4 x 2 Priority Encoder circu

                                                  ram (use appendix A) and refer

                                                  nd Observations

                                                  pin diagprocedure) and record the observations in the following table

                                                  D3 D2 D1 D0 A B 0 0 0 1 0 0 1 x 0 1 x x 1 x x x

                                                  TESTING OF 74148 8 x 3 Octal Priority Encoder

                                                  imal digits There are nine of which three represents

                                                  ing any of the inputs is high

                                                  then it shows that line 0 is selected and if e inputs selected E0 and GS

                                                  cannot be in the same state provided that E1 is enabled

                                                  The 74148 is a priority encoder with active-Low input for dec

                                                  input) and five output linesinputs lines (including an enablethe binary code for the octal digit Function of various pins of this IC is described below

                                                  bull 0 through 7 Active low data inputs representing the octal digits A2 A1 A0 Active low output lines representing the binary code bullbull E1 Active low enable Input bull E0 Active low output indicating none of the inputs is high bull GS Active low output indicatbull VCC and GND Supply connections lines Therefore if GS A2 A1 and A0 are all low

                                                  then it shows that none of thE0 A2 A1 and A0 are all low

                                                  39

                                                  Logic Design amp Switching Theory 1 Lab Session 08 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                  Circuit Diagram

                                                  Figure 82 Pin connections of 74148

                                                  Testing Procedure bull Make connections as sho

                                                  binations of 1s and 0s at data inputs d record your observations in the following table

                                                  GS E0

                                                  wn in the circuit diagram bull Apply different combull Observe the output an Observations

                                                  0 1 2 3 4 5 6 7 A2 A1 A0 1 1 1 1 1 1 1 1 x x x x x x x 0 x x x x x x 0 1 x x x x x 0 1 1 x x x x 0 1 1 1 x x x 0 1 1 1 1 x x 0 1 1 1 1 1 x 0 1 1 1 1 1 1 0 1 1 1 1 1 1 1

                                                  40

                                                  Logic Design amp Switching Theory 1 Lab Session 08 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                  41

                                                  CTIVITY

                                                  Cascade the following two 74148 8 x 3 Priority Encoders to form 16 x 4 Priority

                                                  A 1

                                                  Encoder

                                                  Logic Design amp Switching Theory 1 Lab Session 09 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering `

                                                  Lab Session 09 OBJECT

                                                  Designing an Odd Parity Generator and Checker for a 3-bit Data COMPONENTS AND APPARATUS REQUIRED

                                                  1 Following ICs and their Datasheets

                                                  bull 7486 Quad 2-input Exclusive-OR Gates bull 7404 Hex Inverter

                                                  2 Digital Trainer DT-01 or the following components Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches

                                                  THEORY

                                                  Parity Generator When binary data is transmitted and processed it is ndash as are all electrical signals ndash susceptible to noise that can either alter or distort its contents 1s may be effectively changed to 0s and 0s to 1s To overcome this problem one or more bits are often added to the data as an aid in detecting errors caused by noise The most common of these is a Parity bit that signifies whether the total number of 1s in a code group is odd or even In an Odd Parity system the parity bit is made 0 or 1 as necessary to make the total number 1s odd (counting the parity bit itself) In an Even Parity system the parity bit is chosen to make the total number of 1s even Table 91 shows how parity bits would be added to BCD code group in both systems

                                                  Decimal BCD Value Parity Bit ABCD Odd Parity Even Parity

                                                  0 0000 1 0 1 0001 0 1 2 0010 0 1 3 0011 1 0 4 0100 0 1 5 0101 1 0 6 0110 1 0 7 0111 0 1 8 1000 0 1 9 1001 1 0

                                                  Table 91 Odd and Even Parity in BCD

                                                  When digital data is received a parity checking circuit generates an error signal if the total number of 1s is odd in an even parity system or if it is even in an odd parity system Parity check always detects a single error (one bit change from 0 to 1 or 1 to 0) but may not detect

                                                  42

                                                  Logic Design amp Switching Theory 1 Lab Session 09 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering ` two or more errors Odd parity is used more often than even parity because even parity does not detect a situation where all 0s are created due to short circuit or other fault condition DESIGN OF A 3-BIT ODD PARITY GENERATOR AND CHECKER Let x y and z be the three bits that constitute the message and are the input to the Odd Parity Generator Circuit Since it is an odd parity system the bit P is generated so as to make the total number of 1s odd (including P) The function P can be expressed as follows P = x oplus y Ο z or P = x Ο y oplus z Since the IC available is 7486 which is quad 2input XOR IC therefore we will convert XNOR also to XOR

                                                  P = x oplus y Ο z

                                                  P = ( x oplus y ) Ο z Since for even number of variables ______

                                                  XOR = XNOR Therefore ___________ _________

                                                  P = ( x oplus y ) oplus z = x oplus y oplus z This logical expression can be implemented with two XOR gates and an inverter (see figure 91)

                                                  Figure 91 Circuit Diagram for a 3-bit Parity Generator

                                                  The 3-bit message and the parity bit are transmitted to their destination where they are applied to a Parity Checker Circuit An error occurs during transmission if the parity of the four bits received is even since the binary information transmitted was originally odd The output C of the parity checker should be a 1 when an error occurs ie when the number of 1s in the four inputs is even Therefore the function C can be expressed as

                                                  C = x Ο y Ο z Ο P

                                                  Using the same logic applied for the conversion of the equation of P

                                                  PzyxC oplusoplusoplus= This logical expression can be implemented with three XOR gates and an inverter (see figure 92)

                                                  43

                                                  Logic Design amp Switching Theory 1 Lab Session 09 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering `

                                                  44

                                                  Figure 92 Circuit Diagram for a 3-bit Parity Checker Implementation and Observations Implement the 3-bit Parity Generator and Checker circuits (figure 91 and 92) on a bread board (prepare the pin diagram (use appendix A) and refer to laboratory session 01 for implementation procedure) and record the observations in the following table

                                                  x y z P x y z P C x y z P C 0 0 0 0 0 0 0 1 0 0 0 0 0 1 0 0 0 1 1 0 0 1 0 1 0 0 0 1 0 1 0 1 0 0 1 1 0 0 1 1 1 0 1 1 1 0 0 0 1 0 0 1 1 0 0 1 0 1 0 1 0 1 1 1 0 1 1 1 0 0 1 1 0 1 1 1 0 1 1 1 0 1 1 1 1 1 1 1

                                                  Odd Parity Generation Odd Parity Check ACTIVITY 1 Try using the parity checker of figure 92 as 3-bit parity generator Write the details here

                                                  _____________________________________________________________________________________________________________________________________________________________________________________________________________________ ______________________________________________________________________________________________________________________________________________ _______________________________________________________________________ ______________________________________________________________________________________________________________________________________________

                                                  Logic Design amp Switching Theory 1 Lab Session 10 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                  Lab Session 10 OBJECT

                                                  Driving a seven segment display using 7447 7448 driver IC COMPONENTS AND APPARATUS REQUIRED

                                                  1 Following ICs and their Datasheets

                                                  bull Seven Segment Displays (Common Anode Common Cathode) bull 7447 7448 BCD to Seven Segment Driver

                                                  2 Digital Trainer DT-01 or the following components Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches

                                                  THEORY Seven Segment Displays A Seven Segment Display consists of seven light-emitting segments The segments are designated by letters a through g (see figure 101) By illuminating various combinations of segments the numerals 0 through 9 can be displayed Seven Segment Displays are commonly constructed with light-emitting diodes (LEDs) and with liquid-crystal displays (LCDs) LEDs generally provide greater illumination levels but require much greater power than LCDs An LED display can be a common-anode type or common cathode type In common anode type a high voltage is applied at the common terminal of the display and low voltage is applied at a segmentrsquos terminal for illumination In the common-cathode type a low voltage is applied at the common terminal of the display and high voltage is applied at a segmentrsquos terminal for illumination

                                                  Figure 101 Seven Segment Display

                                                  a f b g

                                                  e c d

                                                  7447 7448 BCD to Seven Segment Driver 7447 7448 IC is particularly used to drive Seven Segment Its input is a BCD number and output drives a seven segment display 7447 is used to drive common-anode displays whereas 7448 is used to drive common cathode displays 7447 7448 is a 16 pin IC Function of various pins of these ICs is described below

                                                  bull A B C D Inputs representing BCD digits (D being the MSB)

                                                  45

                                                  Logic Design amp Switching Theory 1 Lab Session 10 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering bull OA through OG Outputs to drive segments a through g of the display (Active low

                                                  in 7447 and active high in 7448) bull RBI Ripple Blanking Input Turns off all the segments if kept low provided that LT

                                                  is kept high and all other inputs (A B C D BI) are kept low Should be kept high otherwise

                                                  bull BI RBO Wire-AND logic serving as a Blanking Input and or Ripple Blanking Output

                                                  o BI Turns off all the segments if low o RBO Goes to a low level (response condition) along with other outputs when

                                                  RBI and inputs A B C and D are low with LT input at high level bull LT Lamp Test input Tests whether all segments are working or not Illuminates all

                                                  segments if kept low provided that BI is kept high Should be kept high otherwise bull VCC and GND Supply connections lines CIRCUIT DIAGRAM

                                                  Figure 102 Circuit diagram for 7447driving a common-anode display

                                                  IMPLEMENTATION AND OBSERVATIONS

                                                  bull Make connections as shown in the circuit diagram (refer to laboratory session 01 for implementation procedure)

                                                  bull Apply different combinations of 1s and 0s at data inputs bull Observe the output and record your observations in the following table

                                                  46

                                                  Logic Design amp Switching Theory 1 Lab Session 10 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                  47

                                                  Decimal Digit

                                                  BCD Inputs Seven Segment Outputs D C B A a b c d e f g

                                                  0 0 0 0 0 1 0 0 0 1 2 0 0 1 0 3 0 0 1 1 4 0 1 0 0 5 0 1 0 1 6 0 1 1 0 7 0 1 1 1 8 1 0 0 0 9 1 0 0 1

                                                  ACTIVITY 1 Perform the Lamp Test for the designed circuit and write your observations

                                                  ____________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________

                                                  2 How can you use 7447 IC to drive a common-cathode display

                                                  ____________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________

                                                  3 What symbols appear in the seven segment display if inputs DCBA are

                                                  DCBA Symbol

                                                  1010

                                                  1011

                                                  1100

                                                  1101

                                                  1110

                                                  1111

                                                  Logic Design amp Switching Theory 1 Lab Session 11 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                  48

                                                  Lab Session 11 OBJECT

                                                  Testing different modes of JK-FF COMPONENTS AND APPARATUS REQUIRED 1 Following ICs and their Datasheets

                                                  bull 7473 7476 JK Flip-Flop 2 Digital Trainer DT-01 or the following components

                                                  Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches

                                                  THEORY

                                                  Flip-Flop A flip-flop circuit can maintain a binary state indefinitely (as long as the power is delivered to the circuit) until directed by an input signal to switch states The major differences among various types of flip-flops are in the number of inputs they possess and in the manner in which the inputs affect the binary state

                                                  JK Flip-Flop JK flip flop is an edge triggered device A typical JK flip flop has three inputs J K and a clock input The flip-flop can be either positive or negative edge triggered The output Q is available in complemented form as well Beside the usual inputs and output most of the flip-flop IC also possess two asynchronous inputs namely Preset and Clear These inputs are usually active low If used Preset and Clear inputs keep the flip-flop in set and reset state respectively irrespective of the other inputs Both of these inputs cannot be used simultaneously otherwise they will bring the flip-flop in unstable state

                                                  Figure 111 Symbol for JK flip-flop

                                                  (a) positive-edge triggering (b) active low Preset (PR) and Clear (CLR) with positive-edge triggering

                                                  (c) active low Preset (PR) and Clear (CLR) with negative-edge triggering

                                                  Logic Design amp Switching Theory 1 Lab Session 11 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                  49

                                                  TESTING OF 7473 7476 DUAL JK FLIP-FLOP

                                                  Both the ICs 7473 and 7476 are similar in functionality except for one difference The flip-flops in 7473 have only one type of active low asynchronous input which is the Clear input whereas the flip-flops in 7476 have both Preset and Clear inputs Both these ICs have negative edge triggered flip-flops

                                                  Circuit Diagram

                                                  Figure 112 Pin connections of 7476

                                                  Testing Procedure

                                                  bull Make connections as shown in the circuit diagram (figure 112) bull Apply different combinations of 1s and 0s at J and K inputs bull Observe the output and record your observations in the following table

                                                  Observations

                                                  J

                                                  K Q

                                                  0 0 0 1 1 0 1 1

                                                  ACTIVITY

                                                  1 Observe the output Q of JK flip-flop if the clock input is connected to VCC or GND instead of a clock source Write your observations here __________________________________________________________________________________________________________________________________________ _______________________________________________________________________________________________________________________________________________________________________________________________________________

                                                  Logic Design amp Switching Theory 1 Lab Session 12 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                  50

                                                  Lab Session 12 OBJECT

                                                  Designing sequential circuit for the given state diagram using D flip-flop GIVEN STATE DIAGRAM

                                                  00

                                                  11

                                                  Figure 121 State Diagram COMPONENTS AND APPARATUS REQUIRED 1 Following ICs and their Datasheets

                                                  bull 7474 D Flip-Flop bull ICs of basic gates (AND OR NOT XOR etc) as required

                                                  2 Digital Trainer DT-01 or the following components Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches

                                                  THEORY

                                                  Sequential Circuits In Sequential Circuits the output not only depends on the present inputs but also on previous states of the circuit These circuits use memory elements (latches flip-flops) and the binary information stored in the memory elements at any given time defines the state of the sequential circuit Analysis of a Sequential Circuit The behavior of a sequential circuit is determined from the inputs the outputs and the states of its flip-flops Both the outputs and next state are a function of the inputs and the

                                                  10

                                                  01

                                                  00 11 10

                                                  00

                                                  00 11 10 00

                                                  Logic Design amp Switching Theory 1 Lab Session 12 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                  51

                                                  present state The analysis of a sequential circuit form a state diagram comprises of the following bull Selecting a particular flip-flop to design the circuit bull Obtaining state table from the state diagram bull Finding input equations for the selected flip-flop bull Finding state equations (not required for the construction of circuit) bull Implementing the circuit using selected flip-flops and their input equations ANALYZING THE GIVEN STATE DIAGRAM D Flip-Flop D flip-flop is also called transparent flip-flop as it simply transfers the input data to the output For our design we require the graphical symbol and excitation table of D flip-flop (see figure 122)

                                                  Qt Qt+1 T 0 0 0 0 1 1 1 0 0 1 1 1

                                                  (b) Excitation table of D Flip-Flop

                                                  (a) Graphical Symbol

                                                  Figure 122 Characteristic equation of D flip-flop is Q(t+1) = D State Table The given state diagram has four states so we will need two D flip-flops (FF-0 FF-1) Form state table form the given state diagram and record the results in the following table

                                                  Present State Input Next State Output Input to FF-0 D0

                                                  Input to FF-1 D1 Q1t Q0t x Q1(t+1) Q0(t+1) z

                                                  Logic Design amp Switching Theory 1 Lab Session 12 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                  52

                                                  Input Equations Using Karnaugh map the input equations D0 and D1 for the two flip-flops can be found

                                                  D0 D1 Q0x

                                                  Q1

                                                  _ _ Q0x

                                                  _ Q0x

                                                  Q0x

                                                  _ Q0x

                                                  Q0x

                                                  Q1

                                                  _ _ Q0x

                                                  _ Q0x

                                                  Q0x

                                                  _ Q0x

                                                  _ Q1

                                                  _ Q1

                                                  Q1

                                                  Q1

                                                  D0 = _________________ D1 = _________________

                                                  State Equations Using the characteristic equation of D flip-flop we can find the state equations Q0(t+1) and Q1(t+1) for the to flip flops Q0(t+1) = _______________________ Q1(t+1) = _______________________ _______________________ _______________________ _______________________ _______________________ Circuit Diagram

                                                  Logic Design amp Switching Theory 1 Lab Session 12 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                  53

                                                  Implementation Procedure and Observations

                                                  1 Implement the circuit using digital ICs on a bread board (prepare the pin diagram (use appendix A) and refer to laboratory session 01 for procedure)

                                                  2 Make the clear inputs of the flip-flops low (to clear the flip-flops) The flip-flops will remain in clear state as long as the clear inputs are connected to low level

                                                  3 Connect output Q0 and the clock pulse to an oscilloscope 4 Apply 0 to the input x 5 Now make the clear inputs to high 6 Observe the waveform for the first 5 clock pulses and record it 7 Repeat steps 2 to 6 keeping x=1 in step 4 this time 8 Repeat steps 2 to 7 this time connecting Q1 instead of Q0 to the oscilloscope in step

                                                  3 Record your observations (Keep frequency of the clock pulse low (eg1Hz) so that the output waveforms can be observed easily)

                                                  1 2 3 4 5 Clock Pulse

                                                  Output Waveform for Q0 when x=0

                                                  Output Waveform for Q0 when x=1

                                                  Output Waveform for Q1 when x=0

                                                  Output Waveform for Q1 when x=1

                                                  Logic Design amp Switching Theory 1 Lab Session 13 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                  Lab Session 13 OBJECT

                                                  Designing a modulo-5 asynchronous up-counter using JK-FF COMPONENTS AND APPARATUS REQUIRED

                                                  1 Following ICs and their Datasheets

                                                  bull 7400 Quad 2-input or 7410 Triple 3-input NAND Gates bull 7476 7473 JK Flip-Flop

                                                  2 Digital Trainer DT-01 or the following components Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches

                                                  THEORY

                                                  Digital Counters A digital counter is a set of flip-flops whose states change in response to pulses applied at the input to the counter The flip-flops are interconnected so that their combined state at any time is the binary equivalent of the total number of pulses that have occurred up to that time Every counter resets after a certain number of clock pulses Thus as it name implies a counter is used to count pulses An n stage counter can count up to a maximum of 2n states n is equal to the number of flip-flops required for the construction of counter

                                                  Modulus Counters The number of input pulses that causes a counter to reset to its initial count is called the modulus of the counter Thus the modulus equals to total number of distinct states (counts) including zero that a counter can store A binary counter with n stages is a modulo-2n (or mod-2n) counter The largest count a mod-N counter can achieve is N-1 ie a mod-N counter never reaches the binary number equal to its modulus N is always equal to or less than 2n Counters can be classified as bull Synchronous Counters which are clock driven All the flip-flops are driven by a

                                                  single clock bull Asynchronous Counters which are event driven Clock input is given to the first

                                                  flip-flop only Rest of the flip-flops are driven by their preceding flip-flops

                                                  DESIGN OF A MOD-5 ASYNCHRONOUS UP COUNTER The number of flip-flops required to construct a mod-5 counter is 3 because 5 should be less than or equal to 2n This counter will count from 0 to 4 a total of 5 distinct states Since a 3-stage counter can count up to 8 states at maximum a NAND gate is used to reset it after 5 clock pulses Figure 131 shows the logic diagram

                                                  54

                                                  Logic Design amp Switching Theory 1 Lab Session 13 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                  55

                                                  Figure 131 A Mod-5 Asynchronous Up Counter

                                                  Implementation and Observations

                                                  Implement the mod-5 counter circuit (figure 131) on a bread board (prepare the pin diagram (use appendix A) and refer to laboratory session 01 for implementation procedure) and record the observations in the following table

                                                  Clock Pulse Q2 Q1 Q0

                                                  0 1 2 3 4 5 6 7

                                                  ACTIVITY

                                                  Draw the timing diagram for mod-5 counter designed in this laboratory session

                                                  Logic Design amp Switching Theory 1 Lab Session 14 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                  Lab Session 14 OBJECT

                                                  Experimenting with 74194 4-bit bidirectional universal shift register COMPONENTS AND APPARATUS REQUIRED

                                                  1 Following ICs and their Datasheets

                                                  bull 74194 4-bit bidirectional universal shift register 2 Digital Trainer DT-01 or the following components

                                                  Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches

                                                  THEORY

                                                  Shift Registers

                                                  A Register is a set of flip-flops used to store binary data A register which is capable of shifting its binary information either to the right or left is called a shift register The logical configuration of a register consists of a chain of flip-flops connected in cascade with the output of one flip-flop connected to the input of next flip-flop All flip-flops receive a common clock pulse which causes the shift from one stage to the next

                                                  Bidirectional Shift Registers A bi-directional shift register is one whose bits can be shifted from left to right or from right to left

                                                  Universal Shift Registers A universal shift register is a bi-directional register whose input can be in either serial or parallel form and whose output can be in either serial or parallel form

                                                  74194 4-BIT BIDIRECTIONAL UNIVERSAL SHIFT REGISTER

                                                  The 74194 register provides parallel as well as serial loading in both directions Function of various pins of this IC is described below

                                                  bull A B C and D Active high inputs for parallel loading bull QA QB QC and QD Active high outputs bull S0 and S1 Active high mode control inputs The following table shows combinations

                                                  of S1 and S0 to enable various modes

                                                  S1 S0 Clock Action 0 0 x No change 0 1 uarr Shift right 1 0 uarr Shift left 1 1 uarr Parallel load

                                                  uarr shows the rising edge of the clock pulse

                                                  56

                                                  Logic Design amp Switching Theory 1 Lab Session 14 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering bull SR Active high serial input for right shifting bull SL Active high serial input for left shifting bull CLR Active low input Clears all the flip-flops of the register if set to 0 should be

                                                  kept high otherwise bull CLK Clock input bull VCC and GND Supply connections lines Thus A B C and D are inputs for parallel loading whereas SR and SL are inputs for serial loading with right or left shifting respectively S1 and S0 are used to select the loading mode Circuit Diagram

                                                  Figure 141 Pin connections of 74194 Testing Procedure

                                                  bull Make connections as shown in the circuit diagram bull Observe the output for the input combinations given in the following table

                                                  57

                                                  Logic Design amp Switching Theory 1 Lab Session 14 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                  58

                                                  Observations

                                                  S1 S0 SL SR A B C D QA QB QC QD 0 0 0 1 0 0 0 0 0 1 1 0 0 0 0 1 1 0 0 0 0 0 1 0 1 1 0 0 0 0 1 1 0 0 1 1 0 1 0 0 0 1 1 1 0 1 0 1 1 0 1 0 0 1 1 0 1 1 1 0 0 1 1 1 1 1 0 0 1 1 1 1

                                                  ACTIVITY 1 Show connections of 74194 to convert it into a ring counter with right shifting

                                                  Logic Design amp Switching Theory 1 Lab Session 15 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                  Lab Session 15

                                                  OBJECT

                                                  Experimenting with 74245 octal bus transceivers using parallel port PC interfacing COMPONENTS AND APPARATUS REQUIRED 1 Parallel Port Connectors (DB-25) with Cable 2 Personal Computer with Windows 98 and TurboC Compiler Installed 3 Following ICs and their Datasheets

                                                  bull 74245 Octal Bus Transceivers with 3-State Outputs 4 Digital Trainer DT-01 or the following components

                                                  Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches

                                                  THEORY

                                                  3-State Logic Sometimes it is necessary to isolate one part of circuit from the other part For this purpose some TTL ICs are designed with 3-state logic Such devices have three possible output states high low and high impedance The device can be put into high impedance state by a control signal applied to an appropriate pin When such a device is in high impedance state there is very high impedance at its output effectively isolating the device from whatever circuitry the output normally drives 74245 Octal Bus Transceivers A bus is any conducting path or set of paths having electrical connections to one or more devices 74245 octal bus transceivers are mainly used to control connectivity between two devices or circuits It also provides direction control for signal flow Function of various pin of this IC is given below

                                                  bull A1 through A8 Bus A bull B1 through B8 Bus B bull G΄ Active low enable input When high sets all the bus pins to high impedance state bull DIR Direction control for signal flow When set to high logic level transfers bus A

                                                  data to B bus When set to low logic level transfers bus B data to A bus bull VCC and GND Supply connections lines Serial and Parallel Port Connectors A Parallel Port can consist of only 25 pin port adapter called a DB-25 and a serial port can consist of either a 25 pin port adapter called a DB-25 or 9 pin adapter called a DB-9 port adapter Whether the port is a 9 pin or 25 pin it can accomplish all of the same tasks that serial port communications have been designed for

                                                  59

                                                  Logic Design amp Switching Theory 1 Lab Session 15 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                  60

                                                  Each adapter can be a male type connector with pins or a female type adapter with tiny holes Generally a PRINTER port (called LPT1) on the back of a computer is female type adapter and we need to use MALE DB-25 pin cable on it for PRINTER connection or for parallel LAPLINK cable And a COM port on the back of a computer is male for the serial ports but it may not necessarily be Parallel Port Connector ndash DB-25 The DB-25 connector (named for its B-size D-shaped shell and 25 pins) is practically ubiquitous in the electronics industry The DB-25 connector is used for a variety of purposes Two common applications are RS-232EIA-232 (serial) connections and the parallel printer interface on the IBM PC The DB-25 connector is also used for SCSI connections Normally the parallel port is used for output to a printer or other device It sends data 8-bits or one byte at a time in parallel The other lines available on the DB-25 connector are a combination of status lines control lines and ground lines The status and control lines are used for handshaking commands and feedback when we are talking to a printer

                                                  Figure 152 DB-25 Female Figure 151 DB-25 Male

                                                  Figure 153 Pin Layout for DB-25 As can be seen form figure 153 there are four types of pins in this connector

                                                  bull Data pins (8 pins - D0 to D7) Active high bidirectional lines

                                                  Logic Design amp Switching Theory 1 Lab Session 15 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering bull Control pins (4 pins - C0 to C3) C0 C1 and C3 are active low whereas C2 is active

                                                  high These lines also are bidirectional bull Status pins (5 pins ndash S3 to S7) Only S7 is active low rest are active high input lines bull Ground pins (8 pins) Used as a reference signal for the low (below 05 volts) charge

                                                  Parallel Port Addresses A DB-25 connector at a parallel port has three address one for each kind of pins register data status and control The first or base address generally refers to data register Second address is for status register and the third one is for control register In Windows 98 the base address is usually found to be 278H 378H or 3BCH Now if 378H is the base address then it refers to the data register whereas addresses for status and control register are respectively 379H and 37AH For Windows 98 the base address can be found as follows 1 On your Desktop right-click on My Computer and select Properties 2 Click on the Device Manager tab and find LPT1 under Plug and Play BIOS 3 After selecting LPT1 click the Properties button 4 Next select the Resources tab and the address should then appear next to InputOutput

                                                  Range Accessing parallel port through C Language Programming There are multiple functions in C Language for accessing external ports The most commonly used are listed below

                                                  bull unsigned char inportb(int portid) inportb reads a byte from a hardware port

                                                  bull int inport(int portid) reads a word from a hardware port

                                                  bull void outportb(int portid unsigned char value) outputs a byte to a hardware port

                                                  bull void outport(int portid int value) outputs a word to a hardware port

                                                  portid refers to the port address whereas value refers to the data to be sent TESTING 74245 USING PARALLEL PORT PC INTERFACING At one end the parallel port connector will be connected to the PC via parallel port cable and another connector (to be plugged into the PC parallel port slot) At the other end it will be connected to the buffer IC 74245 Data lines of the connector will be used to transfer 8-bit data between the PC and the buffer Out of the 8-bits of 74245 4-bits will be used to enter data which will be displayed at the monitor through a C language

                                                  61

                                                  Logic Design amp Switching Theory 1 Lab Session 15 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering program The remaining 4-bits will receive data from PC as entered by the user via keyboard

                                                  Circuit Diagram

                                                  Figure 154 Interface of 74245 to PC via Parallel Port

                                                  Procedure

                                                  1 Connect the DB-25 connector to the PC at one end and solder it to the circuit board at the other end

                                                  2 Connect various pins of the connector and 74245 according to the circuit diagram shown in figure 152

                                                  3 Using the functions listed in the previous section write a program in C language to operate various pins of the buffer The user interface of the program should provide option to the user whether to send or receive data from the port

                                                  4 Set DIR switch to 1 5 Try sending some data bits to the port The result should be displayed at the LEDs 6 Set DIR switch to 0 7 Set some binary 4-bit value through the switches Try reading it via parallel port

                                                  C Language Program

                                                  A program to access parallel port for data transfers

                                                  use header file include ltstdiohgt main program void main() define variable

                                                  62

                                                  Logic Design amp Switching Theory 1 Lab Session 15 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering unsigned int data=0 char choice while(1) printing option menu clrscr() printf(This program will send or receive a BCD digit from the parallel portn) printf(nPress your choice numbern) printf(n1 Send Data) printf(n2 Receive Data) printf(n3 Exitn) choice = getch() sending entered digit to the port if(choice == 1) input BCD digit printf(nEnter BCD digit to be sent to the port) data = getche() masking the first four bits data = data amp 0x0f sending to the port outportb(0x378data) printf(nThe BCD digit c has been sent to the port data) printing on screen the data received from the port else if(choice == 2) receiving data from the port data = inportb(0x378) masking the last four bits data = data amp 0xf0 shifting first four bits to make them the last four bits datagtgt=4 printf(nThe BCD digit set at the port is c data) exit else if(choice == 3) break key pressed is not in the menu else printf(nEnter valid choice number) printf(nnPress any key to continue) getch()

                                                  63

                                                  Logic Design amp Switching Theory 1 Lab Session 15 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                  ACTIVITY 1 In the above circuit DIR and G΄ inputs are hardwired Connect them to status or

                                                  control pins of the parallel port connector and control their function through your software program Circuit Diagram Program Code ______________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________

                                                  ___________________________________________________________________________________________________________________________________________________

                                                  64

                                                  Logic Design amp Switching Theory 1 Lab Session 15 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                  65

                                                  _____________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ _____________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ _______________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ _________________________________________________ _________________________________________________

                                                  Logic Design amp Switching Theory 1 Appendix A NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                  Appendix A

                                                  PIN DIAGRAMS OF THE ICS REQUIRED FOR THE LABORATORY SESSIONS Consult the TTLIC data book for internal diagrams and electrical characteristics of these ICs 7400 Quad 2-Input NAND 7402 Quad 2-Input NOR

                                                  7404 Hex Inverter 7408 Quad 2-Input AND

                                                  7410 Triple 3-Input NAND 7411 Triple 3-Input AND

                                                  7421 Dual 4-Input AND 7432 Quad 2-Input OR

                                                  66

                                                  Logic Design amp Switching Theory 1 Appendix A NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                  BCD-to-Seven Segm 7448 BCD-to-Seven Segment 7447 ent

                                                  Decoder (15V OC) Decoder (2kΩ pull-up output)

                                                  7473 Dual JK Flip-Flop 7474 Dual D-Type Flip-Flop

                                                  7476 Dual JK Flop-Flop -Bit Binary Full Adder 7483 4 with Fast Carry

                                                  86 Quad 2-Inpu 74138 3-to-8 Line 74 t Exclusive OR Decoder Demultiplexer

                                                  67

                                                  Logic Design amp Switching Theory 1 Appendix A NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                  68

                                                  74148 8-to-3 Line 16-to-1 Line Data

                                                  Priority Encoder 74150 Selector Multiplexer

                                                  74245 Oct nsceivers Universal Shift Register (PIPO) (3-State)

                                                  74194 4-Bit Bidirectional al Bus Tra

                                                  Logic Design amp Switching Theory 1 Appendix B NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                  Appendix B

                                                  DEBOUNCING CIRCUITRY FOR MECHANICAL SWITCHES Mechanical switches form the interface between human beings and computers or other digital systems For example a keyboard is a matrix of switches used to supply alphanumeric data to a computer Whatever the switch design it is a potential source of problems due to contact bounce The contact bounce creates a sense of narrow pulses when a switch is opened or closed An example of device whose operation would be adversely affected by contact bounce is a digital counter used to count the number of times a switch is depressed Eliminating the effects of contact bounce is called debouncing When data is entered into a computer via a keyboard a software debounce is often used This type of debouncing is a program that causes the computer to sample the switch terminal (ie to input data from it) many times in succession during the interval of time that contact bounce occurs If the data is sensed to be 1s (or 0s) for a specific number of consecutive samples then it is assumed that contact bounce has ended and the last value sensed is valid Hardware debouncing is the use of electronic circuitry to eliminate the effects of contact bounce There are numerous versions of such circuitry including those that use monostable multivibrators (one-shots) but the most straightforward is simply an RS latch Figure B1 shows the circuit When the switch is in position 1 R = 0 and S = 1 so the latch is set and the output (Q) is 1 When the switch is in position 0 R = 1and S = 0 so the latch is reset and the output is 0 When the switch is moved form one position to the other the latch changes state and bouncing occurs at either the R or the S input The bouncing does not affect the latch after it has change state An RS latch will remain set for example when its R input is 0 and its S input is alternately changed form 1 to 0

                                                  Figure B1 Use of RS latch to debounce a mechanical switch

                                                  69

                                                  • 01-ldst-Outer title
                                                    • Practical Workbook
                                                    • Logic Design amp Switching Theory I
                                                      • Dept of Computer amp Information Systems Engineering
                                                        • NED University of Engineering amp Technology
                                                        • Karachi ndash 75270 Pakistan
                                                          • 02-ldst-inner Title
                                                            • Practical Workbook
                                                            • Logic Design amp Switching Theory I
                                                              • Dept of Computer amp Information Systems Engineering
                                                                • NED University of Engineering amp Technology
                                                                • Karachi ndash 75270 Pakistan
                                                                  • 03-ldst-general info
                                                                  • 04-ldst-introduction
                                                                  • 05-Table of Contents
                                                                    • CONTENTS
                                                                      • Lab Session No Object Page No
                                                                      • 1
                                                                      • Also implementing and testing the given circuit on a bread board
                                                                        • Working with Electronics Workbench
                                                                          • Driving a seven segment display using 7447 7448 driver IC
                                                                            • Designing a modulus-5 asynchronous up-counter using JK-FF
                                                                              • Experimenting with 74194 4-bit bidirectional universal shift register
                                                                                  • 13
                                                                                      • 06-ldst-Exp01
                                                                                        • Lab Session 01
                                                                                        • OBJECT
                                                                                          • 1 Bread board
                                                                                          • 2 5 V - power supply
                                                                                          • 3 Multimeter
                                                                                          • 4 Logic probe
                                                                                          • 5 LEDs with resistors
                                                                                          • 6 Connecting wires
                                                                                          • 8 Following ICs and their datasheets
                                                                                            • THEORY
                                                                                              • Logic Gates
                                                                                              • 1 The AND Gate ndash An AND gatersquos output is 1 if and only if all its inputs are 1 If A and B are two inputs to an AND gate then output F of the gate is given as F = AB
                                                                                              • 2 The OR Gate - An OR gatersquos output is 1 if at least one of its input is 1 If A and B are two inputs to an OR gate then output F of the gate is given as F = A+B
                                                                                              • 3 The NOT Gate (Inverter) ndash Its output is 1 when its input is 0 and its output is 0 when the input is 1 ie it complements a digital variable If A is the input to a NOT gate then output F of the gate is given as
                                                                                              • 4 The NAND Gate ndash Its output is 1 if at least one of its input is 0 This gate performs the same logic as an AND gate followed by an inverter If A and B are two inputs to a NAND gate then output F of the gate is given as
                                                                                                • 5 The NOR Gate - The output of a NOR gate is 1 if and only if all its inputs are 0 This gate performs the same logic function as an OR gate followed by an inverter If A and B are two inputs to a NAND gate then output F of the gate is given as
                                                                                                    • DATA SHEETS
                                                                                                      • Logic expression for the given logic diagram __________________________________
                                                                                                          • 07-ldst-exp02
                                                                                                            • Working with Electronics Workbench
                                                                                                              • 08-ldst-exp03
                                                                                                                • Designing Half and Full Adder Circuits
                                                                                                                  • COMPONENTS AND APPARATUS REQUIRED
                                                                                                                    • 1 Following ICs and their Datasheets
                                                                                                                    • 7408 Quad 2-input AND Gate
                                                                                                                    • 2 Digital Trainer DT-01 or the following components
                                                                                                                      • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                      • Connecting wires Switches
                                                                                                                        • THEORY
                                                                                                                            • IMPLEMENTATION AND OBSERVATIONS
                                                                                                                              • 09-ldst-Exp04
                                                                                                                                • Lab Session 04
                                                                                                                                • 1 Digital ICs and their Datasheets
                                                                                                                                • 7408 Quad 2-input AND Gate
                                                                                                                                • 2 Digital Trainer DT-01 or the following components
                                                                                                                                  • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                  • Connecting wires Switches
                                                                                                                                  • PROCEDURE
                                                                                                                                  • REDUCTION OF LOGIC EXPRESSION USING KARNAUGH MAP
                                                                                                                                  • OBSERVATIONS
                                                                                                                                  • RESULT
                                                                                                                                      • 10-ldst-Exp05
                                                                                                                                        • Lab Session 05
                                                                                                                                        • 1 Following ICs and their Datasheets
                                                                                                                                        • 7408 Quad 2-input AND Gate
                                                                                                                                        • 2 Digital Trainer DT-01 or the following components
                                                                                                                                          • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                          • (100 Ω) Connecting wires Switches
                                                                                                                                          • THEORY
                                                                                                                                            • IMPLEMENTATION AND OBSERVATIONS
                                                                                                                                              • 11-ldst-Exp06
                                                                                                                                                • OBJECT
                                                                                                                                                • 1 Following ICs and their Datasheets
                                                                                                                                                • 7408 Quad 2-input AND Gates or 7411 Triple 3-input AND Gates
                                                                                                                                                • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                  • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                  • Connecting wires Switches
                                                                                                                                                    • Figure 62 Circuit Diagram for 4 x 1 Multiplexer
                                                                                                                                                    • Implementation and Observations
                                                                                                                                                      • Circuit Diagram
                                                                                                                                                        • ACTIVITY
                                                                                                                                                          • 12-ldst-exp07
                                                                                                                                                            • 1 Following ICs and their Datasheets
                                                                                                                                                            • 7408 Quad 2-input or 7411 Triple 3-input AND Gates
                                                                                                                                                            • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                              • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                              • Connecting wires Switches
                                                                                                                                                                • THEORY
                                                                                                                                                                    • Figure 72 Circuit Diagram for 2 x 4 Decoder 1 x 4 Demultiplexer
                                                                                                                                                                    • Implementation and Observations
                                                                                                                                                                      • Circuit Diagram
                                                                                                                                                                        • ACTIVITY
                                                                                                                                                                          • 13-ldst-Exp08
                                                                                                                                                                            • OBJECT
                                                                                                                                                                            • 1 Following ICs and their Datasheets
                                                                                                                                                                            • 7408 Quad 2-input or 7421 Dual 4-input AND Gates
                                                                                                                                                                            • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                              • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                              • Connecting wires Switches
                                                                                                                                                                                • THEORY
                                                                                                                                                                                    • Figure 81 Circuit Diagram for 4 x 2 Priority Encoder
                                                                                                                                                                                    • Implementation and Observations
                                                                                                                                                                                      • Therefore if GS A2 A1 and A0 are all low then it shows that line 0 is selected and if E0 A2 A1 and A0 are all low then it shows that none of the inputs selected E0 and GS cannot be in the same state provided that E1 is enabled
                                                                                                                                                                                      • Circuit Diagram
                                                                                                                                                                                        • ACTIVITY
                                                                                                                                                                                          • 14-ldst-exp09
                                                                                                                                                                                            • OBJECT
                                                                                                                                                                                            • 1 Following ICs and their Datasheets
                                                                                                                                                                                            • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                              • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                              • Connecting wires Switches
                                                                                                                                                                                                • THEORY
                                                                                                                                                                                                  • Parity Generator
                                                                                                                                                                                                    • Let x y and z be the three bits that constitute the message and are the input to the Odd Parity Generator Circuit Since it is an odd parity system the bit P is generated so as to make the total number of 1s odd (including P) The function P can be expressed as follows
                                                                                                                                                                                                    • Figure 91 Circuit Diagram for a 3-bit Parity Generator
                                                                                                                                                                                                      • C = x Ο y Ο z Ο P
                                                                                                                                                                                                        • Implementation and Observations
                                                                                                                                                                                                          • ACTIVITY
                                                                                                                                                                                                              • 15-ldst-exp10
                                                                                                                                                                                                                • Driving a seven segment display using 7447 7448 driver IC
                                                                                                                                                                                                                • COMPONENTS AND APPARATUS REQUIRED
                                                                                                                                                                                                                • 1 Following ICs and their Datasheets
                                                                                                                                                                                                                • 7447 7448 BCD to Seven Segment Driver
                                                                                                                                                                                                                • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                  • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches
                                                                                                                                                                                                                    • THEORY
                                                                                                                                                                                                                    • Seven Segment Displays
                                                                                                                                                                                                                    • CIRCUIT DIAGRAM
                                                                                                                                                                                                                    • Figure 102 Circuit diagram for 7447driving a common-anode display
                                                                                                                                                                                                                        • IMPLEMENTATION AND OBSERVATIONS
                                                                                                                                                                                                                          • Decimal Digit
                                                                                                                                                                                                                          • BCD Inputs
                                                                                                                                                                                                                          • Seven Segment Outputs
                                                                                                                                                                                                                          • D
                                                                                                                                                                                                                          • C
                                                                                                                                                                                                                          • B
                                                                                                                                                                                                                          • A
                                                                                                                                                                                                                          • a
                                                                                                                                                                                                                          • b
                                                                                                                                                                                                                          • c
                                                                                                                                                                                                                          • d
                                                                                                                                                                                                                          • e
                                                                                                                                                                                                                          • f
                                                                                                                                                                                                                          • g
                                                                                                                                                                                                                          • 0
                                                                                                                                                                                                                          • 0
                                                                                                                                                                                                                          • 0
                                                                                                                                                                                                                          • 0
                                                                                                                                                                                                                          • 0
                                                                                                                                                                                                                          • 1
                                                                                                                                                                                                                          • 0
                                                                                                                                                                                                                          • 0
                                                                                                                                                                                                                          • 0
                                                                                                                                                                                                                          • 1
                                                                                                                                                                                                                          • 2
                                                                                                                                                                                                                          • 0
                                                                                                                                                                                                                          • 0
                                                                                                                                                                                                                          • 1
                                                                                                                                                                                                                          • 0
                                                                                                                                                                                                                          • 3
                                                                                                                                                                                                                          • 0
                                                                                                                                                                                                                          • 0
                                                                                                                                                                                                                          • 1
                                                                                                                                                                                                                          • 1
                                                                                                                                                                                                                          • 4
                                                                                                                                                                                                                          • 0
                                                                                                                                                                                                                          • 1
                                                                                                                                                                                                                          • 0
                                                                                                                                                                                                                          • 0
                                                                                                                                                                                                                          • 5
                                                                                                                                                                                                                          • 0
                                                                                                                                                                                                                          • 1
                                                                                                                                                                                                                          • 0
                                                                                                                                                                                                                          • 1
                                                                                                                                                                                                                          • 6
                                                                                                                                                                                                                          • 0
                                                                                                                                                                                                                          • 1
                                                                                                                                                                                                                          • 1
                                                                                                                                                                                                                          • 0
                                                                                                                                                                                                                          • 7
                                                                                                                                                                                                                          • 0
                                                                                                                                                                                                                          • 1
                                                                                                                                                                                                                          • 1
                                                                                                                                                                                                                          • 1
                                                                                                                                                                                                                          • 8
                                                                                                                                                                                                                          • 1
                                                                                                                                                                                                                          • 0
                                                                                                                                                                                                                          • 0
                                                                                                                                                                                                                          • 0
                                                                                                                                                                                                                          • 9
                                                                                                                                                                                                                          • 1
                                                                                                                                                                                                                          • 0
                                                                                                                                                                                                                          • 0
                                                                                                                                                                                                                          • 1
                                                                                                                                                                                                                            • ACTIVITY
                                                                                                                                                                                                                              • 16-ldst-exp11
                                                                                                                                                                                                                                • Lab Session 11
                                                                                                                                                                                                                                  • OBJECT
                                                                                                                                                                                                                                  • COMPONENTS AND APPARATUS REQUIRED
                                                                                                                                                                                                                                    • 1 Following ICs and their Datasheets
                                                                                                                                                                                                                                    • 7473 7476 JK Flip-Flop
                                                                                                                                                                                                                                    • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                                      • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                                                      • Connecting wires Switches
                                                                                                                                                                                                                                        • THEORY
                                                                                                                                                                                                                                            • Flip-Flop
                                                                                                                                                                                                                                            • JK Flip-Flop
                                                                                                                                                                                                                                              • Circuit Diagram
                                                                                                                                                                                                                                                • Observations
                                                                                                                                                                                                                                                  • ACTIVITY
                                                                                                                                                                                                                                                      • 17-ldst-exp12
                                                                                                                                                                                                                                                        • Lab Session 12
                                                                                                                                                                                                                                                          • OBJECT
                                                                                                                                                                                                                                                          • GIVEN STATE DIAGRAM
                                                                                                                                                                                                                                                          • Figure 121 State Diagram
                                                                                                                                                                                                                                                          • COMPONENTS AND APPARATUS REQUIRED
                                                                                                                                                                                                                                                            • 1 Following ICs and their Datasheets
                                                                                                                                                                                                                                                            • 7474 D Flip-Flop
                                                                                                                                                                                                                                                            • ICs of basic gates (AND OR NOT XOR etc) as required
                                                                                                                                                                                                                                                            • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                                                              • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                                                                              • Connecting wires Switches
                                                                                                                                                                                                                                                                • THEORY
                                                                                                                                                                                                                                                                    • Sequential Circuits
                                                                                                                                                                                                                                                                      • 18-ldst-exp13
                                                                                                                                                                                                                                                                        • Lab Session 13
                                                                                                                                                                                                                                                                          • Designing a modulo-5 asynchronous up-counter using JK-FF
                                                                                                                                                                                                                                                                            • 1 Following ICs and their Datasheets
                                                                                                                                                                                                                                                                            • 7400 Quad 2-input or 7410 Triple 3-input NAND Gates
                                                                                                                                                                                                                                                                            • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                                                                              • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                                                                                              • Connecting wires Switches
                                                                                                                                                                                                                                                                                • THEORY
                                                                                                                                                                                                                                                                                    • Figure 131 A Mod-5 Asynchronous Up Counter
                                                                                                                                                                                                                                                                                    • Implementation and Observations
                                                                                                                                                                                                                                                                                      • ACTIVITY
                                                                                                                                                                                                                                                                                          • 19-ldst-exp14
                                                                                                                                                                                                                                                                                            • Experimenting with 74194 4-bit bidirectional universal shift register
                                                                                                                                                                                                                                                                                            • 1 Following ICs and their Datasheets
                                                                                                                                                                                                                                                                                            • 74194 4-bit bidirectional universal shift register
                                                                                                                                                                                                                                                                                            • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                                                                                              • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                                                                                                              • Connecting wires Switches
                                                                                                                                                                                                                                                                                                • THEORY
                                                                                                                                                                                                                                                                                                  • Shift Registers
                                                                                                                                                                                                                                                                                                  • Bidirectional Shift Registers
                                                                                                                                                                                                                                                                                                  • Universal Shift Registers
                                                                                                                                                                                                                                                                                                    • S1
                                                                                                                                                                                                                                                                                                      • Circuit Diagram
                                                                                                                                                                                                                                                                                                      • ACTIVITY
                                                                                                                                                                                                                                                                                                          • 20-ldst-exp15
                                                                                                                                                                                                                                                                                                            • COMPONENTS AND APPARATUS REQUIRED
                                                                                                                                                                                                                                                                                                            • 1 Parallel Port Connectors (DB-25) with Cable
                                                                                                                                                                                                                                                                                                            • 2 Personal Computer with Windows 98 and TurboC Compiler Installed
                                                                                                                                                                                                                                                                                                            • 3 Following ICs and their Datasheets
                                                                                                                                                                                                                                                                                                            • 74245 Octal Bus Transceivers with 3-State Outputs
                                                                                                                                                                                                                                                                                                            • 4 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                                                                                                              • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                                                                                                                                • Connecting wires Switches
                                                                                                                                                                                                                                                                                                                  • THEORY
                                                                                                                                                                                                                                                                                                                  • 3-State Logic
                                                                                                                                                                                                                                                                                                                    • Serial and Parallel Port Connectors
                                                                                                                                                                                                                                                                                                                    • Parallel Port Connector ndash DB-25
                                                                                                                                                                                                                                                                                                                      • Accessing parallel port through C Language Programming
                                                                                                                                                                                                                                                                                                                          • 21-ldst-appendixA
                                                                                                                                                                                                                                                                                                                          • 22-ldst-appendixB
                                                                                                                                                                                                                                                                                                                            • DEBOUNCING CIRCUITRY FOR MECHANICAL SWITCHES

                                                    Logic Design amp Switching Theory 1 Lab Session 05 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                    Lab Session 05 Lab Session 05 OBJECT OBJECT

                                                    Designing a BCD Adder Designing a BCD Adder COMPONENTS AND APPARATUS REQUIRED COMPONENTS AND APPARATUS REQUIRED

                                                    1 Following ICs and their Datasheets 1 Following ICs and their Datasheets bull 7408 Quad 2-input AND Gate bull 7408 Quad 2-input AND Gate bull 7432 Quad 2-input OR Gate bull 7432 Quad 2-input OR Gate bull 7483 4-bit Binary Adder bull 7483 4-bit Binary Adder

                                                    2 Digital Trainer DT-01 or the following components 2 Digital Trainer DT-01 or the following components Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors (100 Ω) Connecting wires Switches (100 Ω) Connecting wires Switches

                                                    THEORY THEORY

                                                    A BCD Adder is a combinational circuit that adds two BCD digits in parallel and produces a sum digit also in BCD A BCD Adder is a combinational circuit that adds two BCD digits in parallel and produces a sum digit also in BCD

                                                    A4 A3 A2 A1 B4 B3 B2 B1

                                                    7483-BCD ADDER

                                                    Cout (C4 ) Z4 Z3 Z2 Z1 Cin(C0)

                                                    A4 A3 A2 A1 B4 B3 B2 B1

                                                    7483-BCD ADDER

                                                    Cout

                                                    (C4 ) Z4 Z3 Z2 Z1 Cin(C0)

                                                    Figure 51 BCD Adder Circuit

                                                    28

                                                    Logic Design amp Switching Theory 1 Lab Session 05 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                    29

                                                    A BCD adder must include the correction logic in its internal construction The two BCD digits together with the input carry are first added using a 4-bit binary adder to produce the binary sum If no output carry is generated and the binary sum is less than or equal to 9 then the corresponding BCD sum is identical and therefore no conversion is needed When the output carry is equal to 1 or the binary sum is greater than 9 then a binary 0110 is added to the binary sum through another 4-bit binary adder If Cout is the carry output and Z4Z3Z2Z1 is the binary sum form the first 4-bit binary adder then the following equation indicates the condition when a binary 0110 is to be added

                                                    C = COUT + Z4Z2 + Z4Z3 IMPLEMENTATION AND OBSERVATIONS Implement the BCD adder circuit according to figure 51 on a bread board (prepare the pin diagram (use appendix A) and refer to laboratory session 01 for procedure) A BCD adder has nine input bits (two BCD digits and a carry bit) which can result in a total of 512 combinations of which 312 inputs are donrsquot care Since it is a very lengthy procedure to record results for 200 valid input combinations therefore for simplicity just record results for any eight combinations in the following table

                                                    Input Carry

                                                    BCD Digit 1 BCD Digit 2 Carry Output

                                                    BCD Sum A4 A3 A2 A1 B4 B3 B2 B1 Z4 Z3 Z2 Z1

                                                    Logic Design amp Switching Theory 1 lab Session 06 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                    Lab Session 06

                                                    OBJECT

                                                    bull Designing of a 4 x 1 Multiplexer bull Experimenting with 74150 IC

                                                    COMPONENTS AND APPARATUS REQUIRED 1 Following ICs and their Datasheets

                                                    bull 7408 Quad 2-input AND Gates or 7411 Triple 3-input AND Gates bull 7432 Quad 2-input OR Gates bull 7404 Hex Inverter bull 74150 16 x 1 MUX

                                                    2 Digital Trainer DT-01 or the following components Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches THEORY

                                                    Multiplexers A digital data Multiplexer (MUX) is a combinational circuit having several data inputs and a single output A set of data-select inputs is used to control which of the data inputs is routed to the single output A multiplexer is also called a data selector because of this ability to select which data input is connected o the output Normally there are 2n input lines and n selection lines whose bit combination determine which input is selected DESIGN OF A 4 x 1 MULTIPLEXER A 4 x 1 multiplexer is capable of selecting one of four data inputs (see figure 61) The 2-bit binary number at the data select inputs S1 and S0 specifies which of the four data inputs is to be routed to the output Since there are two data select inputs therefore they can select 22 = 4 different data inputs lines

                                                    S0 S1 D0 D1

                                                    D2 D3

                                                    Data-select Inputs Output

                                                    Data Inputs

                                                    Figure 61 Block Diagram of a 4 x1 Multiplexer

                                                    30

                                                    Logic Design amp Switching Theory 1 lab Session 06 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                    Figure 62 Circuit Diagram for 4 x 1 Multiplexer

                                                    Implementation and Observations

                                                    Implement the 4 x 1 Multiplexer circuit (figure 62) on a bread board (prepare the pin diagram (use appendix A) and refer to laboratory session 01 for implementation procedure) and record the observations in the following table For each data select combination specify the switch number as well as the binary value present on that selected switch

                                                    S1 S0 Output 0 0 0 1 1 0 1 1

                                                    TESTING OF 74150 - 16 x 1 MUX

                                                    The 74150 IC has sixteen data inputs and four data-selection lines Function of various pins of this IC is described below

                                                    bull E0 through E15 Data input lines

                                                    31

                                                    Logic Design amp Switching Theory 1 lab Session 06 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering bull A B C D Data select lines with D being the MSB bull W Active low output line bull Grsquo Active low enable line bull VCC and GND Supply connections lines

                                                    Circuit Diagram

                                                    Figure 63 Pin connections of 74150 for selecting E0

                                                    Testing Procedure

                                                    bull Make connections as shown in the circuit diagram bull Apply different data (1 or 0) at data inputs that are labeled as E0 to E15 Only

                                                    connection for E0 is shown is the figure for simplicity bull Select the data input E0 with the help of data selectors A B C and D bull Observe the output which shows the complement of the data from E0 bull Select all the sixteen data inputs one by one and record your observations in the

                                                    following table

                                                    32

                                                    Logic Design amp Switching Theory 1 lab Session 06 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                    33

                                                    Observations

                                                    Grsquo D C B A W Grsquo D C B A W 0 0 0 0 0 0 1 0 0 0 0 0 0 0 1 0 1 0 0 1 0 0 0 1 0 0 1 0 1 0 0 0 0 1 1 0 1 0 1 1 0 0 1 0 0 0 1 1 0 0 0 0 1 0 1 0 1 1 0 1 0 0 1 1 0 0 1 1 1 0 0 0 1 1 1 0 1 1 1 1

                                                    ACTIVITY 1 Consider 4x1 Multiplexer Draw the output wave-form for the following data inputs

                                                    (E0 E1 E2 E3) and select lines A B (B being the MSB) Output is W

                                                    E3 E2 E1 E0 A B

                                                    W

                                                    2 Using the 4 x 1 MUX designed in this laboratory session implement the following logical function F (A B C) = Σ (0147)

                                                    Show your working and input connections in the following block diagram according to the circuit you have implemented

                                                    4 x 1 MUX

                                                    S0 S1

                                                    Output D0

                                                    D1

                                                    D2

                                                    D3

                                                    Logic Design amp Switching Theory 1 Lab Session 07 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                    Lab Session 07

                                                    OBJECT

                                                    bull Designing of a 2 x 4 Decoder 1 x 4 Demultiplexer bull Experimenting with 74138 IC

                                                    COMPONENTS AND APPARATUS REQUIRED 1 Following ICs and their Datasheets

                                                    bull 7408 Quad 2-input or 7411 Triple 3-input AND Gates bull 7404 Hex Inverter bull 74138 3 x 8 Decoder

                                                    2 Digital Trainer DT-01 or the following components Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches THEORY

                                                    Decoder A Decoder is a combinational circuit that converts binary information form n input lines to a maximum of 2n unique output lines In practical applications decoders are often used for selecting one of several devices

                                                    Demultiplexer A decoder with an enable input can function as a Demultiplexer A Demultiplexer (DMUX) id a circuit that receives information on a single line and transmits this information on one of 2n possible output lines The selection of a specific output line is controlled by the bit values of n selection lines DESIGN OF A 2 x 4 DECODER 1 x 4 DEMULTIPLEXER A 2 x 4 decoder is capable of selecting one of four output lines (see figure 71 (a)) The 2-bit binary number at the data inputs S1 and S0 specifies which of the four data inputs is to be selected If we add an enable pin and use it as an input line then this decoder can be converted to a 1 x 4 Demultiplexer where S1 and S0 will select a line to which data input is to be routed (see figure 71 (b))

                                                    Select S0 S0 Inputs

                                                    S1 D0 D1

                                                    D2

                                                    D3

                                                    Enable (a) Block Diagram of a 2 x 4 Decoder

                                                    Figure 71

                                                    S1 D0 D1

                                                    D2

                                                    D3

                                                    Inputs

                                                    Data Input (b) Block Diagram of a 1 x 4 Demulptiplexer

                                                    34

                                                    Logic Design amp Switching Theory 1 Lab Session 07 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                    Figure 72 Circuit Diagram for 2 x 4 Decoder 1 x 4 Demultiplexer

                                                    Implementation and Observations Implement the 2 x 4 Decoder 1 x 4 Demultiplexer circuit (figure 72) on a bread board (prepare the pin diagram (use appendix A) and refer to laboratory session 01 for implementation procedure) and record the observations in the following table

                                                    Enable Data Input S1 S0 D0 D1 D2 D3

                                                    0 0 0 0 0 1 0 1 0 0 1 1 1 0 0 1 0 1 1 1 0 1 1 1

                                                    TESTING OF 74138 3 x 8 Decoder The 74138 IC has three inputs and eight output lines It has three enable inputs and for the IC to function all three inputs need to be enabled Function of various pins of this IC is described below

                                                    35

                                                    Logic Design amp Switching Theory 1 Lab Session 07 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                    bull Y0 through Y7 Active low data outputs bull A B C Input select lines with C being the MSB bull G1 Active high enable Input bull G2Arsquo and G2Brsquo Active low enable Inputs bull VCC and GND Supply connections lines Circuit Diagram

                                                    Figure 73 Pin connections of 74138

                                                    Testing Procedure

                                                    bull Make connections as shown in the circuit diagram bull Apply different combinations of 1s and 0s at data inputs bull Observe the output and record your observations in the following table

                                                    Observations

                                                    C B A Y0 Y1 Y2 Y3 Y4 Y5 Y6 Y7 0 0 0 0 0 1 0 1 0 0 1 1 1 0 0 1 0 1 1 1 0 1 1 1

                                                    36

                                                    Logic Design amp Switching Theory 1 Lab Session 07 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                    37

                                                    ACTIVITY ACTIVITY 1 What will be the binary values at the outputs Y0 through Y7 of 74138 if 1 What will be the binary values at the outputs Y0 through Y7 of 74138 if

                                                    bull All three enable pins are connected to ground bull All three enable pins are connected to ground __________________________________________________________________________________________________________________________________________ __________________________________________________________________________________________________________________________________________ _____________________________________________________________________ _____________________________________________________________________

                                                    bull All three enable pins are connected to VCC bull All three enable pins are connected to VCC _______________________________________________________________________________________________________________________________________________________________________________________________________________

                                                    _______________________________________________________________________________________________________________________________________________________________________________________________________________

                                                    2 Show connections for 74138 in order to use it as a 1 x 8 Demultiplexer 2 Show connections for 74138 in order to use it as a 1 x 8 Demultiplexer

                                                    3 Consider a 2 x 4 Decoder with two enable inputs (one active high - G and one active low ndash Grsquo) Draw the output wave-forms for D0 D1 D2 and D3 if the two select inputs are A and B (B being the MSB) All outputs are active low

                                                    Grsquo

                                                    G

                                                    A B

                                                    D0 D1 D2

                                                    D3

                                                    Logic Design amp Switching Theory 1 Lab Session 08 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                    Lab Session 08 OBJECT

                                                    bull Designing of a 4 x 2 Priority Encoder bull Experimenting with 74148 IC

                                                    COMPONENTS AND APPARATUS REQUIRED

                                                    1 Following ICs and their Datasheets

                                                    bull 7408 Quad 2-input or 7421 Dual 4-input AND Gates bull 7432 Quad 2-input OR Gates bull 7404 Hex Inverter bull 74148 Encoder

                                                    2 Digital Trainer DT-01 or the following components Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches

                                                    THEORY

                                                    Encoder An Encoder is a digital function that produces a reverse operation from that of a decoder An Encoder has 2n (or less) input lines and n output lines The output lines generate the binary code for the 2n input variables Priority Encoder

                                                    A simple encoder may produce an erroneous output if more than one of its inputs is high A Priority Encoder is one that responds to just one input among those that may be simultaneously high in accordance with some priority system The most common priority system is based on the relative magnitudes of the inputs whichever decimal input is largest is the one that is encoded

                                                    DESIGN OF A 4 x 2 Priority Encoder

                                                    The following equations represent the outputs of a 4 x 2 priority encoder 32 DDA +=

                                                    321 DDDB += As can be seen from the equations that input D0 which has a binary code 00 is not used in any equation A binary code 00 at the output indicates two conditions Either D0 is selected or no input is selected In order to differentiate these two conditions we will provide an additional output Z to indicate if at least one of the inputs is a 1 The equation for Z will be

                                                    4321 DDDDZ = If Z is 0 then the binary code 00 at the output indicates that D0 is selected and if Z is 1 then it indicates that no input line is selected

                                                    38

                                                    Logic Design amp Switching Theory 1 Lab Session 08 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                    Figure 81 Circuit Diagram for 4 x 2 Priority Encoder

                                                    it (figure 81) on a bread board (prepare the to laboratory session 01 for implementation

                                                    Implementation a Implement the 4 x 2 Priority Encoder circu

                                                    ram (use appendix A) and refer

                                                    nd Observations

                                                    pin diagprocedure) and record the observations in the following table

                                                    D3 D2 D1 D0 A B 0 0 0 1 0 0 1 x 0 1 x x 1 x x x

                                                    TESTING OF 74148 8 x 3 Octal Priority Encoder

                                                    imal digits There are nine of which three represents

                                                    ing any of the inputs is high

                                                    then it shows that line 0 is selected and if e inputs selected E0 and GS

                                                    cannot be in the same state provided that E1 is enabled

                                                    The 74148 is a priority encoder with active-Low input for dec

                                                    input) and five output linesinputs lines (including an enablethe binary code for the octal digit Function of various pins of this IC is described below

                                                    bull 0 through 7 Active low data inputs representing the octal digits A2 A1 A0 Active low output lines representing the binary code bullbull E1 Active low enable Input bull E0 Active low output indicating none of the inputs is high bull GS Active low output indicatbull VCC and GND Supply connections lines Therefore if GS A2 A1 and A0 are all low

                                                    then it shows that none of thE0 A2 A1 and A0 are all low

                                                    39

                                                    Logic Design amp Switching Theory 1 Lab Session 08 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                    Circuit Diagram

                                                    Figure 82 Pin connections of 74148

                                                    Testing Procedure bull Make connections as sho

                                                    binations of 1s and 0s at data inputs d record your observations in the following table

                                                    GS E0

                                                    wn in the circuit diagram bull Apply different combull Observe the output an Observations

                                                    0 1 2 3 4 5 6 7 A2 A1 A0 1 1 1 1 1 1 1 1 x x x x x x x 0 x x x x x x 0 1 x x x x x 0 1 1 x x x x 0 1 1 1 x x x 0 1 1 1 1 x x 0 1 1 1 1 1 x 0 1 1 1 1 1 1 0 1 1 1 1 1 1 1

                                                    40

                                                    Logic Design amp Switching Theory 1 Lab Session 08 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                    41

                                                    CTIVITY

                                                    Cascade the following two 74148 8 x 3 Priority Encoders to form 16 x 4 Priority

                                                    A 1

                                                    Encoder

                                                    Logic Design amp Switching Theory 1 Lab Session 09 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering `

                                                    Lab Session 09 OBJECT

                                                    Designing an Odd Parity Generator and Checker for a 3-bit Data COMPONENTS AND APPARATUS REQUIRED

                                                    1 Following ICs and their Datasheets

                                                    bull 7486 Quad 2-input Exclusive-OR Gates bull 7404 Hex Inverter

                                                    2 Digital Trainer DT-01 or the following components Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches

                                                    THEORY

                                                    Parity Generator When binary data is transmitted and processed it is ndash as are all electrical signals ndash susceptible to noise that can either alter or distort its contents 1s may be effectively changed to 0s and 0s to 1s To overcome this problem one or more bits are often added to the data as an aid in detecting errors caused by noise The most common of these is a Parity bit that signifies whether the total number of 1s in a code group is odd or even In an Odd Parity system the parity bit is made 0 or 1 as necessary to make the total number 1s odd (counting the parity bit itself) In an Even Parity system the parity bit is chosen to make the total number of 1s even Table 91 shows how parity bits would be added to BCD code group in both systems

                                                    Decimal BCD Value Parity Bit ABCD Odd Parity Even Parity

                                                    0 0000 1 0 1 0001 0 1 2 0010 0 1 3 0011 1 0 4 0100 0 1 5 0101 1 0 6 0110 1 0 7 0111 0 1 8 1000 0 1 9 1001 1 0

                                                    Table 91 Odd and Even Parity in BCD

                                                    When digital data is received a parity checking circuit generates an error signal if the total number of 1s is odd in an even parity system or if it is even in an odd parity system Parity check always detects a single error (one bit change from 0 to 1 or 1 to 0) but may not detect

                                                    42

                                                    Logic Design amp Switching Theory 1 Lab Session 09 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering ` two or more errors Odd parity is used more often than even parity because even parity does not detect a situation where all 0s are created due to short circuit or other fault condition DESIGN OF A 3-BIT ODD PARITY GENERATOR AND CHECKER Let x y and z be the three bits that constitute the message and are the input to the Odd Parity Generator Circuit Since it is an odd parity system the bit P is generated so as to make the total number of 1s odd (including P) The function P can be expressed as follows P = x oplus y Ο z or P = x Ο y oplus z Since the IC available is 7486 which is quad 2input XOR IC therefore we will convert XNOR also to XOR

                                                    P = x oplus y Ο z

                                                    P = ( x oplus y ) Ο z Since for even number of variables ______

                                                    XOR = XNOR Therefore ___________ _________

                                                    P = ( x oplus y ) oplus z = x oplus y oplus z This logical expression can be implemented with two XOR gates and an inverter (see figure 91)

                                                    Figure 91 Circuit Diagram for a 3-bit Parity Generator

                                                    The 3-bit message and the parity bit are transmitted to their destination where they are applied to a Parity Checker Circuit An error occurs during transmission if the parity of the four bits received is even since the binary information transmitted was originally odd The output C of the parity checker should be a 1 when an error occurs ie when the number of 1s in the four inputs is even Therefore the function C can be expressed as

                                                    C = x Ο y Ο z Ο P

                                                    Using the same logic applied for the conversion of the equation of P

                                                    PzyxC oplusoplusoplus= This logical expression can be implemented with three XOR gates and an inverter (see figure 92)

                                                    43

                                                    Logic Design amp Switching Theory 1 Lab Session 09 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering `

                                                    44

                                                    Figure 92 Circuit Diagram for a 3-bit Parity Checker Implementation and Observations Implement the 3-bit Parity Generator and Checker circuits (figure 91 and 92) on a bread board (prepare the pin diagram (use appendix A) and refer to laboratory session 01 for implementation procedure) and record the observations in the following table

                                                    x y z P x y z P C x y z P C 0 0 0 0 0 0 0 1 0 0 0 0 0 1 0 0 0 1 1 0 0 1 0 1 0 0 0 1 0 1 0 1 0 0 1 1 0 0 1 1 1 0 1 1 1 0 0 0 1 0 0 1 1 0 0 1 0 1 0 1 0 1 1 1 0 1 1 1 0 0 1 1 0 1 1 1 0 1 1 1 0 1 1 1 1 1 1 1

                                                    Odd Parity Generation Odd Parity Check ACTIVITY 1 Try using the parity checker of figure 92 as 3-bit parity generator Write the details here

                                                    _____________________________________________________________________________________________________________________________________________________________________________________________________________________ ______________________________________________________________________________________________________________________________________________ _______________________________________________________________________ ______________________________________________________________________________________________________________________________________________

                                                    Logic Design amp Switching Theory 1 Lab Session 10 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                    Lab Session 10 OBJECT

                                                    Driving a seven segment display using 7447 7448 driver IC COMPONENTS AND APPARATUS REQUIRED

                                                    1 Following ICs and their Datasheets

                                                    bull Seven Segment Displays (Common Anode Common Cathode) bull 7447 7448 BCD to Seven Segment Driver

                                                    2 Digital Trainer DT-01 or the following components Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches

                                                    THEORY Seven Segment Displays A Seven Segment Display consists of seven light-emitting segments The segments are designated by letters a through g (see figure 101) By illuminating various combinations of segments the numerals 0 through 9 can be displayed Seven Segment Displays are commonly constructed with light-emitting diodes (LEDs) and with liquid-crystal displays (LCDs) LEDs generally provide greater illumination levels but require much greater power than LCDs An LED display can be a common-anode type or common cathode type In common anode type a high voltage is applied at the common terminal of the display and low voltage is applied at a segmentrsquos terminal for illumination In the common-cathode type a low voltage is applied at the common terminal of the display and high voltage is applied at a segmentrsquos terminal for illumination

                                                    Figure 101 Seven Segment Display

                                                    a f b g

                                                    e c d

                                                    7447 7448 BCD to Seven Segment Driver 7447 7448 IC is particularly used to drive Seven Segment Its input is a BCD number and output drives a seven segment display 7447 is used to drive common-anode displays whereas 7448 is used to drive common cathode displays 7447 7448 is a 16 pin IC Function of various pins of these ICs is described below

                                                    bull A B C D Inputs representing BCD digits (D being the MSB)

                                                    45

                                                    Logic Design amp Switching Theory 1 Lab Session 10 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering bull OA through OG Outputs to drive segments a through g of the display (Active low

                                                    in 7447 and active high in 7448) bull RBI Ripple Blanking Input Turns off all the segments if kept low provided that LT

                                                    is kept high and all other inputs (A B C D BI) are kept low Should be kept high otherwise

                                                    bull BI RBO Wire-AND logic serving as a Blanking Input and or Ripple Blanking Output

                                                    o BI Turns off all the segments if low o RBO Goes to a low level (response condition) along with other outputs when

                                                    RBI and inputs A B C and D are low with LT input at high level bull LT Lamp Test input Tests whether all segments are working or not Illuminates all

                                                    segments if kept low provided that BI is kept high Should be kept high otherwise bull VCC and GND Supply connections lines CIRCUIT DIAGRAM

                                                    Figure 102 Circuit diagram for 7447driving a common-anode display

                                                    IMPLEMENTATION AND OBSERVATIONS

                                                    bull Make connections as shown in the circuit diagram (refer to laboratory session 01 for implementation procedure)

                                                    bull Apply different combinations of 1s and 0s at data inputs bull Observe the output and record your observations in the following table

                                                    46

                                                    Logic Design amp Switching Theory 1 Lab Session 10 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                    47

                                                    Decimal Digit

                                                    BCD Inputs Seven Segment Outputs D C B A a b c d e f g

                                                    0 0 0 0 0 1 0 0 0 1 2 0 0 1 0 3 0 0 1 1 4 0 1 0 0 5 0 1 0 1 6 0 1 1 0 7 0 1 1 1 8 1 0 0 0 9 1 0 0 1

                                                    ACTIVITY 1 Perform the Lamp Test for the designed circuit and write your observations

                                                    ____________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________

                                                    2 How can you use 7447 IC to drive a common-cathode display

                                                    ____________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________

                                                    3 What symbols appear in the seven segment display if inputs DCBA are

                                                    DCBA Symbol

                                                    1010

                                                    1011

                                                    1100

                                                    1101

                                                    1110

                                                    1111

                                                    Logic Design amp Switching Theory 1 Lab Session 11 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                    48

                                                    Lab Session 11 OBJECT

                                                    Testing different modes of JK-FF COMPONENTS AND APPARATUS REQUIRED 1 Following ICs and their Datasheets

                                                    bull 7473 7476 JK Flip-Flop 2 Digital Trainer DT-01 or the following components

                                                    Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches

                                                    THEORY

                                                    Flip-Flop A flip-flop circuit can maintain a binary state indefinitely (as long as the power is delivered to the circuit) until directed by an input signal to switch states The major differences among various types of flip-flops are in the number of inputs they possess and in the manner in which the inputs affect the binary state

                                                    JK Flip-Flop JK flip flop is an edge triggered device A typical JK flip flop has three inputs J K and a clock input The flip-flop can be either positive or negative edge triggered The output Q is available in complemented form as well Beside the usual inputs and output most of the flip-flop IC also possess two asynchronous inputs namely Preset and Clear These inputs are usually active low If used Preset and Clear inputs keep the flip-flop in set and reset state respectively irrespective of the other inputs Both of these inputs cannot be used simultaneously otherwise they will bring the flip-flop in unstable state

                                                    Figure 111 Symbol for JK flip-flop

                                                    (a) positive-edge triggering (b) active low Preset (PR) and Clear (CLR) with positive-edge triggering

                                                    (c) active low Preset (PR) and Clear (CLR) with negative-edge triggering

                                                    Logic Design amp Switching Theory 1 Lab Session 11 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                    49

                                                    TESTING OF 7473 7476 DUAL JK FLIP-FLOP

                                                    Both the ICs 7473 and 7476 are similar in functionality except for one difference The flip-flops in 7473 have only one type of active low asynchronous input which is the Clear input whereas the flip-flops in 7476 have both Preset and Clear inputs Both these ICs have negative edge triggered flip-flops

                                                    Circuit Diagram

                                                    Figure 112 Pin connections of 7476

                                                    Testing Procedure

                                                    bull Make connections as shown in the circuit diagram (figure 112) bull Apply different combinations of 1s and 0s at J and K inputs bull Observe the output and record your observations in the following table

                                                    Observations

                                                    J

                                                    K Q

                                                    0 0 0 1 1 0 1 1

                                                    ACTIVITY

                                                    1 Observe the output Q of JK flip-flop if the clock input is connected to VCC or GND instead of a clock source Write your observations here __________________________________________________________________________________________________________________________________________ _______________________________________________________________________________________________________________________________________________________________________________________________________________

                                                    Logic Design amp Switching Theory 1 Lab Session 12 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                    50

                                                    Lab Session 12 OBJECT

                                                    Designing sequential circuit for the given state diagram using D flip-flop GIVEN STATE DIAGRAM

                                                    00

                                                    11

                                                    Figure 121 State Diagram COMPONENTS AND APPARATUS REQUIRED 1 Following ICs and their Datasheets

                                                    bull 7474 D Flip-Flop bull ICs of basic gates (AND OR NOT XOR etc) as required

                                                    2 Digital Trainer DT-01 or the following components Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches

                                                    THEORY

                                                    Sequential Circuits In Sequential Circuits the output not only depends on the present inputs but also on previous states of the circuit These circuits use memory elements (latches flip-flops) and the binary information stored in the memory elements at any given time defines the state of the sequential circuit Analysis of a Sequential Circuit The behavior of a sequential circuit is determined from the inputs the outputs and the states of its flip-flops Both the outputs and next state are a function of the inputs and the

                                                    10

                                                    01

                                                    00 11 10

                                                    00

                                                    00 11 10 00

                                                    Logic Design amp Switching Theory 1 Lab Session 12 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                    51

                                                    present state The analysis of a sequential circuit form a state diagram comprises of the following bull Selecting a particular flip-flop to design the circuit bull Obtaining state table from the state diagram bull Finding input equations for the selected flip-flop bull Finding state equations (not required for the construction of circuit) bull Implementing the circuit using selected flip-flops and their input equations ANALYZING THE GIVEN STATE DIAGRAM D Flip-Flop D flip-flop is also called transparent flip-flop as it simply transfers the input data to the output For our design we require the graphical symbol and excitation table of D flip-flop (see figure 122)

                                                    Qt Qt+1 T 0 0 0 0 1 1 1 0 0 1 1 1

                                                    (b) Excitation table of D Flip-Flop

                                                    (a) Graphical Symbol

                                                    Figure 122 Characteristic equation of D flip-flop is Q(t+1) = D State Table The given state diagram has four states so we will need two D flip-flops (FF-0 FF-1) Form state table form the given state diagram and record the results in the following table

                                                    Present State Input Next State Output Input to FF-0 D0

                                                    Input to FF-1 D1 Q1t Q0t x Q1(t+1) Q0(t+1) z

                                                    Logic Design amp Switching Theory 1 Lab Session 12 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                    52

                                                    Input Equations Using Karnaugh map the input equations D0 and D1 for the two flip-flops can be found

                                                    D0 D1 Q0x

                                                    Q1

                                                    _ _ Q0x

                                                    _ Q0x

                                                    Q0x

                                                    _ Q0x

                                                    Q0x

                                                    Q1

                                                    _ _ Q0x

                                                    _ Q0x

                                                    Q0x

                                                    _ Q0x

                                                    _ Q1

                                                    _ Q1

                                                    Q1

                                                    Q1

                                                    D0 = _________________ D1 = _________________

                                                    State Equations Using the characteristic equation of D flip-flop we can find the state equations Q0(t+1) and Q1(t+1) for the to flip flops Q0(t+1) = _______________________ Q1(t+1) = _______________________ _______________________ _______________________ _______________________ _______________________ Circuit Diagram

                                                    Logic Design amp Switching Theory 1 Lab Session 12 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                    53

                                                    Implementation Procedure and Observations

                                                    1 Implement the circuit using digital ICs on a bread board (prepare the pin diagram (use appendix A) and refer to laboratory session 01 for procedure)

                                                    2 Make the clear inputs of the flip-flops low (to clear the flip-flops) The flip-flops will remain in clear state as long as the clear inputs are connected to low level

                                                    3 Connect output Q0 and the clock pulse to an oscilloscope 4 Apply 0 to the input x 5 Now make the clear inputs to high 6 Observe the waveform for the first 5 clock pulses and record it 7 Repeat steps 2 to 6 keeping x=1 in step 4 this time 8 Repeat steps 2 to 7 this time connecting Q1 instead of Q0 to the oscilloscope in step

                                                    3 Record your observations (Keep frequency of the clock pulse low (eg1Hz) so that the output waveforms can be observed easily)

                                                    1 2 3 4 5 Clock Pulse

                                                    Output Waveform for Q0 when x=0

                                                    Output Waveform for Q0 when x=1

                                                    Output Waveform for Q1 when x=0

                                                    Output Waveform for Q1 when x=1

                                                    Logic Design amp Switching Theory 1 Lab Session 13 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                    Lab Session 13 OBJECT

                                                    Designing a modulo-5 asynchronous up-counter using JK-FF COMPONENTS AND APPARATUS REQUIRED

                                                    1 Following ICs and their Datasheets

                                                    bull 7400 Quad 2-input or 7410 Triple 3-input NAND Gates bull 7476 7473 JK Flip-Flop

                                                    2 Digital Trainer DT-01 or the following components Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches

                                                    THEORY

                                                    Digital Counters A digital counter is a set of flip-flops whose states change in response to pulses applied at the input to the counter The flip-flops are interconnected so that their combined state at any time is the binary equivalent of the total number of pulses that have occurred up to that time Every counter resets after a certain number of clock pulses Thus as it name implies a counter is used to count pulses An n stage counter can count up to a maximum of 2n states n is equal to the number of flip-flops required for the construction of counter

                                                    Modulus Counters The number of input pulses that causes a counter to reset to its initial count is called the modulus of the counter Thus the modulus equals to total number of distinct states (counts) including zero that a counter can store A binary counter with n stages is a modulo-2n (or mod-2n) counter The largest count a mod-N counter can achieve is N-1 ie a mod-N counter never reaches the binary number equal to its modulus N is always equal to or less than 2n Counters can be classified as bull Synchronous Counters which are clock driven All the flip-flops are driven by a

                                                    single clock bull Asynchronous Counters which are event driven Clock input is given to the first

                                                    flip-flop only Rest of the flip-flops are driven by their preceding flip-flops

                                                    DESIGN OF A MOD-5 ASYNCHRONOUS UP COUNTER The number of flip-flops required to construct a mod-5 counter is 3 because 5 should be less than or equal to 2n This counter will count from 0 to 4 a total of 5 distinct states Since a 3-stage counter can count up to 8 states at maximum a NAND gate is used to reset it after 5 clock pulses Figure 131 shows the logic diagram

                                                    54

                                                    Logic Design amp Switching Theory 1 Lab Session 13 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                    55

                                                    Figure 131 A Mod-5 Asynchronous Up Counter

                                                    Implementation and Observations

                                                    Implement the mod-5 counter circuit (figure 131) on a bread board (prepare the pin diagram (use appendix A) and refer to laboratory session 01 for implementation procedure) and record the observations in the following table

                                                    Clock Pulse Q2 Q1 Q0

                                                    0 1 2 3 4 5 6 7

                                                    ACTIVITY

                                                    Draw the timing diagram for mod-5 counter designed in this laboratory session

                                                    Logic Design amp Switching Theory 1 Lab Session 14 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                    Lab Session 14 OBJECT

                                                    Experimenting with 74194 4-bit bidirectional universal shift register COMPONENTS AND APPARATUS REQUIRED

                                                    1 Following ICs and their Datasheets

                                                    bull 74194 4-bit bidirectional universal shift register 2 Digital Trainer DT-01 or the following components

                                                    Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches

                                                    THEORY

                                                    Shift Registers

                                                    A Register is a set of flip-flops used to store binary data A register which is capable of shifting its binary information either to the right or left is called a shift register The logical configuration of a register consists of a chain of flip-flops connected in cascade with the output of one flip-flop connected to the input of next flip-flop All flip-flops receive a common clock pulse which causes the shift from one stage to the next

                                                    Bidirectional Shift Registers A bi-directional shift register is one whose bits can be shifted from left to right or from right to left

                                                    Universal Shift Registers A universal shift register is a bi-directional register whose input can be in either serial or parallel form and whose output can be in either serial or parallel form

                                                    74194 4-BIT BIDIRECTIONAL UNIVERSAL SHIFT REGISTER

                                                    The 74194 register provides parallel as well as serial loading in both directions Function of various pins of this IC is described below

                                                    bull A B C and D Active high inputs for parallel loading bull QA QB QC and QD Active high outputs bull S0 and S1 Active high mode control inputs The following table shows combinations

                                                    of S1 and S0 to enable various modes

                                                    S1 S0 Clock Action 0 0 x No change 0 1 uarr Shift right 1 0 uarr Shift left 1 1 uarr Parallel load

                                                    uarr shows the rising edge of the clock pulse

                                                    56

                                                    Logic Design amp Switching Theory 1 Lab Session 14 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering bull SR Active high serial input for right shifting bull SL Active high serial input for left shifting bull CLR Active low input Clears all the flip-flops of the register if set to 0 should be

                                                    kept high otherwise bull CLK Clock input bull VCC and GND Supply connections lines Thus A B C and D are inputs for parallel loading whereas SR and SL are inputs for serial loading with right or left shifting respectively S1 and S0 are used to select the loading mode Circuit Diagram

                                                    Figure 141 Pin connections of 74194 Testing Procedure

                                                    bull Make connections as shown in the circuit diagram bull Observe the output for the input combinations given in the following table

                                                    57

                                                    Logic Design amp Switching Theory 1 Lab Session 14 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                    58

                                                    Observations

                                                    S1 S0 SL SR A B C D QA QB QC QD 0 0 0 1 0 0 0 0 0 1 1 0 0 0 0 1 1 0 0 0 0 0 1 0 1 1 0 0 0 0 1 1 0 0 1 1 0 1 0 0 0 1 1 1 0 1 0 1 1 0 1 0 0 1 1 0 1 1 1 0 0 1 1 1 1 1 0 0 1 1 1 1

                                                    ACTIVITY 1 Show connections of 74194 to convert it into a ring counter with right shifting

                                                    Logic Design amp Switching Theory 1 Lab Session 15 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                    Lab Session 15

                                                    OBJECT

                                                    Experimenting with 74245 octal bus transceivers using parallel port PC interfacing COMPONENTS AND APPARATUS REQUIRED 1 Parallel Port Connectors (DB-25) with Cable 2 Personal Computer with Windows 98 and TurboC Compiler Installed 3 Following ICs and their Datasheets

                                                    bull 74245 Octal Bus Transceivers with 3-State Outputs 4 Digital Trainer DT-01 or the following components

                                                    Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches

                                                    THEORY

                                                    3-State Logic Sometimes it is necessary to isolate one part of circuit from the other part For this purpose some TTL ICs are designed with 3-state logic Such devices have three possible output states high low and high impedance The device can be put into high impedance state by a control signal applied to an appropriate pin When such a device is in high impedance state there is very high impedance at its output effectively isolating the device from whatever circuitry the output normally drives 74245 Octal Bus Transceivers A bus is any conducting path or set of paths having electrical connections to one or more devices 74245 octal bus transceivers are mainly used to control connectivity between two devices or circuits It also provides direction control for signal flow Function of various pin of this IC is given below

                                                    bull A1 through A8 Bus A bull B1 through B8 Bus B bull G΄ Active low enable input When high sets all the bus pins to high impedance state bull DIR Direction control for signal flow When set to high logic level transfers bus A

                                                    data to B bus When set to low logic level transfers bus B data to A bus bull VCC and GND Supply connections lines Serial and Parallel Port Connectors A Parallel Port can consist of only 25 pin port adapter called a DB-25 and a serial port can consist of either a 25 pin port adapter called a DB-25 or 9 pin adapter called a DB-9 port adapter Whether the port is a 9 pin or 25 pin it can accomplish all of the same tasks that serial port communications have been designed for

                                                    59

                                                    Logic Design amp Switching Theory 1 Lab Session 15 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                    60

                                                    Each adapter can be a male type connector with pins or a female type adapter with tiny holes Generally a PRINTER port (called LPT1) on the back of a computer is female type adapter and we need to use MALE DB-25 pin cable on it for PRINTER connection or for parallel LAPLINK cable And a COM port on the back of a computer is male for the serial ports but it may not necessarily be Parallel Port Connector ndash DB-25 The DB-25 connector (named for its B-size D-shaped shell and 25 pins) is practically ubiquitous in the electronics industry The DB-25 connector is used for a variety of purposes Two common applications are RS-232EIA-232 (serial) connections and the parallel printer interface on the IBM PC The DB-25 connector is also used for SCSI connections Normally the parallel port is used for output to a printer or other device It sends data 8-bits or one byte at a time in parallel The other lines available on the DB-25 connector are a combination of status lines control lines and ground lines The status and control lines are used for handshaking commands and feedback when we are talking to a printer

                                                    Figure 152 DB-25 Female Figure 151 DB-25 Male

                                                    Figure 153 Pin Layout for DB-25 As can be seen form figure 153 there are four types of pins in this connector

                                                    bull Data pins (8 pins - D0 to D7) Active high bidirectional lines

                                                    Logic Design amp Switching Theory 1 Lab Session 15 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering bull Control pins (4 pins - C0 to C3) C0 C1 and C3 are active low whereas C2 is active

                                                    high These lines also are bidirectional bull Status pins (5 pins ndash S3 to S7) Only S7 is active low rest are active high input lines bull Ground pins (8 pins) Used as a reference signal for the low (below 05 volts) charge

                                                    Parallel Port Addresses A DB-25 connector at a parallel port has three address one for each kind of pins register data status and control The first or base address generally refers to data register Second address is for status register and the third one is for control register In Windows 98 the base address is usually found to be 278H 378H or 3BCH Now if 378H is the base address then it refers to the data register whereas addresses for status and control register are respectively 379H and 37AH For Windows 98 the base address can be found as follows 1 On your Desktop right-click on My Computer and select Properties 2 Click on the Device Manager tab and find LPT1 under Plug and Play BIOS 3 After selecting LPT1 click the Properties button 4 Next select the Resources tab and the address should then appear next to InputOutput

                                                    Range Accessing parallel port through C Language Programming There are multiple functions in C Language for accessing external ports The most commonly used are listed below

                                                    bull unsigned char inportb(int portid) inportb reads a byte from a hardware port

                                                    bull int inport(int portid) reads a word from a hardware port

                                                    bull void outportb(int portid unsigned char value) outputs a byte to a hardware port

                                                    bull void outport(int portid int value) outputs a word to a hardware port

                                                    portid refers to the port address whereas value refers to the data to be sent TESTING 74245 USING PARALLEL PORT PC INTERFACING At one end the parallel port connector will be connected to the PC via parallel port cable and another connector (to be plugged into the PC parallel port slot) At the other end it will be connected to the buffer IC 74245 Data lines of the connector will be used to transfer 8-bit data between the PC and the buffer Out of the 8-bits of 74245 4-bits will be used to enter data which will be displayed at the monitor through a C language

                                                    61

                                                    Logic Design amp Switching Theory 1 Lab Session 15 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering program The remaining 4-bits will receive data from PC as entered by the user via keyboard

                                                    Circuit Diagram

                                                    Figure 154 Interface of 74245 to PC via Parallel Port

                                                    Procedure

                                                    1 Connect the DB-25 connector to the PC at one end and solder it to the circuit board at the other end

                                                    2 Connect various pins of the connector and 74245 according to the circuit diagram shown in figure 152

                                                    3 Using the functions listed in the previous section write a program in C language to operate various pins of the buffer The user interface of the program should provide option to the user whether to send or receive data from the port

                                                    4 Set DIR switch to 1 5 Try sending some data bits to the port The result should be displayed at the LEDs 6 Set DIR switch to 0 7 Set some binary 4-bit value through the switches Try reading it via parallel port

                                                    C Language Program

                                                    A program to access parallel port for data transfers

                                                    use header file include ltstdiohgt main program void main() define variable

                                                    62

                                                    Logic Design amp Switching Theory 1 Lab Session 15 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering unsigned int data=0 char choice while(1) printing option menu clrscr() printf(This program will send or receive a BCD digit from the parallel portn) printf(nPress your choice numbern) printf(n1 Send Data) printf(n2 Receive Data) printf(n3 Exitn) choice = getch() sending entered digit to the port if(choice == 1) input BCD digit printf(nEnter BCD digit to be sent to the port) data = getche() masking the first four bits data = data amp 0x0f sending to the port outportb(0x378data) printf(nThe BCD digit c has been sent to the port data) printing on screen the data received from the port else if(choice == 2) receiving data from the port data = inportb(0x378) masking the last four bits data = data amp 0xf0 shifting first four bits to make them the last four bits datagtgt=4 printf(nThe BCD digit set at the port is c data) exit else if(choice == 3) break key pressed is not in the menu else printf(nEnter valid choice number) printf(nnPress any key to continue) getch()

                                                    63

                                                    Logic Design amp Switching Theory 1 Lab Session 15 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                    ACTIVITY 1 In the above circuit DIR and G΄ inputs are hardwired Connect them to status or

                                                    control pins of the parallel port connector and control their function through your software program Circuit Diagram Program Code ______________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________

                                                    ___________________________________________________________________________________________________________________________________________________

                                                    64

                                                    Logic Design amp Switching Theory 1 Lab Session 15 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                    65

                                                    _____________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ _____________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ _______________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ _________________________________________________ _________________________________________________

                                                    Logic Design amp Switching Theory 1 Appendix A NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                    Appendix A

                                                    PIN DIAGRAMS OF THE ICS REQUIRED FOR THE LABORATORY SESSIONS Consult the TTLIC data book for internal diagrams and electrical characteristics of these ICs 7400 Quad 2-Input NAND 7402 Quad 2-Input NOR

                                                    7404 Hex Inverter 7408 Quad 2-Input AND

                                                    7410 Triple 3-Input NAND 7411 Triple 3-Input AND

                                                    7421 Dual 4-Input AND 7432 Quad 2-Input OR

                                                    66

                                                    Logic Design amp Switching Theory 1 Appendix A NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                    BCD-to-Seven Segm 7448 BCD-to-Seven Segment 7447 ent

                                                    Decoder (15V OC) Decoder (2kΩ pull-up output)

                                                    7473 Dual JK Flip-Flop 7474 Dual D-Type Flip-Flop

                                                    7476 Dual JK Flop-Flop -Bit Binary Full Adder 7483 4 with Fast Carry

                                                    86 Quad 2-Inpu 74138 3-to-8 Line 74 t Exclusive OR Decoder Demultiplexer

                                                    67

                                                    Logic Design amp Switching Theory 1 Appendix A NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                    68

                                                    74148 8-to-3 Line 16-to-1 Line Data

                                                    Priority Encoder 74150 Selector Multiplexer

                                                    74245 Oct nsceivers Universal Shift Register (PIPO) (3-State)

                                                    74194 4-Bit Bidirectional al Bus Tra

                                                    Logic Design amp Switching Theory 1 Appendix B NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                    Appendix B

                                                    DEBOUNCING CIRCUITRY FOR MECHANICAL SWITCHES Mechanical switches form the interface between human beings and computers or other digital systems For example a keyboard is a matrix of switches used to supply alphanumeric data to a computer Whatever the switch design it is a potential source of problems due to contact bounce The contact bounce creates a sense of narrow pulses when a switch is opened or closed An example of device whose operation would be adversely affected by contact bounce is a digital counter used to count the number of times a switch is depressed Eliminating the effects of contact bounce is called debouncing When data is entered into a computer via a keyboard a software debounce is often used This type of debouncing is a program that causes the computer to sample the switch terminal (ie to input data from it) many times in succession during the interval of time that contact bounce occurs If the data is sensed to be 1s (or 0s) for a specific number of consecutive samples then it is assumed that contact bounce has ended and the last value sensed is valid Hardware debouncing is the use of electronic circuitry to eliminate the effects of contact bounce There are numerous versions of such circuitry including those that use monostable multivibrators (one-shots) but the most straightforward is simply an RS latch Figure B1 shows the circuit When the switch is in position 1 R = 0 and S = 1 so the latch is set and the output (Q) is 1 When the switch is in position 0 R = 1and S = 0 so the latch is reset and the output is 0 When the switch is moved form one position to the other the latch changes state and bouncing occurs at either the R or the S input The bouncing does not affect the latch after it has change state An RS latch will remain set for example when its R input is 0 and its S input is alternately changed form 1 to 0

                                                    Figure B1 Use of RS latch to debounce a mechanical switch

                                                    69

                                                    • 01-ldst-Outer title
                                                      • Practical Workbook
                                                      • Logic Design amp Switching Theory I
                                                        • Dept of Computer amp Information Systems Engineering
                                                          • NED University of Engineering amp Technology
                                                          • Karachi ndash 75270 Pakistan
                                                            • 02-ldst-inner Title
                                                              • Practical Workbook
                                                              • Logic Design amp Switching Theory I
                                                                • Dept of Computer amp Information Systems Engineering
                                                                  • NED University of Engineering amp Technology
                                                                  • Karachi ndash 75270 Pakistan
                                                                    • 03-ldst-general info
                                                                    • 04-ldst-introduction
                                                                    • 05-Table of Contents
                                                                      • CONTENTS
                                                                        • Lab Session No Object Page No
                                                                        • 1
                                                                        • Also implementing and testing the given circuit on a bread board
                                                                          • Working with Electronics Workbench
                                                                            • Driving a seven segment display using 7447 7448 driver IC
                                                                              • Designing a modulus-5 asynchronous up-counter using JK-FF
                                                                                • Experimenting with 74194 4-bit bidirectional universal shift register
                                                                                    • 13
                                                                                        • 06-ldst-Exp01
                                                                                          • Lab Session 01
                                                                                          • OBJECT
                                                                                            • 1 Bread board
                                                                                            • 2 5 V - power supply
                                                                                            • 3 Multimeter
                                                                                            • 4 Logic probe
                                                                                            • 5 LEDs with resistors
                                                                                            • 6 Connecting wires
                                                                                            • 8 Following ICs and their datasheets
                                                                                              • THEORY
                                                                                                • Logic Gates
                                                                                                • 1 The AND Gate ndash An AND gatersquos output is 1 if and only if all its inputs are 1 If A and B are two inputs to an AND gate then output F of the gate is given as F = AB
                                                                                                • 2 The OR Gate - An OR gatersquos output is 1 if at least one of its input is 1 If A and B are two inputs to an OR gate then output F of the gate is given as F = A+B
                                                                                                • 3 The NOT Gate (Inverter) ndash Its output is 1 when its input is 0 and its output is 0 when the input is 1 ie it complements a digital variable If A is the input to a NOT gate then output F of the gate is given as
                                                                                                • 4 The NAND Gate ndash Its output is 1 if at least one of its input is 0 This gate performs the same logic as an AND gate followed by an inverter If A and B are two inputs to a NAND gate then output F of the gate is given as
                                                                                                  • 5 The NOR Gate - The output of a NOR gate is 1 if and only if all its inputs are 0 This gate performs the same logic function as an OR gate followed by an inverter If A and B are two inputs to a NAND gate then output F of the gate is given as
                                                                                                      • DATA SHEETS
                                                                                                        • Logic expression for the given logic diagram __________________________________
                                                                                                            • 07-ldst-exp02
                                                                                                              • Working with Electronics Workbench
                                                                                                                • 08-ldst-exp03
                                                                                                                  • Designing Half and Full Adder Circuits
                                                                                                                    • COMPONENTS AND APPARATUS REQUIRED
                                                                                                                      • 1 Following ICs and their Datasheets
                                                                                                                      • 7408 Quad 2-input AND Gate
                                                                                                                      • 2 Digital Trainer DT-01 or the following components
                                                                                                                        • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                        • Connecting wires Switches
                                                                                                                          • THEORY
                                                                                                                              • IMPLEMENTATION AND OBSERVATIONS
                                                                                                                                • 09-ldst-Exp04
                                                                                                                                  • Lab Session 04
                                                                                                                                  • 1 Digital ICs and their Datasheets
                                                                                                                                  • 7408 Quad 2-input AND Gate
                                                                                                                                  • 2 Digital Trainer DT-01 or the following components
                                                                                                                                    • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                    • Connecting wires Switches
                                                                                                                                    • PROCEDURE
                                                                                                                                    • REDUCTION OF LOGIC EXPRESSION USING KARNAUGH MAP
                                                                                                                                    • OBSERVATIONS
                                                                                                                                    • RESULT
                                                                                                                                        • 10-ldst-Exp05
                                                                                                                                          • Lab Session 05
                                                                                                                                          • 1 Following ICs and their Datasheets
                                                                                                                                          • 7408 Quad 2-input AND Gate
                                                                                                                                          • 2 Digital Trainer DT-01 or the following components
                                                                                                                                            • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                            • (100 Ω) Connecting wires Switches
                                                                                                                                            • THEORY
                                                                                                                                              • IMPLEMENTATION AND OBSERVATIONS
                                                                                                                                                • 11-ldst-Exp06
                                                                                                                                                  • OBJECT
                                                                                                                                                  • 1 Following ICs and their Datasheets
                                                                                                                                                  • 7408 Quad 2-input AND Gates or 7411 Triple 3-input AND Gates
                                                                                                                                                  • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                    • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                    • Connecting wires Switches
                                                                                                                                                      • Figure 62 Circuit Diagram for 4 x 1 Multiplexer
                                                                                                                                                      • Implementation and Observations
                                                                                                                                                        • Circuit Diagram
                                                                                                                                                          • ACTIVITY
                                                                                                                                                            • 12-ldst-exp07
                                                                                                                                                              • 1 Following ICs and their Datasheets
                                                                                                                                                              • 7408 Quad 2-input or 7411 Triple 3-input AND Gates
                                                                                                                                                              • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                • Connecting wires Switches
                                                                                                                                                                  • THEORY
                                                                                                                                                                      • Figure 72 Circuit Diagram for 2 x 4 Decoder 1 x 4 Demultiplexer
                                                                                                                                                                      • Implementation and Observations
                                                                                                                                                                        • Circuit Diagram
                                                                                                                                                                          • ACTIVITY
                                                                                                                                                                            • 13-ldst-Exp08
                                                                                                                                                                              • OBJECT
                                                                                                                                                                              • 1 Following ICs and their Datasheets
                                                                                                                                                                              • 7408 Quad 2-input or 7421 Dual 4-input AND Gates
                                                                                                                                                                              • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                • Connecting wires Switches
                                                                                                                                                                                  • THEORY
                                                                                                                                                                                      • Figure 81 Circuit Diagram for 4 x 2 Priority Encoder
                                                                                                                                                                                      • Implementation and Observations
                                                                                                                                                                                        • Therefore if GS A2 A1 and A0 are all low then it shows that line 0 is selected and if E0 A2 A1 and A0 are all low then it shows that none of the inputs selected E0 and GS cannot be in the same state provided that E1 is enabled
                                                                                                                                                                                        • Circuit Diagram
                                                                                                                                                                                          • ACTIVITY
                                                                                                                                                                                            • 14-ldst-exp09
                                                                                                                                                                                              • OBJECT
                                                                                                                                                                                              • 1 Following ICs and their Datasheets
                                                                                                                                                                                              • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                • Connecting wires Switches
                                                                                                                                                                                                  • THEORY
                                                                                                                                                                                                    • Parity Generator
                                                                                                                                                                                                      • Let x y and z be the three bits that constitute the message and are the input to the Odd Parity Generator Circuit Since it is an odd parity system the bit P is generated so as to make the total number of 1s odd (including P) The function P can be expressed as follows
                                                                                                                                                                                                      • Figure 91 Circuit Diagram for a 3-bit Parity Generator
                                                                                                                                                                                                        • C = x Ο y Ο z Ο P
                                                                                                                                                                                                          • Implementation and Observations
                                                                                                                                                                                                            • ACTIVITY
                                                                                                                                                                                                                • 15-ldst-exp10
                                                                                                                                                                                                                  • Driving a seven segment display using 7447 7448 driver IC
                                                                                                                                                                                                                  • COMPONENTS AND APPARATUS REQUIRED
                                                                                                                                                                                                                  • 1 Following ICs and their Datasheets
                                                                                                                                                                                                                  • 7447 7448 BCD to Seven Segment Driver
                                                                                                                                                                                                                  • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                    • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches
                                                                                                                                                                                                                      • THEORY
                                                                                                                                                                                                                      • Seven Segment Displays
                                                                                                                                                                                                                      • CIRCUIT DIAGRAM
                                                                                                                                                                                                                      • Figure 102 Circuit diagram for 7447driving a common-anode display
                                                                                                                                                                                                                          • IMPLEMENTATION AND OBSERVATIONS
                                                                                                                                                                                                                            • Decimal Digit
                                                                                                                                                                                                                            • BCD Inputs
                                                                                                                                                                                                                            • Seven Segment Outputs
                                                                                                                                                                                                                            • D
                                                                                                                                                                                                                            • C
                                                                                                                                                                                                                            • B
                                                                                                                                                                                                                            • A
                                                                                                                                                                                                                            • a
                                                                                                                                                                                                                            • b
                                                                                                                                                                                                                            • c
                                                                                                                                                                                                                            • d
                                                                                                                                                                                                                            • e
                                                                                                                                                                                                                            • f
                                                                                                                                                                                                                            • g
                                                                                                                                                                                                                            • 0
                                                                                                                                                                                                                            • 0
                                                                                                                                                                                                                            • 0
                                                                                                                                                                                                                            • 0
                                                                                                                                                                                                                            • 0
                                                                                                                                                                                                                            • 1
                                                                                                                                                                                                                            • 0
                                                                                                                                                                                                                            • 0
                                                                                                                                                                                                                            • 0
                                                                                                                                                                                                                            • 1
                                                                                                                                                                                                                            • 2
                                                                                                                                                                                                                            • 0
                                                                                                                                                                                                                            • 0
                                                                                                                                                                                                                            • 1
                                                                                                                                                                                                                            • 0
                                                                                                                                                                                                                            • 3
                                                                                                                                                                                                                            • 0
                                                                                                                                                                                                                            • 0
                                                                                                                                                                                                                            • 1
                                                                                                                                                                                                                            • 1
                                                                                                                                                                                                                            • 4
                                                                                                                                                                                                                            • 0
                                                                                                                                                                                                                            • 1
                                                                                                                                                                                                                            • 0
                                                                                                                                                                                                                            • 0
                                                                                                                                                                                                                            • 5
                                                                                                                                                                                                                            • 0
                                                                                                                                                                                                                            • 1
                                                                                                                                                                                                                            • 0
                                                                                                                                                                                                                            • 1
                                                                                                                                                                                                                            • 6
                                                                                                                                                                                                                            • 0
                                                                                                                                                                                                                            • 1
                                                                                                                                                                                                                            • 1
                                                                                                                                                                                                                            • 0
                                                                                                                                                                                                                            • 7
                                                                                                                                                                                                                            • 0
                                                                                                                                                                                                                            • 1
                                                                                                                                                                                                                            • 1
                                                                                                                                                                                                                            • 1
                                                                                                                                                                                                                            • 8
                                                                                                                                                                                                                            • 1
                                                                                                                                                                                                                            • 0
                                                                                                                                                                                                                            • 0
                                                                                                                                                                                                                            • 0
                                                                                                                                                                                                                            • 9
                                                                                                                                                                                                                            • 1
                                                                                                                                                                                                                            • 0
                                                                                                                                                                                                                            • 0
                                                                                                                                                                                                                            • 1
                                                                                                                                                                                                                              • ACTIVITY
                                                                                                                                                                                                                                • 16-ldst-exp11
                                                                                                                                                                                                                                  • Lab Session 11
                                                                                                                                                                                                                                    • OBJECT
                                                                                                                                                                                                                                    • COMPONENTS AND APPARATUS REQUIRED
                                                                                                                                                                                                                                      • 1 Following ICs and their Datasheets
                                                                                                                                                                                                                                      • 7473 7476 JK Flip-Flop
                                                                                                                                                                                                                                      • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                                        • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                                                        • Connecting wires Switches
                                                                                                                                                                                                                                          • THEORY
                                                                                                                                                                                                                                              • Flip-Flop
                                                                                                                                                                                                                                              • JK Flip-Flop
                                                                                                                                                                                                                                                • Circuit Diagram
                                                                                                                                                                                                                                                  • Observations
                                                                                                                                                                                                                                                    • ACTIVITY
                                                                                                                                                                                                                                                        • 17-ldst-exp12
                                                                                                                                                                                                                                                          • Lab Session 12
                                                                                                                                                                                                                                                            • OBJECT
                                                                                                                                                                                                                                                            • GIVEN STATE DIAGRAM
                                                                                                                                                                                                                                                            • Figure 121 State Diagram
                                                                                                                                                                                                                                                            • COMPONENTS AND APPARATUS REQUIRED
                                                                                                                                                                                                                                                              • 1 Following ICs and their Datasheets
                                                                                                                                                                                                                                                              • 7474 D Flip-Flop
                                                                                                                                                                                                                                                              • ICs of basic gates (AND OR NOT XOR etc) as required
                                                                                                                                                                                                                                                              • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                                                                • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                                                                                • Connecting wires Switches
                                                                                                                                                                                                                                                                  • THEORY
                                                                                                                                                                                                                                                                      • Sequential Circuits
                                                                                                                                                                                                                                                                        • 18-ldst-exp13
                                                                                                                                                                                                                                                                          • Lab Session 13
                                                                                                                                                                                                                                                                            • Designing a modulo-5 asynchronous up-counter using JK-FF
                                                                                                                                                                                                                                                                              • 1 Following ICs and their Datasheets
                                                                                                                                                                                                                                                                              • 7400 Quad 2-input or 7410 Triple 3-input NAND Gates
                                                                                                                                                                                                                                                                              • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                                                                                • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                                                                                                • Connecting wires Switches
                                                                                                                                                                                                                                                                                  • THEORY
                                                                                                                                                                                                                                                                                      • Figure 131 A Mod-5 Asynchronous Up Counter
                                                                                                                                                                                                                                                                                      • Implementation and Observations
                                                                                                                                                                                                                                                                                        • ACTIVITY
                                                                                                                                                                                                                                                                                            • 19-ldst-exp14
                                                                                                                                                                                                                                                                                              • Experimenting with 74194 4-bit bidirectional universal shift register
                                                                                                                                                                                                                                                                                              • 1 Following ICs and their Datasheets
                                                                                                                                                                                                                                                                                              • 74194 4-bit bidirectional universal shift register
                                                                                                                                                                                                                                                                                              • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                                                                                                • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                                                                                                                • Connecting wires Switches
                                                                                                                                                                                                                                                                                                  • THEORY
                                                                                                                                                                                                                                                                                                    • Shift Registers
                                                                                                                                                                                                                                                                                                    • Bidirectional Shift Registers
                                                                                                                                                                                                                                                                                                    • Universal Shift Registers
                                                                                                                                                                                                                                                                                                      • S1
                                                                                                                                                                                                                                                                                                        • Circuit Diagram
                                                                                                                                                                                                                                                                                                        • ACTIVITY
                                                                                                                                                                                                                                                                                                            • 20-ldst-exp15
                                                                                                                                                                                                                                                                                                              • COMPONENTS AND APPARATUS REQUIRED
                                                                                                                                                                                                                                                                                                              • 1 Parallel Port Connectors (DB-25) with Cable
                                                                                                                                                                                                                                                                                                              • 2 Personal Computer with Windows 98 and TurboC Compiler Installed
                                                                                                                                                                                                                                                                                                              • 3 Following ICs and their Datasheets
                                                                                                                                                                                                                                                                                                              • 74245 Octal Bus Transceivers with 3-State Outputs
                                                                                                                                                                                                                                                                                                              • 4 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                                                                                                                • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                                                                                                                                  • Connecting wires Switches
                                                                                                                                                                                                                                                                                                                    • THEORY
                                                                                                                                                                                                                                                                                                                    • 3-State Logic
                                                                                                                                                                                                                                                                                                                      • Serial and Parallel Port Connectors
                                                                                                                                                                                                                                                                                                                      • Parallel Port Connector ndash DB-25
                                                                                                                                                                                                                                                                                                                        • Accessing parallel port through C Language Programming
                                                                                                                                                                                                                                                                                                                            • 21-ldst-appendixA
                                                                                                                                                                                                                                                                                                                            • 22-ldst-appendixB
                                                                                                                                                                                                                                                                                                                              • DEBOUNCING CIRCUITRY FOR MECHANICAL SWITCHES

                                                      Logic Design amp Switching Theory 1 Lab Session 05 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                      29

                                                      A BCD adder must include the correction logic in its internal construction The two BCD digits together with the input carry are first added using a 4-bit binary adder to produce the binary sum If no output carry is generated and the binary sum is less than or equal to 9 then the corresponding BCD sum is identical and therefore no conversion is needed When the output carry is equal to 1 or the binary sum is greater than 9 then a binary 0110 is added to the binary sum through another 4-bit binary adder If Cout is the carry output and Z4Z3Z2Z1 is the binary sum form the first 4-bit binary adder then the following equation indicates the condition when a binary 0110 is to be added

                                                      C = COUT + Z4Z2 + Z4Z3 IMPLEMENTATION AND OBSERVATIONS Implement the BCD adder circuit according to figure 51 on a bread board (prepare the pin diagram (use appendix A) and refer to laboratory session 01 for procedure) A BCD adder has nine input bits (two BCD digits and a carry bit) which can result in a total of 512 combinations of which 312 inputs are donrsquot care Since it is a very lengthy procedure to record results for 200 valid input combinations therefore for simplicity just record results for any eight combinations in the following table

                                                      Input Carry

                                                      BCD Digit 1 BCD Digit 2 Carry Output

                                                      BCD Sum A4 A3 A2 A1 B4 B3 B2 B1 Z4 Z3 Z2 Z1

                                                      Logic Design amp Switching Theory 1 lab Session 06 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                      Lab Session 06

                                                      OBJECT

                                                      bull Designing of a 4 x 1 Multiplexer bull Experimenting with 74150 IC

                                                      COMPONENTS AND APPARATUS REQUIRED 1 Following ICs and their Datasheets

                                                      bull 7408 Quad 2-input AND Gates or 7411 Triple 3-input AND Gates bull 7432 Quad 2-input OR Gates bull 7404 Hex Inverter bull 74150 16 x 1 MUX

                                                      2 Digital Trainer DT-01 or the following components Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches THEORY

                                                      Multiplexers A digital data Multiplexer (MUX) is a combinational circuit having several data inputs and a single output A set of data-select inputs is used to control which of the data inputs is routed to the single output A multiplexer is also called a data selector because of this ability to select which data input is connected o the output Normally there are 2n input lines and n selection lines whose bit combination determine which input is selected DESIGN OF A 4 x 1 MULTIPLEXER A 4 x 1 multiplexer is capable of selecting one of four data inputs (see figure 61) The 2-bit binary number at the data select inputs S1 and S0 specifies which of the four data inputs is to be routed to the output Since there are two data select inputs therefore they can select 22 = 4 different data inputs lines

                                                      S0 S1 D0 D1

                                                      D2 D3

                                                      Data-select Inputs Output

                                                      Data Inputs

                                                      Figure 61 Block Diagram of a 4 x1 Multiplexer

                                                      30

                                                      Logic Design amp Switching Theory 1 lab Session 06 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                      Figure 62 Circuit Diagram for 4 x 1 Multiplexer

                                                      Implementation and Observations

                                                      Implement the 4 x 1 Multiplexer circuit (figure 62) on a bread board (prepare the pin diagram (use appendix A) and refer to laboratory session 01 for implementation procedure) and record the observations in the following table For each data select combination specify the switch number as well as the binary value present on that selected switch

                                                      S1 S0 Output 0 0 0 1 1 0 1 1

                                                      TESTING OF 74150 - 16 x 1 MUX

                                                      The 74150 IC has sixteen data inputs and four data-selection lines Function of various pins of this IC is described below

                                                      bull E0 through E15 Data input lines

                                                      31

                                                      Logic Design amp Switching Theory 1 lab Session 06 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering bull A B C D Data select lines with D being the MSB bull W Active low output line bull Grsquo Active low enable line bull VCC and GND Supply connections lines

                                                      Circuit Diagram

                                                      Figure 63 Pin connections of 74150 for selecting E0

                                                      Testing Procedure

                                                      bull Make connections as shown in the circuit diagram bull Apply different data (1 or 0) at data inputs that are labeled as E0 to E15 Only

                                                      connection for E0 is shown is the figure for simplicity bull Select the data input E0 with the help of data selectors A B C and D bull Observe the output which shows the complement of the data from E0 bull Select all the sixteen data inputs one by one and record your observations in the

                                                      following table

                                                      32

                                                      Logic Design amp Switching Theory 1 lab Session 06 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                      33

                                                      Observations

                                                      Grsquo D C B A W Grsquo D C B A W 0 0 0 0 0 0 1 0 0 0 0 0 0 0 1 0 1 0 0 1 0 0 0 1 0 0 1 0 1 0 0 0 0 1 1 0 1 0 1 1 0 0 1 0 0 0 1 1 0 0 0 0 1 0 1 0 1 1 0 1 0 0 1 1 0 0 1 1 1 0 0 0 1 1 1 0 1 1 1 1

                                                      ACTIVITY 1 Consider 4x1 Multiplexer Draw the output wave-form for the following data inputs

                                                      (E0 E1 E2 E3) and select lines A B (B being the MSB) Output is W

                                                      E3 E2 E1 E0 A B

                                                      W

                                                      2 Using the 4 x 1 MUX designed in this laboratory session implement the following logical function F (A B C) = Σ (0147)

                                                      Show your working and input connections in the following block diagram according to the circuit you have implemented

                                                      4 x 1 MUX

                                                      S0 S1

                                                      Output D0

                                                      D1

                                                      D2

                                                      D3

                                                      Logic Design amp Switching Theory 1 Lab Session 07 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                      Lab Session 07

                                                      OBJECT

                                                      bull Designing of a 2 x 4 Decoder 1 x 4 Demultiplexer bull Experimenting with 74138 IC

                                                      COMPONENTS AND APPARATUS REQUIRED 1 Following ICs and their Datasheets

                                                      bull 7408 Quad 2-input or 7411 Triple 3-input AND Gates bull 7404 Hex Inverter bull 74138 3 x 8 Decoder

                                                      2 Digital Trainer DT-01 or the following components Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches THEORY

                                                      Decoder A Decoder is a combinational circuit that converts binary information form n input lines to a maximum of 2n unique output lines In practical applications decoders are often used for selecting one of several devices

                                                      Demultiplexer A decoder with an enable input can function as a Demultiplexer A Demultiplexer (DMUX) id a circuit that receives information on a single line and transmits this information on one of 2n possible output lines The selection of a specific output line is controlled by the bit values of n selection lines DESIGN OF A 2 x 4 DECODER 1 x 4 DEMULTIPLEXER A 2 x 4 decoder is capable of selecting one of four output lines (see figure 71 (a)) The 2-bit binary number at the data inputs S1 and S0 specifies which of the four data inputs is to be selected If we add an enable pin and use it as an input line then this decoder can be converted to a 1 x 4 Demultiplexer where S1 and S0 will select a line to which data input is to be routed (see figure 71 (b))

                                                      Select S0 S0 Inputs

                                                      S1 D0 D1

                                                      D2

                                                      D3

                                                      Enable (a) Block Diagram of a 2 x 4 Decoder

                                                      Figure 71

                                                      S1 D0 D1

                                                      D2

                                                      D3

                                                      Inputs

                                                      Data Input (b) Block Diagram of a 1 x 4 Demulptiplexer

                                                      34

                                                      Logic Design amp Switching Theory 1 Lab Session 07 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                      Figure 72 Circuit Diagram for 2 x 4 Decoder 1 x 4 Demultiplexer

                                                      Implementation and Observations Implement the 2 x 4 Decoder 1 x 4 Demultiplexer circuit (figure 72) on a bread board (prepare the pin diagram (use appendix A) and refer to laboratory session 01 for implementation procedure) and record the observations in the following table

                                                      Enable Data Input S1 S0 D0 D1 D2 D3

                                                      0 0 0 0 0 1 0 1 0 0 1 1 1 0 0 1 0 1 1 1 0 1 1 1

                                                      TESTING OF 74138 3 x 8 Decoder The 74138 IC has three inputs and eight output lines It has three enable inputs and for the IC to function all three inputs need to be enabled Function of various pins of this IC is described below

                                                      35

                                                      Logic Design amp Switching Theory 1 Lab Session 07 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                      bull Y0 through Y7 Active low data outputs bull A B C Input select lines with C being the MSB bull G1 Active high enable Input bull G2Arsquo and G2Brsquo Active low enable Inputs bull VCC and GND Supply connections lines Circuit Diagram

                                                      Figure 73 Pin connections of 74138

                                                      Testing Procedure

                                                      bull Make connections as shown in the circuit diagram bull Apply different combinations of 1s and 0s at data inputs bull Observe the output and record your observations in the following table

                                                      Observations

                                                      C B A Y0 Y1 Y2 Y3 Y4 Y5 Y6 Y7 0 0 0 0 0 1 0 1 0 0 1 1 1 0 0 1 0 1 1 1 0 1 1 1

                                                      36

                                                      Logic Design amp Switching Theory 1 Lab Session 07 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                      37

                                                      ACTIVITY ACTIVITY 1 What will be the binary values at the outputs Y0 through Y7 of 74138 if 1 What will be the binary values at the outputs Y0 through Y7 of 74138 if

                                                      bull All three enable pins are connected to ground bull All three enable pins are connected to ground __________________________________________________________________________________________________________________________________________ __________________________________________________________________________________________________________________________________________ _____________________________________________________________________ _____________________________________________________________________

                                                      bull All three enable pins are connected to VCC bull All three enable pins are connected to VCC _______________________________________________________________________________________________________________________________________________________________________________________________________________

                                                      _______________________________________________________________________________________________________________________________________________________________________________________________________________

                                                      2 Show connections for 74138 in order to use it as a 1 x 8 Demultiplexer 2 Show connections for 74138 in order to use it as a 1 x 8 Demultiplexer

                                                      3 Consider a 2 x 4 Decoder with two enable inputs (one active high - G and one active low ndash Grsquo) Draw the output wave-forms for D0 D1 D2 and D3 if the two select inputs are A and B (B being the MSB) All outputs are active low

                                                      Grsquo

                                                      G

                                                      A B

                                                      D0 D1 D2

                                                      D3

                                                      Logic Design amp Switching Theory 1 Lab Session 08 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                      Lab Session 08 OBJECT

                                                      bull Designing of a 4 x 2 Priority Encoder bull Experimenting with 74148 IC

                                                      COMPONENTS AND APPARATUS REQUIRED

                                                      1 Following ICs and their Datasheets

                                                      bull 7408 Quad 2-input or 7421 Dual 4-input AND Gates bull 7432 Quad 2-input OR Gates bull 7404 Hex Inverter bull 74148 Encoder

                                                      2 Digital Trainer DT-01 or the following components Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches

                                                      THEORY

                                                      Encoder An Encoder is a digital function that produces a reverse operation from that of a decoder An Encoder has 2n (or less) input lines and n output lines The output lines generate the binary code for the 2n input variables Priority Encoder

                                                      A simple encoder may produce an erroneous output if more than one of its inputs is high A Priority Encoder is one that responds to just one input among those that may be simultaneously high in accordance with some priority system The most common priority system is based on the relative magnitudes of the inputs whichever decimal input is largest is the one that is encoded

                                                      DESIGN OF A 4 x 2 Priority Encoder

                                                      The following equations represent the outputs of a 4 x 2 priority encoder 32 DDA +=

                                                      321 DDDB += As can be seen from the equations that input D0 which has a binary code 00 is not used in any equation A binary code 00 at the output indicates two conditions Either D0 is selected or no input is selected In order to differentiate these two conditions we will provide an additional output Z to indicate if at least one of the inputs is a 1 The equation for Z will be

                                                      4321 DDDDZ = If Z is 0 then the binary code 00 at the output indicates that D0 is selected and if Z is 1 then it indicates that no input line is selected

                                                      38

                                                      Logic Design amp Switching Theory 1 Lab Session 08 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                      Figure 81 Circuit Diagram for 4 x 2 Priority Encoder

                                                      it (figure 81) on a bread board (prepare the to laboratory session 01 for implementation

                                                      Implementation a Implement the 4 x 2 Priority Encoder circu

                                                      ram (use appendix A) and refer

                                                      nd Observations

                                                      pin diagprocedure) and record the observations in the following table

                                                      D3 D2 D1 D0 A B 0 0 0 1 0 0 1 x 0 1 x x 1 x x x

                                                      TESTING OF 74148 8 x 3 Octal Priority Encoder

                                                      imal digits There are nine of which three represents

                                                      ing any of the inputs is high

                                                      then it shows that line 0 is selected and if e inputs selected E0 and GS

                                                      cannot be in the same state provided that E1 is enabled

                                                      The 74148 is a priority encoder with active-Low input for dec

                                                      input) and five output linesinputs lines (including an enablethe binary code for the octal digit Function of various pins of this IC is described below

                                                      bull 0 through 7 Active low data inputs representing the octal digits A2 A1 A0 Active low output lines representing the binary code bullbull E1 Active low enable Input bull E0 Active low output indicating none of the inputs is high bull GS Active low output indicatbull VCC and GND Supply connections lines Therefore if GS A2 A1 and A0 are all low

                                                      then it shows that none of thE0 A2 A1 and A0 are all low

                                                      39

                                                      Logic Design amp Switching Theory 1 Lab Session 08 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                      Circuit Diagram

                                                      Figure 82 Pin connections of 74148

                                                      Testing Procedure bull Make connections as sho

                                                      binations of 1s and 0s at data inputs d record your observations in the following table

                                                      GS E0

                                                      wn in the circuit diagram bull Apply different combull Observe the output an Observations

                                                      0 1 2 3 4 5 6 7 A2 A1 A0 1 1 1 1 1 1 1 1 x x x x x x x 0 x x x x x x 0 1 x x x x x 0 1 1 x x x x 0 1 1 1 x x x 0 1 1 1 1 x x 0 1 1 1 1 1 x 0 1 1 1 1 1 1 0 1 1 1 1 1 1 1

                                                      40

                                                      Logic Design amp Switching Theory 1 Lab Session 08 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                      41

                                                      CTIVITY

                                                      Cascade the following two 74148 8 x 3 Priority Encoders to form 16 x 4 Priority

                                                      A 1

                                                      Encoder

                                                      Logic Design amp Switching Theory 1 Lab Session 09 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering `

                                                      Lab Session 09 OBJECT

                                                      Designing an Odd Parity Generator and Checker for a 3-bit Data COMPONENTS AND APPARATUS REQUIRED

                                                      1 Following ICs and their Datasheets

                                                      bull 7486 Quad 2-input Exclusive-OR Gates bull 7404 Hex Inverter

                                                      2 Digital Trainer DT-01 or the following components Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches

                                                      THEORY

                                                      Parity Generator When binary data is transmitted and processed it is ndash as are all electrical signals ndash susceptible to noise that can either alter or distort its contents 1s may be effectively changed to 0s and 0s to 1s To overcome this problem one or more bits are often added to the data as an aid in detecting errors caused by noise The most common of these is a Parity bit that signifies whether the total number of 1s in a code group is odd or even In an Odd Parity system the parity bit is made 0 or 1 as necessary to make the total number 1s odd (counting the parity bit itself) In an Even Parity system the parity bit is chosen to make the total number of 1s even Table 91 shows how parity bits would be added to BCD code group in both systems

                                                      Decimal BCD Value Parity Bit ABCD Odd Parity Even Parity

                                                      0 0000 1 0 1 0001 0 1 2 0010 0 1 3 0011 1 0 4 0100 0 1 5 0101 1 0 6 0110 1 0 7 0111 0 1 8 1000 0 1 9 1001 1 0

                                                      Table 91 Odd and Even Parity in BCD

                                                      When digital data is received a parity checking circuit generates an error signal if the total number of 1s is odd in an even parity system or if it is even in an odd parity system Parity check always detects a single error (one bit change from 0 to 1 or 1 to 0) but may not detect

                                                      42

                                                      Logic Design amp Switching Theory 1 Lab Session 09 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering ` two or more errors Odd parity is used more often than even parity because even parity does not detect a situation where all 0s are created due to short circuit or other fault condition DESIGN OF A 3-BIT ODD PARITY GENERATOR AND CHECKER Let x y and z be the three bits that constitute the message and are the input to the Odd Parity Generator Circuit Since it is an odd parity system the bit P is generated so as to make the total number of 1s odd (including P) The function P can be expressed as follows P = x oplus y Ο z or P = x Ο y oplus z Since the IC available is 7486 which is quad 2input XOR IC therefore we will convert XNOR also to XOR

                                                      P = x oplus y Ο z

                                                      P = ( x oplus y ) Ο z Since for even number of variables ______

                                                      XOR = XNOR Therefore ___________ _________

                                                      P = ( x oplus y ) oplus z = x oplus y oplus z This logical expression can be implemented with two XOR gates and an inverter (see figure 91)

                                                      Figure 91 Circuit Diagram for a 3-bit Parity Generator

                                                      The 3-bit message and the parity bit are transmitted to their destination where they are applied to a Parity Checker Circuit An error occurs during transmission if the parity of the four bits received is even since the binary information transmitted was originally odd The output C of the parity checker should be a 1 when an error occurs ie when the number of 1s in the four inputs is even Therefore the function C can be expressed as

                                                      C = x Ο y Ο z Ο P

                                                      Using the same logic applied for the conversion of the equation of P

                                                      PzyxC oplusoplusoplus= This logical expression can be implemented with three XOR gates and an inverter (see figure 92)

                                                      43

                                                      Logic Design amp Switching Theory 1 Lab Session 09 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering `

                                                      44

                                                      Figure 92 Circuit Diagram for a 3-bit Parity Checker Implementation and Observations Implement the 3-bit Parity Generator and Checker circuits (figure 91 and 92) on a bread board (prepare the pin diagram (use appendix A) and refer to laboratory session 01 for implementation procedure) and record the observations in the following table

                                                      x y z P x y z P C x y z P C 0 0 0 0 0 0 0 1 0 0 0 0 0 1 0 0 0 1 1 0 0 1 0 1 0 0 0 1 0 1 0 1 0 0 1 1 0 0 1 1 1 0 1 1 1 0 0 0 1 0 0 1 1 0 0 1 0 1 0 1 0 1 1 1 0 1 1 1 0 0 1 1 0 1 1 1 0 1 1 1 0 1 1 1 1 1 1 1

                                                      Odd Parity Generation Odd Parity Check ACTIVITY 1 Try using the parity checker of figure 92 as 3-bit parity generator Write the details here

                                                      _____________________________________________________________________________________________________________________________________________________________________________________________________________________ ______________________________________________________________________________________________________________________________________________ _______________________________________________________________________ ______________________________________________________________________________________________________________________________________________

                                                      Logic Design amp Switching Theory 1 Lab Session 10 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                      Lab Session 10 OBJECT

                                                      Driving a seven segment display using 7447 7448 driver IC COMPONENTS AND APPARATUS REQUIRED

                                                      1 Following ICs and their Datasheets

                                                      bull Seven Segment Displays (Common Anode Common Cathode) bull 7447 7448 BCD to Seven Segment Driver

                                                      2 Digital Trainer DT-01 or the following components Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches

                                                      THEORY Seven Segment Displays A Seven Segment Display consists of seven light-emitting segments The segments are designated by letters a through g (see figure 101) By illuminating various combinations of segments the numerals 0 through 9 can be displayed Seven Segment Displays are commonly constructed with light-emitting diodes (LEDs) and with liquid-crystal displays (LCDs) LEDs generally provide greater illumination levels but require much greater power than LCDs An LED display can be a common-anode type or common cathode type In common anode type a high voltage is applied at the common terminal of the display and low voltage is applied at a segmentrsquos terminal for illumination In the common-cathode type a low voltage is applied at the common terminal of the display and high voltage is applied at a segmentrsquos terminal for illumination

                                                      Figure 101 Seven Segment Display

                                                      a f b g

                                                      e c d

                                                      7447 7448 BCD to Seven Segment Driver 7447 7448 IC is particularly used to drive Seven Segment Its input is a BCD number and output drives a seven segment display 7447 is used to drive common-anode displays whereas 7448 is used to drive common cathode displays 7447 7448 is a 16 pin IC Function of various pins of these ICs is described below

                                                      bull A B C D Inputs representing BCD digits (D being the MSB)

                                                      45

                                                      Logic Design amp Switching Theory 1 Lab Session 10 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering bull OA through OG Outputs to drive segments a through g of the display (Active low

                                                      in 7447 and active high in 7448) bull RBI Ripple Blanking Input Turns off all the segments if kept low provided that LT

                                                      is kept high and all other inputs (A B C D BI) are kept low Should be kept high otherwise

                                                      bull BI RBO Wire-AND logic serving as a Blanking Input and or Ripple Blanking Output

                                                      o BI Turns off all the segments if low o RBO Goes to a low level (response condition) along with other outputs when

                                                      RBI and inputs A B C and D are low with LT input at high level bull LT Lamp Test input Tests whether all segments are working or not Illuminates all

                                                      segments if kept low provided that BI is kept high Should be kept high otherwise bull VCC and GND Supply connections lines CIRCUIT DIAGRAM

                                                      Figure 102 Circuit diagram for 7447driving a common-anode display

                                                      IMPLEMENTATION AND OBSERVATIONS

                                                      bull Make connections as shown in the circuit diagram (refer to laboratory session 01 for implementation procedure)

                                                      bull Apply different combinations of 1s and 0s at data inputs bull Observe the output and record your observations in the following table

                                                      46

                                                      Logic Design amp Switching Theory 1 Lab Session 10 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                      47

                                                      Decimal Digit

                                                      BCD Inputs Seven Segment Outputs D C B A a b c d e f g

                                                      0 0 0 0 0 1 0 0 0 1 2 0 0 1 0 3 0 0 1 1 4 0 1 0 0 5 0 1 0 1 6 0 1 1 0 7 0 1 1 1 8 1 0 0 0 9 1 0 0 1

                                                      ACTIVITY 1 Perform the Lamp Test for the designed circuit and write your observations

                                                      ____________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________

                                                      2 How can you use 7447 IC to drive a common-cathode display

                                                      ____________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________

                                                      3 What symbols appear in the seven segment display if inputs DCBA are

                                                      DCBA Symbol

                                                      1010

                                                      1011

                                                      1100

                                                      1101

                                                      1110

                                                      1111

                                                      Logic Design amp Switching Theory 1 Lab Session 11 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                      48

                                                      Lab Session 11 OBJECT

                                                      Testing different modes of JK-FF COMPONENTS AND APPARATUS REQUIRED 1 Following ICs and their Datasheets

                                                      bull 7473 7476 JK Flip-Flop 2 Digital Trainer DT-01 or the following components

                                                      Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches

                                                      THEORY

                                                      Flip-Flop A flip-flop circuit can maintain a binary state indefinitely (as long as the power is delivered to the circuit) until directed by an input signal to switch states The major differences among various types of flip-flops are in the number of inputs they possess and in the manner in which the inputs affect the binary state

                                                      JK Flip-Flop JK flip flop is an edge triggered device A typical JK flip flop has three inputs J K and a clock input The flip-flop can be either positive or negative edge triggered The output Q is available in complemented form as well Beside the usual inputs and output most of the flip-flop IC also possess two asynchronous inputs namely Preset and Clear These inputs are usually active low If used Preset and Clear inputs keep the flip-flop in set and reset state respectively irrespective of the other inputs Both of these inputs cannot be used simultaneously otherwise they will bring the flip-flop in unstable state

                                                      Figure 111 Symbol for JK flip-flop

                                                      (a) positive-edge triggering (b) active low Preset (PR) and Clear (CLR) with positive-edge triggering

                                                      (c) active low Preset (PR) and Clear (CLR) with negative-edge triggering

                                                      Logic Design amp Switching Theory 1 Lab Session 11 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                      49

                                                      TESTING OF 7473 7476 DUAL JK FLIP-FLOP

                                                      Both the ICs 7473 and 7476 are similar in functionality except for one difference The flip-flops in 7473 have only one type of active low asynchronous input which is the Clear input whereas the flip-flops in 7476 have both Preset and Clear inputs Both these ICs have negative edge triggered flip-flops

                                                      Circuit Diagram

                                                      Figure 112 Pin connections of 7476

                                                      Testing Procedure

                                                      bull Make connections as shown in the circuit diagram (figure 112) bull Apply different combinations of 1s and 0s at J and K inputs bull Observe the output and record your observations in the following table

                                                      Observations

                                                      J

                                                      K Q

                                                      0 0 0 1 1 0 1 1

                                                      ACTIVITY

                                                      1 Observe the output Q of JK flip-flop if the clock input is connected to VCC or GND instead of a clock source Write your observations here __________________________________________________________________________________________________________________________________________ _______________________________________________________________________________________________________________________________________________________________________________________________________________

                                                      Logic Design amp Switching Theory 1 Lab Session 12 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                      50

                                                      Lab Session 12 OBJECT

                                                      Designing sequential circuit for the given state diagram using D flip-flop GIVEN STATE DIAGRAM

                                                      00

                                                      11

                                                      Figure 121 State Diagram COMPONENTS AND APPARATUS REQUIRED 1 Following ICs and their Datasheets

                                                      bull 7474 D Flip-Flop bull ICs of basic gates (AND OR NOT XOR etc) as required

                                                      2 Digital Trainer DT-01 or the following components Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches

                                                      THEORY

                                                      Sequential Circuits In Sequential Circuits the output not only depends on the present inputs but also on previous states of the circuit These circuits use memory elements (latches flip-flops) and the binary information stored in the memory elements at any given time defines the state of the sequential circuit Analysis of a Sequential Circuit The behavior of a sequential circuit is determined from the inputs the outputs and the states of its flip-flops Both the outputs and next state are a function of the inputs and the

                                                      10

                                                      01

                                                      00 11 10

                                                      00

                                                      00 11 10 00

                                                      Logic Design amp Switching Theory 1 Lab Session 12 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                      51

                                                      present state The analysis of a sequential circuit form a state diagram comprises of the following bull Selecting a particular flip-flop to design the circuit bull Obtaining state table from the state diagram bull Finding input equations for the selected flip-flop bull Finding state equations (not required for the construction of circuit) bull Implementing the circuit using selected flip-flops and their input equations ANALYZING THE GIVEN STATE DIAGRAM D Flip-Flop D flip-flop is also called transparent flip-flop as it simply transfers the input data to the output For our design we require the graphical symbol and excitation table of D flip-flop (see figure 122)

                                                      Qt Qt+1 T 0 0 0 0 1 1 1 0 0 1 1 1

                                                      (b) Excitation table of D Flip-Flop

                                                      (a) Graphical Symbol

                                                      Figure 122 Characteristic equation of D flip-flop is Q(t+1) = D State Table The given state diagram has four states so we will need two D flip-flops (FF-0 FF-1) Form state table form the given state diagram and record the results in the following table

                                                      Present State Input Next State Output Input to FF-0 D0

                                                      Input to FF-1 D1 Q1t Q0t x Q1(t+1) Q0(t+1) z

                                                      Logic Design amp Switching Theory 1 Lab Session 12 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                      52

                                                      Input Equations Using Karnaugh map the input equations D0 and D1 for the two flip-flops can be found

                                                      D0 D1 Q0x

                                                      Q1

                                                      _ _ Q0x

                                                      _ Q0x

                                                      Q0x

                                                      _ Q0x

                                                      Q0x

                                                      Q1

                                                      _ _ Q0x

                                                      _ Q0x

                                                      Q0x

                                                      _ Q0x

                                                      _ Q1

                                                      _ Q1

                                                      Q1

                                                      Q1

                                                      D0 = _________________ D1 = _________________

                                                      State Equations Using the characteristic equation of D flip-flop we can find the state equations Q0(t+1) and Q1(t+1) for the to flip flops Q0(t+1) = _______________________ Q1(t+1) = _______________________ _______________________ _______________________ _______________________ _______________________ Circuit Diagram

                                                      Logic Design amp Switching Theory 1 Lab Session 12 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                      53

                                                      Implementation Procedure and Observations

                                                      1 Implement the circuit using digital ICs on a bread board (prepare the pin diagram (use appendix A) and refer to laboratory session 01 for procedure)

                                                      2 Make the clear inputs of the flip-flops low (to clear the flip-flops) The flip-flops will remain in clear state as long as the clear inputs are connected to low level

                                                      3 Connect output Q0 and the clock pulse to an oscilloscope 4 Apply 0 to the input x 5 Now make the clear inputs to high 6 Observe the waveform for the first 5 clock pulses and record it 7 Repeat steps 2 to 6 keeping x=1 in step 4 this time 8 Repeat steps 2 to 7 this time connecting Q1 instead of Q0 to the oscilloscope in step

                                                      3 Record your observations (Keep frequency of the clock pulse low (eg1Hz) so that the output waveforms can be observed easily)

                                                      1 2 3 4 5 Clock Pulse

                                                      Output Waveform for Q0 when x=0

                                                      Output Waveform for Q0 when x=1

                                                      Output Waveform for Q1 when x=0

                                                      Output Waveform for Q1 when x=1

                                                      Logic Design amp Switching Theory 1 Lab Session 13 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                      Lab Session 13 OBJECT

                                                      Designing a modulo-5 asynchronous up-counter using JK-FF COMPONENTS AND APPARATUS REQUIRED

                                                      1 Following ICs and their Datasheets

                                                      bull 7400 Quad 2-input or 7410 Triple 3-input NAND Gates bull 7476 7473 JK Flip-Flop

                                                      2 Digital Trainer DT-01 or the following components Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches

                                                      THEORY

                                                      Digital Counters A digital counter is a set of flip-flops whose states change in response to pulses applied at the input to the counter The flip-flops are interconnected so that their combined state at any time is the binary equivalent of the total number of pulses that have occurred up to that time Every counter resets after a certain number of clock pulses Thus as it name implies a counter is used to count pulses An n stage counter can count up to a maximum of 2n states n is equal to the number of flip-flops required for the construction of counter

                                                      Modulus Counters The number of input pulses that causes a counter to reset to its initial count is called the modulus of the counter Thus the modulus equals to total number of distinct states (counts) including zero that a counter can store A binary counter with n stages is a modulo-2n (or mod-2n) counter The largest count a mod-N counter can achieve is N-1 ie a mod-N counter never reaches the binary number equal to its modulus N is always equal to or less than 2n Counters can be classified as bull Synchronous Counters which are clock driven All the flip-flops are driven by a

                                                      single clock bull Asynchronous Counters which are event driven Clock input is given to the first

                                                      flip-flop only Rest of the flip-flops are driven by their preceding flip-flops

                                                      DESIGN OF A MOD-5 ASYNCHRONOUS UP COUNTER The number of flip-flops required to construct a mod-5 counter is 3 because 5 should be less than or equal to 2n This counter will count from 0 to 4 a total of 5 distinct states Since a 3-stage counter can count up to 8 states at maximum a NAND gate is used to reset it after 5 clock pulses Figure 131 shows the logic diagram

                                                      54

                                                      Logic Design amp Switching Theory 1 Lab Session 13 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                      55

                                                      Figure 131 A Mod-5 Asynchronous Up Counter

                                                      Implementation and Observations

                                                      Implement the mod-5 counter circuit (figure 131) on a bread board (prepare the pin diagram (use appendix A) and refer to laboratory session 01 for implementation procedure) and record the observations in the following table

                                                      Clock Pulse Q2 Q1 Q0

                                                      0 1 2 3 4 5 6 7

                                                      ACTIVITY

                                                      Draw the timing diagram for mod-5 counter designed in this laboratory session

                                                      Logic Design amp Switching Theory 1 Lab Session 14 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                      Lab Session 14 OBJECT

                                                      Experimenting with 74194 4-bit bidirectional universal shift register COMPONENTS AND APPARATUS REQUIRED

                                                      1 Following ICs and their Datasheets

                                                      bull 74194 4-bit bidirectional universal shift register 2 Digital Trainer DT-01 or the following components

                                                      Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches

                                                      THEORY

                                                      Shift Registers

                                                      A Register is a set of flip-flops used to store binary data A register which is capable of shifting its binary information either to the right or left is called a shift register The logical configuration of a register consists of a chain of flip-flops connected in cascade with the output of one flip-flop connected to the input of next flip-flop All flip-flops receive a common clock pulse which causes the shift from one stage to the next

                                                      Bidirectional Shift Registers A bi-directional shift register is one whose bits can be shifted from left to right or from right to left

                                                      Universal Shift Registers A universal shift register is a bi-directional register whose input can be in either serial or parallel form and whose output can be in either serial or parallel form

                                                      74194 4-BIT BIDIRECTIONAL UNIVERSAL SHIFT REGISTER

                                                      The 74194 register provides parallel as well as serial loading in both directions Function of various pins of this IC is described below

                                                      bull A B C and D Active high inputs for parallel loading bull QA QB QC and QD Active high outputs bull S0 and S1 Active high mode control inputs The following table shows combinations

                                                      of S1 and S0 to enable various modes

                                                      S1 S0 Clock Action 0 0 x No change 0 1 uarr Shift right 1 0 uarr Shift left 1 1 uarr Parallel load

                                                      uarr shows the rising edge of the clock pulse

                                                      56

                                                      Logic Design amp Switching Theory 1 Lab Session 14 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering bull SR Active high serial input for right shifting bull SL Active high serial input for left shifting bull CLR Active low input Clears all the flip-flops of the register if set to 0 should be

                                                      kept high otherwise bull CLK Clock input bull VCC and GND Supply connections lines Thus A B C and D are inputs for parallel loading whereas SR and SL are inputs for serial loading with right or left shifting respectively S1 and S0 are used to select the loading mode Circuit Diagram

                                                      Figure 141 Pin connections of 74194 Testing Procedure

                                                      bull Make connections as shown in the circuit diagram bull Observe the output for the input combinations given in the following table

                                                      57

                                                      Logic Design amp Switching Theory 1 Lab Session 14 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                      58

                                                      Observations

                                                      S1 S0 SL SR A B C D QA QB QC QD 0 0 0 1 0 0 0 0 0 1 1 0 0 0 0 1 1 0 0 0 0 0 1 0 1 1 0 0 0 0 1 1 0 0 1 1 0 1 0 0 0 1 1 1 0 1 0 1 1 0 1 0 0 1 1 0 1 1 1 0 0 1 1 1 1 1 0 0 1 1 1 1

                                                      ACTIVITY 1 Show connections of 74194 to convert it into a ring counter with right shifting

                                                      Logic Design amp Switching Theory 1 Lab Session 15 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                      Lab Session 15

                                                      OBJECT

                                                      Experimenting with 74245 octal bus transceivers using parallel port PC interfacing COMPONENTS AND APPARATUS REQUIRED 1 Parallel Port Connectors (DB-25) with Cable 2 Personal Computer with Windows 98 and TurboC Compiler Installed 3 Following ICs and their Datasheets

                                                      bull 74245 Octal Bus Transceivers with 3-State Outputs 4 Digital Trainer DT-01 or the following components

                                                      Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches

                                                      THEORY

                                                      3-State Logic Sometimes it is necessary to isolate one part of circuit from the other part For this purpose some TTL ICs are designed with 3-state logic Such devices have three possible output states high low and high impedance The device can be put into high impedance state by a control signal applied to an appropriate pin When such a device is in high impedance state there is very high impedance at its output effectively isolating the device from whatever circuitry the output normally drives 74245 Octal Bus Transceivers A bus is any conducting path or set of paths having electrical connections to one or more devices 74245 octal bus transceivers are mainly used to control connectivity between two devices or circuits It also provides direction control for signal flow Function of various pin of this IC is given below

                                                      bull A1 through A8 Bus A bull B1 through B8 Bus B bull G΄ Active low enable input When high sets all the bus pins to high impedance state bull DIR Direction control for signal flow When set to high logic level transfers bus A

                                                      data to B bus When set to low logic level transfers bus B data to A bus bull VCC and GND Supply connections lines Serial and Parallel Port Connectors A Parallel Port can consist of only 25 pin port adapter called a DB-25 and a serial port can consist of either a 25 pin port adapter called a DB-25 or 9 pin adapter called a DB-9 port adapter Whether the port is a 9 pin or 25 pin it can accomplish all of the same tasks that serial port communications have been designed for

                                                      59

                                                      Logic Design amp Switching Theory 1 Lab Session 15 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                      60

                                                      Each adapter can be a male type connector with pins or a female type adapter with tiny holes Generally a PRINTER port (called LPT1) on the back of a computer is female type adapter and we need to use MALE DB-25 pin cable on it for PRINTER connection or for parallel LAPLINK cable And a COM port on the back of a computer is male for the serial ports but it may not necessarily be Parallel Port Connector ndash DB-25 The DB-25 connector (named for its B-size D-shaped shell and 25 pins) is practically ubiquitous in the electronics industry The DB-25 connector is used for a variety of purposes Two common applications are RS-232EIA-232 (serial) connections and the parallel printer interface on the IBM PC The DB-25 connector is also used for SCSI connections Normally the parallel port is used for output to a printer or other device It sends data 8-bits or one byte at a time in parallel The other lines available on the DB-25 connector are a combination of status lines control lines and ground lines The status and control lines are used for handshaking commands and feedback when we are talking to a printer

                                                      Figure 152 DB-25 Female Figure 151 DB-25 Male

                                                      Figure 153 Pin Layout for DB-25 As can be seen form figure 153 there are four types of pins in this connector

                                                      bull Data pins (8 pins - D0 to D7) Active high bidirectional lines

                                                      Logic Design amp Switching Theory 1 Lab Session 15 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering bull Control pins (4 pins - C0 to C3) C0 C1 and C3 are active low whereas C2 is active

                                                      high These lines also are bidirectional bull Status pins (5 pins ndash S3 to S7) Only S7 is active low rest are active high input lines bull Ground pins (8 pins) Used as a reference signal for the low (below 05 volts) charge

                                                      Parallel Port Addresses A DB-25 connector at a parallel port has three address one for each kind of pins register data status and control The first or base address generally refers to data register Second address is for status register and the third one is for control register In Windows 98 the base address is usually found to be 278H 378H or 3BCH Now if 378H is the base address then it refers to the data register whereas addresses for status and control register are respectively 379H and 37AH For Windows 98 the base address can be found as follows 1 On your Desktop right-click on My Computer and select Properties 2 Click on the Device Manager tab and find LPT1 under Plug and Play BIOS 3 After selecting LPT1 click the Properties button 4 Next select the Resources tab and the address should then appear next to InputOutput

                                                      Range Accessing parallel port through C Language Programming There are multiple functions in C Language for accessing external ports The most commonly used are listed below

                                                      bull unsigned char inportb(int portid) inportb reads a byte from a hardware port

                                                      bull int inport(int portid) reads a word from a hardware port

                                                      bull void outportb(int portid unsigned char value) outputs a byte to a hardware port

                                                      bull void outport(int portid int value) outputs a word to a hardware port

                                                      portid refers to the port address whereas value refers to the data to be sent TESTING 74245 USING PARALLEL PORT PC INTERFACING At one end the parallel port connector will be connected to the PC via parallel port cable and another connector (to be plugged into the PC parallel port slot) At the other end it will be connected to the buffer IC 74245 Data lines of the connector will be used to transfer 8-bit data between the PC and the buffer Out of the 8-bits of 74245 4-bits will be used to enter data which will be displayed at the monitor through a C language

                                                      61

                                                      Logic Design amp Switching Theory 1 Lab Session 15 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering program The remaining 4-bits will receive data from PC as entered by the user via keyboard

                                                      Circuit Diagram

                                                      Figure 154 Interface of 74245 to PC via Parallel Port

                                                      Procedure

                                                      1 Connect the DB-25 connector to the PC at one end and solder it to the circuit board at the other end

                                                      2 Connect various pins of the connector and 74245 according to the circuit diagram shown in figure 152

                                                      3 Using the functions listed in the previous section write a program in C language to operate various pins of the buffer The user interface of the program should provide option to the user whether to send or receive data from the port

                                                      4 Set DIR switch to 1 5 Try sending some data bits to the port The result should be displayed at the LEDs 6 Set DIR switch to 0 7 Set some binary 4-bit value through the switches Try reading it via parallel port

                                                      C Language Program

                                                      A program to access parallel port for data transfers

                                                      use header file include ltstdiohgt main program void main() define variable

                                                      62

                                                      Logic Design amp Switching Theory 1 Lab Session 15 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering unsigned int data=0 char choice while(1) printing option menu clrscr() printf(This program will send or receive a BCD digit from the parallel portn) printf(nPress your choice numbern) printf(n1 Send Data) printf(n2 Receive Data) printf(n3 Exitn) choice = getch() sending entered digit to the port if(choice == 1) input BCD digit printf(nEnter BCD digit to be sent to the port) data = getche() masking the first four bits data = data amp 0x0f sending to the port outportb(0x378data) printf(nThe BCD digit c has been sent to the port data) printing on screen the data received from the port else if(choice == 2) receiving data from the port data = inportb(0x378) masking the last four bits data = data amp 0xf0 shifting first four bits to make them the last four bits datagtgt=4 printf(nThe BCD digit set at the port is c data) exit else if(choice == 3) break key pressed is not in the menu else printf(nEnter valid choice number) printf(nnPress any key to continue) getch()

                                                      63

                                                      Logic Design amp Switching Theory 1 Lab Session 15 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                      ACTIVITY 1 In the above circuit DIR and G΄ inputs are hardwired Connect them to status or

                                                      control pins of the parallel port connector and control their function through your software program Circuit Diagram Program Code ______________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________

                                                      ___________________________________________________________________________________________________________________________________________________

                                                      64

                                                      Logic Design amp Switching Theory 1 Lab Session 15 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                      65

                                                      _____________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ _____________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ _______________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ _________________________________________________ _________________________________________________

                                                      Logic Design amp Switching Theory 1 Appendix A NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                      Appendix A

                                                      PIN DIAGRAMS OF THE ICS REQUIRED FOR THE LABORATORY SESSIONS Consult the TTLIC data book for internal diagrams and electrical characteristics of these ICs 7400 Quad 2-Input NAND 7402 Quad 2-Input NOR

                                                      7404 Hex Inverter 7408 Quad 2-Input AND

                                                      7410 Triple 3-Input NAND 7411 Triple 3-Input AND

                                                      7421 Dual 4-Input AND 7432 Quad 2-Input OR

                                                      66

                                                      Logic Design amp Switching Theory 1 Appendix A NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                      BCD-to-Seven Segm 7448 BCD-to-Seven Segment 7447 ent

                                                      Decoder (15V OC) Decoder (2kΩ pull-up output)

                                                      7473 Dual JK Flip-Flop 7474 Dual D-Type Flip-Flop

                                                      7476 Dual JK Flop-Flop -Bit Binary Full Adder 7483 4 with Fast Carry

                                                      86 Quad 2-Inpu 74138 3-to-8 Line 74 t Exclusive OR Decoder Demultiplexer

                                                      67

                                                      Logic Design amp Switching Theory 1 Appendix A NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                      68

                                                      74148 8-to-3 Line 16-to-1 Line Data

                                                      Priority Encoder 74150 Selector Multiplexer

                                                      74245 Oct nsceivers Universal Shift Register (PIPO) (3-State)

                                                      74194 4-Bit Bidirectional al Bus Tra

                                                      Logic Design amp Switching Theory 1 Appendix B NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                      Appendix B

                                                      DEBOUNCING CIRCUITRY FOR MECHANICAL SWITCHES Mechanical switches form the interface between human beings and computers or other digital systems For example a keyboard is a matrix of switches used to supply alphanumeric data to a computer Whatever the switch design it is a potential source of problems due to contact bounce The contact bounce creates a sense of narrow pulses when a switch is opened or closed An example of device whose operation would be adversely affected by contact bounce is a digital counter used to count the number of times a switch is depressed Eliminating the effects of contact bounce is called debouncing When data is entered into a computer via a keyboard a software debounce is often used This type of debouncing is a program that causes the computer to sample the switch terminal (ie to input data from it) many times in succession during the interval of time that contact bounce occurs If the data is sensed to be 1s (or 0s) for a specific number of consecutive samples then it is assumed that contact bounce has ended and the last value sensed is valid Hardware debouncing is the use of electronic circuitry to eliminate the effects of contact bounce There are numerous versions of such circuitry including those that use monostable multivibrators (one-shots) but the most straightforward is simply an RS latch Figure B1 shows the circuit When the switch is in position 1 R = 0 and S = 1 so the latch is set and the output (Q) is 1 When the switch is in position 0 R = 1and S = 0 so the latch is reset and the output is 0 When the switch is moved form one position to the other the latch changes state and bouncing occurs at either the R or the S input The bouncing does not affect the latch after it has change state An RS latch will remain set for example when its R input is 0 and its S input is alternately changed form 1 to 0

                                                      Figure B1 Use of RS latch to debounce a mechanical switch

                                                      69

                                                      • 01-ldst-Outer title
                                                        • Practical Workbook
                                                        • Logic Design amp Switching Theory I
                                                          • Dept of Computer amp Information Systems Engineering
                                                            • NED University of Engineering amp Technology
                                                            • Karachi ndash 75270 Pakistan
                                                              • 02-ldst-inner Title
                                                                • Practical Workbook
                                                                • Logic Design amp Switching Theory I
                                                                  • Dept of Computer amp Information Systems Engineering
                                                                    • NED University of Engineering amp Technology
                                                                    • Karachi ndash 75270 Pakistan
                                                                      • 03-ldst-general info
                                                                      • 04-ldst-introduction
                                                                      • 05-Table of Contents
                                                                        • CONTENTS
                                                                          • Lab Session No Object Page No
                                                                          • 1
                                                                          • Also implementing and testing the given circuit on a bread board
                                                                            • Working with Electronics Workbench
                                                                              • Driving a seven segment display using 7447 7448 driver IC
                                                                                • Designing a modulus-5 asynchronous up-counter using JK-FF
                                                                                  • Experimenting with 74194 4-bit bidirectional universal shift register
                                                                                      • 13
                                                                                          • 06-ldst-Exp01
                                                                                            • Lab Session 01
                                                                                            • OBJECT
                                                                                              • 1 Bread board
                                                                                              • 2 5 V - power supply
                                                                                              • 3 Multimeter
                                                                                              • 4 Logic probe
                                                                                              • 5 LEDs with resistors
                                                                                              • 6 Connecting wires
                                                                                              • 8 Following ICs and their datasheets
                                                                                                • THEORY
                                                                                                  • Logic Gates
                                                                                                  • 1 The AND Gate ndash An AND gatersquos output is 1 if and only if all its inputs are 1 If A and B are two inputs to an AND gate then output F of the gate is given as F = AB
                                                                                                  • 2 The OR Gate - An OR gatersquos output is 1 if at least one of its input is 1 If A and B are two inputs to an OR gate then output F of the gate is given as F = A+B
                                                                                                  • 3 The NOT Gate (Inverter) ndash Its output is 1 when its input is 0 and its output is 0 when the input is 1 ie it complements a digital variable If A is the input to a NOT gate then output F of the gate is given as
                                                                                                  • 4 The NAND Gate ndash Its output is 1 if at least one of its input is 0 This gate performs the same logic as an AND gate followed by an inverter If A and B are two inputs to a NAND gate then output F of the gate is given as
                                                                                                    • 5 The NOR Gate - The output of a NOR gate is 1 if and only if all its inputs are 0 This gate performs the same logic function as an OR gate followed by an inverter If A and B are two inputs to a NAND gate then output F of the gate is given as
                                                                                                        • DATA SHEETS
                                                                                                          • Logic expression for the given logic diagram __________________________________
                                                                                                              • 07-ldst-exp02
                                                                                                                • Working with Electronics Workbench
                                                                                                                  • 08-ldst-exp03
                                                                                                                    • Designing Half and Full Adder Circuits
                                                                                                                      • COMPONENTS AND APPARATUS REQUIRED
                                                                                                                        • 1 Following ICs and their Datasheets
                                                                                                                        • 7408 Quad 2-input AND Gate
                                                                                                                        • 2 Digital Trainer DT-01 or the following components
                                                                                                                          • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                          • Connecting wires Switches
                                                                                                                            • THEORY
                                                                                                                                • IMPLEMENTATION AND OBSERVATIONS
                                                                                                                                  • 09-ldst-Exp04
                                                                                                                                    • Lab Session 04
                                                                                                                                    • 1 Digital ICs and their Datasheets
                                                                                                                                    • 7408 Quad 2-input AND Gate
                                                                                                                                    • 2 Digital Trainer DT-01 or the following components
                                                                                                                                      • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                      • Connecting wires Switches
                                                                                                                                      • PROCEDURE
                                                                                                                                      • REDUCTION OF LOGIC EXPRESSION USING KARNAUGH MAP
                                                                                                                                      • OBSERVATIONS
                                                                                                                                      • RESULT
                                                                                                                                          • 10-ldst-Exp05
                                                                                                                                            • Lab Session 05
                                                                                                                                            • 1 Following ICs and their Datasheets
                                                                                                                                            • 7408 Quad 2-input AND Gate
                                                                                                                                            • 2 Digital Trainer DT-01 or the following components
                                                                                                                                              • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                              • (100 Ω) Connecting wires Switches
                                                                                                                                              • THEORY
                                                                                                                                                • IMPLEMENTATION AND OBSERVATIONS
                                                                                                                                                  • 11-ldst-Exp06
                                                                                                                                                    • OBJECT
                                                                                                                                                    • 1 Following ICs and their Datasheets
                                                                                                                                                    • 7408 Quad 2-input AND Gates or 7411 Triple 3-input AND Gates
                                                                                                                                                    • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                      • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                      • Connecting wires Switches
                                                                                                                                                        • Figure 62 Circuit Diagram for 4 x 1 Multiplexer
                                                                                                                                                        • Implementation and Observations
                                                                                                                                                          • Circuit Diagram
                                                                                                                                                            • ACTIVITY
                                                                                                                                                              • 12-ldst-exp07
                                                                                                                                                                • 1 Following ICs and their Datasheets
                                                                                                                                                                • 7408 Quad 2-input or 7411 Triple 3-input AND Gates
                                                                                                                                                                • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                  • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                  • Connecting wires Switches
                                                                                                                                                                    • THEORY
                                                                                                                                                                        • Figure 72 Circuit Diagram for 2 x 4 Decoder 1 x 4 Demultiplexer
                                                                                                                                                                        • Implementation and Observations
                                                                                                                                                                          • Circuit Diagram
                                                                                                                                                                            • ACTIVITY
                                                                                                                                                                              • 13-ldst-Exp08
                                                                                                                                                                                • OBJECT
                                                                                                                                                                                • 1 Following ICs and their Datasheets
                                                                                                                                                                                • 7408 Quad 2-input or 7421 Dual 4-input AND Gates
                                                                                                                                                                                • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                  • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                  • Connecting wires Switches
                                                                                                                                                                                    • THEORY
                                                                                                                                                                                        • Figure 81 Circuit Diagram for 4 x 2 Priority Encoder
                                                                                                                                                                                        • Implementation and Observations
                                                                                                                                                                                          • Therefore if GS A2 A1 and A0 are all low then it shows that line 0 is selected and if E0 A2 A1 and A0 are all low then it shows that none of the inputs selected E0 and GS cannot be in the same state provided that E1 is enabled
                                                                                                                                                                                          • Circuit Diagram
                                                                                                                                                                                            • ACTIVITY
                                                                                                                                                                                              • 14-ldst-exp09
                                                                                                                                                                                                • OBJECT
                                                                                                                                                                                                • 1 Following ICs and their Datasheets
                                                                                                                                                                                                • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                  • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                  • Connecting wires Switches
                                                                                                                                                                                                    • THEORY
                                                                                                                                                                                                      • Parity Generator
                                                                                                                                                                                                        • Let x y and z be the three bits that constitute the message and are the input to the Odd Parity Generator Circuit Since it is an odd parity system the bit P is generated so as to make the total number of 1s odd (including P) The function P can be expressed as follows
                                                                                                                                                                                                        • Figure 91 Circuit Diagram for a 3-bit Parity Generator
                                                                                                                                                                                                          • C = x Ο y Ο z Ο P
                                                                                                                                                                                                            • Implementation and Observations
                                                                                                                                                                                                              • ACTIVITY
                                                                                                                                                                                                                  • 15-ldst-exp10
                                                                                                                                                                                                                    • Driving a seven segment display using 7447 7448 driver IC
                                                                                                                                                                                                                    • COMPONENTS AND APPARATUS REQUIRED
                                                                                                                                                                                                                    • 1 Following ICs and their Datasheets
                                                                                                                                                                                                                    • 7447 7448 BCD to Seven Segment Driver
                                                                                                                                                                                                                    • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                      • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches
                                                                                                                                                                                                                        • THEORY
                                                                                                                                                                                                                        • Seven Segment Displays
                                                                                                                                                                                                                        • CIRCUIT DIAGRAM
                                                                                                                                                                                                                        • Figure 102 Circuit diagram for 7447driving a common-anode display
                                                                                                                                                                                                                            • IMPLEMENTATION AND OBSERVATIONS
                                                                                                                                                                                                                              • Decimal Digit
                                                                                                                                                                                                                              • BCD Inputs
                                                                                                                                                                                                                              • Seven Segment Outputs
                                                                                                                                                                                                                              • D
                                                                                                                                                                                                                              • C
                                                                                                                                                                                                                              • B
                                                                                                                                                                                                                              • A
                                                                                                                                                                                                                              • a
                                                                                                                                                                                                                              • b
                                                                                                                                                                                                                              • c
                                                                                                                                                                                                                              • d
                                                                                                                                                                                                                              • e
                                                                                                                                                                                                                              • f
                                                                                                                                                                                                                              • g
                                                                                                                                                                                                                              • 0
                                                                                                                                                                                                                              • 0
                                                                                                                                                                                                                              • 0
                                                                                                                                                                                                                              • 0
                                                                                                                                                                                                                              • 0
                                                                                                                                                                                                                              • 1
                                                                                                                                                                                                                              • 0
                                                                                                                                                                                                                              • 0
                                                                                                                                                                                                                              • 0
                                                                                                                                                                                                                              • 1
                                                                                                                                                                                                                              • 2
                                                                                                                                                                                                                              • 0
                                                                                                                                                                                                                              • 0
                                                                                                                                                                                                                              • 1
                                                                                                                                                                                                                              • 0
                                                                                                                                                                                                                              • 3
                                                                                                                                                                                                                              • 0
                                                                                                                                                                                                                              • 0
                                                                                                                                                                                                                              • 1
                                                                                                                                                                                                                              • 1
                                                                                                                                                                                                                              • 4
                                                                                                                                                                                                                              • 0
                                                                                                                                                                                                                              • 1
                                                                                                                                                                                                                              • 0
                                                                                                                                                                                                                              • 0
                                                                                                                                                                                                                              • 5
                                                                                                                                                                                                                              • 0
                                                                                                                                                                                                                              • 1
                                                                                                                                                                                                                              • 0
                                                                                                                                                                                                                              • 1
                                                                                                                                                                                                                              • 6
                                                                                                                                                                                                                              • 0
                                                                                                                                                                                                                              • 1
                                                                                                                                                                                                                              • 1
                                                                                                                                                                                                                              • 0
                                                                                                                                                                                                                              • 7
                                                                                                                                                                                                                              • 0
                                                                                                                                                                                                                              • 1
                                                                                                                                                                                                                              • 1
                                                                                                                                                                                                                              • 1
                                                                                                                                                                                                                              • 8
                                                                                                                                                                                                                              • 1
                                                                                                                                                                                                                              • 0
                                                                                                                                                                                                                              • 0
                                                                                                                                                                                                                              • 0
                                                                                                                                                                                                                              • 9
                                                                                                                                                                                                                              • 1
                                                                                                                                                                                                                              • 0
                                                                                                                                                                                                                              • 0
                                                                                                                                                                                                                              • 1
                                                                                                                                                                                                                                • ACTIVITY
                                                                                                                                                                                                                                  • 16-ldst-exp11
                                                                                                                                                                                                                                    • Lab Session 11
                                                                                                                                                                                                                                      • OBJECT
                                                                                                                                                                                                                                      • COMPONENTS AND APPARATUS REQUIRED
                                                                                                                                                                                                                                        • 1 Following ICs and their Datasheets
                                                                                                                                                                                                                                        • 7473 7476 JK Flip-Flop
                                                                                                                                                                                                                                        • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                                          • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                                                          • Connecting wires Switches
                                                                                                                                                                                                                                            • THEORY
                                                                                                                                                                                                                                                • Flip-Flop
                                                                                                                                                                                                                                                • JK Flip-Flop
                                                                                                                                                                                                                                                  • Circuit Diagram
                                                                                                                                                                                                                                                    • Observations
                                                                                                                                                                                                                                                      • ACTIVITY
                                                                                                                                                                                                                                                          • 17-ldst-exp12
                                                                                                                                                                                                                                                            • Lab Session 12
                                                                                                                                                                                                                                                              • OBJECT
                                                                                                                                                                                                                                                              • GIVEN STATE DIAGRAM
                                                                                                                                                                                                                                                              • Figure 121 State Diagram
                                                                                                                                                                                                                                                              • COMPONENTS AND APPARATUS REQUIRED
                                                                                                                                                                                                                                                                • 1 Following ICs and their Datasheets
                                                                                                                                                                                                                                                                • 7474 D Flip-Flop
                                                                                                                                                                                                                                                                • ICs of basic gates (AND OR NOT XOR etc) as required
                                                                                                                                                                                                                                                                • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                                                                  • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                                                                                  • Connecting wires Switches
                                                                                                                                                                                                                                                                    • THEORY
                                                                                                                                                                                                                                                                        • Sequential Circuits
                                                                                                                                                                                                                                                                          • 18-ldst-exp13
                                                                                                                                                                                                                                                                            • Lab Session 13
                                                                                                                                                                                                                                                                              • Designing a modulo-5 asynchronous up-counter using JK-FF
                                                                                                                                                                                                                                                                                • 1 Following ICs and their Datasheets
                                                                                                                                                                                                                                                                                • 7400 Quad 2-input or 7410 Triple 3-input NAND Gates
                                                                                                                                                                                                                                                                                • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                                                                                  • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                                                                                                  • Connecting wires Switches
                                                                                                                                                                                                                                                                                    • THEORY
                                                                                                                                                                                                                                                                                        • Figure 131 A Mod-5 Asynchronous Up Counter
                                                                                                                                                                                                                                                                                        • Implementation and Observations
                                                                                                                                                                                                                                                                                          • ACTIVITY
                                                                                                                                                                                                                                                                                              • 19-ldst-exp14
                                                                                                                                                                                                                                                                                                • Experimenting with 74194 4-bit bidirectional universal shift register
                                                                                                                                                                                                                                                                                                • 1 Following ICs and their Datasheets
                                                                                                                                                                                                                                                                                                • 74194 4-bit bidirectional universal shift register
                                                                                                                                                                                                                                                                                                • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                                                                                                  • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                                                                                                                  • Connecting wires Switches
                                                                                                                                                                                                                                                                                                    • THEORY
                                                                                                                                                                                                                                                                                                      • Shift Registers
                                                                                                                                                                                                                                                                                                      • Bidirectional Shift Registers
                                                                                                                                                                                                                                                                                                      • Universal Shift Registers
                                                                                                                                                                                                                                                                                                        • S1
                                                                                                                                                                                                                                                                                                          • Circuit Diagram
                                                                                                                                                                                                                                                                                                          • ACTIVITY
                                                                                                                                                                                                                                                                                                              • 20-ldst-exp15
                                                                                                                                                                                                                                                                                                                • COMPONENTS AND APPARATUS REQUIRED
                                                                                                                                                                                                                                                                                                                • 1 Parallel Port Connectors (DB-25) with Cable
                                                                                                                                                                                                                                                                                                                • 2 Personal Computer with Windows 98 and TurboC Compiler Installed
                                                                                                                                                                                                                                                                                                                • 3 Following ICs and their Datasheets
                                                                                                                                                                                                                                                                                                                • 74245 Octal Bus Transceivers with 3-State Outputs
                                                                                                                                                                                                                                                                                                                • 4 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                                                                                                                  • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                                                                                                                                    • Connecting wires Switches
                                                                                                                                                                                                                                                                                                                      • THEORY
                                                                                                                                                                                                                                                                                                                      • 3-State Logic
                                                                                                                                                                                                                                                                                                                        • Serial and Parallel Port Connectors
                                                                                                                                                                                                                                                                                                                        • Parallel Port Connector ndash DB-25
                                                                                                                                                                                                                                                                                                                          • Accessing parallel port through C Language Programming
                                                                                                                                                                                                                                                                                                                              • 21-ldst-appendixA
                                                                                                                                                                                                                                                                                                                              • 22-ldst-appendixB
                                                                                                                                                                                                                                                                                                                                • DEBOUNCING CIRCUITRY FOR MECHANICAL SWITCHES

                                                        Logic Design amp Switching Theory 1 lab Session 06 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                        Lab Session 06

                                                        OBJECT

                                                        bull Designing of a 4 x 1 Multiplexer bull Experimenting with 74150 IC

                                                        COMPONENTS AND APPARATUS REQUIRED 1 Following ICs and their Datasheets

                                                        bull 7408 Quad 2-input AND Gates or 7411 Triple 3-input AND Gates bull 7432 Quad 2-input OR Gates bull 7404 Hex Inverter bull 74150 16 x 1 MUX

                                                        2 Digital Trainer DT-01 or the following components Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches THEORY

                                                        Multiplexers A digital data Multiplexer (MUX) is a combinational circuit having several data inputs and a single output A set of data-select inputs is used to control which of the data inputs is routed to the single output A multiplexer is also called a data selector because of this ability to select which data input is connected o the output Normally there are 2n input lines and n selection lines whose bit combination determine which input is selected DESIGN OF A 4 x 1 MULTIPLEXER A 4 x 1 multiplexer is capable of selecting one of four data inputs (see figure 61) The 2-bit binary number at the data select inputs S1 and S0 specifies which of the four data inputs is to be routed to the output Since there are two data select inputs therefore they can select 22 = 4 different data inputs lines

                                                        S0 S1 D0 D1

                                                        D2 D3

                                                        Data-select Inputs Output

                                                        Data Inputs

                                                        Figure 61 Block Diagram of a 4 x1 Multiplexer

                                                        30

                                                        Logic Design amp Switching Theory 1 lab Session 06 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                        Figure 62 Circuit Diagram for 4 x 1 Multiplexer

                                                        Implementation and Observations

                                                        Implement the 4 x 1 Multiplexer circuit (figure 62) on a bread board (prepare the pin diagram (use appendix A) and refer to laboratory session 01 for implementation procedure) and record the observations in the following table For each data select combination specify the switch number as well as the binary value present on that selected switch

                                                        S1 S0 Output 0 0 0 1 1 0 1 1

                                                        TESTING OF 74150 - 16 x 1 MUX

                                                        The 74150 IC has sixteen data inputs and four data-selection lines Function of various pins of this IC is described below

                                                        bull E0 through E15 Data input lines

                                                        31

                                                        Logic Design amp Switching Theory 1 lab Session 06 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering bull A B C D Data select lines with D being the MSB bull W Active low output line bull Grsquo Active low enable line bull VCC and GND Supply connections lines

                                                        Circuit Diagram

                                                        Figure 63 Pin connections of 74150 for selecting E0

                                                        Testing Procedure

                                                        bull Make connections as shown in the circuit diagram bull Apply different data (1 or 0) at data inputs that are labeled as E0 to E15 Only

                                                        connection for E0 is shown is the figure for simplicity bull Select the data input E0 with the help of data selectors A B C and D bull Observe the output which shows the complement of the data from E0 bull Select all the sixteen data inputs one by one and record your observations in the

                                                        following table

                                                        32

                                                        Logic Design amp Switching Theory 1 lab Session 06 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                        33

                                                        Observations

                                                        Grsquo D C B A W Grsquo D C B A W 0 0 0 0 0 0 1 0 0 0 0 0 0 0 1 0 1 0 0 1 0 0 0 1 0 0 1 0 1 0 0 0 0 1 1 0 1 0 1 1 0 0 1 0 0 0 1 1 0 0 0 0 1 0 1 0 1 1 0 1 0 0 1 1 0 0 1 1 1 0 0 0 1 1 1 0 1 1 1 1

                                                        ACTIVITY 1 Consider 4x1 Multiplexer Draw the output wave-form for the following data inputs

                                                        (E0 E1 E2 E3) and select lines A B (B being the MSB) Output is W

                                                        E3 E2 E1 E0 A B

                                                        W

                                                        2 Using the 4 x 1 MUX designed in this laboratory session implement the following logical function F (A B C) = Σ (0147)

                                                        Show your working and input connections in the following block diagram according to the circuit you have implemented

                                                        4 x 1 MUX

                                                        S0 S1

                                                        Output D0

                                                        D1

                                                        D2

                                                        D3

                                                        Logic Design amp Switching Theory 1 Lab Session 07 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                        Lab Session 07

                                                        OBJECT

                                                        bull Designing of a 2 x 4 Decoder 1 x 4 Demultiplexer bull Experimenting with 74138 IC

                                                        COMPONENTS AND APPARATUS REQUIRED 1 Following ICs and their Datasheets

                                                        bull 7408 Quad 2-input or 7411 Triple 3-input AND Gates bull 7404 Hex Inverter bull 74138 3 x 8 Decoder

                                                        2 Digital Trainer DT-01 or the following components Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches THEORY

                                                        Decoder A Decoder is a combinational circuit that converts binary information form n input lines to a maximum of 2n unique output lines In practical applications decoders are often used for selecting one of several devices

                                                        Demultiplexer A decoder with an enable input can function as a Demultiplexer A Demultiplexer (DMUX) id a circuit that receives information on a single line and transmits this information on one of 2n possible output lines The selection of a specific output line is controlled by the bit values of n selection lines DESIGN OF A 2 x 4 DECODER 1 x 4 DEMULTIPLEXER A 2 x 4 decoder is capable of selecting one of four output lines (see figure 71 (a)) The 2-bit binary number at the data inputs S1 and S0 specifies which of the four data inputs is to be selected If we add an enable pin and use it as an input line then this decoder can be converted to a 1 x 4 Demultiplexer where S1 and S0 will select a line to which data input is to be routed (see figure 71 (b))

                                                        Select S0 S0 Inputs

                                                        S1 D0 D1

                                                        D2

                                                        D3

                                                        Enable (a) Block Diagram of a 2 x 4 Decoder

                                                        Figure 71

                                                        S1 D0 D1

                                                        D2

                                                        D3

                                                        Inputs

                                                        Data Input (b) Block Diagram of a 1 x 4 Demulptiplexer

                                                        34

                                                        Logic Design amp Switching Theory 1 Lab Session 07 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                        Figure 72 Circuit Diagram for 2 x 4 Decoder 1 x 4 Demultiplexer

                                                        Implementation and Observations Implement the 2 x 4 Decoder 1 x 4 Demultiplexer circuit (figure 72) on a bread board (prepare the pin diagram (use appendix A) and refer to laboratory session 01 for implementation procedure) and record the observations in the following table

                                                        Enable Data Input S1 S0 D0 D1 D2 D3

                                                        0 0 0 0 0 1 0 1 0 0 1 1 1 0 0 1 0 1 1 1 0 1 1 1

                                                        TESTING OF 74138 3 x 8 Decoder The 74138 IC has three inputs and eight output lines It has three enable inputs and for the IC to function all three inputs need to be enabled Function of various pins of this IC is described below

                                                        35

                                                        Logic Design amp Switching Theory 1 Lab Session 07 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                        bull Y0 through Y7 Active low data outputs bull A B C Input select lines with C being the MSB bull G1 Active high enable Input bull G2Arsquo and G2Brsquo Active low enable Inputs bull VCC and GND Supply connections lines Circuit Diagram

                                                        Figure 73 Pin connections of 74138

                                                        Testing Procedure

                                                        bull Make connections as shown in the circuit diagram bull Apply different combinations of 1s and 0s at data inputs bull Observe the output and record your observations in the following table

                                                        Observations

                                                        C B A Y0 Y1 Y2 Y3 Y4 Y5 Y6 Y7 0 0 0 0 0 1 0 1 0 0 1 1 1 0 0 1 0 1 1 1 0 1 1 1

                                                        36

                                                        Logic Design amp Switching Theory 1 Lab Session 07 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                        37

                                                        ACTIVITY ACTIVITY 1 What will be the binary values at the outputs Y0 through Y7 of 74138 if 1 What will be the binary values at the outputs Y0 through Y7 of 74138 if

                                                        bull All three enable pins are connected to ground bull All three enable pins are connected to ground __________________________________________________________________________________________________________________________________________ __________________________________________________________________________________________________________________________________________ _____________________________________________________________________ _____________________________________________________________________

                                                        bull All three enable pins are connected to VCC bull All three enable pins are connected to VCC _______________________________________________________________________________________________________________________________________________________________________________________________________________

                                                        _______________________________________________________________________________________________________________________________________________________________________________________________________________

                                                        2 Show connections for 74138 in order to use it as a 1 x 8 Demultiplexer 2 Show connections for 74138 in order to use it as a 1 x 8 Demultiplexer

                                                        3 Consider a 2 x 4 Decoder with two enable inputs (one active high - G and one active low ndash Grsquo) Draw the output wave-forms for D0 D1 D2 and D3 if the two select inputs are A and B (B being the MSB) All outputs are active low

                                                        Grsquo

                                                        G

                                                        A B

                                                        D0 D1 D2

                                                        D3

                                                        Logic Design amp Switching Theory 1 Lab Session 08 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                        Lab Session 08 OBJECT

                                                        bull Designing of a 4 x 2 Priority Encoder bull Experimenting with 74148 IC

                                                        COMPONENTS AND APPARATUS REQUIRED

                                                        1 Following ICs and their Datasheets

                                                        bull 7408 Quad 2-input or 7421 Dual 4-input AND Gates bull 7432 Quad 2-input OR Gates bull 7404 Hex Inverter bull 74148 Encoder

                                                        2 Digital Trainer DT-01 or the following components Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches

                                                        THEORY

                                                        Encoder An Encoder is a digital function that produces a reverse operation from that of a decoder An Encoder has 2n (or less) input lines and n output lines The output lines generate the binary code for the 2n input variables Priority Encoder

                                                        A simple encoder may produce an erroneous output if more than one of its inputs is high A Priority Encoder is one that responds to just one input among those that may be simultaneously high in accordance with some priority system The most common priority system is based on the relative magnitudes of the inputs whichever decimal input is largest is the one that is encoded

                                                        DESIGN OF A 4 x 2 Priority Encoder

                                                        The following equations represent the outputs of a 4 x 2 priority encoder 32 DDA +=

                                                        321 DDDB += As can be seen from the equations that input D0 which has a binary code 00 is not used in any equation A binary code 00 at the output indicates two conditions Either D0 is selected or no input is selected In order to differentiate these two conditions we will provide an additional output Z to indicate if at least one of the inputs is a 1 The equation for Z will be

                                                        4321 DDDDZ = If Z is 0 then the binary code 00 at the output indicates that D0 is selected and if Z is 1 then it indicates that no input line is selected

                                                        38

                                                        Logic Design amp Switching Theory 1 Lab Session 08 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                        Figure 81 Circuit Diagram for 4 x 2 Priority Encoder

                                                        it (figure 81) on a bread board (prepare the to laboratory session 01 for implementation

                                                        Implementation a Implement the 4 x 2 Priority Encoder circu

                                                        ram (use appendix A) and refer

                                                        nd Observations

                                                        pin diagprocedure) and record the observations in the following table

                                                        D3 D2 D1 D0 A B 0 0 0 1 0 0 1 x 0 1 x x 1 x x x

                                                        TESTING OF 74148 8 x 3 Octal Priority Encoder

                                                        imal digits There are nine of which three represents

                                                        ing any of the inputs is high

                                                        then it shows that line 0 is selected and if e inputs selected E0 and GS

                                                        cannot be in the same state provided that E1 is enabled

                                                        The 74148 is a priority encoder with active-Low input for dec

                                                        input) and five output linesinputs lines (including an enablethe binary code for the octal digit Function of various pins of this IC is described below

                                                        bull 0 through 7 Active low data inputs representing the octal digits A2 A1 A0 Active low output lines representing the binary code bullbull E1 Active low enable Input bull E0 Active low output indicating none of the inputs is high bull GS Active low output indicatbull VCC and GND Supply connections lines Therefore if GS A2 A1 and A0 are all low

                                                        then it shows that none of thE0 A2 A1 and A0 are all low

                                                        39

                                                        Logic Design amp Switching Theory 1 Lab Session 08 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                        Circuit Diagram

                                                        Figure 82 Pin connections of 74148

                                                        Testing Procedure bull Make connections as sho

                                                        binations of 1s and 0s at data inputs d record your observations in the following table

                                                        GS E0

                                                        wn in the circuit diagram bull Apply different combull Observe the output an Observations

                                                        0 1 2 3 4 5 6 7 A2 A1 A0 1 1 1 1 1 1 1 1 x x x x x x x 0 x x x x x x 0 1 x x x x x 0 1 1 x x x x 0 1 1 1 x x x 0 1 1 1 1 x x 0 1 1 1 1 1 x 0 1 1 1 1 1 1 0 1 1 1 1 1 1 1

                                                        40

                                                        Logic Design amp Switching Theory 1 Lab Session 08 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                        41

                                                        CTIVITY

                                                        Cascade the following two 74148 8 x 3 Priority Encoders to form 16 x 4 Priority

                                                        A 1

                                                        Encoder

                                                        Logic Design amp Switching Theory 1 Lab Session 09 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering `

                                                        Lab Session 09 OBJECT

                                                        Designing an Odd Parity Generator and Checker for a 3-bit Data COMPONENTS AND APPARATUS REQUIRED

                                                        1 Following ICs and their Datasheets

                                                        bull 7486 Quad 2-input Exclusive-OR Gates bull 7404 Hex Inverter

                                                        2 Digital Trainer DT-01 or the following components Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches

                                                        THEORY

                                                        Parity Generator When binary data is transmitted and processed it is ndash as are all electrical signals ndash susceptible to noise that can either alter or distort its contents 1s may be effectively changed to 0s and 0s to 1s To overcome this problem one or more bits are often added to the data as an aid in detecting errors caused by noise The most common of these is a Parity bit that signifies whether the total number of 1s in a code group is odd or even In an Odd Parity system the parity bit is made 0 or 1 as necessary to make the total number 1s odd (counting the parity bit itself) In an Even Parity system the parity bit is chosen to make the total number of 1s even Table 91 shows how parity bits would be added to BCD code group in both systems

                                                        Decimal BCD Value Parity Bit ABCD Odd Parity Even Parity

                                                        0 0000 1 0 1 0001 0 1 2 0010 0 1 3 0011 1 0 4 0100 0 1 5 0101 1 0 6 0110 1 0 7 0111 0 1 8 1000 0 1 9 1001 1 0

                                                        Table 91 Odd and Even Parity in BCD

                                                        When digital data is received a parity checking circuit generates an error signal if the total number of 1s is odd in an even parity system or if it is even in an odd parity system Parity check always detects a single error (one bit change from 0 to 1 or 1 to 0) but may not detect

                                                        42

                                                        Logic Design amp Switching Theory 1 Lab Session 09 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering ` two or more errors Odd parity is used more often than even parity because even parity does not detect a situation where all 0s are created due to short circuit or other fault condition DESIGN OF A 3-BIT ODD PARITY GENERATOR AND CHECKER Let x y and z be the three bits that constitute the message and are the input to the Odd Parity Generator Circuit Since it is an odd parity system the bit P is generated so as to make the total number of 1s odd (including P) The function P can be expressed as follows P = x oplus y Ο z or P = x Ο y oplus z Since the IC available is 7486 which is quad 2input XOR IC therefore we will convert XNOR also to XOR

                                                        P = x oplus y Ο z

                                                        P = ( x oplus y ) Ο z Since for even number of variables ______

                                                        XOR = XNOR Therefore ___________ _________

                                                        P = ( x oplus y ) oplus z = x oplus y oplus z This logical expression can be implemented with two XOR gates and an inverter (see figure 91)

                                                        Figure 91 Circuit Diagram for a 3-bit Parity Generator

                                                        The 3-bit message and the parity bit are transmitted to their destination where they are applied to a Parity Checker Circuit An error occurs during transmission if the parity of the four bits received is even since the binary information transmitted was originally odd The output C of the parity checker should be a 1 when an error occurs ie when the number of 1s in the four inputs is even Therefore the function C can be expressed as

                                                        C = x Ο y Ο z Ο P

                                                        Using the same logic applied for the conversion of the equation of P

                                                        PzyxC oplusoplusoplus= This logical expression can be implemented with three XOR gates and an inverter (see figure 92)

                                                        43

                                                        Logic Design amp Switching Theory 1 Lab Session 09 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering `

                                                        44

                                                        Figure 92 Circuit Diagram for a 3-bit Parity Checker Implementation and Observations Implement the 3-bit Parity Generator and Checker circuits (figure 91 and 92) on a bread board (prepare the pin diagram (use appendix A) and refer to laboratory session 01 for implementation procedure) and record the observations in the following table

                                                        x y z P x y z P C x y z P C 0 0 0 0 0 0 0 1 0 0 0 0 0 1 0 0 0 1 1 0 0 1 0 1 0 0 0 1 0 1 0 1 0 0 1 1 0 0 1 1 1 0 1 1 1 0 0 0 1 0 0 1 1 0 0 1 0 1 0 1 0 1 1 1 0 1 1 1 0 0 1 1 0 1 1 1 0 1 1 1 0 1 1 1 1 1 1 1

                                                        Odd Parity Generation Odd Parity Check ACTIVITY 1 Try using the parity checker of figure 92 as 3-bit parity generator Write the details here

                                                        _____________________________________________________________________________________________________________________________________________________________________________________________________________________ ______________________________________________________________________________________________________________________________________________ _______________________________________________________________________ ______________________________________________________________________________________________________________________________________________

                                                        Logic Design amp Switching Theory 1 Lab Session 10 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                        Lab Session 10 OBJECT

                                                        Driving a seven segment display using 7447 7448 driver IC COMPONENTS AND APPARATUS REQUIRED

                                                        1 Following ICs and their Datasheets

                                                        bull Seven Segment Displays (Common Anode Common Cathode) bull 7447 7448 BCD to Seven Segment Driver

                                                        2 Digital Trainer DT-01 or the following components Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches

                                                        THEORY Seven Segment Displays A Seven Segment Display consists of seven light-emitting segments The segments are designated by letters a through g (see figure 101) By illuminating various combinations of segments the numerals 0 through 9 can be displayed Seven Segment Displays are commonly constructed with light-emitting diodes (LEDs) and with liquid-crystal displays (LCDs) LEDs generally provide greater illumination levels but require much greater power than LCDs An LED display can be a common-anode type or common cathode type In common anode type a high voltage is applied at the common terminal of the display and low voltage is applied at a segmentrsquos terminal for illumination In the common-cathode type a low voltage is applied at the common terminal of the display and high voltage is applied at a segmentrsquos terminal for illumination

                                                        Figure 101 Seven Segment Display

                                                        a f b g

                                                        e c d

                                                        7447 7448 BCD to Seven Segment Driver 7447 7448 IC is particularly used to drive Seven Segment Its input is a BCD number and output drives a seven segment display 7447 is used to drive common-anode displays whereas 7448 is used to drive common cathode displays 7447 7448 is a 16 pin IC Function of various pins of these ICs is described below

                                                        bull A B C D Inputs representing BCD digits (D being the MSB)

                                                        45

                                                        Logic Design amp Switching Theory 1 Lab Session 10 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering bull OA through OG Outputs to drive segments a through g of the display (Active low

                                                        in 7447 and active high in 7448) bull RBI Ripple Blanking Input Turns off all the segments if kept low provided that LT

                                                        is kept high and all other inputs (A B C D BI) are kept low Should be kept high otherwise

                                                        bull BI RBO Wire-AND logic serving as a Blanking Input and or Ripple Blanking Output

                                                        o BI Turns off all the segments if low o RBO Goes to a low level (response condition) along with other outputs when

                                                        RBI and inputs A B C and D are low with LT input at high level bull LT Lamp Test input Tests whether all segments are working or not Illuminates all

                                                        segments if kept low provided that BI is kept high Should be kept high otherwise bull VCC and GND Supply connections lines CIRCUIT DIAGRAM

                                                        Figure 102 Circuit diagram for 7447driving a common-anode display

                                                        IMPLEMENTATION AND OBSERVATIONS

                                                        bull Make connections as shown in the circuit diagram (refer to laboratory session 01 for implementation procedure)

                                                        bull Apply different combinations of 1s and 0s at data inputs bull Observe the output and record your observations in the following table

                                                        46

                                                        Logic Design amp Switching Theory 1 Lab Session 10 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                        47

                                                        Decimal Digit

                                                        BCD Inputs Seven Segment Outputs D C B A a b c d e f g

                                                        0 0 0 0 0 1 0 0 0 1 2 0 0 1 0 3 0 0 1 1 4 0 1 0 0 5 0 1 0 1 6 0 1 1 0 7 0 1 1 1 8 1 0 0 0 9 1 0 0 1

                                                        ACTIVITY 1 Perform the Lamp Test for the designed circuit and write your observations

                                                        ____________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________

                                                        2 How can you use 7447 IC to drive a common-cathode display

                                                        ____________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________

                                                        3 What symbols appear in the seven segment display if inputs DCBA are

                                                        DCBA Symbol

                                                        1010

                                                        1011

                                                        1100

                                                        1101

                                                        1110

                                                        1111

                                                        Logic Design amp Switching Theory 1 Lab Session 11 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                        48

                                                        Lab Session 11 OBJECT

                                                        Testing different modes of JK-FF COMPONENTS AND APPARATUS REQUIRED 1 Following ICs and their Datasheets

                                                        bull 7473 7476 JK Flip-Flop 2 Digital Trainer DT-01 or the following components

                                                        Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches

                                                        THEORY

                                                        Flip-Flop A flip-flop circuit can maintain a binary state indefinitely (as long as the power is delivered to the circuit) until directed by an input signal to switch states The major differences among various types of flip-flops are in the number of inputs they possess and in the manner in which the inputs affect the binary state

                                                        JK Flip-Flop JK flip flop is an edge triggered device A typical JK flip flop has three inputs J K and a clock input The flip-flop can be either positive or negative edge triggered The output Q is available in complemented form as well Beside the usual inputs and output most of the flip-flop IC also possess two asynchronous inputs namely Preset and Clear These inputs are usually active low If used Preset and Clear inputs keep the flip-flop in set and reset state respectively irrespective of the other inputs Both of these inputs cannot be used simultaneously otherwise they will bring the flip-flop in unstable state

                                                        Figure 111 Symbol for JK flip-flop

                                                        (a) positive-edge triggering (b) active low Preset (PR) and Clear (CLR) with positive-edge triggering

                                                        (c) active low Preset (PR) and Clear (CLR) with negative-edge triggering

                                                        Logic Design amp Switching Theory 1 Lab Session 11 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                        49

                                                        TESTING OF 7473 7476 DUAL JK FLIP-FLOP

                                                        Both the ICs 7473 and 7476 are similar in functionality except for one difference The flip-flops in 7473 have only one type of active low asynchronous input which is the Clear input whereas the flip-flops in 7476 have both Preset and Clear inputs Both these ICs have negative edge triggered flip-flops

                                                        Circuit Diagram

                                                        Figure 112 Pin connections of 7476

                                                        Testing Procedure

                                                        bull Make connections as shown in the circuit diagram (figure 112) bull Apply different combinations of 1s and 0s at J and K inputs bull Observe the output and record your observations in the following table

                                                        Observations

                                                        J

                                                        K Q

                                                        0 0 0 1 1 0 1 1

                                                        ACTIVITY

                                                        1 Observe the output Q of JK flip-flop if the clock input is connected to VCC or GND instead of a clock source Write your observations here __________________________________________________________________________________________________________________________________________ _______________________________________________________________________________________________________________________________________________________________________________________________________________

                                                        Logic Design amp Switching Theory 1 Lab Session 12 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                        50

                                                        Lab Session 12 OBJECT

                                                        Designing sequential circuit for the given state diagram using D flip-flop GIVEN STATE DIAGRAM

                                                        00

                                                        11

                                                        Figure 121 State Diagram COMPONENTS AND APPARATUS REQUIRED 1 Following ICs and their Datasheets

                                                        bull 7474 D Flip-Flop bull ICs of basic gates (AND OR NOT XOR etc) as required

                                                        2 Digital Trainer DT-01 or the following components Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches

                                                        THEORY

                                                        Sequential Circuits In Sequential Circuits the output not only depends on the present inputs but also on previous states of the circuit These circuits use memory elements (latches flip-flops) and the binary information stored in the memory elements at any given time defines the state of the sequential circuit Analysis of a Sequential Circuit The behavior of a sequential circuit is determined from the inputs the outputs and the states of its flip-flops Both the outputs and next state are a function of the inputs and the

                                                        10

                                                        01

                                                        00 11 10

                                                        00

                                                        00 11 10 00

                                                        Logic Design amp Switching Theory 1 Lab Session 12 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                        51

                                                        present state The analysis of a sequential circuit form a state diagram comprises of the following bull Selecting a particular flip-flop to design the circuit bull Obtaining state table from the state diagram bull Finding input equations for the selected flip-flop bull Finding state equations (not required for the construction of circuit) bull Implementing the circuit using selected flip-flops and their input equations ANALYZING THE GIVEN STATE DIAGRAM D Flip-Flop D flip-flop is also called transparent flip-flop as it simply transfers the input data to the output For our design we require the graphical symbol and excitation table of D flip-flop (see figure 122)

                                                        Qt Qt+1 T 0 0 0 0 1 1 1 0 0 1 1 1

                                                        (b) Excitation table of D Flip-Flop

                                                        (a) Graphical Symbol

                                                        Figure 122 Characteristic equation of D flip-flop is Q(t+1) = D State Table The given state diagram has four states so we will need two D flip-flops (FF-0 FF-1) Form state table form the given state diagram and record the results in the following table

                                                        Present State Input Next State Output Input to FF-0 D0

                                                        Input to FF-1 D1 Q1t Q0t x Q1(t+1) Q0(t+1) z

                                                        Logic Design amp Switching Theory 1 Lab Session 12 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                        52

                                                        Input Equations Using Karnaugh map the input equations D0 and D1 for the two flip-flops can be found

                                                        D0 D1 Q0x

                                                        Q1

                                                        _ _ Q0x

                                                        _ Q0x

                                                        Q0x

                                                        _ Q0x

                                                        Q0x

                                                        Q1

                                                        _ _ Q0x

                                                        _ Q0x

                                                        Q0x

                                                        _ Q0x

                                                        _ Q1

                                                        _ Q1

                                                        Q1

                                                        Q1

                                                        D0 = _________________ D1 = _________________

                                                        State Equations Using the characteristic equation of D flip-flop we can find the state equations Q0(t+1) and Q1(t+1) for the to flip flops Q0(t+1) = _______________________ Q1(t+1) = _______________________ _______________________ _______________________ _______________________ _______________________ Circuit Diagram

                                                        Logic Design amp Switching Theory 1 Lab Session 12 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                        53

                                                        Implementation Procedure and Observations

                                                        1 Implement the circuit using digital ICs on a bread board (prepare the pin diagram (use appendix A) and refer to laboratory session 01 for procedure)

                                                        2 Make the clear inputs of the flip-flops low (to clear the flip-flops) The flip-flops will remain in clear state as long as the clear inputs are connected to low level

                                                        3 Connect output Q0 and the clock pulse to an oscilloscope 4 Apply 0 to the input x 5 Now make the clear inputs to high 6 Observe the waveform for the first 5 clock pulses and record it 7 Repeat steps 2 to 6 keeping x=1 in step 4 this time 8 Repeat steps 2 to 7 this time connecting Q1 instead of Q0 to the oscilloscope in step

                                                        3 Record your observations (Keep frequency of the clock pulse low (eg1Hz) so that the output waveforms can be observed easily)

                                                        1 2 3 4 5 Clock Pulse

                                                        Output Waveform for Q0 when x=0

                                                        Output Waveform for Q0 when x=1

                                                        Output Waveform for Q1 when x=0

                                                        Output Waveform for Q1 when x=1

                                                        Logic Design amp Switching Theory 1 Lab Session 13 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                        Lab Session 13 OBJECT

                                                        Designing a modulo-5 asynchronous up-counter using JK-FF COMPONENTS AND APPARATUS REQUIRED

                                                        1 Following ICs and their Datasheets

                                                        bull 7400 Quad 2-input or 7410 Triple 3-input NAND Gates bull 7476 7473 JK Flip-Flop

                                                        2 Digital Trainer DT-01 or the following components Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches

                                                        THEORY

                                                        Digital Counters A digital counter is a set of flip-flops whose states change in response to pulses applied at the input to the counter The flip-flops are interconnected so that their combined state at any time is the binary equivalent of the total number of pulses that have occurred up to that time Every counter resets after a certain number of clock pulses Thus as it name implies a counter is used to count pulses An n stage counter can count up to a maximum of 2n states n is equal to the number of flip-flops required for the construction of counter

                                                        Modulus Counters The number of input pulses that causes a counter to reset to its initial count is called the modulus of the counter Thus the modulus equals to total number of distinct states (counts) including zero that a counter can store A binary counter with n stages is a modulo-2n (or mod-2n) counter The largest count a mod-N counter can achieve is N-1 ie a mod-N counter never reaches the binary number equal to its modulus N is always equal to or less than 2n Counters can be classified as bull Synchronous Counters which are clock driven All the flip-flops are driven by a

                                                        single clock bull Asynchronous Counters which are event driven Clock input is given to the first

                                                        flip-flop only Rest of the flip-flops are driven by their preceding flip-flops

                                                        DESIGN OF A MOD-5 ASYNCHRONOUS UP COUNTER The number of flip-flops required to construct a mod-5 counter is 3 because 5 should be less than or equal to 2n This counter will count from 0 to 4 a total of 5 distinct states Since a 3-stage counter can count up to 8 states at maximum a NAND gate is used to reset it after 5 clock pulses Figure 131 shows the logic diagram

                                                        54

                                                        Logic Design amp Switching Theory 1 Lab Session 13 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                        55

                                                        Figure 131 A Mod-5 Asynchronous Up Counter

                                                        Implementation and Observations

                                                        Implement the mod-5 counter circuit (figure 131) on a bread board (prepare the pin diagram (use appendix A) and refer to laboratory session 01 for implementation procedure) and record the observations in the following table

                                                        Clock Pulse Q2 Q1 Q0

                                                        0 1 2 3 4 5 6 7

                                                        ACTIVITY

                                                        Draw the timing diagram for mod-5 counter designed in this laboratory session

                                                        Logic Design amp Switching Theory 1 Lab Session 14 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                        Lab Session 14 OBJECT

                                                        Experimenting with 74194 4-bit bidirectional universal shift register COMPONENTS AND APPARATUS REQUIRED

                                                        1 Following ICs and their Datasheets

                                                        bull 74194 4-bit bidirectional universal shift register 2 Digital Trainer DT-01 or the following components

                                                        Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches

                                                        THEORY

                                                        Shift Registers

                                                        A Register is a set of flip-flops used to store binary data A register which is capable of shifting its binary information either to the right or left is called a shift register The logical configuration of a register consists of a chain of flip-flops connected in cascade with the output of one flip-flop connected to the input of next flip-flop All flip-flops receive a common clock pulse which causes the shift from one stage to the next

                                                        Bidirectional Shift Registers A bi-directional shift register is one whose bits can be shifted from left to right or from right to left

                                                        Universal Shift Registers A universal shift register is a bi-directional register whose input can be in either serial or parallel form and whose output can be in either serial or parallel form

                                                        74194 4-BIT BIDIRECTIONAL UNIVERSAL SHIFT REGISTER

                                                        The 74194 register provides parallel as well as serial loading in both directions Function of various pins of this IC is described below

                                                        bull A B C and D Active high inputs for parallel loading bull QA QB QC and QD Active high outputs bull S0 and S1 Active high mode control inputs The following table shows combinations

                                                        of S1 and S0 to enable various modes

                                                        S1 S0 Clock Action 0 0 x No change 0 1 uarr Shift right 1 0 uarr Shift left 1 1 uarr Parallel load

                                                        uarr shows the rising edge of the clock pulse

                                                        56

                                                        Logic Design amp Switching Theory 1 Lab Session 14 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering bull SR Active high serial input for right shifting bull SL Active high serial input for left shifting bull CLR Active low input Clears all the flip-flops of the register if set to 0 should be

                                                        kept high otherwise bull CLK Clock input bull VCC and GND Supply connections lines Thus A B C and D are inputs for parallel loading whereas SR and SL are inputs for serial loading with right or left shifting respectively S1 and S0 are used to select the loading mode Circuit Diagram

                                                        Figure 141 Pin connections of 74194 Testing Procedure

                                                        bull Make connections as shown in the circuit diagram bull Observe the output for the input combinations given in the following table

                                                        57

                                                        Logic Design amp Switching Theory 1 Lab Session 14 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                        58

                                                        Observations

                                                        S1 S0 SL SR A B C D QA QB QC QD 0 0 0 1 0 0 0 0 0 1 1 0 0 0 0 1 1 0 0 0 0 0 1 0 1 1 0 0 0 0 1 1 0 0 1 1 0 1 0 0 0 1 1 1 0 1 0 1 1 0 1 0 0 1 1 0 1 1 1 0 0 1 1 1 1 1 0 0 1 1 1 1

                                                        ACTIVITY 1 Show connections of 74194 to convert it into a ring counter with right shifting

                                                        Logic Design amp Switching Theory 1 Lab Session 15 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                        Lab Session 15

                                                        OBJECT

                                                        Experimenting with 74245 octal bus transceivers using parallel port PC interfacing COMPONENTS AND APPARATUS REQUIRED 1 Parallel Port Connectors (DB-25) with Cable 2 Personal Computer with Windows 98 and TurboC Compiler Installed 3 Following ICs and their Datasheets

                                                        bull 74245 Octal Bus Transceivers with 3-State Outputs 4 Digital Trainer DT-01 or the following components

                                                        Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches

                                                        THEORY

                                                        3-State Logic Sometimes it is necessary to isolate one part of circuit from the other part For this purpose some TTL ICs are designed with 3-state logic Such devices have three possible output states high low and high impedance The device can be put into high impedance state by a control signal applied to an appropriate pin When such a device is in high impedance state there is very high impedance at its output effectively isolating the device from whatever circuitry the output normally drives 74245 Octal Bus Transceivers A bus is any conducting path or set of paths having electrical connections to one or more devices 74245 octal bus transceivers are mainly used to control connectivity between two devices or circuits It also provides direction control for signal flow Function of various pin of this IC is given below

                                                        bull A1 through A8 Bus A bull B1 through B8 Bus B bull G΄ Active low enable input When high sets all the bus pins to high impedance state bull DIR Direction control for signal flow When set to high logic level transfers bus A

                                                        data to B bus When set to low logic level transfers bus B data to A bus bull VCC and GND Supply connections lines Serial and Parallel Port Connectors A Parallel Port can consist of only 25 pin port adapter called a DB-25 and a serial port can consist of either a 25 pin port adapter called a DB-25 or 9 pin adapter called a DB-9 port adapter Whether the port is a 9 pin or 25 pin it can accomplish all of the same tasks that serial port communications have been designed for

                                                        59

                                                        Logic Design amp Switching Theory 1 Lab Session 15 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                        60

                                                        Each adapter can be a male type connector with pins or a female type adapter with tiny holes Generally a PRINTER port (called LPT1) on the back of a computer is female type adapter and we need to use MALE DB-25 pin cable on it for PRINTER connection or for parallel LAPLINK cable And a COM port on the back of a computer is male for the serial ports but it may not necessarily be Parallel Port Connector ndash DB-25 The DB-25 connector (named for its B-size D-shaped shell and 25 pins) is practically ubiquitous in the electronics industry The DB-25 connector is used for a variety of purposes Two common applications are RS-232EIA-232 (serial) connections and the parallel printer interface on the IBM PC The DB-25 connector is also used for SCSI connections Normally the parallel port is used for output to a printer or other device It sends data 8-bits or one byte at a time in parallel The other lines available on the DB-25 connector are a combination of status lines control lines and ground lines The status and control lines are used for handshaking commands and feedback when we are talking to a printer

                                                        Figure 152 DB-25 Female Figure 151 DB-25 Male

                                                        Figure 153 Pin Layout for DB-25 As can be seen form figure 153 there are four types of pins in this connector

                                                        bull Data pins (8 pins - D0 to D7) Active high bidirectional lines

                                                        Logic Design amp Switching Theory 1 Lab Session 15 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering bull Control pins (4 pins - C0 to C3) C0 C1 and C3 are active low whereas C2 is active

                                                        high These lines also are bidirectional bull Status pins (5 pins ndash S3 to S7) Only S7 is active low rest are active high input lines bull Ground pins (8 pins) Used as a reference signal for the low (below 05 volts) charge

                                                        Parallel Port Addresses A DB-25 connector at a parallel port has three address one for each kind of pins register data status and control The first or base address generally refers to data register Second address is for status register and the third one is for control register In Windows 98 the base address is usually found to be 278H 378H or 3BCH Now if 378H is the base address then it refers to the data register whereas addresses for status and control register are respectively 379H and 37AH For Windows 98 the base address can be found as follows 1 On your Desktop right-click on My Computer and select Properties 2 Click on the Device Manager tab and find LPT1 under Plug and Play BIOS 3 After selecting LPT1 click the Properties button 4 Next select the Resources tab and the address should then appear next to InputOutput

                                                        Range Accessing parallel port through C Language Programming There are multiple functions in C Language for accessing external ports The most commonly used are listed below

                                                        bull unsigned char inportb(int portid) inportb reads a byte from a hardware port

                                                        bull int inport(int portid) reads a word from a hardware port

                                                        bull void outportb(int portid unsigned char value) outputs a byte to a hardware port

                                                        bull void outport(int portid int value) outputs a word to a hardware port

                                                        portid refers to the port address whereas value refers to the data to be sent TESTING 74245 USING PARALLEL PORT PC INTERFACING At one end the parallel port connector will be connected to the PC via parallel port cable and another connector (to be plugged into the PC parallel port slot) At the other end it will be connected to the buffer IC 74245 Data lines of the connector will be used to transfer 8-bit data between the PC and the buffer Out of the 8-bits of 74245 4-bits will be used to enter data which will be displayed at the monitor through a C language

                                                        61

                                                        Logic Design amp Switching Theory 1 Lab Session 15 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering program The remaining 4-bits will receive data from PC as entered by the user via keyboard

                                                        Circuit Diagram

                                                        Figure 154 Interface of 74245 to PC via Parallel Port

                                                        Procedure

                                                        1 Connect the DB-25 connector to the PC at one end and solder it to the circuit board at the other end

                                                        2 Connect various pins of the connector and 74245 according to the circuit diagram shown in figure 152

                                                        3 Using the functions listed in the previous section write a program in C language to operate various pins of the buffer The user interface of the program should provide option to the user whether to send or receive data from the port

                                                        4 Set DIR switch to 1 5 Try sending some data bits to the port The result should be displayed at the LEDs 6 Set DIR switch to 0 7 Set some binary 4-bit value through the switches Try reading it via parallel port

                                                        C Language Program

                                                        A program to access parallel port for data transfers

                                                        use header file include ltstdiohgt main program void main() define variable

                                                        62

                                                        Logic Design amp Switching Theory 1 Lab Session 15 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering unsigned int data=0 char choice while(1) printing option menu clrscr() printf(This program will send or receive a BCD digit from the parallel portn) printf(nPress your choice numbern) printf(n1 Send Data) printf(n2 Receive Data) printf(n3 Exitn) choice = getch() sending entered digit to the port if(choice == 1) input BCD digit printf(nEnter BCD digit to be sent to the port) data = getche() masking the first four bits data = data amp 0x0f sending to the port outportb(0x378data) printf(nThe BCD digit c has been sent to the port data) printing on screen the data received from the port else if(choice == 2) receiving data from the port data = inportb(0x378) masking the last four bits data = data amp 0xf0 shifting first four bits to make them the last four bits datagtgt=4 printf(nThe BCD digit set at the port is c data) exit else if(choice == 3) break key pressed is not in the menu else printf(nEnter valid choice number) printf(nnPress any key to continue) getch()

                                                        63

                                                        Logic Design amp Switching Theory 1 Lab Session 15 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                        ACTIVITY 1 In the above circuit DIR and G΄ inputs are hardwired Connect them to status or

                                                        control pins of the parallel port connector and control their function through your software program Circuit Diagram Program Code ______________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________

                                                        ___________________________________________________________________________________________________________________________________________________

                                                        64

                                                        Logic Design amp Switching Theory 1 Lab Session 15 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                        65

                                                        _____________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ _____________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ _______________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ _________________________________________________ _________________________________________________

                                                        Logic Design amp Switching Theory 1 Appendix A NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                        Appendix A

                                                        PIN DIAGRAMS OF THE ICS REQUIRED FOR THE LABORATORY SESSIONS Consult the TTLIC data book for internal diagrams and electrical characteristics of these ICs 7400 Quad 2-Input NAND 7402 Quad 2-Input NOR

                                                        7404 Hex Inverter 7408 Quad 2-Input AND

                                                        7410 Triple 3-Input NAND 7411 Triple 3-Input AND

                                                        7421 Dual 4-Input AND 7432 Quad 2-Input OR

                                                        66

                                                        Logic Design amp Switching Theory 1 Appendix A NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                        BCD-to-Seven Segm 7448 BCD-to-Seven Segment 7447 ent

                                                        Decoder (15V OC) Decoder (2kΩ pull-up output)

                                                        7473 Dual JK Flip-Flop 7474 Dual D-Type Flip-Flop

                                                        7476 Dual JK Flop-Flop -Bit Binary Full Adder 7483 4 with Fast Carry

                                                        86 Quad 2-Inpu 74138 3-to-8 Line 74 t Exclusive OR Decoder Demultiplexer

                                                        67

                                                        Logic Design amp Switching Theory 1 Appendix A NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                        68

                                                        74148 8-to-3 Line 16-to-1 Line Data

                                                        Priority Encoder 74150 Selector Multiplexer

                                                        74245 Oct nsceivers Universal Shift Register (PIPO) (3-State)

                                                        74194 4-Bit Bidirectional al Bus Tra

                                                        Logic Design amp Switching Theory 1 Appendix B NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                        Appendix B

                                                        DEBOUNCING CIRCUITRY FOR MECHANICAL SWITCHES Mechanical switches form the interface between human beings and computers or other digital systems For example a keyboard is a matrix of switches used to supply alphanumeric data to a computer Whatever the switch design it is a potential source of problems due to contact bounce The contact bounce creates a sense of narrow pulses when a switch is opened or closed An example of device whose operation would be adversely affected by contact bounce is a digital counter used to count the number of times a switch is depressed Eliminating the effects of contact bounce is called debouncing When data is entered into a computer via a keyboard a software debounce is often used This type of debouncing is a program that causes the computer to sample the switch terminal (ie to input data from it) many times in succession during the interval of time that contact bounce occurs If the data is sensed to be 1s (or 0s) for a specific number of consecutive samples then it is assumed that contact bounce has ended and the last value sensed is valid Hardware debouncing is the use of electronic circuitry to eliminate the effects of contact bounce There are numerous versions of such circuitry including those that use monostable multivibrators (one-shots) but the most straightforward is simply an RS latch Figure B1 shows the circuit When the switch is in position 1 R = 0 and S = 1 so the latch is set and the output (Q) is 1 When the switch is in position 0 R = 1and S = 0 so the latch is reset and the output is 0 When the switch is moved form one position to the other the latch changes state and bouncing occurs at either the R or the S input The bouncing does not affect the latch after it has change state An RS latch will remain set for example when its R input is 0 and its S input is alternately changed form 1 to 0

                                                        Figure B1 Use of RS latch to debounce a mechanical switch

                                                        69

                                                        • 01-ldst-Outer title
                                                          • Practical Workbook
                                                          • Logic Design amp Switching Theory I
                                                            • Dept of Computer amp Information Systems Engineering
                                                              • NED University of Engineering amp Technology
                                                              • Karachi ndash 75270 Pakistan
                                                                • 02-ldst-inner Title
                                                                  • Practical Workbook
                                                                  • Logic Design amp Switching Theory I
                                                                    • Dept of Computer amp Information Systems Engineering
                                                                      • NED University of Engineering amp Technology
                                                                      • Karachi ndash 75270 Pakistan
                                                                        • 03-ldst-general info
                                                                        • 04-ldst-introduction
                                                                        • 05-Table of Contents
                                                                          • CONTENTS
                                                                            • Lab Session No Object Page No
                                                                            • 1
                                                                            • Also implementing and testing the given circuit on a bread board
                                                                              • Working with Electronics Workbench
                                                                                • Driving a seven segment display using 7447 7448 driver IC
                                                                                  • Designing a modulus-5 asynchronous up-counter using JK-FF
                                                                                    • Experimenting with 74194 4-bit bidirectional universal shift register
                                                                                        • 13
                                                                                            • 06-ldst-Exp01
                                                                                              • Lab Session 01
                                                                                              • OBJECT
                                                                                                • 1 Bread board
                                                                                                • 2 5 V - power supply
                                                                                                • 3 Multimeter
                                                                                                • 4 Logic probe
                                                                                                • 5 LEDs with resistors
                                                                                                • 6 Connecting wires
                                                                                                • 8 Following ICs and their datasheets
                                                                                                  • THEORY
                                                                                                    • Logic Gates
                                                                                                    • 1 The AND Gate ndash An AND gatersquos output is 1 if and only if all its inputs are 1 If A and B are two inputs to an AND gate then output F of the gate is given as F = AB
                                                                                                    • 2 The OR Gate - An OR gatersquos output is 1 if at least one of its input is 1 If A and B are two inputs to an OR gate then output F of the gate is given as F = A+B
                                                                                                    • 3 The NOT Gate (Inverter) ndash Its output is 1 when its input is 0 and its output is 0 when the input is 1 ie it complements a digital variable If A is the input to a NOT gate then output F of the gate is given as
                                                                                                    • 4 The NAND Gate ndash Its output is 1 if at least one of its input is 0 This gate performs the same logic as an AND gate followed by an inverter If A and B are two inputs to a NAND gate then output F of the gate is given as
                                                                                                      • 5 The NOR Gate - The output of a NOR gate is 1 if and only if all its inputs are 0 This gate performs the same logic function as an OR gate followed by an inverter If A and B are two inputs to a NAND gate then output F of the gate is given as
                                                                                                          • DATA SHEETS
                                                                                                            • Logic expression for the given logic diagram __________________________________
                                                                                                                • 07-ldst-exp02
                                                                                                                  • Working with Electronics Workbench
                                                                                                                    • 08-ldst-exp03
                                                                                                                      • Designing Half and Full Adder Circuits
                                                                                                                        • COMPONENTS AND APPARATUS REQUIRED
                                                                                                                          • 1 Following ICs and their Datasheets
                                                                                                                          • 7408 Quad 2-input AND Gate
                                                                                                                          • 2 Digital Trainer DT-01 or the following components
                                                                                                                            • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                            • Connecting wires Switches
                                                                                                                              • THEORY
                                                                                                                                  • IMPLEMENTATION AND OBSERVATIONS
                                                                                                                                    • 09-ldst-Exp04
                                                                                                                                      • Lab Session 04
                                                                                                                                      • 1 Digital ICs and their Datasheets
                                                                                                                                      • 7408 Quad 2-input AND Gate
                                                                                                                                      • 2 Digital Trainer DT-01 or the following components
                                                                                                                                        • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                        • Connecting wires Switches
                                                                                                                                        • PROCEDURE
                                                                                                                                        • REDUCTION OF LOGIC EXPRESSION USING KARNAUGH MAP
                                                                                                                                        • OBSERVATIONS
                                                                                                                                        • RESULT
                                                                                                                                            • 10-ldst-Exp05
                                                                                                                                              • Lab Session 05
                                                                                                                                              • 1 Following ICs and their Datasheets
                                                                                                                                              • 7408 Quad 2-input AND Gate
                                                                                                                                              • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                • (100 Ω) Connecting wires Switches
                                                                                                                                                • THEORY
                                                                                                                                                  • IMPLEMENTATION AND OBSERVATIONS
                                                                                                                                                    • 11-ldst-Exp06
                                                                                                                                                      • OBJECT
                                                                                                                                                      • 1 Following ICs and their Datasheets
                                                                                                                                                      • 7408 Quad 2-input AND Gates or 7411 Triple 3-input AND Gates
                                                                                                                                                      • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                        • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                        • Connecting wires Switches
                                                                                                                                                          • Figure 62 Circuit Diagram for 4 x 1 Multiplexer
                                                                                                                                                          • Implementation and Observations
                                                                                                                                                            • Circuit Diagram
                                                                                                                                                              • ACTIVITY
                                                                                                                                                                • 12-ldst-exp07
                                                                                                                                                                  • 1 Following ICs and their Datasheets
                                                                                                                                                                  • 7408 Quad 2-input or 7411 Triple 3-input AND Gates
                                                                                                                                                                  • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                    • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                    • Connecting wires Switches
                                                                                                                                                                      • THEORY
                                                                                                                                                                          • Figure 72 Circuit Diagram for 2 x 4 Decoder 1 x 4 Demultiplexer
                                                                                                                                                                          • Implementation and Observations
                                                                                                                                                                            • Circuit Diagram
                                                                                                                                                                              • ACTIVITY
                                                                                                                                                                                • 13-ldst-Exp08
                                                                                                                                                                                  • OBJECT
                                                                                                                                                                                  • 1 Following ICs and their Datasheets
                                                                                                                                                                                  • 7408 Quad 2-input or 7421 Dual 4-input AND Gates
                                                                                                                                                                                  • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                    • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                    • Connecting wires Switches
                                                                                                                                                                                      • THEORY
                                                                                                                                                                                          • Figure 81 Circuit Diagram for 4 x 2 Priority Encoder
                                                                                                                                                                                          • Implementation and Observations
                                                                                                                                                                                            • Therefore if GS A2 A1 and A0 are all low then it shows that line 0 is selected and if E0 A2 A1 and A0 are all low then it shows that none of the inputs selected E0 and GS cannot be in the same state provided that E1 is enabled
                                                                                                                                                                                            • Circuit Diagram
                                                                                                                                                                                              • ACTIVITY
                                                                                                                                                                                                • 14-ldst-exp09
                                                                                                                                                                                                  • OBJECT
                                                                                                                                                                                                  • 1 Following ICs and their Datasheets
                                                                                                                                                                                                  • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                    • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                    • Connecting wires Switches
                                                                                                                                                                                                      • THEORY
                                                                                                                                                                                                        • Parity Generator
                                                                                                                                                                                                          • Let x y and z be the three bits that constitute the message and are the input to the Odd Parity Generator Circuit Since it is an odd parity system the bit P is generated so as to make the total number of 1s odd (including P) The function P can be expressed as follows
                                                                                                                                                                                                          • Figure 91 Circuit Diagram for a 3-bit Parity Generator
                                                                                                                                                                                                            • C = x Ο y Ο z Ο P
                                                                                                                                                                                                              • Implementation and Observations
                                                                                                                                                                                                                • ACTIVITY
                                                                                                                                                                                                                    • 15-ldst-exp10
                                                                                                                                                                                                                      • Driving a seven segment display using 7447 7448 driver IC
                                                                                                                                                                                                                      • COMPONENTS AND APPARATUS REQUIRED
                                                                                                                                                                                                                      • 1 Following ICs and their Datasheets
                                                                                                                                                                                                                      • 7447 7448 BCD to Seven Segment Driver
                                                                                                                                                                                                                      • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                        • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches
                                                                                                                                                                                                                          • THEORY
                                                                                                                                                                                                                          • Seven Segment Displays
                                                                                                                                                                                                                          • CIRCUIT DIAGRAM
                                                                                                                                                                                                                          • Figure 102 Circuit diagram for 7447driving a common-anode display
                                                                                                                                                                                                                              • IMPLEMENTATION AND OBSERVATIONS
                                                                                                                                                                                                                                • Decimal Digit
                                                                                                                                                                                                                                • BCD Inputs
                                                                                                                                                                                                                                • Seven Segment Outputs
                                                                                                                                                                                                                                • D
                                                                                                                                                                                                                                • C
                                                                                                                                                                                                                                • B
                                                                                                                                                                                                                                • A
                                                                                                                                                                                                                                • a
                                                                                                                                                                                                                                • b
                                                                                                                                                                                                                                • c
                                                                                                                                                                                                                                • d
                                                                                                                                                                                                                                • e
                                                                                                                                                                                                                                • f
                                                                                                                                                                                                                                • g
                                                                                                                                                                                                                                • 0
                                                                                                                                                                                                                                • 0
                                                                                                                                                                                                                                • 0
                                                                                                                                                                                                                                • 0
                                                                                                                                                                                                                                • 0
                                                                                                                                                                                                                                • 1
                                                                                                                                                                                                                                • 0
                                                                                                                                                                                                                                • 0
                                                                                                                                                                                                                                • 0
                                                                                                                                                                                                                                • 1
                                                                                                                                                                                                                                • 2
                                                                                                                                                                                                                                • 0
                                                                                                                                                                                                                                • 0
                                                                                                                                                                                                                                • 1
                                                                                                                                                                                                                                • 0
                                                                                                                                                                                                                                • 3
                                                                                                                                                                                                                                • 0
                                                                                                                                                                                                                                • 0
                                                                                                                                                                                                                                • 1
                                                                                                                                                                                                                                • 1
                                                                                                                                                                                                                                • 4
                                                                                                                                                                                                                                • 0
                                                                                                                                                                                                                                • 1
                                                                                                                                                                                                                                • 0
                                                                                                                                                                                                                                • 0
                                                                                                                                                                                                                                • 5
                                                                                                                                                                                                                                • 0
                                                                                                                                                                                                                                • 1
                                                                                                                                                                                                                                • 0
                                                                                                                                                                                                                                • 1
                                                                                                                                                                                                                                • 6
                                                                                                                                                                                                                                • 0
                                                                                                                                                                                                                                • 1
                                                                                                                                                                                                                                • 1
                                                                                                                                                                                                                                • 0
                                                                                                                                                                                                                                • 7
                                                                                                                                                                                                                                • 0
                                                                                                                                                                                                                                • 1
                                                                                                                                                                                                                                • 1
                                                                                                                                                                                                                                • 1
                                                                                                                                                                                                                                • 8
                                                                                                                                                                                                                                • 1
                                                                                                                                                                                                                                • 0
                                                                                                                                                                                                                                • 0
                                                                                                                                                                                                                                • 0
                                                                                                                                                                                                                                • 9
                                                                                                                                                                                                                                • 1
                                                                                                                                                                                                                                • 0
                                                                                                                                                                                                                                • 0
                                                                                                                                                                                                                                • 1
                                                                                                                                                                                                                                  • ACTIVITY
                                                                                                                                                                                                                                    • 16-ldst-exp11
                                                                                                                                                                                                                                      • Lab Session 11
                                                                                                                                                                                                                                        • OBJECT
                                                                                                                                                                                                                                        • COMPONENTS AND APPARATUS REQUIRED
                                                                                                                                                                                                                                          • 1 Following ICs and their Datasheets
                                                                                                                                                                                                                                          • 7473 7476 JK Flip-Flop
                                                                                                                                                                                                                                          • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                                            • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                                                            • Connecting wires Switches
                                                                                                                                                                                                                                              • THEORY
                                                                                                                                                                                                                                                  • Flip-Flop
                                                                                                                                                                                                                                                  • JK Flip-Flop
                                                                                                                                                                                                                                                    • Circuit Diagram
                                                                                                                                                                                                                                                      • Observations
                                                                                                                                                                                                                                                        • ACTIVITY
                                                                                                                                                                                                                                                            • 17-ldst-exp12
                                                                                                                                                                                                                                                              • Lab Session 12
                                                                                                                                                                                                                                                                • OBJECT
                                                                                                                                                                                                                                                                • GIVEN STATE DIAGRAM
                                                                                                                                                                                                                                                                • Figure 121 State Diagram
                                                                                                                                                                                                                                                                • COMPONENTS AND APPARATUS REQUIRED
                                                                                                                                                                                                                                                                  • 1 Following ICs and their Datasheets
                                                                                                                                                                                                                                                                  • 7474 D Flip-Flop
                                                                                                                                                                                                                                                                  • ICs of basic gates (AND OR NOT XOR etc) as required
                                                                                                                                                                                                                                                                  • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                                                                    • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                                                                                    • Connecting wires Switches
                                                                                                                                                                                                                                                                      • THEORY
                                                                                                                                                                                                                                                                          • Sequential Circuits
                                                                                                                                                                                                                                                                            • 18-ldst-exp13
                                                                                                                                                                                                                                                                              • Lab Session 13
                                                                                                                                                                                                                                                                                • Designing a modulo-5 asynchronous up-counter using JK-FF
                                                                                                                                                                                                                                                                                  • 1 Following ICs and their Datasheets
                                                                                                                                                                                                                                                                                  • 7400 Quad 2-input or 7410 Triple 3-input NAND Gates
                                                                                                                                                                                                                                                                                  • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                                                                                    • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                                                                                                    • Connecting wires Switches
                                                                                                                                                                                                                                                                                      • THEORY
                                                                                                                                                                                                                                                                                          • Figure 131 A Mod-5 Asynchronous Up Counter
                                                                                                                                                                                                                                                                                          • Implementation and Observations
                                                                                                                                                                                                                                                                                            • ACTIVITY
                                                                                                                                                                                                                                                                                                • 19-ldst-exp14
                                                                                                                                                                                                                                                                                                  • Experimenting with 74194 4-bit bidirectional universal shift register
                                                                                                                                                                                                                                                                                                  • 1 Following ICs and their Datasheets
                                                                                                                                                                                                                                                                                                  • 74194 4-bit bidirectional universal shift register
                                                                                                                                                                                                                                                                                                  • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                                                                                                    • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                                                                                                                    • Connecting wires Switches
                                                                                                                                                                                                                                                                                                      • THEORY
                                                                                                                                                                                                                                                                                                        • Shift Registers
                                                                                                                                                                                                                                                                                                        • Bidirectional Shift Registers
                                                                                                                                                                                                                                                                                                        • Universal Shift Registers
                                                                                                                                                                                                                                                                                                          • S1
                                                                                                                                                                                                                                                                                                            • Circuit Diagram
                                                                                                                                                                                                                                                                                                            • ACTIVITY
                                                                                                                                                                                                                                                                                                                • 20-ldst-exp15
                                                                                                                                                                                                                                                                                                                  • COMPONENTS AND APPARATUS REQUIRED
                                                                                                                                                                                                                                                                                                                  • 1 Parallel Port Connectors (DB-25) with Cable
                                                                                                                                                                                                                                                                                                                  • 2 Personal Computer with Windows 98 and TurboC Compiler Installed
                                                                                                                                                                                                                                                                                                                  • 3 Following ICs and their Datasheets
                                                                                                                                                                                                                                                                                                                  • 74245 Octal Bus Transceivers with 3-State Outputs
                                                                                                                                                                                                                                                                                                                  • 4 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                                                                                                                    • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                                                                                                                                      • Connecting wires Switches
                                                                                                                                                                                                                                                                                                                        • THEORY
                                                                                                                                                                                                                                                                                                                        • 3-State Logic
                                                                                                                                                                                                                                                                                                                          • Serial and Parallel Port Connectors
                                                                                                                                                                                                                                                                                                                          • Parallel Port Connector ndash DB-25
                                                                                                                                                                                                                                                                                                                            • Accessing parallel port through C Language Programming
                                                                                                                                                                                                                                                                                                                                • 21-ldst-appendixA
                                                                                                                                                                                                                                                                                                                                • 22-ldst-appendixB
                                                                                                                                                                                                                                                                                                                                  • DEBOUNCING CIRCUITRY FOR MECHANICAL SWITCHES

                                                          Logic Design amp Switching Theory 1 lab Session 06 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                          Figure 62 Circuit Diagram for 4 x 1 Multiplexer

                                                          Implementation and Observations

                                                          Implement the 4 x 1 Multiplexer circuit (figure 62) on a bread board (prepare the pin diagram (use appendix A) and refer to laboratory session 01 for implementation procedure) and record the observations in the following table For each data select combination specify the switch number as well as the binary value present on that selected switch

                                                          S1 S0 Output 0 0 0 1 1 0 1 1

                                                          TESTING OF 74150 - 16 x 1 MUX

                                                          The 74150 IC has sixteen data inputs and four data-selection lines Function of various pins of this IC is described below

                                                          bull E0 through E15 Data input lines

                                                          31

                                                          Logic Design amp Switching Theory 1 lab Session 06 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering bull A B C D Data select lines with D being the MSB bull W Active low output line bull Grsquo Active low enable line bull VCC and GND Supply connections lines

                                                          Circuit Diagram

                                                          Figure 63 Pin connections of 74150 for selecting E0

                                                          Testing Procedure

                                                          bull Make connections as shown in the circuit diagram bull Apply different data (1 or 0) at data inputs that are labeled as E0 to E15 Only

                                                          connection for E0 is shown is the figure for simplicity bull Select the data input E0 with the help of data selectors A B C and D bull Observe the output which shows the complement of the data from E0 bull Select all the sixteen data inputs one by one and record your observations in the

                                                          following table

                                                          32

                                                          Logic Design amp Switching Theory 1 lab Session 06 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                          33

                                                          Observations

                                                          Grsquo D C B A W Grsquo D C B A W 0 0 0 0 0 0 1 0 0 0 0 0 0 0 1 0 1 0 0 1 0 0 0 1 0 0 1 0 1 0 0 0 0 1 1 0 1 0 1 1 0 0 1 0 0 0 1 1 0 0 0 0 1 0 1 0 1 1 0 1 0 0 1 1 0 0 1 1 1 0 0 0 1 1 1 0 1 1 1 1

                                                          ACTIVITY 1 Consider 4x1 Multiplexer Draw the output wave-form for the following data inputs

                                                          (E0 E1 E2 E3) and select lines A B (B being the MSB) Output is W

                                                          E3 E2 E1 E0 A B

                                                          W

                                                          2 Using the 4 x 1 MUX designed in this laboratory session implement the following logical function F (A B C) = Σ (0147)

                                                          Show your working and input connections in the following block diagram according to the circuit you have implemented

                                                          4 x 1 MUX

                                                          S0 S1

                                                          Output D0

                                                          D1

                                                          D2

                                                          D3

                                                          Logic Design amp Switching Theory 1 Lab Session 07 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                          Lab Session 07

                                                          OBJECT

                                                          bull Designing of a 2 x 4 Decoder 1 x 4 Demultiplexer bull Experimenting with 74138 IC

                                                          COMPONENTS AND APPARATUS REQUIRED 1 Following ICs and their Datasheets

                                                          bull 7408 Quad 2-input or 7411 Triple 3-input AND Gates bull 7404 Hex Inverter bull 74138 3 x 8 Decoder

                                                          2 Digital Trainer DT-01 or the following components Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches THEORY

                                                          Decoder A Decoder is a combinational circuit that converts binary information form n input lines to a maximum of 2n unique output lines In practical applications decoders are often used for selecting one of several devices

                                                          Demultiplexer A decoder with an enable input can function as a Demultiplexer A Demultiplexer (DMUX) id a circuit that receives information on a single line and transmits this information on one of 2n possible output lines The selection of a specific output line is controlled by the bit values of n selection lines DESIGN OF A 2 x 4 DECODER 1 x 4 DEMULTIPLEXER A 2 x 4 decoder is capable of selecting one of four output lines (see figure 71 (a)) The 2-bit binary number at the data inputs S1 and S0 specifies which of the four data inputs is to be selected If we add an enable pin and use it as an input line then this decoder can be converted to a 1 x 4 Demultiplexer where S1 and S0 will select a line to which data input is to be routed (see figure 71 (b))

                                                          Select S0 S0 Inputs

                                                          S1 D0 D1

                                                          D2

                                                          D3

                                                          Enable (a) Block Diagram of a 2 x 4 Decoder

                                                          Figure 71

                                                          S1 D0 D1

                                                          D2

                                                          D3

                                                          Inputs

                                                          Data Input (b) Block Diagram of a 1 x 4 Demulptiplexer

                                                          34

                                                          Logic Design amp Switching Theory 1 Lab Session 07 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                          Figure 72 Circuit Diagram for 2 x 4 Decoder 1 x 4 Demultiplexer

                                                          Implementation and Observations Implement the 2 x 4 Decoder 1 x 4 Demultiplexer circuit (figure 72) on a bread board (prepare the pin diagram (use appendix A) and refer to laboratory session 01 for implementation procedure) and record the observations in the following table

                                                          Enable Data Input S1 S0 D0 D1 D2 D3

                                                          0 0 0 0 0 1 0 1 0 0 1 1 1 0 0 1 0 1 1 1 0 1 1 1

                                                          TESTING OF 74138 3 x 8 Decoder The 74138 IC has three inputs and eight output lines It has three enable inputs and for the IC to function all three inputs need to be enabled Function of various pins of this IC is described below

                                                          35

                                                          Logic Design amp Switching Theory 1 Lab Session 07 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                          bull Y0 through Y7 Active low data outputs bull A B C Input select lines with C being the MSB bull G1 Active high enable Input bull G2Arsquo and G2Brsquo Active low enable Inputs bull VCC and GND Supply connections lines Circuit Diagram

                                                          Figure 73 Pin connections of 74138

                                                          Testing Procedure

                                                          bull Make connections as shown in the circuit diagram bull Apply different combinations of 1s and 0s at data inputs bull Observe the output and record your observations in the following table

                                                          Observations

                                                          C B A Y0 Y1 Y2 Y3 Y4 Y5 Y6 Y7 0 0 0 0 0 1 0 1 0 0 1 1 1 0 0 1 0 1 1 1 0 1 1 1

                                                          36

                                                          Logic Design amp Switching Theory 1 Lab Session 07 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                          37

                                                          ACTIVITY ACTIVITY 1 What will be the binary values at the outputs Y0 through Y7 of 74138 if 1 What will be the binary values at the outputs Y0 through Y7 of 74138 if

                                                          bull All three enable pins are connected to ground bull All three enable pins are connected to ground __________________________________________________________________________________________________________________________________________ __________________________________________________________________________________________________________________________________________ _____________________________________________________________________ _____________________________________________________________________

                                                          bull All three enable pins are connected to VCC bull All three enable pins are connected to VCC _______________________________________________________________________________________________________________________________________________________________________________________________________________

                                                          _______________________________________________________________________________________________________________________________________________________________________________________________________________

                                                          2 Show connections for 74138 in order to use it as a 1 x 8 Demultiplexer 2 Show connections for 74138 in order to use it as a 1 x 8 Demultiplexer

                                                          3 Consider a 2 x 4 Decoder with two enable inputs (one active high - G and one active low ndash Grsquo) Draw the output wave-forms for D0 D1 D2 and D3 if the two select inputs are A and B (B being the MSB) All outputs are active low

                                                          Grsquo

                                                          G

                                                          A B

                                                          D0 D1 D2

                                                          D3

                                                          Logic Design amp Switching Theory 1 Lab Session 08 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                          Lab Session 08 OBJECT

                                                          bull Designing of a 4 x 2 Priority Encoder bull Experimenting with 74148 IC

                                                          COMPONENTS AND APPARATUS REQUIRED

                                                          1 Following ICs and their Datasheets

                                                          bull 7408 Quad 2-input or 7421 Dual 4-input AND Gates bull 7432 Quad 2-input OR Gates bull 7404 Hex Inverter bull 74148 Encoder

                                                          2 Digital Trainer DT-01 or the following components Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches

                                                          THEORY

                                                          Encoder An Encoder is a digital function that produces a reverse operation from that of a decoder An Encoder has 2n (or less) input lines and n output lines The output lines generate the binary code for the 2n input variables Priority Encoder

                                                          A simple encoder may produce an erroneous output if more than one of its inputs is high A Priority Encoder is one that responds to just one input among those that may be simultaneously high in accordance with some priority system The most common priority system is based on the relative magnitudes of the inputs whichever decimal input is largest is the one that is encoded

                                                          DESIGN OF A 4 x 2 Priority Encoder

                                                          The following equations represent the outputs of a 4 x 2 priority encoder 32 DDA +=

                                                          321 DDDB += As can be seen from the equations that input D0 which has a binary code 00 is not used in any equation A binary code 00 at the output indicates two conditions Either D0 is selected or no input is selected In order to differentiate these two conditions we will provide an additional output Z to indicate if at least one of the inputs is a 1 The equation for Z will be

                                                          4321 DDDDZ = If Z is 0 then the binary code 00 at the output indicates that D0 is selected and if Z is 1 then it indicates that no input line is selected

                                                          38

                                                          Logic Design amp Switching Theory 1 Lab Session 08 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                          Figure 81 Circuit Diagram for 4 x 2 Priority Encoder

                                                          it (figure 81) on a bread board (prepare the to laboratory session 01 for implementation

                                                          Implementation a Implement the 4 x 2 Priority Encoder circu

                                                          ram (use appendix A) and refer

                                                          nd Observations

                                                          pin diagprocedure) and record the observations in the following table

                                                          D3 D2 D1 D0 A B 0 0 0 1 0 0 1 x 0 1 x x 1 x x x

                                                          TESTING OF 74148 8 x 3 Octal Priority Encoder

                                                          imal digits There are nine of which three represents

                                                          ing any of the inputs is high

                                                          then it shows that line 0 is selected and if e inputs selected E0 and GS

                                                          cannot be in the same state provided that E1 is enabled

                                                          The 74148 is a priority encoder with active-Low input for dec

                                                          input) and five output linesinputs lines (including an enablethe binary code for the octal digit Function of various pins of this IC is described below

                                                          bull 0 through 7 Active low data inputs representing the octal digits A2 A1 A0 Active low output lines representing the binary code bullbull E1 Active low enable Input bull E0 Active low output indicating none of the inputs is high bull GS Active low output indicatbull VCC and GND Supply connections lines Therefore if GS A2 A1 and A0 are all low

                                                          then it shows that none of thE0 A2 A1 and A0 are all low

                                                          39

                                                          Logic Design amp Switching Theory 1 Lab Session 08 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                          Circuit Diagram

                                                          Figure 82 Pin connections of 74148

                                                          Testing Procedure bull Make connections as sho

                                                          binations of 1s and 0s at data inputs d record your observations in the following table

                                                          GS E0

                                                          wn in the circuit diagram bull Apply different combull Observe the output an Observations

                                                          0 1 2 3 4 5 6 7 A2 A1 A0 1 1 1 1 1 1 1 1 x x x x x x x 0 x x x x x x 0 1 x x x x x 0 1 1 x x x x 0 1 1 1 x x x 0 1 1 1 1 x x 0 1 1 1 1 1 x 0 1 1 1 1 1 1 0 1 1 1 1 1 1 1

                                                          40

                                                          Logic Design amp Switching Theory 1 Lab Session 08 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                          41

                                                          CTIVITY

                                                          Cascade the following two 74148 8 x 3 Priority Encoders to form 16 x 4 Priority

                                                          A 1

                                                          Encoder

                                                          Logic Design amp Switching Theory 1 Lab Session 09 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering `

                                                          Lab Session 09 OBJECT

                                                          Designing an Odd Parity Generator and Checker for a 3-bit Data COMPONENTS AND APPARATUS REQUIRED

                                                          1 Following ICs and their Datasheets

                                                          bull 7486 Quad 2-input Exclusive-OR Gates bull 7404 Hex Inverter

                                                          2 Digital Trainer DT-01 or the following components Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches

                                                          THEORY

                                                          Parity Generator When binary data is transmitted and processed it is ndash as are all electrical signals ndash susceptible to noise that can either alter or distort its contents 1s may be effectively changed to 0s and 0s to 1s To overcome this problem one or more bits are often added to the data as an aid in detecting errors caused by noise The most common of these is a Parity bit that signifies whether the total number of 1s in a code group is odd or even In an Odd Parity system the parity bit is made 0 or 1 as necessary to make the total number 1s odd (counting the parity bit itself) In an Even Parity system the parity bit is chosen to make the total number of 1s even Table 91 shows how parity bits would be added to BCD code group in both systems

                                                          Decimal BCD Value Parity Bit ABCD Odd Parity Even Parity

                                                          0 0000 1 0 1 0001 0 1 2 0010 0 1 3 0011 1 0 4 0100 0 1 5 0101 1 0 6 0110 1 0 7 0111 0 1 8 1000 0 1 9 1001 1 0

                                                          Table 91 Odd and Even Parity in BCD

                                                          When digital data is received a parity checking circuit generates an error signal if the total number of 1s is odd in an even parity system or if it is even in an odd parity system Parity check always detects a single error (one bit change from 0 to 1 or 1 to 0) but may not detect

                                                          42

                                                          Logic Design amp Switching Theory 1 Lab Session 09 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering ` two or more errors Odd parity is used more often than even parity because even parity does not detect a situation where all 0s are created due to short circuit or other fault condition DESIGN OF A 3-BIT ODD PARITY GENERATOR AND CHECKER Let x y and z be the three bits that constitute the message and are the input to the Odd Parity Generator Circuit Since it is an odd parity system the bit P is generated so as to make the total number of 1s odd (including P) The function P can be expressed as follows P = x oplus y Ο z or P = x Ο y oplus z Since the IC available is 7486 which is quad 2input XOR IC therefore we will convert XNOR also to XOR

                                                          P = x oplus y Ο z

                                                          P = ( x oplus y ) Ο z Since for even number of variables ______

                                                          XOR = XNOR Therefore ___________ _________

                                                          P = ( x oplus y ) oplus z = x oplus y oplus z This logical expression can be implemented with two XOR gates and an inverter (see figure 91)

                                                          Figure 91 Circuit Diagram for a 3-bit Parity Generator

                                                          The 3-bit message and the parity bit are transmitted to their destination where they are applied to a Parity Checker Circuit An error occurs during transmission if the parity of the four bits received is even since the binary information transmitted was originally odd The output C of the parity checker should be a 1 when an error occurs ie when the number of 1s in the four inputs is even Therefore the function C can be expressed as

                                                          C = x Ο y Ο z Ο P

                                                          Using the same logic applied for the conversion of the equation of P

                                                          PzyxC oplusoplusoplus= This logical expression can be implemented with three XOR gates and an inverter (see figure 92)

                                                          43

                                                          Logic Design amp Switching Theory 1 Lab Session 09 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering `

                                                          44

                                                          Figure 92 Circuit Diagram for a 3-bit Parity Checker Implementation and Observations Implement the 3-bit Parity Generator and Checker circuits (figure 91 and 92) on a bread board (prepare the pin diagram (use appendix A) and refer to laboratory session 01 for implementation procedure) and record the observations in the following table

                                                          x y z P x y z P C x y z P C 0 0 0 0 0 0 0 1 0 0 0 0 0 1 0 0 0 1 1 0 0 1 0 1 0 0 0 1 0 1 0 1 0 0 1 1 0 0 1 1 1 0 1 1 1 0 0 0 1 0 0 1 1 0 0 1 0 1 0 1 0 1 1 1 0 1 1 1 0 0 1 1 0 1 1 1 0 1 1 1 0 1 1 1 1 1 1 1

                                                          Odd Parity Generation Odd Parity Check ACTIVITY 1 Try using the parity checker of figure 92 as 3-bit parity generator Write the details here

                                                          _____________________________________________________________________________________________________________________________________________________________________________________________________________________ ______________________________________________________________________________________________________________________________________________ _______________________________________________________________________ ______________________________________________________________________________________________________________________________________________

                                                          Logic Design amp Switching Theory 1 Lab Session 10 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                          Lab Session 10 OBJECT

                                                          Driving a seven segment display using 7447 7448 driver IC COMPONENTS AND APPARATUS REQUIRED

                                                          1 Following ICs and their Datasheets

                                                          bull Seven Segment Displays (Common Anode Common Cathode) bull 7447 7448 BCD to Seven Segment Driver

                                                          2 Digital Trainer DT-01 or the following components Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches

                                                          THEORY Seven Segment Displays A Seven Segment Display consists of seven light-emitting segments The segments are designated by letters a through g (see figure 101) By illuminating various combinations of segments the numerals 0 through 9 can be displayed Seven Segment Displays are commonly constructed with light-emitting diodes (LEDs) and with liquid-crystal displays (LCDs) LEDs generally provide greater illumination levels but require much greater power than LCDs An LED display can be a common-anode type or common cathode type In common anode type a high voltage is applied at the common terminal of the display and low voltage is applied at a segmentrsquos terminal for illumination In the common-cathode type a low voltage is applied at the common terminal of the display and high voltage is applied at a segmentrsquos terminal for illumination

                                                          Figure 101 Seven Segment Display

                                                          a f b g

                                                          e c d

                                                          7447 7448 BCD to Seven Segment Driver 7447 7448 IC is particularly used to drive Seven Segment Its input is a BCD number and output drives a seven segment display 7447 is used to drive common-anode displays whereas 7448 is used to drive common cathode displays 7447 7448 is a 16 pin IC Function of various pins of these ICs is described below

                                                          bull A B C D Inputs representing BCD digits (D being the MSB)

                                                          45

                                                          Logic Design amp Switching Theory 1 Lab Session 10 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering bull OA through OG Outputs to drive segments a through g of the display (Active low

                                                          in 7447 and active high in 7448) bull RBI Ripple Blanking Input Turns off all the segments if kept low provided that LT

                                                          is kept high and all other inputs (A B C D BI) are kept low Should be kept high otherwise

                                                          bull BI RBO Wire-AND logic serving as a Blanking Input and or Ripple Blanking Output

                                                          o BI Turns off all the segments if low o RBO Goes to a low level (response condition) along with other outputs when

                                                          RBI and inputs A B C and D are low with LT input at high level bull LT Lamp Test input Tests whether all segments are working or not Illuminates all

                                                          segments if kept low provided that BI is kept high Should be kept high otherwise bull VCC and GND Supply connections lines CIRCUIT DIAGRAM

                                                          Figure 102 Circuit diagram for 7447driving a common-anode display

                                                          IMPLEMENTATION AND OBSERVATIONS

                                                          bull Make connections as shown in the circuit diagram (refer to laboratory session 01 for implementation procedure)

                                                          bull Apply different combinations of 1s and 0s at data inputs bull Observe the output and record your observations in the following table

                                                          46

                                                          Logic Design amp Switching Theory 1 Lab Session 10 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                          47

                                                          Decimal Digit

                                                          BCD Inputs Seven Segment Outputs D C B A a b c d e f g

                                                          0 0 0 0 0 1 0 0 0 1 2 0 0 1 0 3 0 0 1 1 4 0 1 0 0 5 0 1 0 1 6 0 1 1 0 7 0 1 1 1 8 1 0 0 0 9 1 0 0 1

                                                          ACTIVITY 1 Perform the Lamp Test for the designed circuit and write your observations

                                                          ____________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________

                                                          2 How can you use 7447 IC to drive a common-cathode display

                                                          ____________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________

                                                          3 What symbols appear in the seven segment display if inputs DCBA are

                                                          DCBA Symbol

                                                          1010

                                                          1011

                                                          1100

                                                          1101

                                                          1110

                                                          1111

                                                          Logic Design amp Switching Theory 1 Lab Session 11 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                          48

                                                          Lab Session 11 OBJECT

                                                          Testing different modes of JK-FF COMPONENTS AND APPARATUS REQUIRED 1 Following ICs and their Datasheets

                                                          bull 7473 7476 JK Flip-Flop 2 Digital Trainer DT-01 or the following components

                                                          Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches

                                                          THEORY

                                                          Flip-Flop A flip-flop circuit can maintain a binary state indefinitely (as long as the power is delivered to the circuit) until directed by an input signal to switch states The major differences among various types of flip-flops are in the number of inputs they possess and in the manner in which the inputs affect the binary state

                                                          JK Flip-Flop JK flip flop is an edge triggered device A typical JK flip flop has three inputs J K and a clock input The flip-flop can be either positive or negative edge triggered The output Q is available in complemented form as well Beside the usual inputs and output most of the flip-flop IC also possess two asynchronous inputs namely Preset and Clear These inputs are usually active low If used Preset and Clear inputs keep the flip-flop in set and reset state respectively irrespective of the other inputs Both of these inputs cannot be used simultaneously otherwise they will bring the flip-flop in unstable state

                                                          Figure 111 Symbol for JK flip-flop

                                                          (a) positive-edge triggering (b) active low Preset (PR) and Clear (CLR) with positive-edge triggering

                                                          (c) active low Preset (PR) and Clear (CLR) with negative-edge triggering

                                                          Logic Design amp Switching Theory 1 Lab Session 11 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                          49

                                                          TESTING OF 7473 7476 DUAL JK FLIP-FLOP

                                                          Both the ICs 7473 and 7476 are similar in functionality except for one difference The flip-flops in 7473 have only one type of active low asynchronous input which is the Clear input whereas the flip-flops in 7476 have both Preset and Clear inputs Both these ICs have negative edge triggered flip-flops

                                                          Circuit Diagram

                                                          Figure 112 Pin connections of 7476

                                                          Testing Procedure

                                                          bull Make connections as shown in the circuit diagram (figure 112) bull Apply different combinations of 1s and 0s at J and K inputs bull Observe the output and record your observations in the following table

                                                          Observations

                                                          J

                                                          K Q

                                                          0 0 0 1 1 0 1 1

                                                          ACTIVITY

                                                          1 Observe the output Q of JK flip-flop if the clock input is connected to VCC or GND instead of a clock source Write your observations here __________________________________________________________________________________________________________________________________________ _______________________________________________________________________________________________________________________________________________________________________________________________________________

                                                          Logic Design amp Switching Theory 1 Lab Session 12 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                          50

                                                          Lab Session 12 OBJECT

                                                          Designing sequential circuit for the given state diagram using D flip-flop GIVEN STATE DIAGRAM

                                                          00

                                                          11

                                                          Figure 121 State Diagram COMPONENTS AND APPARATUS REQUIRED 1 Following ICs and their Datasheets

                                                          bull 7474 D Flip-Flop bull ICs of basic gates (AND OR NOT XOR etc) as required

                                                          2 Digital Trainer DT-01 or the following components Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches

                                                          THEORY

                                                          Sequential Circuits In Sequential Circuits the output not only depends on the present inputs but also on previous states of the circuit These circuits use memory elements (latches flip-flops) and the binary information stored in the memory elements at any given time defines the state of the sequential circuit Analysis of a Sequential Circuit The behavior of a sequential circuit is determined from the inputs the outputs and the states of its flip-flops Both the outputs and next state are a function of the inputs and the

                                                          10

                                                          01

                                                          00 11 10

                                                          00

                                                          00 11 10 00

                                                          Logic Design amp Switching Theory 1 Lab Session 12 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                          51

                                                          present state The analysis of a sequential circuit form a state diagram comprises of the following bull Selecting a particular flip-flop to design the circuit bull Obtaining state table from the state diagram bull Finding input equations for the selected flip-flop bull Finding state equations (not required for the construction of circuit) bull Implementing the circuit using selected flip-flops and their input equations ANALYZING THE GIVEN STATE DIAGRAM D Flip-Flop D flip-flop is also called transparent flip-flop as it simply transfers the input data to the output For our design we require the graphical symbol and excitation table of D flip-flop (see figure 122)

                                                          Qt Qt+1 T 0 0 0 0 1 1 1 0 0 1 1 1

                                                          (b) Excitation table of D Flip-Flop

                                                          (a) Graphical Symbol

                                                          Figure 122 Characteristic equation of D flip-flop is Q(t+1) = D State Table The given state diagram has four states so we will need two D flip-flops (FF-0 FF-1) Form state table form the given state diagram and record the results in the following table

                                                          Present State Input Next State Output Input to FF-0 D0

                                                          Input to FF-1 D1 Q1t Q0t x Q1(t+1) Q0(t+1) z

                                                          Logic Design amp Switching Theory 1 Lab Session 12 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                          52

                                                          Input Equations Using Karnaugh map the input equations D0 and D1 for the two flip-flops can be found

                                                          D0 D1 Q0x

                                                          Q1

                                                          _ _ Q0x

                                                          _ Q0x

                                                          Q0x

                                                          _ Q0x

                                                          Q0x

                                                          Q1

                                                          _ _ Q0x

                                                          _ Q0x

                                                          Q0x

                                                          _ Q0x

                                                          _ Q1

                                                          _ Q1

                                                          Q1

                                                          Q1

                                                          D0 = _________________ D1 = _________________

                                                          State Equations Using the characteristic equation of D flip-flop we can find the state equations Q0(t+1) and Q1(t+1) for the to flip flops Q0(t+1) = _______________________ Q1(t+1) = _______________________ _______________________ _______________________ _______________________ _______________________ Circuit Diagram

                                                          Logic Design amp Switching Theory 1 Lab Session 12 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                          53

                                                          Implementation Procedure and Observations

                                                          1 Implement the circuit using digital ICs on a bread board (prepare the pin diagram (use appendix A) and refer to laboratory session 01 for procedure)

                                                          2 Make the clear inputs of the flip-flops low (to clear the flip-flops) The flip-flops will remain in clear state as long as the clear inputs are connected to low level

                                                          3 Connect output Q0 and the clock pulse to an oscilloscope 4 Apply 0 to the input x 5 Now make the clear inputs to high 6 Observe the waveform for the first 5 clock pulses and record it 7 Repeat steps 2 to 6 keeping x=1 in step 4 this time 8 Repeat steps 2 to 7 this time connecting Q1 instead of Q0 to the oscilloscope in step

                                                          3 Record your observations (Keep frequency of the clock pulse low (eg1Hz) so that the output waveforms can be observed easily)

                                                          1 2 3 4 5 Clock Pulse

                                                          Output Waveform for Q0 when x=0

                                                          Output Waveform for Q0 when x=1

                                                          Output Waveform for Q1 when x=0

                                                          Output Waveform for Q1 when x=1

                                                          Logic Design amp Switching Theory 1 Lab Session 13 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                          Lab Session 13 OBJECT

                                                          Designing a modulo-5 asynchronous up-counter using JK-FF COMPONENTS AND APPARATUS REQUIRED

                                                          1 Following ICs and their Datasheets

                                                          bull 7400 Quad 2-input or 7410 Triple 3-input NAND Gates bull 7476 7473 JK Flip-Flop

                                                          2 Digital Trainer DT-01 or the following components Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches

                                                          THEORY

                                                          Digital Counters A digital counter is a set of flip-flops whose states change in response to pulses applied at the input to the counter The flip-flops are interconnected so that their combined state at any time is the binary equivalent of the total number of pulses that have occurred up to that time Every counter resets after a certain number of clock pulses Thus as it name implies a counter is used to count pulses An n stage counter can count up to a maximum of 2n states n is equal to the number of flip-flops required for the construction of counter

                                                          Modulus Counters The number of input pulses that causes a counter to reset to its initial count is called the modulus of the counter Thus the modulus equals to total number of distinct states (counts) including zero that a counter can store A binary counter with n stages is a modulo-2n (or mod-2n) counter The largest count a mod-N counter can achieve is N-1 ie a mod-N counter never reaches the binary number equal to its modulus N is always equal to or less than 2n Counters can be classified as bull Synchronous Counters which are clock driven All the flip-flops are driven by a

                                                          single clock bull Asynchronous Counters which are event driven Clock input is given to the first

                                                          flip-flop only Rest of the flip-flops are driven by their preceding flip-flops

                                                          DESIGN OF A MOD-5 ASYNCHRONOUS UP COUNTER The number of flip-flops required to construct a mod-5 counter is 3 because 5 should be less than or equal to 2n This counter will count from 0 to 4 a total of 5 distinct states Since a 3-stage counter can count up to 8 states at maximum a NAND gate is used to reset it after 5 clock pulses Figure 131 shows the logic diagram

                                                          54

                                                          Logic Design amp Switching Theory 1 Lab Session 13 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                          55

                                                          Figure 131 A Mod-5 Asynchronous Up Counter

                                                          Implementation and Observations

                                                          Implement the mod-5 counter circuit (figure 131) on a bread board (prepare the pin diagram (use appendix A) and refer to laboratory session 01 for implementation procedure) and record the observations in the following table

                                                          Clock Pulse Q2 Q1 Q0

                                                          0 1 2 3 4 5 6 7

                                                          ACTIVITY

                                                          Draw the timing diagram for mod-5 counter designed in this laboratory session

                                                          Logic Design amp Switching Theory 1 Lab Session 14 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                          Lab Session 14 OBJECT

                                                          Experimenting with 74194 4-bit bidirectional universal shift register COMPONENTS AND APPARATUS REQUIRED

                                                          1 Following ICs and their Datasheets

                                                          bull 74194 4-bit bidirectional universal shift register 2 Digital Trainer DT-01 or the following components

                                                          Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches

                                                          THEORY

                                                          Shift Registers

                                                          A Register is a set of flip-flops used to store binary data A register which is capable of shifting its binary information either to the right or left is called a shift register The logical configuration of a register consists of a chain of flip-flops connected in cascade with the output of one flip-flop connected to the input of next flip-flop All flip-flops receive a common clock pulse which causes the shift from one stage to the next

                                                          Bidirectional Shift Registers A bi-directional shift register is one whose bits can be shifted from left to right or from right to left

                                                          Universal Shift Registers A universal shift register is a bi-directional register whose input can be in either serial or parallel form and whose output can be in either serial or parallel form

                                                          74194 4-BIT BIDIRECTIONAL UNIVERSAL SHIFT REGISTER

                                                          The 74194 register provides parallel as well as serial loading in both directions Function of various pins of this IC is described below

                                                          bull A B C and D Active high inputs for parallel loading bull QA QB QC and QD Active high outputs bull S0 and S1 Active high mode control inputs The following table shows combinations

                                                          of S1 and S0 to enable various modes

                                                          S1 S0 Clock Action 0 0 x No change 0 1 uarr Shift right 1 0 uarr Shift left 1 1 uarr Parallel load

                                                          uarr shows the rising edge of the clock pulse

                                                          56

                                                          Logic Design amp Switching Theory 1 Lab Session 14 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering bull SR Active high serial input for right shifting bull SL Active high serial input for left shifting bull CLR Active low input Clears all the flip-flops of the register if set to 0 should be

                                                          kept high otherwise bull CLK Clock input bull VCC and GND Supply connections lines Thus A B C and D are inputs for parallel loading whereas SR and SL are inputs for serial loading with right or left shifting respectively S1 and S0 are used to select the loading mode Circuit Diagram

                                                          Figure 141 Pin connections of 74194 Testing Procedure

                                                          bull Make connections as shown in the circuit diagram bull Observe the output for the input combinations given in the following table

                                                          57

                                                          Logic Design amp Switching Theory 1 Lab Session 14 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                          58

                                                          Observations

                                                          S1 S0 SL SR A B C D QA QB QC QD 0 0 0 1 0 0 0 0 0 1 1 0 0 0 0 1 1 0 0 0 0 0 1 0 1 1 0 0 0 0 1 1 0 0 1 1 0 1 0 0 0 1 1 1 0 1 0 1 1 0 1 0 0 1 1 0 1 1 1 0 0 1 1 1 1 1 0 0 1 1 1 1

                                                          ACTIVITY 1 Show connections of 74194 to convert it into a ring counter with right shifting

                                                          Logic Design amp Switching Theory 1 Lab Session 15 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                          Lab Session 15

                                                          OBJECT

                                                          Experimenting with 74245 octal bus transceivers using parallel port PC interfacing COMPONENTS AND APPARATUS REQUIRED 1 Parallel Port Connectors (DB-25) with Cable 2 Personal Computer with Windows 98 and TurboC Compiler Installed 3 Following ICs and their Datasheets

                                                          bull 74245 Octal Bus Transceivers with 3-State Outputs 4 Digital Trainer DT-01 or the following components

                                                          Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches

                                                          THEORY

                                                          3-State Logic Sometimes it is necessary to isolate one part of circuit from the other part For this purpose some TTL ICs are designed with 3-state logic Such devices have three possible output states high low and high impedance The device can be put into high impedance state by a control signal applied to an appropriate pin When such a device is in high impedance state there is very high impedance at its output effectively isolating the device from whatever circuitry the output normally drives 74245 Octal Bus Transceivers A bus is any conducting path or set of paths having electrical connections to one or more devices 74245 octal bus transceivers are mainly used to control connectivity between two devices or circuits It also provides direction control for signal flow Function of various pin of this IC is given below

                                                          bull A1 through A8 Bus A bull B1 through B8 Bus B bull G΄ Active low enable input When high sets all the bus pins to high impedance state bull DIR Direction control for signal flow When set to high logic level transfers bus A

                                                          data to B bus When set to low logic level transfers bus B data to A bus bull VCC and GND Supply connections lines Serial and Parallel Port Connectors A Parallel Port can consist of only 25 pin port adapter called a DB-25 and a serial port can consist of either a 25 pin port adapter called a DB-25 or 9 pin adapter called a DB-9 port adapter Whether the port is a 9 pin or 25 pin it can accomplish all of the same tasks that serial port communications have been designed for

                                                          59

                                                          Logic Design amp Switching Theory 1 Lab Session 15 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                          60

                                                          Each adapter can be a male type connector with pins or a female type adapter with tiny holes Generally a PRINTER port (called LPT1) on the back of a computer is female type adapter and we need to use MALE DB-25 pin cable on it for PRINTER connection or for parallel LAPLINK cable And a COM port on the back of a computer is male for the serial ports but it may not necessarily be Parallel Port Connector ndash DB-25 The DB-25 connector (named for its B-size D-shaped shell and 25 pins) is practically ubiquitous in the electronics industry The DB-25 connector is used for a variety of purposes Two common applications are RS-232EIA-232 (serial) connections and the parallel printer interface on the IBM PC The DB-25 connector is also used for SCSI connections Normally the parallel port is used for output to a printer or other device It sends data 8-bits or one byte at a time in parallel The other lines available on the DB-25 connector are a combination of status lines control lines and ground lines The status and control lines are used for handshaking commands and feedback when we are talking to a printer

                                                          Figure 152 DB-25 Female Figure 151 DB-25 Male

                                                          Figure 153 Pin Layout for DB-25 As can be seen form figure 153 there are four types of pins in this connector

                                                          bull Data pins (8 pins - D0 to D7) Active high bidirectional lines

                                                          Logic Design amp Switching Theory 1 Lab Session 15 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering bull Control pins (4 pins - C0 to C3) C0 C1 and C3 are active low whereas C2 is active

                                                          high These lines also are bidirectional bull Status pins (5 pins ndash S3 to S7) Only S7 is active low rest are active high input lines bull Ground pins (8 pins) Used as a reference signal for the low (below 05 volts) charge

                                                          Parallel Port Addresses A DB-25 connector at a parallel port has three address one for each kind of pins register data status and control The first or base address generally refers to data register Second address is for status register and the third one is for control register In Windows 98 the base address is usually found to be 278H 378H or 3BCH Now if 378H is the base address then it refers to the data register whereas addresses for status and control register are respectively 379H and 37AH For Windows 98 the base address can be found as follows 1 On your Desktop right-click on My Computer and select Properties 2 Click on the Device Manager tab and find LPT1 under Plug and Play BIOS 3 After selecting LPT1 click the Properties button 4 Next select the Resources tab and the address should then appear next to InputOutput

                                                          Range Accessing parallel port through C Language Programming There are multiple functions in C Language for accessing external ports The most commonly used are listed below

                                                          bull unsigned char inportb(int portid) inportb reads a byte from a hardware port

                                                          bull int inport(int portid) reads a word from a hardware port

                                                          bull void outportb(int portid unsigned char value) outputs a byte to a hardware port

                                                          bull void outport(int portid int value) outputs a word to a hardware port

                                                          portid refers to the port address whereas value refers to the data to be sent TESTING 74245 USING PARALLEL PORT PC INTERFACING At one end the parallel port connector will be connected to the PC via parallel port cable and another connector (to be plugged into the PC parallel port slot) At the other end it will be connected to the buffer IC 74245 Data lines of the connector will be used to transfer 8-bit data between the PC and the buffer Out of the 8-bits of 74245 4-bits will be used to enter data which will be displayed at the monitor through a C language

                                                          61

                                                          Logic Design amp Switching Theory 1 Lab Session 15 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering program The remaining 4-bits will receive data from PC as entered by the user via keyboard

                                                          Circuit Diagram

                                                          Figure 154 Interface of 74245 to PC via Parallel Port

                                                          Procedure

                                                          1 Connect the DB-25 connector to the PC at one end and solder it to the circuit board at the other end

                                                          2 Connect various pins of the connector and 74245 according to the circuit diagram shown in figure 152

                                                          3 Using the functions listed in the previous section write a program in C language to operate various pins of the buffer The user interface of the program should provide option to the user whether to send or receive data from the port

                                                          4 Set DIR switch to 1 5 Try sending some data bits to the port The result should be displayed at the LEDs 6 Set DIR switch to 0 7 Set some binary 4-bit value through the switches Try reading it via parallel port

                                                          C Language Program

                                                          A program to access parallel port for data transfers

                                                          use header file include ltstdiohgt main program void main() define variable

                                                          62

                                                          Logic Design amp Switching Theory 1 Lab Session 15 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering unsigned int data=0 char choice while(1) printing option menu clrscr() printf(This program will send or receive a BCD digit from the parallel portn) printf(nPress your choice numbern) printf(n1 Send Data) printf(n2 Receive Data) printf(n3 Exitn) choice = getch() sending entered digit to the port if(choice == 1) input BCD digit printf(nEnter BCD digit to be sent to the port) data = getche() masking the first four bits data = data amp 0x0f sending to the port outportb(0x378data) printf(nThe BCD digit c has been sent to the port data) printing on screen the data received from the port else if(choice == 2) receiving data from the port data = inportb(0x378) masking the last four bits data = data amp 0xf0 shifting first four bits to make them the last four bits datagtgt=4 printf(nThe BCD digit set at the port is c data) exit else if(choice == 3) break key pressed is not in the menu else printf(nEnter valid choice number) printf(nnPress any key to continue) getch()

                                                          63

                                                          Logic Design amp Switching Theory 1 Lab Session 15 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                          ACTIVITY 1 In the above circuit DIR and G΄ inputs are hardwired Connect them to status or

                                                          control pins of the parallel port connector and control their function through your software program Circuit Diagram Program Code ______________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________

                                                          ___________________________________________________________________________________________________________________________________________________

                                                          64

                                                          Logic Design amp Switching Theory 1 Lab Session 15 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                          65

                                                          _____________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ _____________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ _______________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ _________________________________________________ _________________________________________________

                                                          Logic Design amp Switching Theory 1 Appendix A NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                          Appendix A

                                                          PIN DIAGRAMS OF THE ICS REQUIRED FOR THE LABORATORY SESSIONS Consult the TTLIC data book for internal diagrams and electrical characteristics of these ICs 7400 Quad 2-Input NAND 7402 Quad 2-Input NOR

                                                          7404 Hex Inverter 7408 Quad 2-Input AND

                                                          7410 Triple 3-Input NAND 7411 Triple 3-Input AND

                                                          7421 Dual 4-Input AND 7432 Quad 2-Input OR

                                                          66

                                                          Logic Design amp Switching Theory 1 Appendix A NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                          BCD-to-Seven Segm 7448 BCD-to-Seven Segment 7447 ent

                                                          Decoder (15V OC) Decoder (2kΩ pull-up output)

                                                          7473 Dual JK Flip-Flop 7474 Dual D-Type Flip-Flop

                                                          7476 Dual JK Flop-Flop -Bit Binary Full Adder 7483 4 with Fast Carry

                                                          86 Quad 2-Inpu 74138 3-to-8 Line 74 t Exclusive OR Decoder Demultiplexer

                                                          67

                                                          Logic Design amp Switching Theory 1 Appendix A NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                          68

                                                          74148 8-to-3 Line 16-to-1 Line Data

                                                          Priority Encoder 74150 Selector Multiplexer

                                                          74245 Oct nsceivers Universal Shift Register (PIPO) (3-State)

                                                          74194 4-Bit Bidirectional al Bus Tra

                                                          Logic Design amp Switching Theory 1 Appendix B NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                          Appendix B

                                                          DEBOUNCING CIRCUITRY FOR MECHANICAL SWITCHES Mechanical switches form the interface between human beings and computers or other digital systems For example a keyboard is a matrix of switches used to supply alphanumeric data to a computer Whatever the switch design it is a potential source of problems due to contact bounce The contact bounce creates a sense of narrow pulses when a switch is opened or closed An example of device whose operation would be adversely affected by contact bounce is a digital counter used to count the number of times a switch is depressed Eliminating the effects of contact bounce is called debouncing When data is entered into a computer via a keyboard a software debounce is often used This type of debouncing is a program that causes the computer to sample the switch terminal (ie to input data from it) many times in succession during the interval of time that contact bounce occurs If the data is sensed to be 1s (or 0s) for a specific number of consecutive samples then it is assumed that contact bounce has ended and the last value sensed is valid Hardware debouncing is the use of electronic circuitry to eliminate the effects of contact bounce There are numerous versions of such circuitry including those that use monostable multivibrators (one-shots) but the most straightforward is simply an RS latch Figure B1 shows the circuit When the switch is in position 1 R = 0 and S = 1 so the latch is set and the output (Q) is 1 When the switch is in position 0 R = 1and S = 0 so the latch is reset and the output is 0 When the switch is moved form one position to the other the latch changes state and bouncing occurs at either the R or the S input The bouncing does not affect the latch after it has change state An RS latch will remain set for example when its R input is 0 and its S input is alternately changed form 1 to 0

                                                          Figure B1 Use of RS latch to debounce a mechanical switch

                                                          69

                                                          • 01-ldst-Outer title
                                                            • Practical Workbook
                                                            • Logic Design amp Switching Theory I
                                                              • Dept of Computer amp Information Systems Engineering
                                                                • NED University of Engineering amp Technology
                                                                • Karachi ndash 75270 Pakistan
                                                                  • 02-ldst-inner Title
                                                                    • Practical Workbook
                                                                    • Logic Design amp Switching Theory I
                                                                      • Dept of Computer amp Information Systems Engineering
                                                                        • NED University of Engineering amp Technology
                                                                        • Karachi ndash 75270 Pakistan
                                                                          • 03-ldst-general info
                                                                          • 04-ldst-introduction
                                                                          • 05-Table of Contents
                                                                            • CONTENTS
                                                                              • Lab Session No Object Page No
                                                                              • 1
                                                                              • Also implementing and testing the given circuit on a bread board
                                                                                • Working with Electronics Workbench
                                                                                  • Driving a seven segment display using 7447 7448 driver IC
                                                                                    • Designing a modulus-5 asynchronous up-counter using JK-FF
                                                                                      • Experimenting with 74194 4-bit bidirectional universal shift register
                                                                                          • 13
                                                                                              • 06-ldst-Exp01
                                                                                                • Lab Session 01
                                                                                                • OBJECT
                                                                                                  • 1 Bread board
                                                                                                  • 2 5 V - power supply
                                                                                                  • 3 Multimeter
                                                                                                  • 4 Logic probe
                                                                                                  • 5 LEDs with resistors
                                                                                                  • 6 Connecting wires
                                                                                                  • 8 Following ICs and their datasheets
                                                                                                    • THEORY
                                                                                                      • Logic Gates
                                                                                                      • 1 The AND Gate ndash An AND gatersquos output is 1 if and only if all its inputs are 1 If A and B are two inputs to an AND gate then output F of the gate is given as F = AB
                                                                                                      • 2 The OR Gate - An OR gatersquos output is 1 if at least one of its input is 1 If A and B are two inputs to an OR gate then output F of the gate is given as F = A+B
                                                                                                      • 3 The NOT Gate (Inverter) ndash Its output is 1 when its input is 0 and its output is 0 when the input is 1 ie it complements a digital variable If A is the input to a NOT gate then output F of the gate is given as
                                                                                                      • 4 The NAND Gate ndash Its output is 1 if at least one of its input is 0 This gate performs the same logic as an AND gate followed by an inverter If A and B are two inputs to a NAND gate then output F of the gate is given as
                                                                                                        • 5 The NOR Gate - The output of a NOR gate is 1 if and only if all its inputs are 0 This gate performs the same logic function as an OR gate followed by an inverter If A and B are two inputs to a NAND gate then output F of the gate is given as
                                                                                                            • DATA SHEETS
                                                                                                              • Logic expression for the given logic diagram __________________________________
                                                                                                                  • 07-ldst-exp02
                                                                                                                    • Working with Electronics Workbench
                                                                                                                      • 08-ldst-exp03
                                                                                                                        • Designing Half and Full Adder Circuits
                                                                                                                          • COMPONENTS AND APPARATUS REQUIRED
                                                                                                                            • 1 Following ICs and their Datasheets
                                                                                                                            • 7408 Quad 2-input AND Gate
                                                                                                                            • 2 Digital Trainer DT-01 or the following components
                                                                                                                              • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                              • Connecting wires Switches
                                                                                                                                • THEORY
                                                                                                                                    • IMPLEMENTATION AND OBSERVATIONS
                                                                                                                                      • 09-ldst-Exp04
                                                                                                                                        • Lab Session 04
                                                                                                                                        • 1 Digital ICs and their Datasheets
                                                                                                                                        • 7408 Quad 2-input AND Gate
                                                                                                                                        • 2 Digital Trainer DT-01 or the following components
                                                                                                                                          • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                          • Connecting wires Switches
                                                                                                                                          • PROCEDURE
                                                                                                                                          • REDUCTION OF LOGIC EXPRESSION USING KARNAUGH MAP
                                                                                                                                          • OBSERVATIONS
                                                                                                                                          • RESULT
                                                                                                                                              • 10-ldst-Exp05
                                                                                                                                                • Lab Session 05
                                                                                                                                                • 1 Following ICs and their Datasheets
                                                                                                                                                • 7408 Quad 2-input AND Gate
                                                                                                                                                • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                  • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                  • (100 Ω) Connecting wires Switches
                                                                                                                                                  • THEORY
                                                                                                                                                    • IMPLEMENTATION AND OBSERVATIONS
                                                                                                                                                      • 11-ldst-Exp06
                                                                                                                                                        • OBJECT
                                                                                                                                                        • 1 Following ICs and their Datasheets
                                                                                                                                                        • 7408 Quad 2-input AND Gates or 7411 Triple 3-input AND Gates
                                                                                                                                                        • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                          • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                          • Connecting wires Switches
                                                                                                                                                            • Figure 62 Circuit Diagram for 4 x 1 Multiplexer
                                                                                                                                                            • Implementation and Observations
                                                                                                                                                              • Circuit Diagram
                                                                                                                                                                • ACTIVITY
                                                                                                                                                                  • 12-ldst-exp07
                                                                                                                                                                    • 1 Following ICs and their Datasheets
                                                                                                                                                                    • 7408 Quad 2-input or 7411 Triple 3-input AND Gates
                                                                                                                                                                    • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                      • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                      • Connecting wires Switches
                                                                                                                                                                        • THEORY
                                                                                                                                                                            • Figure 72 Circuit Diagram for 2 x 4 Decoder 1 x 4 Demultiplexer
                                                                                                                                                                            • Implementation and Observations
                                                                                                                                                                              • Circuit Diagram
                                                                                                                                                                                • ACTIVITY
                                                                                                                                                                                  • 13-ldst-Exp08
                                                                                                                                                                                    • OBJECT
                                                                                                                                                                                    • 1 Following ICs and their Datasheets
                                                                                                                                                                                    • 7408 Quad 2-input or 7421 Dual 4-input AND Gates
                                                                                                                                                                                    • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                      • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                      • Connecting wires Switches
                                                                                                                                                                                        • THEORY
                                                                                                                                                                                            • Figure 81 Circuit Diagram for 4 x 2 Priority Encoder
                                                                                                                                                                                            • Implementation and Observations
                                                                                                                                                                                              • Therefore if GS A2 A1 and A0 are all low then it shows that line 0 is selected and if E0 A2 A1 and A0 are all low then it shows that none of the inputs selected E0 and GS cannot be in the same state provided that E1 is enabled
                                                                                                                                                                                              • Circuit Diagram
                                                                                                                                                                                                • ACTIVITY
                                                                                                                                                                                                  • 14-ldst-exp09
                                                                                                                                                                                                    • OBJECT
                                                                                                                                                                                                    • 1 Following ICs and their Datasheets
                                                                                                                                                                                                    • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                      • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                      • Connecting wires Switches
                                                                                                                                                                                                        • THEORY
                                                                                                                                                                                                          • Parity Generator
                                                                                                                                                                                                            • Let x y and z be the three bits that constitute the message and are the input to the Odd Parity Generator Circuit Since it is an odd parity system the bit P is generated so as to make the total number of 1s odd (including P) The function P can be expressed as follows
                                                                                                                                                                                                            • Figure 91 Circuit Diagram for a 3-bit Parity Generator
                                                                                                                                                                                                              • C = x Ο y Ο z Ο P
                                                                                                                                                                                                                • Implementation and Observations
                                                                                                                                                                                                                  • ACTIVITY
                                                                                                                                                                                                                      • 15-ldst-exp10
                                                                                                                                                                                                                        • Driving a seven segment display using 7447 7448 driver IC
                                                                                                                                                                                                                        • COMPONENTS AND APPARATUS REQUIRED
                                                                                                                                                                                                                        • 1 Following ICs and their Datasheets
                                                                                                                                                                                                                        • 7447 7448 BCD to Seven Segment Driver
                                                                                                                                                                                                                        • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                          • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches
                                                                                                                                                                                                                            • THEORY
                                                                                                                                                                                                                            • Seven Segment Displays
                                                                                                                                                                                                                            • CIRCUIT DIAGRAM
                                                                                                                                                                                                                            • Figure 102 Circuit diagram for 7447driving a common-anode display
                                                                                                                                                                                                                                • IMPLEMENTATION AND OBSERVATIONS
                                                                                                                                                                                                                                  • Decimal Digit
                                                                                                                                                                                                                                  • BCD Inputs
                                                                                                                                                                                                                                  • Seven Segment Outputs
                                                                                                                                                                                                                                  • D
                                                                                                                                                                                                                                  • C
                                                                                                                                                                                                                                  • B
                                                                                                                                                                                                                                  • A
                                                                                                                                                                                                                                  • a
                                                                                                                                                                                                                                  • b
                                                                                                                                                                                                                                  • c
                                                                                                                                                                                                                                  • d
                                                                                                                                                                                                                                  • e
                                                                                                                                                                                                                                  • f
                                                                                                                                                                                                                                  • g
                                                                                                                                                                                                                                  • 0
                                                                                                                                                                                                                                  • 0
                                                                                                                                                                                                                                  • 0
                                                                                                                                                                                                                                  • 0
                                                                                                                                                                                                                                  • 0
                                                                                                                                                                                                                                  • 1
                                                                                                                                                                                                                                  • 0
                                                                                                                                                                                                                                  • 0
                                                                                                                                                                                                                                  • 0
                                                                                                                                                                                                                                  • 1
                                                                                                                                                                                                                                  • 2
                                                                                                                                                                                                                                  • 0
                                                                                                                                                                                                                                  • 0
                                                                                                                                                                                                                                  • 1
                                                                                                                                                                                                                                  • 0
                                                                                                                                                                                                                                  • 3
                                                                                                                                                                                                                                  • 0
                                                                                                                                                                                                                                  • 0
                                                                                                                                                                                                                                  • 1
                                                                                                                                                                                                                                  • 1
                                                                                                                                                                                                                                  • 4
                                                                                                                                                                                                                                  • 0
                                                                                                                                                                                                                                  • 1
                                                                                                                                                                                                                                  • 0
                                                                                                                                                                                                                                  • 0
                                                                                                                                                                                                                                  • 5
                                                                                                                                                                                                                                  • 0
                                                                                                                                                                                                                                  • 1
                                                                                                                                                                                                                                  • 0
                                                                                                                                                                                                                                  • 1
                                                                                                                                                                                                                                  • 6
                                                                                                                                                                                                                                  • 0
                                                                                                                                                                                                                                  • 1
                                                                                                                                                                                                                                  • 1
                                                                                                                                                                                                                                  • 0
                                                                                                                                                                                                                                  • 7
                                                                                                                                                                                                                                  • 0
                                                                                                                                                                                                                                  • 1
                                                                                                                                                                                                                                  • 1
                                                                                                                                                                                                                                  • 1
                                                                                                                                                                                                                                  • 8
                                                                                                                                                                                                                                  • 1
                                                                                                                                                                                                                                  • 0
                                                                                                                                                                                                                                  • 0
                                                                                                                                                                                                                                  • 0
                                                                                                                                                                                                                                  • 9
                                                                                                                                                                                                                                  • 1
                                                                                                                                                                                                                                  • 0
                                                                                                                                                                                                                                  • 0
                                                                                                                                                                                                                                  • 1
                                                                                                                                                                                                                                    • ACTIVITY
                                                                                                                                                                                                                                      • 16-ldst-exp11
                                                                                                                                                                                                                                        • Lab Session 11
                                                                                                                                                                                                                                          • OBJECT
                                                                                                                                                                                                                                          • COMPONENTS AND APPARATUS REQUIRED
                                                                                                                                                                                                                                            • 1 Following ICs and their Datasheets
                                                                                                                                                                                                                                            • 7473 7476 JK Flip-Flop
                                                                                                                                                                                                                                            • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                                              • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                                                              • Connecting wires Switches
                                                                                                                                                                                                                                                • THEORY
                                                                                                                                                                                                                                                    • Flip-Flop
                                                                                                                                                                                                                                                    • JK Flip-Flop
                                                                                                                                                                                                                                                      • Circuit Diagram
                                                                                                                                                                                                                                                        • Observations
                                                                                                                                                                                                                                                          • ACTIVITY
                                                                                                                                                                                                                                                              • 17-ldst-exp12
                                                                                                                                                                                                                                                                • Lab Session 12
                                                                                                                                                                                                                                                                  • OBJECT
                                                                                                                                                                                                                                                                  • GIVEN STATE DIAGRAM
                                                                                                                                                                                                                                                                  • Figure 121 State Diagram
                                                                                                                                                                                                                                                                  • COMPONENTS AND APPARATUS REQUIRED
                                                                                                                                                                                                                                                                    • 1 Following ICs and their Datasheets
                                                                                                                                                                                                                                                                    • 7474 D Flip-Flop
                                                                                                                                                                                                                                                                    • ICs of basic gates (AND OR NOT XOR etc) as required
                                                                                                                                                                                                                                                                    • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                                                                      • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                                                                                      • Connecting wires Switches
                                                                                                                                                                                                                                                                        • THEORY
                                                                                                                                                                                                                                                                            • Sequential Circuits
                                                                                                                                                                                                                                                                              • 18-ldst-exp13
                                                                                                                                                                                                                                                                                • Lab Session 13
                                                                                                                                                                                                                                                                                  • Designing a modulo-5 asynchronous up-counter using JK-FF
                                                                                                                                                                                                                                                                                    • 1 Following ICs and their Datasheets
                                                                                                                                                                                                                                                                                    • 7400 Quad 2-input or 7410 Triple 3-input NAND Gates
                                                                                                                                                                                                                                                                                    • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                                                                                      • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                                                                                                      • Connecting wires Switches
                                                                                                                                                                                                                                                                                        • THEORY
                                                                                                                                                                                                                                                                                            • Figure 131 A Mod-5 Asynchronous Up Counter
                                                                                                                                                                                                                                                                                            • Implementation and Observations
                                                                                                                                                                                                                                                                                              • ACTIVITY
                                                                                                                                                                                                                                                                                                  • 19-ldst-exp14
                                                                                                                                                                                                                                                                                                    • Experimenting with 74194 4-bit bidirectional universal shift register
                                                                                                                                                                                                                                                                                                    • 1 Following ICs and their Datasheets
                                                                                                                                                                                                                                                                                                    • 74194 4-bit bidirectional universal shift register
                                                                                                                                                                                                                                                                                                    • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                                                                                                      • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                                                                                                                      • Connecting wires Switches
                                                                                                                                                                                                                                                                                                        • THEORY
                                                                                                                                                                                                                                                                                                          • Shift Registers
                                                                                                                                                                                                                                                                                                          • Bidirectional Shift Registers
                                                                                                                                                                                                                                                                                                          • Universal Shift Registers
                                                                                                                                                                                                                                                                                                            • S1
                                                                                                                                                                                                                                                                                                              • Circuit Diagram
                                                                                                                                                                                                                                                                                                              • ACTIVITY
                                                                                                                                                                                                                                                                                                                  • 20-ldst-exp15
                                                                                                                                                                                                                                                                                                                    • COMPONENTS AND APPARATUS REQUIRED
                                                                                                                                                                                                                                                                                                                    • 1 Parallel Port Connectors (DB-25) with Cable
                                                                                                                                                                                                                                                                                                                    • 2 Personal Computer with Windows 98 and TurboC Compiler Installed
                                                                                                                                                                                                                                                                                                                    • 3 Following ICs and their Datasheets
                                                                                                                                                                                                                                                                                                                    • 74245 Octal Bus Transceivers with 3-State Outputs
                                                                                                                                                                                                                                                                                                                    • 4 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                                                                                                                      • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                                                                                                                                        • Connecting wires Switches
                                                                                                                                                                                                                                                                                                                          • THEORY
                                                                                                                                                                                                                                                                                                                          • 3-State Logic
                                                                                                                                                                                                                                                                                                                            • Serial and Parallel Port Connectors
                                                                                                                                                                                                                                                                                                                            • Parallel Port Connector ndash DB-25
                                                                                                                                                                                                                                                                                                                              • Accessing parallel port through C Language Programming
                                                                                                                                                                                                                                                                                                                                  • 21-ldst-appendixA
                                                                                                                                                                                                                                                                                                                                  • 22-ldst-appendixB
                                                                                                                                                                                                                                                                                                                                    • DEBOUNCING CIRCUITRY FOR MECHANICAL SWITCHES

                                                            Logic Design amp Switching Theory 1 lab Session 06 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering bull A B C D Data select lines with D being the MSB bull W Active low output line bull Grsquo Active low enable line bull VCC and GND Supply connections lines

                                                            Circuit Diagram

                                                            Figure 63 Pin connections of 74150 for selecting E0

                                                            Testing Procedure

                                                            bull Make connections as shown in the circuit diagram bull Apply different data (1 or 0) at data inputs that are labeled as E0 to E15 Only

                                                            connection for E0 is shown is the figure for simplicity bull Select the data input E0 with the help of data selectors A B C and D bull Observe the output which shows the complement of the data from E0 bull Select all the sixteen data inputs one by one and record your observations in the

                                                            following table

                                                            32

                                                            Logic Design amp Switching Theory 1 lab Session 06 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                            33

                                                            Observations

                                                            Grsquo D C B A W Grsquo D C B A W 0 0 0 0 0 0 1 0 0 0 0 0 0 0 1 0 1 0 0 1 0 0 0 1 0 0 1 0 1 0 0 0 0 1 1 0 1 0 1 1 0 0 1 0 0 0 1 1 0 0 0 0 1 0 1 0 1 1 0 1 0 0 1 1 0 0 1 1 1 0 0 0 1 1 1 0 1 1 1 1

                                                            ACTIVITY 1 Consider 4x1 Multiplexer Draw the output wave-form for the following data inputs

                                                            (E0 E1 E2 E3) and select lines A B (B being the MSB) Output is W

                                                            E3 E2 E1 E0 A B

                                                            W

                                                            2 Using the 4 x 1 MUX designed in this laboratory session implement the following logical function F (A B C) = Σ (0147)

                                                            Show your working and input connections in the following block diagram according to the circuit you have implemented

                                                            4 x 1 MUX

                                                            S0 S1

                                                            Output D0

                                                            D1

                                                            D2

                                                            D3

                                                            Logic Design amp Switching Theory 1 Lab Session 07 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                            Lab Session 07

                                                            OBJECT

                                                            bull Designing of a 2 x 4 Decoder 1 x 4 Demultiplexer bull Experimenting with 74138 IC

                                                            COMPONENTS AND APPARATUS REQUIRED 1 Following ICs and their Datasheets

                                                            bull 7408 Quad 2-input or 7411 Triple 3-input AND Gates bull 7404 Hex Inverter bull 74138 3 x 8 Decoder

                                                            2 Digital Trainer DT-01 or the following components Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches THEORY

                                                            Decoder A Decoder is a combinational circuit that converts binary information form n input lines to a maximum of 2n unique output lines In practical applications decoders are often used for selecting one of several devices

                                                            Demultiplexer A decoder with an enable input can function as a Demultiplexer A Demultiplexer (DMUX) id a circuit that receives information on a single line and transmits this information on one of 2n possible output lines The selection of a specific output line is controlled by the bit values of n selection lines DESIGN OF A 2 x 4 DECODER 1 x 4 DEMULTIPLEXER A 2 x 4 decoder is capable of selecting one of four output lines (see figure 71 (a)) The 2-bit binary number at the data inputs S1 and S0 specifies which of the four data inputs is to be selected If we add an enable pin and use it as an input line then this decoder can be converted to a 1 x 4 Demultiplexer where S1 and S0 will select a line to which data input is to be routed (see figure 71 (b))

                                                            Select S0 S0 Inputs

                                                            S1 D0 D1

                                                            D2

                                                            D3

                                                            Enable (a) Block Diagram of a 2 x 4 Decoder

                                                            Figure 71

                                                            S1 D0 D1

                                                            D2

                                                            D3

                                                            Inputs

                                                            Data Input (b) Block Diagram of a 1 x 4 Demulptiplexer

                                                            34

                                                            Logic Design amp Switching Theory 1 Lab Session 07 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                            Figure 72 Circuit Diagram for 2 x 4 Decoder 1 x 4 Demultiplexer

                                                            Implementation and Observations Implement the 2 x 4 Decoder 1 x 4 Demultiplexer circuit (figure 72) on a bread board (prepare the pin diagram (use appendix A) and refer to laboratory session 01 for implementation procedure) and record the observations in the following table

                                                            Enable Data Input S1 S0 D0 D1 D2 D3

                                                            0 0 0 0 0 1 0 1 0 0 1 1 1 0 0 1 0 1 1 1 0 1 1 1

                                                            TESTING OF 74138 3 x 8 Decoder The 74138 IC has three inputs and eight output lines It has three enable inputs and for the IC to function all three inputs need to be enabled Function of various pins of this IC is described below

                                                            35

                                                            Logic Design amp Switching Theory 1 Lab Session 07 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                            bull Y0 through Y7 Active low data outputs bull A B C Input select lines with C being the MSB bull G1 Active high enable Input bull G2Arsquo and G2Brsquo Active low enable Inputs bull VCC and GND Supply connections lines Circuit Diagram

                                                            Figure 73 Pin connections of 74138

                                                            Testing Procedure

                                                            bull Make connections as shown in the circuit diagram bull Apply different combinations of 1s and 0s at data inputs bull Observe the output and record your observations in the following table

                                                            Observations

                                                            C B A Y0 Y1 Y2 Y3 Y4 Y5 Y6 Y7 0 0 0 0 0 1 0 1 0 0 1 1 1 0 0 1 0 1 1 1 0 1 1 1

                                                            36

                                                            Logic Design amp Switching Theory 1 Lab Session 07 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                            37

                                                            ACTIVITY ACTIVITY 1 What will be the binary values at the outputs Y0 through Y7 of 74138 if 1 What will be the binary values at the outputs Y0 through Y7 of 74138 if

                                                            bull All three enable pins are connected to ground bull All three enable pins are connected to ground __________________________________________________________________________________________________________________________________________ __________________________________________________________________________________________________________________________________________ _____________________________________________________________________ _____________________________________________________________________

                                                            bull All three enable pins are connected to VCC bull All three enable pins are connected to VCC _______________________________________________________________________________________________________________________________________________________________________________________________________________

                                                            _______________________________________________________________________________________________________________________________________________________________________________________________________________

                                                            2 Show connections for 74138 in order to use it as a 1 x 8 Demultiplexer 2 Show connections for 74138 in order to use it as a 1 x 8 Demultiplexer

                                                            3 Consider a 2 x 4 Decoder with two enable inputs (one active high - G and one active low ndash Grsquo) Draw the output wave-forms for D0 D1 D2 and D3 if the two select inputs are A and B (B being the MSB) All outputs are active low

                                                            Grsquo

                                                            G

                                                            A B

                                                            D0 D1 D2

                                                            D3

                                                            Logic Design amp Switching Theory 1 Lab Session 08 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                            Lab Session 08 OBJECT

                                                            bull Designing of a 4 x 2 Priority Encoder bull Experimenting with 74148 IC

                                                            COMPONENTS AND APPARATUS REQUIRED

                                                            1 Following ICs and their Datasheets

                                                            bull 7408 Quad 2-input or 7421 Dual 4-input AND Gates bull 7432 Quad 2-input OR Gates bull 7404 Hex Inverter bull 74148 Encoder

                                                            2 Digital Trainer DT-01 or the following components Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches

                                                            THEORY

                                                            Encoder An Encoder is a digital function that produces a reverse operation from that of a decoder An Encoder has 2n (or less) input lines and n output lines The output lines generate the binary code for the 2n input variables Priority Encoder

                                                            A simple encoder may produce an erroneous output if more than one of its inputs is high A Priority Encoder is one that responds to just one input among those that may be simultaneously high in accordance with some priority system The most common priority system is based on the relative magnitudes of the inputs whichever decimal input is largest is the one that is encoded

                                                            DESIGN OF A 4 x 2 Priority Encoder

                                                            The following equations represent the outputs of a 4 x 2 priority encoder 32 DDA +=

                                                            321 DDDB += As can be seen from the equations that input D0 which has a binary code 00 is not used in any equation A binary code 00 at the output indicates two conditions Either D0 is selected or no input is selected In order to differentiate these two conditions we will provide an additional output Z to indicate if at least one of the inputs is a 1 The equation for Z will be

                                                            4321 DDDDZ = If Z is 0 then the binary code 00 at the output indicates that D0 is selected and if Z is 1 then it indicates that no input line is selected

                                                            38

                                                            Logic Design amp Switching Theory 1 Lab Session 08 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                            Figure 81 Circuit Diagram for 4 x 2 Priority Encoder

                                                            it (figure 81) on a bread board (prepare the to laboratory session 01 for implementation

                                                            Implementation a Implement the 4 x 2 Priority Encoder circu

                                                            ram (use appendix A) and refer

                                                            nd Observations

                                                            pin diagprocedure) and record the observations in the following table

                                                            D3 D2 D1 D0 A B 0 0 0 1 0 0 1 x 0 1 x x 1 x x x

                                                            TESTING OF 74148 8 x 3 Octal Priority Encoder

                                                            imal digits There are nine of which three represents

                                                            ing any of the inputs is high

                                                            then it shows that line 0 is selected and if e inputs selected E0 and GS

                                                            cannot be in the same state provided that E1 is enabled

                                                            The 74148 is a priority encoder with active-Low input for dec

                                                            input) and five output linesinputs lines (including an enablethe binary code for the octal digit Function of various pins of this IC is described below

                                                            bull 0 through 7 Active low data inputs representing the octal digits A2 A1 A0 Active low output lines representing the binary code bullbull E1 Active low enable Input bull E0 Active low output indicating none of the inputs is high bull GS Active low output indicatbull VCC and GND Supply connections lines Therefore if GS A2 A1 and A0 are all low

                                                            then it shows that none of thE0 A2 A1 and A0 are all low

                                                            39

                                                            Logic Design amp Switching Theory 1 Lab Session 08 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                            Circuit Diagram

                                                            Figure 82 Pin connections of 74148

                                                            Testing Procedure bull Make connections as sho

                                                            binations of 1s and 0s at data inputs d record your observations in the following table

                                                            GS E0

                                                            wn in the circuit diagram bull Apply different combull Observe the output an Observations

                                                            0 1 2 3 4 5 6 7 A2 A1 A0 1 1 1 1 1 1 1 1 x x x x x x x 0 x x x x x x 0 1 x x x x x 0 1 1 x x x x 0 1 1 1 x x x 0 1 1 1 1 x x 0 1 1 1 1 1 x 0 1 1 1 1 1 1 0 1 1 1 1 1 1 1

                                                            40

                                                            Logic Design amp Switching Theory 1 Lab Session 08 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                            41

                                                            CTIVITY

                                                            Cascade the following two 74148 8 x 3 Priority Encoders to form 16 x 4 Priority

                                                            A 1

                                                            Encoder

                                                            Logic Design amp Switching Theory 1 Lab Session 09 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering `

                                                            Lab Session 09 OBJECT

                                                            Designing an Odd Parity Generator and Checker for a 3-bit Data COMPONENTS AND APPARATUS REQUIRED

                                                            1 Following ICs and their Datasheets

                                                            bull 7486 Quad 2-input Exclusive-OR Gates bull 7404 Hex Inverter

                                                            2 Digital Trainer DT-01 or the following components Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches

                                                            THEORY

                                                            Parity Generator When binary data is transmitted and processed it is ndash as are all electrical signals ndash susceptible to noise that can either alter or distort its contents 1s may be effectively changed to 0s and 0s to 1s To overcome this problem one or more bits are often added to the data as an aid in detecting errors caused by noise The most common of these is a Parity bit that signifies whether the total number of 1s in a code group is odd or even In an Odd Parity system the parity bit is made 0 or 1 as necessary to make the total number 1s odd (counting the parity bit itself) In an Even Parity system the parity bit is chosen to make the total number of 1s even Table 91 shows how parity bits would be added to BCD code group in both systems

                                                            Decimal BCD Value Parity Bit ABCD Odd Parity Even Parity

                                                            0 0000 1 0 1 0001 0 1 2 0010 0 1 3 0011 1 0 4 0100 0 1 5 0101 1 0 6 0110 1 0 7 0111 0 1 8 1000 0 1 9 1001 1 0

                                                            Table 91 Odd and Even Parity in BCD

                                                            When digital data is received a parity checking circuit generates an error signal if the total number of 1s is odd in an even parity system or if it is even in an odd parity system Parity check always detects a single error (one bit change from 0 to 1 or 1 to 0) but may not detect

                                                            42

                                                            Logic Design amp Switching Theory 1 Lab Session 09 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering ` two or more errors Odd parity is used more often than even parity because even parity does not detect a situation where all 0s are created due to short circuit or other fault condition DESIGN OF A 3-BIT ODD PARITY GENERATOR AND CHECKER Let x y and z be the three bits that constitute the message and are the input to the Odd Parity Generator Circuit Since it is an odd parity system the bit P is generated so as to make the total number of 1s odd (including P) The function P can be expressed as follows P = x oplus y Ο z or P = x Ο y oplus z Since the IC available is 7486 which is quad 2input XOR IC therefore we will convert XNOR also to XOR

                                                            P = x oplus y Ο z

                                                            P = ( x oplus y ) Ο z Since for even number of variables ______

                                                            XOR = XNOR Therefore ___________ _________

                                                            P = ( x oplus y ) oplus z = x oplus y oplus z This logical expression can be implemented with two XOR gates and an inverter (see figure 91)

                                                            Figure 91 Circuit Diagram for a 3-bit Parity Generator

                                                            The 3-bit message and the parity bit are transmitted to their destination where they are applied to a Parity Checker Circuit An error occurs during transmission if the parity of the four bits received is even since the binary information transmitted was originally odd The output C of the parity checker should be a 1 when an error occurs ie when the number of 1s in the four inputs is even Therefore the function C can be expressed as

                                                            C = x Ο y Ο z Ο P

                                                            Using the same logic applied for the conversion of the equation of P

                                                            PzyxC oplusoplusoplus= This logical expression can be implemented with three XOR gates and an inverter (see figure 92)

                                                            43

                                                            Logic Design amp Switching Theory 1 Lab Session 09 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering `

                                                            44

                                                            Figure 92 Circuit Diagram for a 3-bit Parity Checker Implementation and Observations Implement the 3-bit Parity Generator and Checker circuits (figure 91 and 92) on a bread board (prepare the pin diagram (use appendix A) and refer to laboratory session 01 for implementation procedure) and record the observations in the following table

                                                            x y z P x y z P C x y z P C 0 0 0 0 0 0 0 1 0 0 0 0 0 1 0 0 0 1 1 0 0 1 0 1 0 0 0 1 0 1 0 1 0 0 1 1 0 0 1 1 1 0 1 1 1 0 0 0 1 0 0 1 1 0 0 1 0 1 0 1 0 1 1 1 0 1 1 1 0 0 1 1 0 1 1 1 0 1 1 1 0 1 1 1 1 1 1 1

                                                            Odd Parity Generation Odd Parity Check ACTIVITY 1 Try using the parity checker of figure 92 as 3-bit parity generator Write the details here

                                                            _____________________________________________________________________________________________________________________________________________________________________________________________________________________ ______________________________________________________________________________________________________________________________________________ _______________________________________________________________________ ______________________________________________________________________________________________________________________________________________

                                                            Logic Design amp Switching Theory 1 Lab Session 10 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                            Lab Session 10 OBJECT

                                                            Driving a seven segment display using 7447 7448 driver IC COMPONENTS AND APPARATUS REQUIRED

                                                            1 Following ICs and their Datasheets

                                                            bull Seven Segment Displays (Common Anode Common Cathode) bull 7447 7448 BCD to Seven Segment Driver

                                                            2 Digital Trainer DT-01 or the following components Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches

                                                            THEORY Seven Segment Displays A Seven Segment Display consists of seven light-emitting segments The segments are designated by letters a through g (see figure 101) By illuminating various combinations of segments the numerals 0 through 9 can be displayed Seven Segment Displays are commonly constructed with light-emitting diodes (LEDs) and with liquid-crystal displays (LCDs) LEDs generally provide greater illumination levels but require much greater power than LCDs An LED display can be a common-anode type or common cathode type In common anode type a high voltage is applied at the common terminal of the display and low voltage is applied at a segmentrsquos terminal for illumination In the common-cathode type a low voltage is applied at the common terminal of the display and high voltage is applied at a segmentrsquos terminal for illumination

                                                            Figure 101 Seven Segment Display

                                                            a f b g

                                                            e c d

                                                            7447 7448 BCD to Seven Segment Driver 7447 7448 IC is particularly used to drive Seven Segment Its input is a BCD number and output drives a seven segment display 7447 is used to drive common-anode displays whereas 7448 is used to drive common cathode displays 7447 7448 is a 16 pin IC Function of various pins of these ICs is described below

                                                            bull A B C D Inputs representing BCD digits (D being the MSB)

                                                            45

                                                            Logic Design amp Switching Theory 1 Lab Session 10 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering bull OA through OG Outputs to drive segments a through g of the display (Active low

                                                            in 7447 and active high in 7448) bull RBI Ripple Blanking Input Turns off all the segments if kept low provided that LT

                                                            is kept high and all other inputs (A B C D BI) are kept low Should be kept high otherwise

                                                            bull BI RBO Wire-AND logic serving as a Blanking Input and or Ripple Blanking Output

                                                            o BI Turns off all the segments if low o RBO Goes to a low level (response condition) along with other outputs when

                                                            RBI and inputs A B C and D are low with LT input at high level bull LT Lamp Test input Tests whether all segments are working or not Illuminates all

                                                            segments if kept low provided that BI is kept high Should be kept high otherwise bull VCC and GND Supply connections lines CIRCUIT DIAGRAM

                                                            Figure 102 Circuit diagram for 7447driving a common-anode display

                                                            IMPLEMENTATION AND OBSERVATIONS

                                                            bull Make connections as shown in the circuit diagram (refer to laboratory session 01 for implementation procedure)

                                                            bull Apply different combinations of 1s and 0s at data inputs bull Observe the output and record your observations in the following table

                                                            46

                                                            Logic Design amp Switching Theory 1 Lab Session 10 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                            47

                                                            Decimal Digit

                                                            BCD Inputs Seven Segment Outputs D C B A a b c d e f g

                                                            0 0 0 0 0 1 0 0 0 1 2 0 0 1 0 3 0 0 1 1 4 0 1 0 0 5 0 1 0 1 6 0 1 1 0 7 0 1 1 1 8 1 0 0 0 9 1 0 0 1

                                                            ACTIVITY 1 Perform the Lamp Test for the designed circuit and write your observations

                                                            ____________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________

                                                            2 How can you use 7447 IC to drive a common-cathode display

                                                            ____________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________

                                                            3 What symbols appear in the seven segment display if inputs DCBA are

                                                            DCBA Symbol

                                                            1010

                                                            1011

                                                            1100

                                                            1101

                                                            1110

                                                            1111

                                                            Logic Design amp Switching Theory 1 Lab Session 11 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                            48

                                                            Lab Session 11 OBJECT

                                                            Testing different modes of JK-FF COMPONENTS AND APPARATUS REQUIRED 1 Following ICs and their Datasheets

                                                            bull 7473 7476 JK Flip-Flop 2 Digital Trainer DT-01 or the following components

                                                            Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches

                                                            THEORY

                                                            Flip-Flop A flip-flop circuit can maintain a binary state indefinitely (as long as the power is delivered to the circuit) until directed by an input signal to switch states The major differences among various types of flip-flops are in the number of inputs they possess and in the manner in which the inputs affect the binary state

                                                            JK Flip-Flop JK flip flop is an edge triggered device A typical JK flip flop has three inputs J K and a clock input The flip-flop can be either positive or negative edge triggered The output Q is available in complemented form as well Beside the usual inputs and output most of the flip-flop IC also possess two asynchronous inputs namely Preset and Clear These inputs are usually active low If used Preset and Clear inputs keep the flip-flop in set and reset state respectively irrespective of the other inputs Both of these inputs cannot be used simultaneously otherwise they will bring the flip-flop in unstable state

                                                            Figure 111 Symbol for JK flip-flop

                                                            (a) positive-edge triggering (b) active low Preset (PR) and Clear (CLR) with positive-edge triggering

                                                            (c) active low Preset (PR) and Clear (CLR) with negative-edge triggering

                                                            Logic Design amp Switching Theory 1 Lab Session 11 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                            49

                                                            TESTING OF 7473 7476 DUAL JK FLIP-FLOP

                                                            Both the ICs 7473 and 7476 are similar in functionality except for one difference The flip-flops in 7473 have only one type of active low asynchronous input which is the Clear input whereas the flip-flops in 7476 have both Preset and Clear inputs Both these ICs have negative edge triggered flip-flops

                                                            Circuit Diagram

                                                            Figure 112 Pin connections of 7476

                                                            Testing Procedure

                                                            bull Make connections as shown in the circuit diagram (figure 112) bull Apply different combinations of 1s and 0s at J and K inputs bull Observe the output and record your observations in the following table

                                                            Observations

                                                            J

                                                            K Q

                                                            0 0 0 1 1 0 1 1

                                                            ACTIVITY

                                                            1 Observe the output Q of JK flip-flop if the clock input is connected to VCC or GND instead of a clock source Write your observations here __________________________________________________________________________________________________________________________________________ _______________________________________________________________________________________________________________________________________________________________________________________________________________

                                                            Logic Design amp Switching Theory 1 Lab Session 12 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                            50

                                                            Lab Session 12 OBJECT

                                                            Designing sequential circuit for the given state diagram using D flip-flop GIVEN STATE DIAGRAM

                                                            00

                                                            11

                                                            Figure 121 State Diagram COMPONENTS AND APPARATUS REQUIRED 1 Following ICs and their Datasheets

                                                            bull 7474 D Flip-Flop bull ICs of basic gates (AND OR NOT XOR etc) as required

                                                            2 Digital Trainer DT-01 or the following components Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches

                                                            THEORY

                                                            Sequential Circuits In Sequential Circuits the output not only depends on the present inputs but also on previous states of the circuit These circuits use memory elements (latches flip-flops) and the binary information stored in the memory elements at any given time defines the state of the sequential circuit Analysis of a Sequential Circuit The behavior of a sequential circuit is determined from the inputs the outputs and the states of its flip-flops Both the outputs and next state are a function of the inputs and the

                                                            10

                                                            01

                                                            00 11 10

                                                            00

                                                            00 11 10 00

                                                            Logic Design amp Switching Theory 1 Lab Session 12 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                            51

                                                            present state The analysis of a sequential circuit form a state diagram comprises of the following bull Selecting a particular flip-flop to design the circuit bull Obtaining state table from the state diagram bull Finding input equations for the selected flip-flop bull Finding state equations (not required for the construction of circuit) bull Implementing the circuit using selected flip-flops and their input equations ANALYZING THE GIVEN STATE DIAGRAM D Flip-Flop D flip-flop is also called transparent flip-flop as it simply transfers the input data to the output For our design we require the graphical symbol and excitation table of D flip-flop (see figure 122)

                                                            Qt Qt+1 T 0 0 0 0 1 1 1 0 0 1 1 1

                                                            (b) Excitation table of D Flip-Flop

                                                            (a) Graphical Symbol

                                                            Figure 122 Characteristic equation of D flip-flop is Q(t+1) = D State Table The given state diagram has four states so we will need two D flip-flops (FF-0 FF-1) Form state table form the given state diagram and record the results in the following table

                                                            Present State Input Next State Output Input to FF-0 D0

                                                            Input to FF-1 D1 Q1t Q0t x Q1(t+1) Q0(t+1) z

                                                            Logic Design amp Switching Theory 1 Lab Session 12 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                            52

                                                            Input Equations Using Karnaugh map the input equations D0 and D1 for the two flip-flops can be found

                                                            D0 D1 Q0x

                                                            Q1

                                                            _ _ Q0x

                                                            _ Q0x

                                                            Q0x

                                                            _ Q0x

                                                            Q0x

                                                            Q1

                                                            _ _ Q0x

                                                            _ Q0x

                                                            Q0x

                                                            _ Q0x

                                                            _ Q1

                                                            _ Q1

                                                            Q1

                                                            Q1

                                                            D0 = _________________ D1 = _________________

                                                            State Equations Using the characteristic equation of D flip-flop we can find the state equations Q0(t+1) and Q1(t+1) for the to flip flops Q0(t+1) = _______________________ Q1(t+1) = _______________________ _______________________ _______________________ _______________________ _______________________ Circuit Diagram

                                                            Logic Design amp Switching Theory 1 Lab Session 12 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                            53

                                                            Implementation Procedure and Observations

                                                            1 Implement the circuit using digital ICs on a bread board (prepare the pin diagram (use appendix A) and refer to laboratory session 01 for procedure)

                                                            2 Make the clear inputs of the flip-flops low (to clear the flip-flops) The flip-flops will remain in clear state as long as the clear inputs are connected to low level

                                                            3 Connect output Q0 and the clock pulse to an oscilloscope 4 Apply 0 to the input x 5 Now make the clear inputs to high 6 Observe the waveform for the first 5 clock pulses and record it 7 Repeat steps 2 to 6 keeping x=1 in step 4 this time 8 Repeat steps 2 to 7 this time connecting Q1 instead of Q0 to the oscilloscope in step

                                                            3 Record your observations (Keep frequency of the clock pulse low (eg1Hz) so that the output waveforms can be observed easily)

                                                            1 2 3 4 5 Clock Pulse

                                                            Output Waveform for Q0 when x=0

                                                            Output Waveform for Q0 when x=1

                                                            Output Waveform for Q1 when x=0

                                                            Output Waveform for Q1 when x=1

                                                            Logic Design amp Switching Theory 1 Lab Session 13 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                            Lab Session 13 OBJECT

                                                            Designing a modulo-5 asynchronous up-counter using JK-FF COMPONENTS AND APPARATUS REQUIRED

                                                            1 Following ICs and their Datasheets

                                                            bull 7400 Quad 2-input or 7410 Triple 3-input NAND Gates bull 7476 7473 JK Flip-Flop

                                                            2 Digital Trainer DT-01 or the following components Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches

                                                            THEORY

                                                            Digital Counters A digital counter is a set of flip-flops whose states change in response to pulses applied at the input to the counter The flip-flops are interconnected so that their combined state at any time is the binary equivalent of the total number of pulses that have occurred up to that time Every counter resets after a certain number of clock pulses Thus as it name implies a counter is used to count pulses An n stage counter can count up to a maximum of 2n states n is equal to the number of flip-flops required for the construction of counter

                                                            Modulus Counters The number of input pulses that causes a counter to reset to its initial count is called the modulus of the counter Thus the modulus equals to total number of distinct states (counts) including zero that a counter can store A binary counter with n stages is a modulo-2n (or mod-2n) counter The largest count a mod-N counter can achieve is N-1 ie a mod-N counter never reaches the binary number equal to its modulus N is always equal to or less than 2n Counters can be classified as bull Synchronous Counters which are clock driven All the flip-flops are driven by a

                                                            single clock bull Asynchronous Counters which are event driven Clock input is given to the first

                                                            flip-flop only Rest of the flip-flops are driven by their preceding flip-flops

                                                            DESIGN OF A MOD-5 ASYNCHRONOUS UP COUNTER The number of flip-flops required to construct a mod-5 counter is 3 because 5 should be less than or equal to 2n This counter will count from 0 to 4 a total of 5 distinct states Since a 3-stage counter can count up to 8 states at maximum a NAND gate is used to reset it after 5 clock pulses Figure 131 shows the logic diagram

                                                            54

                                                            Logic Design amp Switching Theory 1 Lab Session 13 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                            55

                                                            Figure 131 A Mod-5 Asynchronous Up Counter

                                                            Implementation and Observations

                                                            Implement the mod-5 counter circuit (figure 131) on a bread board (prepare the pin diagram (use appendix A) and refer to laboratory session 01 for implementation procedure) and record the observations in the following table

                                                            Clock Pulse Q2 Q1 Q0

                                                            0 1 2 3 4 5 6 7

                                                            ACTIVITY

                                                            Draw the timing diagram for mod-5 counter designed in this laboratory session

                                                            Logic Design amp Switching Theory 1 Lab Session 14 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                            Lab Session 14 OBJECT

                                                            Experimenting with 74194 4-bit bidirectional universal shift register COMPONENTS AND APPARATUS REQUIRED

                                                            1 Following ICs and their Datasheets

                                                            bull 74194 4-bit bidirectional universal shift register 2 Digital Trainer DT-01 or the following components

                                                            Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches

                                                            THEORY

                                                            Shift Registers

                                                            A Register is a set of flip-flops used to store binary data A register which is capable of shifting its binary information either to the right or left is called a shift register The logical configuration of a register consists of a chain of flip-flops connected in cascade with the output of one flip-flop connected to the input of next flip-flop All flip-flops receive a common clock pulse which causes the shift from one stage to the next

                                                            Bidirectional Shift Registers A bi-directional shift register is one whose bits can be shifted from left to right or from right to left

                                                            Universal Shift Registers A universal shift register is a bi-directional register whose input can be in either serial or parallel form and whose output can be in either serial or parallel form

                                                            74194 4-BIT BIDIRECTIONAL UNIVERSAL SHIFT REGISTER

                                                            The 74194 register provides parallel as well as serial loading in both directions Function of various pins of this IC is described below

                                                            bull A B C and D Active high inputs for parallel loading bull QA QB QC and QD Active high outputs bull S0 and S1 Active high mode control inputs The following table shows combinations

                                                            of S1 and S0 to enable various modes

                                                            S1 S0 Clock Action 0 0 x No change 0 1 uarr Shift right 1 0 uarr Shift left 1 1 uarr Parallel load

                                                            uarr shows the rising edge of the clock pulse

                                                            56

                                                            Logic Design amp Switching Theory 1 Lab Session 14 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering bull SR Active high serial input for right shifting bull SL Active high serial input for left shifting bull CLR Active low input Clears all the flip-flops of the register if set to 0 should be

                                                            kept high otherwise bull CLK Clock input bull VCC and GND Supply connections lines Thus A B C and D are inputs for parallel loading whereas SR and SL are inputs for serial loading with right or left shifting respectively S1 and S0 are used to select the loading mode Circuit Diagram

                                                            Figure 141 Pin connections of 74194 Testing Procedure

                                                            bull Make connections as shown in the circuit diagram bull Observe the output for the input combinations given in the following table

                                                            57

                                                            Logic Design amp Switching Theory 1 Lab Session 14 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                            58

                                                            Observations

                                                            S1 S0 SL SR A B C D QA QB QC QD 0 0 0 1 0 0 0 0 0 1 1 0 0 0 0 1 1 0 0 0 0 0 1 0 1 1 0 0 0 0 1 1 0 0 1 1 0 1 0 0 0 1 1 1 0 1 0 1 1 0 1 0 0 1 1 0 1 1 1 0 0 1 1 1 1 1 0 0 1 1 1 1

                                                            ACTIVITY 1 Show connections of 74194 to convert it into a ring counter with right shifting

                                                            Logic Design amp Switching Theory 1 Lab Session 15 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                            Lab Session 15

                                                            OBJECT

                                                            Experimenting with 74245 octal bus transceivers using parallel port PC interfacing COMPONENTS AND APPARATUS REQUIRED 1 Parallel Port Connectors (DB-25) with Cable 2 Personal Computer with Windows 98 and TurboC Compiler Installed 3 Following ICs and their Datasheets

                                                            bull 74245 Octal Bus Transceivers with 3-State Outputs 4 Digital Trainer DT-01 or the following components

                                                            Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches

                                                            THEORY

                                                            3-State Logic Sometimes it is necessary to isolate one part of circuit from the other part For this purpose some TTL ICs are designed with 3-state logic Such devices have three possible output states high low and high impedance The device can be put into high impedance state by a control signal applied to an appropriate pin When such a device is in high impedance state there is very high impedance at its output effectively isolating the device from whatever circuitry the output normally drives 74245 Octal Bus Transceivers A bus is any conducting path or set of paths having electrical connections to one or more devices 74245 octal bus transceivers are mainly used to control connectivity between two devices or circuits It also provides direction control for signal flow Function of various pin of this IC is given below

                                                            bull A1 through A8 Bus A bull B1 through B8 Bus B bull G΄ Active low enable input When high sets all the bus pins to high impedance state bull DIR Direction control for signal flow When set to high logic level transfers bus A

                                                            data to B bus When set to low logic level transfers bus B data to A bus bull VCC and GND Supply connections lines Serial and Parallel Port Connectors A Parallel Port can consist of only 25 pin port adapter called a DB-25 and a serial port can consist of either a 25 pin port adapter called a DB-25 or 9 pin adapter called a DB-9 port adapter Whether the port is a 9 pin or 25 pin it can accomplish all of the same tasks that serial port communications have been designed for

                                                            59

                                                            Logic Design amp Switching Theory 1 Lab Session 15 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                            60

                                                            Each adapter can be a male type connector with pins or a female type adapter with tiny holes Generally a PRINTER port (called LPT1) on the back of a computer is female type adapter and we need to use MALE DB-25 pin cable on it for PRINTER connection or for parallel LAPLINK cable And a COM port on the back of a computer is male for the serial ports but it may not necessarily be Parallel Port Connector ndash DB-25 The DB-25 connector (named for its B-size D-shaped shell and 25 pins) is practically ubiquitous in the electronics industry The DB-25 connector is used for a variety of purposes Two common applications are RS-232EIA-232 (serial) connections and the parallel printer interface on the IBM PC The DB-25 connector is also used for SCSI connections Normally the parallel port is used for output to a printer or other device It sends data 8-bits or one byte at a time in parallel The other lines available on the DB-25 connector are a combination of status lines control lines and ground lines The status and control lines are used for handshaking commands and feedback when we are talking to a printer

                                                            Figure 152 DB-25 Female Figure 151 DB-25 Male

                                                            Figure 153 Pin Layout for DB-25 As can be seen form figure 153 there are four types of pins in this connector

                                                            bull Data pins (8 pins - D0 to D7) Active high bidirectional lines

                                                            Logic Design amp Switching Theory 1 Lab Session 15 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering bull Control pins (4 pins - C0 to C3) C0 C1 and C3 are active low whereas C2 is active

                                                            high These lines also are bidirectional bull Status pins (5 pins ndash S3 to S7) Only S7 is active low rest are active high input lines bull Ground pins (8 pins) Used as a reference signal for the low (below 05 volts) charge

                                                            Parallel Port Addresses A DB-25 connector at a parallel port has three address one for each kind of pins register data status and control The first or base address generally refers to data register Second address is for status register and the third one is for control register In Windows 98 the base address is usually found to be 278H 378H or 3BCH Now if 378H is the base address then it refers to the data register whereas addresses for status and control register are respectively 379H and 37AH For Windows 98 the base address can be found as follows 1 On your Desktop right-click on My Computer and select Properties 2 Click on the Device Manager tab and find LPT1 under Plug and Play BIOS 3 After selecting LPT1 click the Properties button 4 Next select the Resources tab and the address should then appear next to InputOutput

                                                            Range Accessing parallel port through C Language Programming There are multiple functions in C Language for accessing external ports The most commonly used are listed below

                                                            bull unsigned char inportb(int portid) inportb reads a byte from a hardware port

                                                            bull int inport(int portid) reads a word from a hardware port

                                                            bull void outportb(int portid unsigned char value) outputs a byte to a hardware port

                                                            bull void outport(int portid int value) outputs a word to a hardware port

                                                            portid refers to the port address whereas value refers to the data to be sent TESTING 74245 USING PARALLEL PORT PC INTERFACING At one end the parallel port connector will be connected to the PC via parallel port cable and another connector (to be plugged into the PC parallel port slot) At the other end it will be connected to the buffer IC 74245 Data lines of the connector will be used to transfer 8-bit data between the PC and the buffer Out of the 8-bits of 74245 4-bits will be used to enter data which will be displayed at the monitor through a C language

                                                            61

                                                            Logic Design amp Switching Theory 1 Lab Session 15 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering program The remaining 4-bits will receive data from PC as entered by the user via keyboard

                                                            Circuit Diagram

                                                            Figure 154 Interface of 74245 to PC via Parallel Port

                                                            Procedure

                                                            1 Connect the DB-25 connector to the PC at one end and solder it to the circuit board at the other end

                                                            2 Connect various pins of the connector and 74245 according to the circuit diagram shown in figure 152

                                                            3 Using the functions listed in the previous section write a program in C language to operate various pins of the buffer The user interface of the program should provide option to the user whether to send or receive data from the port

                                                            4 Set DIR switch to 1 5 Try sending some data bits to the port The result should be displayed at the LEDs 6 Set DIR switch to 0 7 Set some binary 4-bit value through the switches Try reading it via parallel port

                                                            C Language Program

                                                            A program to access parallel port for data transfers

                                                            use header file include ltstdiohgt main program void main() define variable

                                                            62

                                                            Logic Design amp Switching Theory 1 Lab Session 15 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering unsigned int data=0 char choice while(1) printing option menu clrscr() printf(This program will send or receive a BCD digit from the parallel portn) printf(nPress your choice numbern) printf(n1 Send Data) printf(n2 Receive Data) printf(n3 Exitn) choice = getch() sending entered digit to the port if(choice == 1) input BCD digit printf(nEnter BCD digit to be sent to the port) data = getche() masking the first four bits data = data amp 0x0f sending to the port outportb(0x378data) printf(nThe BCD digit c has been sent to the port data) printing on screen the data received from the port else if(choice == 2) receiving data from the port data = inportb(0x378) masking the last four bits data = data amp 0xf0 shifting first four bits to make them the last four bits datagtgt=4 printf(nThe BCD digit set at the port is c data) exit else if(choice == 3) break key pressed is not in the menu else printf(nEnter valid choice number) printf(nnPress any key to continue) getch()

                                                            63

                                                            Logic Design amp Switching Theory 1 Lab Session 15 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                            ACTIVITY 1 In the above circuit DIR and G΄ inputs are hardwired Connect them to status or

                                                            control pins of the parallel port connector and control their function through your software program Circuit Diagram Program Code ______________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________

                                                            ___________________________________________________________________________________________________________________________________________________

                                                            64

                                                            Logic Design amp Switching Theory 1 Lab Session 15 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                            65

                                                            _____________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ _____________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ _______________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ _________________________________________________ _________________________________________________

                                                            Logic Design amp Switching Theory 1 Appendix A NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                            Appendix A

                                                            PIN DIAGRAMS OF THE ICS REQUIRED FOR THE LABORATORY SESSIONS Consult the TTLIC data book for internal diagrams and electrical characteristics of these ICs 7400 Quad 2-Input NAND 7402 Quad 2-Input NOR

                                                            7404 Hex Inverter 7408 Quad 2-Input AND

                                                            7410 Triple 3-Input NAND 7411 Triple 3-Input AND

                                                            7421 Dual 4-Input AND 7432 Quad 2-Input OR

                                                            66

                                                            Logic Design amp Switching Theory 1 Appendix A NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                            BCD-to-Seven Segm 7448 BCD-to-Seven Segment 7447 ent

                                                            Decoder (15V OC) Decoder (2kΩ pull-up output)

                                                            7473 Dual JK Flip-Flop 7474 Dual D-Type Flip-Flop

                                                            7476 Dual JK Flop-Flop -Bit Binary Full Adder 7483 4 with Fast Carry

                                                            86 Quad 2-Inpu 74138 3-to-8 Line 74 t Exclusive OR Decoder Demultiplexer

                                                            67

                                                            Logic Design amp Switching Theory 1 Appendix A NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                            68

                                                            74148 8-to-3 Line 16-to-1 Line Data

                                                            Priority Encoder 74150 Selector Multiplexer

                                                            74245 Oct nsceivers Universal Shift Register (PIPO) (3-State)

                                                            74194 4-Bit Bidirectional al Bus Tra

                                                            Logic Design amp Switching Theory 1 Appendix B NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                            Appendix B

                                                            DEBOUNCING CIRCUITRY FOR MECHANICAL SWITCHES Mechanical switches form the interface between human beings and computers or other digital systems For example a keyboard is a matrix of switches used to supply alphanumeric data to a computer Whatever the switch design it is a potential source of problems due to contact bounce The contact bounce creates a sense of narrow pulses when a switch is opened or closed An example of device whose operation would be adversely affected by contact bounce is a digital counter used to count the number of times a switch is depressed Eliminating the effects of contact bounce is called debouncing When data is entered into a computer via a keyboard a software debounce is often used This type of debouncing is a program that causes the computer to sample the switch terminal (ie to input data from it) many times in succession during the interval of time that contact bounce occurs If the data is sensed to be 1s (or 0s) for a specific number of consecutive samples then it is assumed that contact bounce has ended and the last value sensed is valid Hardware debouncing is the use of electronic circuitry to eliminate the effects of contact bounce There are numerous versions of such circuitry including those that use monostable multivibrators (one-shots) but the most straightforward is simply an RS latch Figure B1 shows the circuit When the switch is in position 1 R = 0 and S = 1 so the latch is set and the output (Q) is 1 When the switch is in position 0 R = 1and S = 0 so the latch is reset and the output is 0 When the switch is moved form one position to the other the latch changes state and bouncing occurs at either the R or the S input The bouncing does not affect the latch after it has change state An RS latch will remain set for example when its R input is 0 and its S input is alternately changed form 1 to 0

                                                            Figure B1 Use of RS latch to debounce a mechanical switch

                                                            69

                                                            • 01-ldst-Outer title
                                                              • Practical Workbook
                                                              • Logic Design amp Switching Theory I
                                                                • Dept of Computer amp Information Systems Engineering
                                                                  • NED University of Engineering amp Technology
                                                                  • Karachi ndash 75270 Pakistan
                                                                    • 02-ldst-inner Title
                                                                      • Practical Workbook
                                                                      • Logic Design amp Switching Theory I
                                                                        • Dept of Computer amp Information Systems Engineering
                                                                          • NED University of Engineering amp Technology
                                                                          • Karachi ndash 75270 Pakistan
                                                                            • 03-ldst-general info
                                                                            • 04-ldst-introduction
                                                                            • 05-Table of Contents
                                                                              • CONTENTS
                                                                                • Lab Session No Object Page No
                                                                                • 1
                                                                                • Also implementing and testing the given circuit on a bread board
                                                                                  • Working with Electronics Workbench
                                                                                    • Driving a seven segment display using 7447 7448 driver IC
                                                                                      • Designing a modulus-5 asynchronous up-counter using JK-FF
                                                                                        • Experimenting with 74194 4-bit bidirectional universal shift register
                                                                                            • 13
                                                                                                • 06-ldst-Exp01
                                                                                                  • Lab Session 01
                                                                                                  • OBJECT
                                                                                                    • 1 Bread board
                                                                                                    • 2 5 V - power supply
                                                                                                    • 3 Multimeter
                                                                                                    • 4 Logic probe
                                                                                                    • 5 LEDs with resistors
                                                                                                    • 6 Connecting wires
                                                                                                    • 8 Following ICs and their datasheets
                                                                                                      • THEORY
                                                                                                        • Logic Gates
                                                                                                        • 1 The AND Gate ndash An AND gatersquos output is 1 if and only if all its inputs are 1 If A and B are two inputs to an AND gate then output F of the gate is given as F = AB
                                                                                                        • 2 The OR Gate - An OR gatersquos output is 1 if at least one of its input is 1 If A and B are two inputs to an OR gate then output F of the gate is given as F = A+B
                                                                                                        • 3 The NOT Gate (Inverter) ndash Its output is 1 when its input is 0 and its output is 0 when the input is 1 ie it complements a digital variable If A is the input to a NOT gate then output F of the gate is given as
                                                                                                        • 4 The NAND Gate ndash Its output is 1 if at least one of its input is 0 This gate performs the same logic as an AND gate followed by an inverter If A and B are two inputs to a NAND gate then output F of the gate is given as
                                                                                                          • 5 The NOR Gate - The output of a NOR gate is 1 if and only if all its inputs are 0 This gate performs the same logic function as an OR gate followed by an inverter If A and B are two inputs to a NAND gate then output F of the gate is given as
                                                                                                              • DATA SHEETS
                                                                                                                • Logic expression for the given logic diagram __________________________________
                                                                                                                    • 07-ldst-exp02
                                                                                                                      • Working with Electronics Workbench
                                                                                                                        • 08-ldst-exp03
                                                                                                                          • Designing Half and Full Adder Circuits
                                                                                                                            • COMPONENTS AND APPARATUS REQUIRED
                                                                                                                              • 1 Following ICs and their Datasheets
                                                                                                                              • 7408 Quad 2-input AND Gate
                                                                                                                              • 2 Digital Trainer DT-01 or the following components
                                                                                                                                • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                • Connecting wires Switches
                                                                                                                                  • THEORY
                                                                                                                                      • IMPLEMENTATION AND OBSERVATIONS
                                                                                                                                        • 09-ldst-Exp04
                                                                                                                                          • Lab Session 04
                                                                                                                                          • 1 Digital ICs and their Datasheets
                                                                                                                                          • 7408 Quad 2-input AND Gate
                                                                                                                                          • 2 Digital Trainer DT-01 or the following components
                                                                                                                                            • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                            • Connecting wires Switches
                                                                                                                                            • PROCEDURE
                                                                                                                                            • REDUCTION OF LOGIC EXPRESSION USING KARNAUGH MAP
                                                                                                                                            • OBSERVATIONS
                                                                                                                                            • RESULT
                                                                                                                                                • 10-ldst-Exp05
                                                                                                                                                  • Lab Session 05
                                                                                                                                                  • 1 Following ICs and their Datasheets
                                                                                                                                                  • 7408 Quad 2-input AND Gate
                                                                                                                                                  • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                    • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                    • (100 Ω) Connecting wires Switches
                                                                                                                                                    • THEORY
                                                                                                                                                      • IMPLEMENTATION AND OBSERVATIONS
                                                                                                                                                        • 11-ldst-Exp06
                                                                                                                                                          • OBJECT
                                                                                                                                                          • 1 Following ICs and their Datasheets
                                                                                                                                                          • 7408 Quad 2-input AND Gates or 7411 Triple 3-input AND Gates
                                                                                                                                                          • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                            • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                            • Connecting wires Switches
                                                                                                                                                              • Figure 62 Circuit Diagram for 4 x 1 Multiplexer
                                                                                                                                                              • Implementation and Observations
                                                                                                                                                                • Circuit Diagram
                                                                                                                                                                  • ACTIVITY
                                                                                                                                                                    • 12-ldst-exp07
                                                                                                                                                                      • 1 Following ICs and their Datasheets
                                                                                                                                                                      • 7408 Quad 2-input or 7411 Triple 3-input AND Gates
                                                                                                                                                                      • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                        • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                        • Connecting wires Switches
                                                                                                                                                                          • THEORY
                                                                                                                                                                              • Figure 72 Circuit Diagram for 2 x 4 Decoder 1 x 4 Demultiplexer
                                                                                                                                                                              • Implementation and Observations
                                                                                                                                                                                • Circuit Diagram
                                                                                                                                                                                  • ACTIVITY
                                                                                                                                                                                    • 13-ldst-Exp08
                                                                                                                                                                                      • OBJECT
                                                                                                                                                                                      • 1 Following ICs and their Datasheets
                                                                                                                                                                                      • 7408 Quad 2-input or 7421 Dual 4-input AND Gates
                                                                                                                                                                                      • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                        • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                        • Connecting wires Switches
                                                                                                                                                                                          • THEORY
                                                                                                                                                                                              • Figure 81 Circuit Diagram for 4 x 2 Priority Encoder
                                                                                                                                                                                              • Implementation and Observations
                                                                                                                                                                                                • Therefore if GS A2 A1 and A0 are all low then it shows that line 0 is selected and if E0 A2 A1 and A0 are all low then it shows that none of the inputs selected E0 and GS cannot be in the same state provided that E1 is enabled
                                                                                                                                                                                                • Circuit Diagram
                                                                                                                                                                                                  • ACTIVITY
                                                                                                                                                                                                    • 14-ldst-exp09
                                                                                                                                                                                                      • OBJECT
                                                                                                                                                                                                      • 1 Following ICs and their Datasheets
                                                                                                                                                                                                      • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                        • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                        • Connecting wires Switches
                                                                                                                                                                                                          • THEORY
                                                                                                                                                                                                            • Parity Generator
                                                                                                                                                                                                              • Let x y and z be the three bits that constitute the message and are the input to the Odd Parity Generator Circuit Since it is an odd parity system the bit P is generated so as to make the total number of 1s odd (including P) The function P can be expressed as follows
                                                                                                                                                                                                              • Figure 91 Circuit Diagram for a 3-bit Parity Generator
                                                                                                                                                                                                                • C = x Ο y Ο z Ο P
                                                                                                                                                                                                                  • Implementation and Observations
                                                                                                                                                                                                                    • ACTIVITY
                                                                                                                                                                                                                        • 15-ldst-exp10
                                                                                                                                                                                                                          • Driving a seven segment display using 7447 7448 driver IC
                                                                                                                                                                                                                          • COMPONENTS AND APPARATUS REQUIRED
                                                                                                                                                                                                                          • 1 Following ICs and their Datasheets
                                                                                                                                                                                                                          • 7447 7448 BCD to Seven Segment Driver
                                                                                                                                                                                                                          • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                            • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches
                                                                                                                                                                                                                              • THEORY
                                                                                                                                                                                                                              • Seven Segment Displays
                                                                                                                                                                                                                              • CIRCUIT DIAGRAM
                                                                                                                                                                                                                              • Figure 102 Circuit diagram for 7447driving a common-anode display
                                                                                                                                                                                                                                  • IMPLEMENTATION AND OBSERVATIONS
                                                                                                                                                                                                                                    • Decimal Digit
                                                                                                                                                                                                                                    • BCD Inputs
                                                                                                                                                                                                                                    • Seven Segment Outputs
                                                                                                                                                                                                                                    • D
                                                                                                                                                                                                                                    • C
                                                                                                                                                                                                                                    • B
                                                                                                                                                                                                                                    • A
                                                                                                                                                                                                                                    • a
                                                                                                                                                                                                                                    • b
                                                                                                                                                                                                                                    • c
                                                                                                                                                                                                                                    • d
                                                                                                                                                                                                                                    • e
                                                                                                                                                                                                                                    • f
                                                                                                                                                                                                                                    • g
                                                                                                                                                                                                                                    • 0
                                                                                                                                                                                                                                    • 0
                                                                                                                                                                                                                                    • 0
                                                                                                                                                                                                                                    • 0
                                                                                                                                                                                                                                    • 0
                                                                                                                                                                                                                                    • 1
                                                                                                                                                                                                                                    • 0
                                                                                                                                                                                                                                    • 0
                                                                                                                                                                                                                                    • 0
                                                                                                                                                                                                                                    • 1
                                                                                                                                                                                                                                    • 2
                                                                                                                                                                                                                                    • 0
                                                                                                                                                                                                                                    • 0
                                                                                                                                                                                                                                    • 1
                                                                                                                                                                                                                                    • 0
                                                                                                                                                                                                                                    • 3
                                                                                                                                                                                                                                    • 0
                                                                                                                                                                                                                                    • 0
                                                                                                                                                                                                                                    • 1
                                                                                                                                                                                                                                    • 1
                                                                                                                                                                                                                                    • 4
                                                                                                                                                                                                                                    • 0
                                                                                                                                                                                                                                    • 1
                                                                                                                                                                                                                                    • 0
                                                                                                                                                                                                                                    • 0
                                                                                                                                                                                                                                    • 5
                                                                                                                                                                                                                                    • 0
                                                                                                                                                                                                                                    • 1
                                                                                                                                                                                                                                    • 0
                                                                                                                                                                                                                                    • 1
                                                                                                                                                                                                                                    • 6
                                                                                                                                                                                                                                    • 0
                                                                                                                                                                                                                                    • 1
                                                                                                                                                                                                                                    • 1
                                                                                                                                                                                                                                    • 0
                                                                                                                                                                                                                                    • 7
                                                                                                                                                                                                                                    • 0
                                                                                                                                                                                                                                    • 1
                                                                                                                                                                                                                                    • 1
                                                                                                                                                                                                                                    • 1
                                                                                                                                                                                                                                    • 8
                                                                                                                                                                                                                                    • 1
                                                                                                                                                                                                                                    • 0
                                                                                                                                                                                                                                    • 0
                                                                                                                                                                                                                                    • 0
                                                                                                                                                                                                                                    • 9
                                                                                                                                                                                                                                    • 1
                                                                                                                                                                                                                                    • 0
                                                                                                                                                                                                                                    • 0
                                                                                                                                                                                                                                    • 1
                                                                                                                                                                                                                                      • ACTIVITY
                                                                                                                                                                                                                                        • 16-ldst-exp11
                                                                                                                                                                                                                                          • Lab Session 11
                                                                                                                                                                                                                                            • OBJECT
                                                                                                                                                                                                                                            • COMPONENTS AND APPARATUS REQUIRED
                                                                                                                                                                                                                                              • 1 Following ICs and their Datasheets
                                                                                                                                                                                                                                              • 7473 7476 JK Flip-Flop
                                                                                                                                                                                                                                              • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                                                • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                                                                • Connecting wires Switches
                                                                                                                                                                                                                                                  • THEORY
                                                                                                                                                                                                                                                      • Flip-Flop
                                                                                                                                                                                                                                                      • JK Flip-Flop
                                                                                                                                                                                                                                                        • Circuit Diagram
                                                                                                                                                                                                                                                          • Observations
                                                                                                                                                                                                                                                            • ACTIVITY
                                                                                                                                                                                                                                                                • 17-ldst-exp12
                                                                                                                                                                                                                                                                  • Lab Session 12
                                                                                                                                                                                                                                                                    • OBJECT
                                                                                                                                                                                                                                                                    • GIVEN STATE DIAGRAM
                                                                                                                                                                                                                                                                    • Figure 121 State Diagram
                                                                                                                                                                                                                                                                    • COMPONENTS AND APPARATUS REQUIRED
                                                                                                                                                                                                                                                                      • 1 Following ICs and their Datasheets
                                                                                                                                                                                                                                                                      • 7474 D Flip-Flop
                                                                                                                                                                                                                                                                      • ICs of basic gates (AND OR NOT XOR etc) as required
                                                                                                                                                                                                                                                                      • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                                                                        • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                                                                                        • Connecting wires Switches
                                                                                                                                                                                                                                                                          • THEORY
                                                                                                                                                                                                                                                                              • Sequential Circuits
                                                                                                                                                                                                                                                                                • 18-ldst-exp13
                                                                                                                                                                                                                                                                                  • Lab Session 13
                                                                                                                                                                                                                                                                                    • Designing a modulo-5 asynchronous up-counter using JK-FF
                                                                                                                                                                                                                                                                                      • 1 Following ICs and their Datasheets
                                                                                                                                                                                                                                                                                      • 7400 Quad 2-input or 7410 Triple 3-input NAND Gates
                                                                                                                                                                                                                                                                                      • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                                                                                        • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                                                                                                        • Connecting wires Switches
                                                                                                                                                                                                                                                                                          • THEORY
                                                                                                                                                                                                                                                                                              • Figure 131 A Mod-5 Asynchronous Up Counter
                                                                                                                                                                                                                                                                                              • Implementation and Observations
                                                                                                                                                                                                                                                                                                • ACTIVITY
                                                                                                                                                                                                                                                                                                    • 19-ldst-exp14
                                                                                                                                                                                                                                                                                                      • Experimenting with 74194 4-bit bidirectional universal shift register
                                                                                                                                                                                                                                                                                                      • 1 Following ICs and their Datasheets
                                                                                                                                                                                                                                                                                                      • 74194 4-bit bidirectional universal shift register
                                                                                                                                                                                                                                                                                                      • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                                                                                                        • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                                                                                                                        • Connecting wires Switches
                                                                                                                                                                                                                                                                                                          • THEORY
                                                                                                                                                                                                                                                                                                            • Shift Registers
                                                                                                                                                                                                                                                                                                            • Bidirectional Shift Registers
                                                                                                                                                                                                                                                                                                            • Universal Shift Registers
                                                                                                                                                                                                                                                                                                              • S1
                                                                                                                                                                                                                                                                                                                • Circuit Diagram
                                                                                                                                                                                                                                                                                                                • ACTIVITY
                                                                                                                                                                                                                                                                                                                    • 20-ldst-exp15
                                                                                                                                                                                                                                                                                                                      • COMPONENTS AND APPARATUS REQUIRED
                                                                                                                                                                                                                                                                                                                      • 1 Parallel Port Connectors (DB-25) with Cable
                                                                                                                                                                                                                                                                                                                      • 2 Personal Computer with Windows 98 and TurboC Compiler Installed
                                                                                                                                                                                                                                                                                                                      • 3 Following ICs and their Datasheets
                                                                                                                                                                                                                                                                                                                      • 74245 Octal Bus Transceivers with 3-State Outputs
                                                                                                                                                                                                                                                                                                                      • 4 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                                                                                                                        • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                                                                                                                                          • Connecting wires Switches
                                                                                                                                                                                                                                                                                                                            • THEORY
                                                                                                                                                                                                                                                                                                                            • 3-State Logic
                                                                                                                                                                                                                                                                                                                              • Serial and Parallel Port Connectors
                                                                                                                                                                                                                                                                                                                              • Parallel Port Connector ndash DB-25
                                                                                                                                                                                                                                                                                                                                • Accessing parallel port through C Language Programming
                                                                                                                                                                                                                                                                                                                                    • 21-ldst-appendixA
                                                                                                                                                                                                                                                                                                                                    • 22-ldst-appendixB
                                                                                                                                                                                                                                                                                                                                      • DEBOUNCING CIRCUITRY FOR MECHANICAL SWITCHES

                                                              Logic Design amp Switching Theory 1 lab Session 06 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                              33

                                                              Observations

                                                              Grsquo D C B A W Grsquo D C B A W 0 0 0 0 0 0 1 0 0 0 0 0 0 0 1 0 1 0 0 1 0 0 0 1 0 0 1 0 1 0 0 0 0 1 1 0 1 0 1 1 0 0 1 0 0 0 1 1 0 0 0 0 1 0 1 0 1 1 0 1 0 0 1 1 0 0 1 1 1 0 0 0 1 1 1 0 1 1 1 1

                                                              ACTIVITY 1 Consider 4x1 Multiplexer Draw the output wave-form for the following data inputs

                                                              (E0 E1 E2 E3) and select lines A B (B being the MSB) Output is W

                                                              E3 E2 E1 E0 A B

                                                              W

                                                              2 Using the 4 x 1 MUX designed in this laboratory session implement the following logical function F (A B C) = Σ (0147)

                                                              Show your working and input connections in the following block diagram according to the circuit you have implemented

                                                              4 x 1 MUX

                                                              S0 S1

                                                              Output D0

                                                              D1

                                                              D2

                                                              D3

                                                              Logic Design amp Switching Theory 1 Lab Session 07 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                              Lab Session 07

                                                              OBJECT

                                                              bull Designing of a 2 x 4 Decoder 1 x 4 Demultiplexer bull Experimenting with 74138 IC

                                                              COMPONENTS AND APPARATUS REQUIRED 1 Following ICs and their Datasheets

                                                              bull 7408 Quad 2-input or 7411 Triple 3-input AND Gates bull 7404 Hex Inverter bull 74138 3 x 8 Decoder

                                                              2 Digital Trainer DT-01 or the following components Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches THEORY

                                                              Decoder A Decoder is a combinational circuit that converts binary information form n input lines to a maximum of 2n unique output lines In practical applications decoders are often used for selecting one of several devices

                                                              Demultiplexer A decoder with an enable input can function as a Demultiplexer A Demultiplexer (DMUX) id a circuit that receives information on a single line and transmits this information on one of 2n possible output lines The selection of a specific output line is controlled by the bit values of n selection lines DESIGN OF A 2 x 4 DECODER 1 x 4 DEMULTIPLEXER A 2 x 4 decoder is capable of selecting one of four output lines (see figure 71 (a)) The 2-bit binary number at the data inputs S1 and S0 specifies which of the four data inputs is to be selected If we add an enable pin and use it as an input line then this decoder can be converted to a 1 x 4 Demultiplexer where S1 and S0 will select a line to which data input is to be routed (see figure 71 (b))

                                                              Select S0 S0 Inputs

                                                              S1 D0 D1

                                                              D2

                                                              D3

                                                              Enable (a) Block Diagram of a 2 x 4 Decoder

                                                              Figure 71

                                                              S1 D0 D1

                                                              D2

                                                              D3

                                                              Inputs

                                                              Data Input (b) Block Diagram of a 1 x 4 Demulptiplexer

                                                              34

                                                              Logic Design amp Switching Theory 1 Lab Session 07 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                              Figure 72 Circuit Diagram for 2 x 4 Decoder 1 x 4 Demultiplexer

                                                              Implementation and Observations Implement the 2 x 4 Decoder 1 x 4 Demultiplexer circuit (figure 72) on a bread board (prepare the pin diagram (use appendix A) and refer to laboratory session 01 for implementation procedure) and record the observations in the following table

                                                              Enable Data Input S1 S0 D0 D1 D2 D3

                                                              0 0 0 0 0 1 0 1 0 0 1 1 1 0 0 1 0 1 1 1 0 1 1 1

                                                              TESTING OF 74138 3 x 8 Decoder The 74138 IC has three inputs and eight output lines It has three enable inputs and for the IC to function all three inputs need to be enabled Function of various pins of this IC is described below

                                                              35

                                                              Logic Design amp Switching Theory 1 Lab Session 07 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                              bull Y0 through Y7 Active low data outputs bull A B C Input select lines with C being the MSB bull G1 Active high enable Input bull G2Arsquo and G2Brsquo Active low enable Inputs bull VCC and GND Supply connections lines Circuit Diagram

                                                              Figure 73 Pin connections of 74138

                                                              Testing Procedure

                                                              bull Make connections as shown in the circuit diagram bull Apply different combinations of 1s and 0s at data inputs bull Observe the output and record your observations in the following table

                                                              Observations

                                                              C B A Y0 Y1 Y2 Y3 Y4 Y5 Y6 Y7 0 0 0 0 0 1 0 1 0 0 1 1 1 0 0 1 0 1 1 1 0 1 1 1

                                                              36

                                                              Logic Design amp Switching Theory 1 Lab Session 07 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                              37

                                                              ACTIVITY ACTIVITY 1 What will be the binary values at the outputs Y0 through Y7 of 74138 if 1 What will be the binary values at the outputs Y0 through Y7 of 74138 if

                                                              bull All three enable pins are connected to ground bull All three enable pins are connected to ground __________________________________________________________________________________________________________________________________________ __________________________________________________________________________________________________________________________________________ _____________________________________________________________________ _____________________________________________________________________

                                                              bull All three enable pins are connected to VCC bull All three enable pins are connected to VCC _______________________________________________________________________________________________________________________________________________________________________________________________________________

                                                              _______________________________________________________________________________________________________________________________________________________________________________________________________________

                                                              2 Show connections for 74138 in order to use it as a 1 x 8 Demultiplexer 2 Show connections for 74138 in order to use it as a 1 x 8 Demultiplexer

                                                              3 Consider a 2 x 4 Decoder with two enable inputs (one active high - G and one active low ndash Grsquo) Draw the output wave-forms for D0 D1 D2 and D3 if the two select inputs are A and B (B being the MSB) All outputs are active low

                                                              Grsquo

                                                              G

                                                              A B

                                                              D0 D1 D2

                                                              D3

                                                              Logic Design amp Switching Theory 1 Lab Session 08 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                              Lab Session 08 OBJECT

                                                              bull Designing of a 4 x 2 Priority Encoder bull Experimenting with 74148 IC

                                                              COMPONENTS AND APPARATUS REQUIRED

                                                              1 Following ICs and their Datasheets

                                                              bull 7408 Quad 2-input or 7421 Dual 4-input AND Gates bull 7432 Quad 2-input OR Gates bull 7404 Hex Inverter bull 74148 Encoder

                                                              2 Digital Trainer DT-01 or the following components Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches

                                                              THEORY

                                                              Encoder An Encoder is a digital function that produces a reverse operation from that of a decoder An Encoder has 2n (or less) input lines and n output lines The output lines generate the binary code for the 2n input variables Priority Encoder

                                                              A simple encoder may produce an erroneous output if more than one of its inputs is high A Priority Encoder is one that responds to just one input among those that may be simultaneously high in accordance with some priority system The most common priority system is based on the relative magnitudes of the inputs whichever decimal input is largest is the one that is encoded

                                                              DESIGN OF A 4 x 2 Priority Encoder

                                                              The following equations represent the outputs of a 4 x 2 priority encoder 32 DDA +=

                                                              321 DDDB += As can be seen from the equations that input D0 which has a binary code 00 is not used in any equation A binary code 00 at the output indicates two conditions Either D0 is selected or no input is selected In order to differentiate these two conditions we will provide an additional output Z to indicate if at least one of the inputs is a 1 The equation for Z will be

                                                              4321 DDDDZ = If Z is 0 then the binary code 00 at the output indicates that D0 is selected and if Z is 1 then it indicates that no input line is selected

                                                              38

                                                              Logic Design amp Switching Theory 1 Lab Session 08 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                              Figure 81 Circuit Diagram for 4 x 2 Priority Encoder

                                                              it (figure 81) on a bread board (prepare the to laboratory session 01 for implementation

                                                              Implementation a Implement the 4 x 2 Priority Encoder circu

                                                              ram (use appendix A) and refer

                                                              nd Observations

                                                              pin diagprocedure) and record the observations in the following table

                                                              D3 D2 D1 D0 A B 0 0 0 1 0 0 1 x 0 1 x x 1 x x x

                                                              TESTING OF 74148 8 x 3 Octal Priority Encoder

                                                              imal digits There are nine of which three represents

                                                              ing any of the inputs is high

                                                              then it shows that line 0 is selected and if e inputs selected E0 and GS

                                                              cannot be in the same state provided that E1 is enabled

                                                              The 74148 is a priority encoder with active-Low input for dec

                                                              input) and five output linesinputs lines (including an enablethe binary code for the octal digit Function of various pins of this IC is described below

                                                              bull 0 through 7 Active low data inputs representing the octal digits A2 A1 A0 Active low output lines representing the binary code bullbull E1 Active low enable Input bull E0 Active low output indicating none of the inputs is high bull GS Active low output indicatbull VCC and GND Supply connections lines Therefore if GS A2 A1 and A0 are all low

                                                              then it shows that none of thE0 A2 A1 and A0 are all low

                                                              39

                                                              Logic Design amp Switching Theory 1 Lab Session 08 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                              Circuit Diagram

                                                              Figure 82 Pin connections of 74148

                                                              Testing Procedure bull Make connections as sho

                                                              binations of 1s and 0s at data inputs d record your observations in the following table

                                                              GS E0

                                                              wn in the circuit diagram bull Apply different combull Observe the output an Observations

                                                              0 1 2 3 4 5 6 7 A2 A1 A0 1 1 1 1 1 1 1 1 x x x x x x x 0 x x x x x x 0 1 x x x x x 0 1 1 x x x x 0 1 1 1 x x x 0 1 1 1 1 x x 0 1 1 1 1 1 x 0 1 1 1 1 1 1 0 1 1 1 1 1 1 1

                                                              40

                                                              Logic Design amp Switching Theory 1 Lab Session 08 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                              41

                                                              CTIVITY

                                                              Cascade the following two 74148 8 x 3 Priority Encoders to form 16 x 4 Priority

                                                              A 1

                                                              Encoder

                                                              Logic Design amp Switching Theory 1 Lab Session 09 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering `

                                                              Lab Session 09 OBJECT

                                                              Designing an Odd Parity Generator and Checker for a 3-bit Data COMPONENTS AND APPARATUS REQUIRED

                                                              1 Following ICs and their Datasheets

                                                              bull 7486 Quad 2-input Exclusive-OR Gates bull 7404 Hex Inverter

                                                              2 Digital Trainer DT-01 or the following components Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches

                                                              THEORY

                                                              Parity Generator When binary data is transmitted and processed it is ndash as are all electrical signals ndash susceptible to noise that can either alter or distort its contents 1s may be effectively changed to 0s and 0s to 1s To overcome this problem one or more bits are often added to the data as an aid in detecting errors caused by noise The most common of these is a Parity bit that signifies whether the total number of 1s in a code group is odd or even In an Odd Parity system the parity bit is made 0 or 1 as necessary to make the total number 1s odd (counting the parity bit itself) In an Even Parity system the parity bit is chosen to make the total number of 1s even Table 91 shows how parity bits would be added to BCD code group in both systems

                                                              Decimal BCD Value Parity Bit ABCD Odd Parity Even Parity

                                                              0 0000 1 0 1 0001 0 1 2 0010 0 1 3 0011 1 0 4 0100 0 1 5 0101 1 0 6 0110 1 0 7 0111 0 1 8 1000 0 1 9 1001 1 0

                                                              Table 91 Odd and Even Parity in BCD

                                                              When digital data is received a parity checking circuit generates an error signal if the total number of 1s is odd in an even parity system or if it is even in an odd parity system Parity check always detects a single error (one bit change from 0 to 1 or 1 to 0) but may not detect

                                                              42

                                                              Logic Design amp Switching Theory 1 Lab Session 09 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering ` two or more errors Odd parity is used more often than even parity because even parity does not detect a situation where all 0s are created due to short circuit or other fault condition DESIGN OF A 3-BIT ODD PARITY GENERATOR AND CHECKER Let x y and z be the three bits that constitute the message and are the input to the Odd Parity Generator Circuit Since it is an odd parity system the bit P is generated so as to make the total number of 1s odd (including P) The function P can be expressed as follows P = x oplus y Ο z or P = x Ο y oplus z Since the IC available is 7486 which is quad 2input XOR IC therefore we will convert XNOR also to XOR

                                                              P = x oplus y Ο z

                                                              P = ( x oplus y ) Ο z Since for even number of variables ______

                                                              XOR = XNOR Therefore ___________ _________

                                                              P = ( x oplus y ) oplus z = x oplus y oplus z This logical expression can be implemented with two XOR gates and an inverter (see figure 91)

                                                              Figure 91 Circuit Diagram for a 3-bit Parity Generator

                                                              The 3-bit message and the parity bit are transmitted to their destination where they are applied to a Parity Checker Circuit An error occurs during transmission if the parity of the four bits received is even since the binary information transmitted was originally odd The output C of the parity checker should be a 1 when an error occurs ie when the number of 1s in the four inputs is even Therefore the function C can be expressed as

                                                              C = x Ο y Ο z Ο P

                                                              Using the same logic applied for the conversion of the equation of P

                                                              PzyxC oplusoplusoplus= This logical expression can be implemented with three XOR gates and an inverter (see figure 92)

                                                              43

                                                              Logic Design amp Switching Theory 1 Lab Session 09 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering `

                                                              44

                                                              Figure 92 Circuit Diagram for a 3-bit Parity Checker Implementation and Observations Implement the 3-bit Parity Generator and Checker circuits (figure 91 and 92) on a bread board (prepare the pin diagram (use appendix A) and refer to laboratory session 01 for implementation procedure) and record the observations in the following table

                                                              x y z P x y z P C x y z P C 0 0 0 0 0 0 0 1 0 0 0 0 0 1 0 0 0 1 1 0 0 1 0 1 0 0 0 1 0 1 0 1 0 0 1 1 0 0 1 1 1 0 1 1 1 0 0 0 1 0 0 1 1 0 0 1 0 1 0 1 0 1 1 1 0 1 1 1 0 0 1 1 0 1 1 1 0 1 1 1 0 1 1 1 1 1 1 1

                                                              Odd Parity Generation Odd Parity Check ACTIVITY 1 Try using the parity checker of figure 92 as 3-bit parity generator Write the details here

                                                              _____________________________________________________________________________________________________________________________________________________________________________________________________________________ ______________________________________________________________________________________________________________________________________________ _______________________________________________________________________ ______________________________________________________________________________________________________________________________________________

                                                              Logic Design amp Switching Theory 1 Lab Session 10 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                              Lab Session 10 OBJECT

                                                              Driving a seven segment display using 7447 7448 driver IC COMPONENTS AND APPARATUS REQUIRED

                                                              1 Following ICs and their Datasheets

                                                              bull Seven Segment Displays (Common Anode Common Cathode) bull 7447 7448 BCD to Seven Segment Driver

                                                              2 Digital Trainer DT-01 or the following components Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches

                                                              THEORY Seven Segment Displays A Seven Segment Display consists of seven light-emitting segments The segments are designated by letters a through g (see figure 101) By illuminating various combinations of segments the numerals 0 through 9 can be displayed Seven Segment Displays are commonly constructed with light-emitting diodes (LEDs) and with liquid-crystal displays (LCDs) LEDs generally provide greater illumination levels but require much greater power than LCDs An LED display can be a common-anode type or common cathode type In common anode type a high voltage is applied at the common terminal of the display and low voltage is applied at a segmentrsquos terminal for illumination In the common-cathode type a low voltage is applied at the common terminal of the display and high voltage is applied at a segmentrsquos terminal for illumination

                                                              Figure 101 Seven Segment Display

                                                              a f b g

                                                              e c d

                                                              7447 7448 BCD to Seven Segment Driver 7447 7448 IC is particularly used to drive Seven Segment Its input is a BCD number and output drives a seven segment display 7447 is used to drive common-anode displays whereas 7448 is used to drive common cathode displays 7447 7448 is a 16 pin IC Function of various pins of these ICs is described below

                                                              bull A B C D Inputs representing BCD digits (D being the MSB)

                                                              45

                                                              Logic Design amp Switching Theory 1 Lab Session 10 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering bull OA through OG Outputs to drive segments a through g of the display (Active low

                                                              in 7447 and active high in 7448) bull RBI Ripple Blanking Input Turns off all the segments if kept low provided that LT

                                                              is kept high and all other inputs (A B C D BI) are kept low Should be kept high otherwise

                                                              bull BI RBO Wire-AND logic serving as a Blanking Input and or Ripple Blanking Output

                                                              o BI Turns off all the segments if low o RBO Goes to a low level (response condition) along with other outputs when

                                                              RBI and inputs A B C and D are low with LT input at high level bull LT Lamp Test input Tests whether all segments are working or not Illuminates all

                                                              segments if kept low provided that BI is kept high Should be kept high otherwise bull VCC and GND Supply connections lines CIRCUIT DIAGRAM

                                                              Figure 102 Circuit diagram for 7447driving a common-anode display

                                                              IMPLEMENTATION AND OBSERVATIONS

                                                              bull Make connections as shown in the circuit diagram (refer to laboratory session 01 for implementation procedure)

                                                              bull Apply different combinations of 1s and 0s at data inputs bull Observe the output and record your observations in the following table

                                                              46

                                                              Logic Design amp Switching Theory 1 Lab Session 10 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                              47

                                                              Decimal Digit

                                                              BCD Inputs Seven Segment Outputs D C B A a b c d e f g

                                                              0 0 0 0 0 1 0 0 0 1 2 0 0 1 0 3 0 0 1 1 4 0 1 0 0 5 0 1 0 1 6 0 1 1 0 7 0 1 1 1 8 1 0 0 0 9 1 0 0 1

                                                              ACTIVITY 1 Perform the Lamp Test for the designed circuit and write your observations

                                                              ____________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________

                                                              2 How can you use 7447 IC to drive a common-cathode display

                                                              ____________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________

                                                              3 What symbols appear in the seven segment display if inputs DCBA are

                                                              DCBA Symbol

                                                              1010

                                                              1011

                                                              1100

                                                              1101

                                                              1110

                                                              1111

                                                              Logic Design amp Switching Theory 1 Lab Session 11 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                              48

                                                              Lab Session 11 OBJECT

                                                              Testing different modes of JK-FF COMPONENTS AND APPARATUS REQUIRED 1 Following ICs and their Datasheets

                                                              bull 7473 7476 JK Flip-Flop 2 Digital Trainer DT-01 or the following components

                                                              Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches

                                                              THEORY

                                                              Flip-Flop A flip-flop circuit can maintain a binary state indefinitely (as long as the power is delivered to the circuit) until directed by an input signal to switch states The major differences among various types of flip-flops are in the number of inputs they possess and in the manner in which the inputs affect the binary state

                                                              JK Flip-Flop JK flip flop is an edge triggered device A typical JK flip flop has three inputs J K and a clock input The flip-flop can be either positive or negative edge triggered The output Q is available in complemented form as well Beside the usual inputs and output most of the flip-flop IC also possess two asynchronous inputs namely Preset and Clear These inputs are usually active low If used Preset and Clear inputs keep the flip-flop in set and reset state respectively irrespective of the other inputs Both of these inputs cannot be used simultaneously otherwise they will bring the flip-flop in unstable state

                                                              Figure 111 Symbol for JK flip-flop

                                                              (a) positive-edge triggering (b) active low Preset (PR) and Clear (CLR) with positive-edge triggering

                                                              (c) active low Preset (PR) and Clear (CLR) with negative-edge triggering

                                                              Logic Design amp Switching Theory 1 Lab Session 11 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                              49

                                                              TESTING OF 7473 7476 DUAL JK FLIP-FLOP

                                                              Both the ICs 7473 and 7476 are similar in functionality except for one difference The flip-flops in 7473 have only one type of active low asynchronous input which is the Clear input whereas the flip-flops in 7476 have both Preset and Clear inputs Both these ICs have negative edge triggered flip-flops

                                                              Circuit Diagram

                                                              Figure 112 Pin connections of 7476

                                                              Testing Procedure

                                                              bull Make connections as shown in the circuit diagram (figure 112) bull Apply different combinations of 1s and 0s at J and K inputs bull Observe the output and record your observations in the following table

                                                              Observations

                                                              J

                                                              K Q

                                                              0 0 0 1 1 0 1 1

                                                              ACTIVITY

                                                              1 Observe the output Q of JK flip-flop if the clock input is connected to VCC or GND instead of a clock source Write your observations here __________________________________________________________________________________________________________________________________________ _______________________________________________________________________________________________________________________________________________________________________________________________________________

                                                              Logic Design amp Switching Theory 1 Lab Session 12 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                              50

                                                              Lab Session 12 OBJECT

                                                              Designing sequential circuit for the given state diagram using D flip-flop GIVEN STATE DIAGRAM

                                                              00

                                                              11

                                                              Figure 121 State Diagram COMPONENTS AND APPARATUS REQUIRED 1 Following ICs and their Datasheets

                                                              bull 7474 D Flip-Flop bull ICs of basic gates (AND OR NOT XOR etc) as required

                                                              2 Digital Trainer DT-01 or the following components Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches

                                                              THEORY

                                                              Sequential Circuits In Sequential Circuits the output not only depends on the present inputs but also on previous states of the circuit These circuits use memory elements (latches flip-flops) and the binary information stored in the memory elements at any given time defines the state of the sequential circuit Analysis of a Sequential Circuit The behavior of a sequential circuit is determined from the inputs the outputs and the states of its flip-flops Both the outputs and next state are a function of the inputs and the

                                                              10

                                                              01

                                                              00 11 10

                                                              00

                                                              00 11 10 00

                                                              Logic Design amp Switching Theory 1 Lab Session 12 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                              51

                                                              present state The analysis of a sequential circuit form a state diagram comprises of the following bull Selecting a particular flip-flop to design the circuit bull Obtaining state table from the state diagram bull Finding input equations for the selected flip-flop bull Finding state equations (not required for the construction of circuit) bull Implementing the circuit using selected flip-flops and their input equations ANALYZING THE GIVEN STATE DIAGRAM D Flip-Flop D flip-flop is also called transparent flip-flop as it simply transfers the input data to the output For our design we require the graphical symbol and excitation table of D flip-flop (see figure 122)

                                                              Qt Qt+1 T 0 0 0 0 1 1 1 0 0 1 1 1

                                                              (b) Excitation table of D Flip-Flop

                                                              (a) Graphical Symbol

                                                              Figure 122 Characteristic equation of D flip-flop is Q(t+1) = D State Table The given state diagram has four states so we will need two D flip-flops (FF-0 FF-1) Form state table form the given state diagram and record the results in the following table

                                                              Present State Input Next State Output Input to FF-0 D0

                                                              Input to FF-1 D1 Q1t Q0t x Q1(t+1) Q0(t+1) z

                                                              Logic Design amp Switching Theory 1 Lab Session 12 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                              52

                                                              Input Equations Using Karnaugh map the input equations D0 and D1 for the two flip-flops can be found

                                                              D0 D1 Q0x

                                                              Q1

                                                              _ _ Q0x

                                                              _ Q0x

                                                              Q0x

                                                              _ Q0x

                                                              Q0x

                                                              Q1

                                                              _ _ Q0x

                                                              _ Q0x

                                                              Q0x

                                                              _ Q0x

                                                              _ Q1

                                                              _ Q1

                                                              Q1

                                                              Q1

                                                              D0 = _________________ D1 = _________________

                                                              State Equations Using the characteristic equation of D flip-flop we can find the state equations Q0(t+1) and Q1(t+1) for the to flip flops Q0(t+1) = _______________________ Q1(t+1) = _______________________ _______________________ _______________________ _______________________ _______________________ Circuit Diagram

                                                              Logic Design amp Switching Theory 1 Lab Session 12 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                              53

                                                              Implementation Procedure and Observations

                                                              1 Implement the circuit using digital ICs on a bread board (prepare the pin diagram (use appendix A) and refer to laboratory session 01 for procedure)

                                                              2 Make the clear inputs of the flip-flops low (to clear the flip-flops) The flip-flops will remain in clear state as long as the clear inputs are connected to low level

                                                              3 Connect output Q0 and the clock pulse to an oscilloscope 4 Apply 0 to the input x 5 Now make the clear inputs to high 6 Observe the waveform for the first 5 clock pulses and record it 7 Repeat steps 2 to 6 keeping x=1 in step 4 this time 8 Repeat steps 2 to 7 this time connecting Q1 instead of Q0 to the oscilloscope in step

                                                              3 Record your observations (Keep frequency of the clock pulse low (eg1Hz) so that the output waveforms can be observed easily)

                                                              1 2 3 4 5 Clock Pulse

                                                              Output Waveform for Q0 when x=0

                                                              Output Waveform for Q0 when x=1

                                                              Output Waveform for Q1 when x=0

                                                              Output Waveform for Q1 when x=1

                                                              Logic Design amp Switching Theory 1 Lab Session 13 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                              Lab Session 13 OBJECT

                                                              Designing a modulo-5 asynchronous up-counter using JK-FF COMPONENTS AND APPARATUS REQUIRED

                                                              1 Following ICs and their Datasheets

                                                              bull 7400 Quad 2-input or 7410 Triple 3-input NAND Gates bull 7476 7473 JK Flip-Flop

                                                              2 Digital Trainer DT-01 or the following components Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches

                                                              THEORY

                                                              Digital Counters A digital counter is a set of flip-flops whose states change in response to pulses applied at the input to the counter The flip-flops are interconnected so that their combined state at any time is the binary equivalent of the total number of pulses that have occurred up to that time Every counter resets after a certain number of clock pulses Thus as it name implies a counter is used to count pulses An n stage counter can count up to a maximum of 2n states n is equal to the number of flip-flops required for the construction of counter

                                                              Modulus Counters The number of input pulses that causes a counter to reset to its initial count is called the modulus of the counter Thus the modulus equals to total number of distinct states (counts) including zero that a counter can store A binary counter with n stages is a modulo-2n (or mod-2n) counter The largest count a mod-N counter can achieve is N-1 ie a mod-N counter never reaches the binary number equal to its modulus N is always equal to or less than 2n Counters can be classified as bull Synchronous Counters which are clock driven All the flip-flops are driven by a

                                                              single clock bull Asynchronous Counters which are event driven Clock input is given to the first

                                                              flip-flop only Rest of the flip-flops are driven by their preceding flip-flops

                                                              DESIGN OF A MOD-5 ASYNCHRONOUS UP COUNTER The number of flip-flops required to construct a mod-5 counter is 3 because 5 should be less than or equal to 2n This counter will count from 0 to 4 a total of 5 distinct states Since a 3-stage counter can count up to 8 states at maximum a NAND gate is used to reset it after 5 clock pulses Figure 131 shows the logic diagram

                                                              54

                                                              Logic Design amp Switching Theory 1 Lab Session 13 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                              55

                                                              Figure 131 A Mod-5 Asynchronous Up Counter

                                                              Implementation and Observations

                                                              Implement the mod-5 counter circuit (figure 131) on a bread board (prepare the pin diagram (use appendix A) and refer to laboratory session 01 for implementation procedure) and record the observations in the following table

                                                              Clock Pulse Q2 Q1 Q0

                                                              0 1 2 3 4 5 6 7

                                                              ACTIVITY

                                                              Draw the timing diagram for mod-5 counter designed in this laboratory session

                                                              Logic Design amp Switching Theory 1 Lab Session 14 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                              Lab Session 14 OBJECT

                                                              Experimenting with 74194 4-bit bidirectional universal shift register COMPONENTS AND APPARATUS REQUIRED

                                                              1 Following ICs and their Datasheets

                                                              bull 74194 4-bit bidirectional universal shift register 2 Digital Trainer DT-01 or the following components

                                                              Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches

                                                              THEORY

                                                              Shift Registers

                                                              A Register is a set of flip-flops used to store binary data A register which is capable of shifting its binary information either to the right or left is called a shift register The logical configuration of a register consists of a chain of flip-flops connected in cascade with the output of one flip-flop connected to the input of next flip-flop All flip-flops receive a common clock pulse which causes the shift from one stage to the next

                                                              Bidirectional Shift Registers A bi-directional shift register is one whose bits can be shifted from left to right or from right to left

                                                              Universal Shift Registers A universal shift register is a bi-directional register whose input can be in either serial or parallel form and whose output can be in either serial or parallel form

                                                              74194 4-BIT BIDIRECTIONAL UNIVERSAL SHIFT REGISTER

                                                              The 74194 register provides parallel as well as serial loading in both directions Function of various pins of this IC is described below

                                                              bull A B C and D Active high inputs for parallel loading bull QA QB QC and QD Active high outputs bull S0 and S1 Active high mode control inputs The following table shows combinations

                                                              of S1 and S0 to enable various modes

                                                              S1 S0 Clock Action 0 0 x No change 0 1 uarr Shift right 1 0 uarr Shift left 1 1 uarr Parallel load

                                                              uarr shows the rising edge of the clock pulse

                                                              56

                                                              Logic Design amp Switching Theory 1 Lab Session 14 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering bull SR Active high serial input for right shifting bull SL Active high serial input for left shifting bull CLR Active low input Clears all the flip-flops of the register if set to 0 should be

                                                              kept high otherwise bull CLK Clock input bull VCC and GND Supply connections lines Thus A B C and D are inputs for parallel loading whereas SR and SL are inputs for serial loading with right or left shifting respectively S1 and S0 are used to select the loading mode Circuit Diagram

                                                              Figure 141 Pin connections of 74194 Testing Procedure

                                                              bull Make connections as shown in the circuit diagram bull Observe the output for the input combinations given in the following table

                                                              57

                                                              Logic Design amp Switching Theory 1 Lab Session 14 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                              58

                                                              Observations

                                                              S1 S0 SL SR A B C D QA QB QC QD 0 0 0 1 0 0 0 0 0 1 1 0 0 0 0 1 1 0 0 0 0 0 1 0 1 1 0 0 0 0 1 1 0 0 1 1 0 1 0 0 0 1 1 1 0 1 0 1 1 0 1 0 0 1 1 0 1 1 1 0 0 1 1 1 1 1 0 0 1 1 1 1

                                                              ACTIVITY 1 Show connections of 74194 to convert it into a ring counter with right shifting

                                                              Logic Design amp Switching Theory 1 Lab Session 15 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                              Lab Session 15

                                                              OBJECT

                                                              Experimenting with 74245 octal bus transceivers using parallel port PC interfacing COMPONENTS AND APPARATUS REQUIRED 1 Parallel Port Connectors (DB-25) with Cable 2 Personal Computer with Windows 98 and TurboC Compiler Installed 3 Following ICs and their Datasheets

                                                              bull 74245 Octal Bus Transceivers with 3-State Outputs 4 Digital Trainer DT-01 or the following components

                                                              Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches

                                                              THEORY

                                                              3-State Logic Sometimes it is necessary to isolate one part of circuit from the other part For this purpose some TTL ICs are designed with 3-state logic Such devices have three possible output states high low and high impedance The device can be put into high impedance state by a control signal applied to an appropriate pin When such a device is in high impedance state there is very high impedance at its output effectively isolating the device from whatever circuitry the output normally drives 74245 Octal Bus Transceivers A bus is any conducting path or set of paths having electrical connections to one or more devices 74245 octal bus transceivers are mainly used to control connectivity between two devices or circuits It also provides direction control for signal flow Function of various pin of this IC is given below

                                                              bull A1 through A8 Bus A bull B1 through B8 Bus B bull G΄ Active low enable input When high sets all the bus pins to high impedance state bull DIR Direction control for signal flow When set to high logic level transfers bus A

                                                              data to B bus When set to low logic level transfers bus B data to A bus bull VCC and GND Supply connections lines Serial and Parallel Port Connectors A Parallel Port can consist of only 25 pin port adapter called a DB-25 and a serial port can consist of either a 25 pin port adapter called a DB-25 or 9 pin adapter called a DB-9 port adapter Whether the port is a 9 pin or 25 pin it can accomplish all of the same tasks that serial port communications have been designed for

                                                              59

                                                              Logic Design amp Switching Theory 1 Lab Session 15 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                              60

                                                              Each adapter can be a male type connector with pins or a female type adapter with tiny holes Generally a PRINTER port (called LPT1) on the back of a computer is female type adapter and we need to use MALE DB-25 pin cable on it for PRINTER connection or for parallel LAPLINK cable And a COM port on the back of a computer is male for the serial ports but it may not necessarily be Parallel Port Connector ndash DB-25 The DB-25 connector (named for its B-size D-shaped shell and 25 pins) is practically ubiquitous in the electronics industry The DB-25 connector is used for a variety of purposes Two common applications are RS-232EIA-232 (serial) connections and the parallel printer interface on the IBM PC The DB-25 connector is also used for SCSI connections Normally the parallel port is used for output to a printer or other device It sends data 8-bits or one byte at a time in parallel The other lines available on the DB-25 connector are a combination of status lines control lines and ground lines The status and control lines are used for handshaking commands and feedback when we are talking to a printer

                                                              Figure 152 DB-25 Female Figure 151 DB-25 Male

                                                              Figure 153 Pin Layout for DB-25 As can be seen form figure 153 there are four types of pins in this connector

                                                              bull Data pins (8 pins - D0 to D7) Active high bidirectional lines

                                                              Logic Design amp Switching Theory 1 Lab Session 15 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering bull Control pins (4 pins - C0 to C3) C0 C1 and C3 are active low whereas C2 is active

                                                              high These lines also are bidirectional bull Status pins (5 pins ndash S3 to S7) Only S7 is active low rest are active high input lines bull Ground pins (8 pins) Used as a reference signal for the low (below 05 volts) charge

                                                              Parallel Port Addresses A DB-25 connector at a parallel port has three address one for each kind of pins register data status and control The first or base address generally refers to data register Second address is for status register and the third one is for control register In Windows 98 the base address is usually found to be 278H 378H or 3BCH Now if 378H is the base address then it refers to the data register whereas addresses for status and control register are respectively 379H and 37AH For Windows 98 the base address can be found as follows 1 On your Desktop right-click on My Computer and select Properties 2 Click on the Device Manager tab and find LPT1 under Plug and Play BIOS 3 After selecting LPT1 click the Properties button 4 Next select the Resources tab and the address should then appear next to InputOutput

                                                              Range Accessing parallel port through C Language Programming There are multiple functions in C Language for accessing external ports The most commonly used are listed below

                                                              bull unsigned char inportb(int portid) inportb reads a byte from a hardware port

                                                              bull int inport(int portid) reads a word from a hardware port

                                                              bull void outportb(int portid unsigned char value) outputs a byte to a hardware port

                                                              bull void outport(int portid int value) outputs a word to a hardware port

                                                              portid refers to the port address whereas value refers to the data to be sent TESTING 74245 USING PARALLEL PORT PC INTERFACING At one end the parallel port connector will be connected to the PC via parallel port cable and another connector (to be plugged into the PC parallel port slot) At the other end it will be connected to the buffer IC 74245 Data lines of the connector will be used to transfer 8-bit data between the PC and the buffer Out of the 8-bits of 74245 4-bits will be used to enter data which will be displayed at the monitor through a C language

                                                              61

                                                              Logic Design amp Switching Theory 1 Lab Session 15 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering program The remaining 4-bits will receive data from PC as entered by the user via keyboard

                                                              Circuit Diagram

                                                              Figure 154 Interface of 74245 to PC via Parallel Port

                                                              Procedure

                                                              1 Connect the DB-25 connector to the PC at one end and solder it to the circuit board at the other end

                                                              2 Connect various pins of the connector and 74245 according to the circuit diagram shown in figure 152

                                                              3 Using the functions listed in the previous section write a program in C language to operate various pins of the buffer The user interface of the program should provide option to the user whether to send or receive data from the port

                                                              4 Set DIR switch to 1 5 Try sending some data bits to the port The result should be displayed at the LEDs 6 Set DIR switch to 0 7 Set some binary 4-bit value through the switches Try reading it via parallel port

                                                              C Language Program

                                                              A program to access parallel port for data transfers

                                                              use header file include ltstdiohgt main program void main() define variable

                                                              62

                                                              Logic Design amp Switching Theory 1 Lab Session 15 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering unsigned int data=0 char choice while(1) printing option menu clrscr() printf(This program will send or receive a BCD digit from the parallel portn) printf(nPress your choice numbern) printf(n1 Send Data) printf(n2 Receive Data) printf(n3 Exitn) choice = getch() sending entered digit to the port if(choice == 1) input BCD digit printf(nEnter BCD digit to be sent to the port) data = getche() masking the first four bits data = data amp 0x0f sending to the port outportb(0x378data) printf(nThe BCD digit c has been sent to the port data) printing on screen the data received from the port else if(choice == 2) receiving data from the port data = inportb(0x378) masking the last four bits data = data amp 0xf0 shifting first four bits to make them the last four bits datagtgt=4 printf(nThe BCD digit set at the port is c data) exit else if(choice == 3) break key pressed is not in the menu else printf(nEnter valid choice number) printf(nnPress any key to continue) getch()

                                                              63

                                                              Logic Design amp Switching Theory 1 Lab Session 15 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                              ACTIVITY 1 In the above circuit DIR and G΄ inputs are hardwired Connect them to status or

                                                              control pins of the parallel port connector and control their function through your software program Circuit Diagram Program Code ______________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________

                                                              ___________________________________________________________________________________________________________________________________________________

                                                              64

                                                              Logic Design amp Switching Theory 1 Lab Session 15 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                              65

                                                              _____________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ _____________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ _______________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ _________________________________________________ _________________________________________________

                                                              Logic Design amp Switching Theory 1 Appendix A NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                              Appendix A

                                                              PIN DIAGRAMS OF THE ICS REQUIRED FOR THE LABORATORY SESSIONS Consult the TTLIC data book for internal diagrams and electrical characteristics of these ICs 7400 Quad 2-Input NAND 7402 Quad 2-Input NOR

                                                              7404 Hex Inverter 7408 Quad 2-Input AND

                                                              7410 Triple 3-Input NAND 7411 Triple 3-Input AND

                                                              7421 Dual 4-Input AND 7432 Quad 2-Input OR

                                                              66

                                                              Logic Design amp Switching Theory 1 Appendix A NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                              BCD-to-Seven Segm 7448 BCD-to-Seven Segment 7447 ent

                                                              Decoder (15V OC) Decoder (2kΩ pull-up output)

                                                              7473 Dual JK Flip-Flop 7474 Dual D-Type Flip-Flop

                                                              7476 Dual JK Flop-Flop -Bit Binary Full Adder 7483 4 with Fast Carry

                                                              86 Quad 2-Inpu 74138 3-to-8 Line 74 t Exclusive OR Decoder Demultiplexer

                                                              67

                                                              Logic Design amp Switching Theory 1 Appendix A NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                              68

                                                              74148 8-to-3 Line 16-to-1 Line Data

                                                              Priority Encoder 74150 Selector Multiplexer

                                                              74245 Oct nsceivers Universal Shift Register (PIPO) (3-State)

                                                              74194 4-Bit Bidirectional al Bus Tra

                                                              Logic Design amp Switching Theory 1 Appendix B NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                              Appendix B

                                                              DEBOUNCING CIRCUITRY FOR MECHANICAL SWITCHES Mechanical switches form the interface between human beings and computers or other digital systems For example a keyboard is a matrix of switches used to supply alphanumeric data to a computer Whatever the switch design it is a potential source of problems due to contact bounce The contact bounce creates a sense of narrow pulses when a switch is opened or closed An example of device whose operation would be adversely affected by contact bounce is a digital counter used to count the number of times a switch is depressed Eliminating the effects of contact bounce is called debouncing When data is entered into a computer via a keyboard a software debounce is often used This type of debouncing is a program that causes the computer to sample the switch terminal (ie to input data from it) many times in succession during the interval of time that contact bounce occurs If the data is sensed to be 1s (or 0s) for a specific number of consecutive samples then it is assumed that contact bounce has ended and the last value sensed is valid Hardware debouncing is the use of electronic circuitry to eliminate the effects of contact bounce There are numerous versions of such circuitry including those that use monostable multivibrators (one-shots) but the most straightforward is simply an RS latch Figure B1 shows the circuit When the switch is in position 1 R = 0 and S = 1 so the latch is set and the output (Q) is 1 When the switch is in position 0 R = 1and S = 0 so the latch is reset and the output is 0 When the switch is moved form one position to the other the latch changes state and bouncing occurs at either the R or the S input The bouncing does not affect the latch after it has change state An RS latch will remain set for example when its R input is 0 and its S input is alternately changed form 1 to 0

                                                              Figure B1 Use of RS latch to debounce a mechanical switch

                                                              69

                                                              • 01-ldst-Outer title
                                                                • Practical Workbook
                                                                • Logic Design amp Switching Theory I
                                                                  • Dept of Computer amp Information Systems Engineering
                                                                    • NED University of Engineering amp Technology
                                                                    • Karachi ndash 75270 Pakistan
                                                                      • 02-ldst-inner Title
                                                                        • Practical Workbook
                                                                        • Logic Design amp Switching Theory I
                                                                          • Dept of Computer amp Information Systems Engineering
                                                                            • NED University of Engineering amp Technology
                                                                            • Karachi ndash 75270 Pakistan
                                                                              • 03-ldst-general info
                                                                              • 04-ldst-introduction
                                                                              • 05-Table of Contents
                                                                                • CONTENTS
                                                                                  • Lab Session No Object Page No
                                                                                  • 1
                                                                                  • Also implementing and testing the given circuit on a bread board
                                                                                    • Working with Electronics Workbench
                                                                                      • Driving a seven segment display using 7447 7448 driver IC
                                                                                        • Designing a modulus-5 asynchronous up-counter using JK-FF
                                                                                          • Experimenting with 74194 4-bit bidirectional universal shift register
                                                                                              • 13
                                                                                                  • 06-ldst-Exp01
                                                                                                    • Lab Session 01
                                                                                                    • OBJECT
                                                                                                      • 1 Bread board
                                                                                                      • 2 5 V - power supply
                                                                                                      • 3 Multimeter
                                                                                                      • 4 Logic probe
                                                                                                      • 5 LEDs with resistors
                                                                                                      • 6 Connecting wires
                                                                                                      • 8 Following ICs and their datasheets
                                                                                                        • THEORY
                                                                                                          • Logic Gates
                                                                                                          • 1 The AND Gate ndash An AND gatersquos output is 1 if and only if all its inputs are 1 If A and B are two inputs to an AND gate then output F of the gate is given as F = AB
                                                                                                          • 2 The OR Gate - An OR gatersquos output is 1 if at least one of its input is 1 If A and B are two inputs to an OR gate then output F of the gate is given as F = A+B
                                                                                                          • 3 The NOT Gate (Inverter) ndash Its output is 1 when its input is 0 and its output is 0 when the input is 1 ie it complements a digital variable If A is the input to a NOT gate then output F of the gate is given as
                                                                                                          • 4 The NAND Gate ndash Its output is 1 if at least one of its input is 0 This gate performs the same logic as an AND gate followed by an inverter If A and B are two inputs to a NAND gate then output F of the gate is given as
                                                                                                            • 5 The NOR Gate - The output of a NOR gate is 1 if and only if all its inputs are 0 This gate performs the same logic function as an OR gate followed by an inverter If A and B are two inputs to a NAND gate then output F of the gate is given as
                                                                                                                • DATA SHEETS
                                                                                                                  • Logic expression for the given logic diagram __________________________________
                                                                                                                      • 07-ldst-exp02
                                                                                                                        • Working with Electronics Workbench
                                                                                                                          • 08-ldst-exp03
                                                                                                                            • Designing Half and Full Adder Circuits
                                                                                                                              • COMPONENTS AND APPARATUS REQUIRED
                                                                                                                                • 1 Following ICs and their Datasheets
                                                                                                                                • 7408 Quad 2-input AND Gate
                                                                                                                                • 2 Digital Trainer DT-01 or the following components
                                                                                                                                  • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                  • Connecting wires Switches
                                                                                                                                    • THEORY
                                                                                                                                        • IMPLEMENTATION AND OBSERVATIONS
                                                                                                                                          • 09-ldst-Exp04
                                                                                                                                            • Lab Session 04
                                                                                                                                            • 1 Digital ICs and their Datasheets
                                                                                                                                            • 7408 Quad 2-input AND Gate
                                                                                                                                            • 2 Digital Trainer DT-01 or the following components
                                                                                                                                              • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                              • Connecting wires Switches
                                                                                                                                              • PROCEDURE
                                                                                                                                              • REDUCTION OF LOGIC EXPRESSION USING KARNAUGH MAP
                                                                                                                                              • OBSERVATIONS
                                                                                                                                              • RESULT
                                                                                                                                                  • 10-ldst-Exp05
                                                                                                                                                    • Lab Session 05
                                                                                                                                                    • 1 Following ICs and their Datasheets
                                                                                                                                                    • 7408 Quad 2-input AND Gate
                                                                                                                                                    • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                      • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                      • (100 Ω) Connecting wires Switches
                                                                                                                                                      • THEORY
                                                                                                                                                        • IMPLEMENTATION AND OBSERVATIONS
                                                                                                                                                          • 11-ldst-Exp06
                                                                                                                                                            • OBJECT
                                                                                                                                                            • 1 Following ICs and their Datasheets
                                                                                                                                                            • 7408 Quad 2-input AND Gates or 7411 Triple 3-input AND Gates
                                                                                                                                                            • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                              • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                              • Connecting wires Switches
                                                                                                                                                                • Figure 62 Circuit Diagram for 4 x 1 Multiplexer
                                                                                                                                                                • Implementation and Observations
                                                                                                                                                                  • Circuit Diagram
                                                                                                                                                                    • ACTIVITY
                                                                                                                                                                      • 12-ldst-exp07
                                                                                                                                                                        • 1 Following ICs and their Datasheets
                                                                                                                                                                        • 7408 Quad 2-input or 7411 Triple 3-input AND Gates
                                                                                                                                                                        • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                          • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                          • Connecting wires Switches
                                                                                                                                                                            • THEORY
                                                                                                                                                                                • Figure 72 Circuit Diagram for 2 x 4 Decoder 1 x 4 Demultiplexer
                                                                                                                                                                                • Implementation and Observations
                                                                                                                                                                                  • Circuit Diagram
                                                                                                                                                                                    • ACTIVITY
                                                                                                                                                                                      • 13-ldst-Exp08
                                                                                                                                                                                        • OBJECT
                                                                                                                                                                                        • 1 Following ICs and their Datasheets
                                                                                                                                                                                        • 7408 Quad 2-input or 7421 Dual 4-input AND Gates
                                                                                                                                                                                        • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                          • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                          • Connecting wires Switches
                                                                                                                                                                                            • THEORY
                                                                                                                                                                                                • Figure 81 Circuit Diagram for 4 x 2 Priority Encoder
                                                                                                                                                                                                • Implementation and Observations
                                                                                                                                                                                                  • Therefore if GS A2 A1 and A0 are all low then it shows that line 0 is selected and if E0 A2 A1 and A0 are all low then it shows that none of the inputs selected E0 and GS cannot be in the same state provided that E1 is enabled
                                                                                                                                                                                                  • Circuit Diagram
                                                                                                                                                                                                    • ACTIVITY
                                                                                                                                                                                                      • 14-ldst-exp09
                                                                                                                                                                                                        • OBJECT
                                                                                                                                                                                                        • 1 Following ICs and their Datasheets
                                                                                                                                                                                                        • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                          • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                          • Connecting wires Switches
                                                                                                                                                                                                            • THEORY
                                                                                                                                                                                                              • Parity Generator
                                                                                                                                                                                                                • Let x y and z be the three bits that constitute the message and are the input to the Odd Parity Generator Circuit Since it is an odd parity system the bit P is generated so as to make the total number of 1s odd (including P) The function P can be expressed as follows
                                                                                                                                                                                                                • Figure 91 Circuit Diagram for a 3-bit Parity Generator
                                                                                                                                                                                                                  • C = x Ο y Ο z Ο P
                                                                                                                                                                                                                    • Implementation and Observations
                                                                                                                                                                                                                      • ACTIVITY
                                                                                                                                                                                                                          • 15-ldst-exp10
                                                                                                                                                                                                                            • Driving a seven segment display using 7447 7448 driver IC
                                                                                                                                                                                                                            • COMPONENTS AND APPARATUS REQUIRED
                                                                                                                                                                                                                            • 1 Following ICs and their Datasheets
                                                                                                                                                                                                                            • 7447 7448 BCD to Seven Segment Driver
                                                                                                                                                                                                                            • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                              • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches
                                                                                                                                                                                                                                • THEORY
                                                                                                                                                                                                                                • Seven Segment Displays
                                                                                                                                                                                                                                • CIRCUIT DIAGRAM
                                                                                                                                                                                                                                • Figure 102 Circuit diagram for 7447driving a common-anode display
                                                                                                                                                                                                                                    • IMPLEMENTATION AND OBSERVATIONS
                                                                                                                                                                                                                                      • Decimal Digit
                                                                                                                                                                                                                                      • BCD Inputs
                                                                                                                                                                                                                                      • Seven Segment Outputs
                                                                                                                                                                                                                                      • D
                                                                                                                                                                                                                                      • C
                                                                                                                                                                                                                                      • B
                                                                                                                                                                                                                                      • A
                                                                                                                                                                                                                                      • a
                                                                                                                                                                                                                                      • b
                                                                                                                                                                                                                                      • c
                                                                                                                                                                                                                                      • d
                                                                                                                                                                                                                                      • e
                                                                                                                                                                                                                                      • f
                                                                                                                                                                                                                                      • g
                                                                                                                                                                                                                                      • 0
                                                                                                                                                                                                                                      • 0
                                                                                                                                                                                                                                      • 0
                                                                                                                                                                                                                                      • 0
                                                                                                                                                                                                                                      • 0
                                                                                                                                                                                                                                      • 1
                                                                                                                                                                                                                                      • 0
                                                                                                                                                                                                                                      • 0
                                                                                                                                                                                                                                      • 0
                                                                                                                                                                                                                                      • 1
                                                                                                                                                                                                                                      • 2
                                                                                                                                                                                                                                      • 0
                                                                                                                                                                                                                                      • 0
                                                                                                                                                                                                                                      • 1
                                                                                                                                                                                                                                      • 0
                                                                                                                                                                                                                                      • 3
                                                                                                                                                                                                                                      • 0
                                                                                                                                                                                                                                      • 0
                                                                                                                                                                                                                                      • 1
                                                                                                                                                                                                                                      • 1
                                                                                                                                                                                                                                      • 4
                                                                                                                                                                                                                                      • 0
                                                                                                                                                                                                                                      • 1
                                                                                                                                                                                                                                      • 0
                                                                                                                                                                                                                                      • 0
                                                                                                                                                                                                                                      • 5
                                                                                                                                                                                                                                      • 0
                                                                                                                                                                                                                                      • 1
                                                                                                                                                                                                                                      • 0
                                                                                                                                                                                                                                      • 1
                                                                                                                                                                                                                                      • 6
                                                                                                                                                                                                                                      • 0
                                                                                                                                                                                                                                      • 1
                                                                                                                                                                                                                                      • 1
                                                                                                                                                                                                                                      • 0
                                                                                                                                                                                                                                      • 7
                                                                                                                                                                                                                                      • 0
                                                                                                                                                                                                                                      • 1
                                                                                                                                                                                                                                      • 1
                                                                                                                                                                                                                                      • 1
                                                                                                                                                                                                                                      • 8
                                                                                                                                                                                                                                      • 1
                                                                                                                                                                                                                                      • 0
                                                                                                                                                                                                                                      • 0
                                                                                                                                                                                                                                      • 0
                                                                                                                                                                                                                                      • 9
                                                                                                                                                                                                                                      • 1
                                                                                                                                                                                                                                      • 0
                                                                                                                                                                                                                                      • 0
                                                                                                                                                                                                                                      • 1
                                                                                                                                                                                                                                        • ACTIVITY
                                                                                                                                                                                                                                          • 16-ldst-exp11
                                                                                                                                                                                                                                            • Lab Session 11
                                                                                                                                                                                                                                              • OBJECT
                                                                                                                                                                                                                                              • COMPONENTS AND APPARATUS REQUIRED
                                                                                                                                                                                                                                                • 1 Following ICs and their Datasheets
                                                                                                                                                                                                                                                • 7473 7476 JK Flip-Flop
                                                                                                                                                                                                                                                • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                                                  • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                                                                  • Connecting wires Switches
                                                                                                                                                                                                                                                    • THEORY
                                                                                                                                                                                                                                                        • Flip-Flop
                                                                                                                                                                                                                                                        • JK Flip-Flop
                                                                                                                                                                                                                                                          • Circuit Diagram
                                                                                                                                                                                                                                                            • Observations
                                                                                                                                                                                                                                                              • ACTIVITY
                                                                                                                                                                                                                                                                  • 17-ldst-exp12
                                                                                                                                                                                                                                                                    • Lab Session 12
                                                                                                                                                                                                                                                                      • OBJECT
                                                                                                                                                                                                                                                                      • GIVEN STATE DIAGRAM
                                                                                                                                                                                                                                                                      • Figure 121 State Diagram
                                                                                                                                                                                                                                                                      • COMPONENTS AND APPARATUS REQUIRED
                                                                                                                                                                                                                                                                        • 1 Following ICs and their Datasheets
                                                                                                                                                                                                                                                                        • 7474 D Flip-Flop
                                                                                                                                                                                                                                                                        • ICs of basic gates (AND OR NOT XOR etc) as required
                                                                                                                                                                                                                                                                        • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                                                                          • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                                                                                          • Connecting wires Switches
                                                                                                                                                                                                                                                                            • THEORY
                                                                                                                                                                                                                                                                                • Sequential Circuits
                                                                                                                                                                                                                                                                                  • 18-ldst-exp13
                                                                                                                                                                                                                                                                                    • Lab Session 13
                                                                                                                                                                                                                                                                                      • Designing a modulo-5 asynchronous up-counter using JK-FF
                                                                                                                                                                                                                                                                                        • 1 Following ICs and their Datasheets
                                                                                                                                                                                                                                                                                        • 7400 Quad 2-input or 7410 Triple 3-input NAND Gates
                                                                                                                                                                                                                                                                                        • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                                                                                          • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                                                                                                          • Connecting wires Switches
                                                                                                                                                                                                                                                                                            • THEORY
                                                                                                                                                                                                                                                                                                • Figure 131 A Mod-5 Asynchronous Up Counter
                                                                                                                                                                                                                                                                                                • Implementation and Observations
                                                                                                                                                                                                                                                                                                  • ACTIVITY
                                                                                                                                                                                                                                                                                                      • 19-ldst-exp14
                                                                                                                                                                                                                                                                                                        • Experimenting with 74194 4-bit bidirectional universal shift register
                                                                                                                                                                                                                                                                                                        • 1 Following ICs and their Datasheets
                                                                                                                                                                                                                                                                                                        • 74194 4-bit bidirectional universal shift register
                                                                                                                                                                                                                                                                                                        • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                                                                                                          • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                                                                                                                          • Connecting wires Switches
                                                                                                                                                                                                                                                                                                            • THEORY
                                                                                                                                                                                                                                                                                                              • Shift Registers
                                                                                                                                                                                                                                                                                                              • Bidirectional Shift Registers
                                                                                                                                                                                                                                                                                                              • Universal Shift Registers
                                                                                                                                                                                                                                                                                                                • S1
                                                                                                                                                                                                                                                                                                                  • Circuit Diagram
                                                                                                                                                                                                                                                                                                                  • ACTIVITY
                                                                                                                                                                                                                                                                                                                      • 20-ldst-exp15
                                                                                                                                                                                                                                                                                                                        • COMPONENTS AND APPARATUS REQUIRED
                                                                                                                                                                                                                                                                                                                        • 1 Parallel Port Connectors (DB-25) with Cable
                                                                                                                                                                                                                                                                                                                        • 2 Personal Computer with Windows 98 and TurboC Compiler Installed
                                                                                                                                                                                                                                                                                                                        • 3 Following ICs and their Datasheets
                                                                                                                                                                                                                                                                                                                        • 74245 Octal Bus Transceivers with 3-State Outputs
                                                                                                                                                                                                                                                                                                                        • 4 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                                                                                                                          • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                                                                                                                                            • Connecting wires Switches
                                                                                                                                                                                                                                                                                                                              • THEORY
                                                                                                                                                                                                                                                                                                                              • 3-State Logic
                                                                                                                                                                                                                                                                                                                                • Serial and Parallel Port Connectors
                                                                                                                                                                                                                                                                                                                                • Parallel Port Connector ndash DB-25
                                                                                                                                                                                                                                                                                                                                  • Accessing parallel port through C Language Programming
                                                                                                                                                                                                                                                                                                                                      • 21-ldst-appendixA
                                                                                                                                                                                                                                                                                                                                      • 22-ldst-appendixB
                                                                                                                                                                                                                                                                                                                                        • DEBOUNCING CIRCUITRY FOR MECHANICAL SWITCHES

                                                                Logic Design amp Switching Theory 1 Lab Session 07 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                Lab Session 07

                                                                OBJECT

                                                                bull Designing of a 2 x 4 Decoder 1 x 4 Demultiplexer bull Experimenting with 74138 IC

                                                                COMPONENTS AND APPARATUS REQUIRED 1 Following ICs and their Datasheets

                                                                bull 7408 Quad 2-input or 7411 Triple 3-input AND Gates bull 7404 Hex Inverter bull 74138 3 x 8 Decoder

                                                                2 Digital Trainer DT-01 or the following components Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches THEORY

                                                                Decoder A Decoder is a combinational circuit that converts binary information form n input lines to a maximum of 2n unique output lines In practical applications decoders are often used for selecting one of several devices

                                                                Demultiplexer A decoder with an enable input can function as a Demultiplexer A Demultiplexer (DMUX) id a circuit that receives information on a single line and transmits this information on one of 2n possible output lines The selection of a specific output line is controlled by the bit values of n selection lines DESIGN OF A 2 x 4 DECODER 1 x 4 DEMULTIPLEXER A 2 x 4 decoder is capable of selecting one of four output lines (see figure 71 (a)) The 2-bit binary number at the data inputs S1 and S0 specifies which of the four data inputs is to be selected If we add an enable pin and use it as an input line then this decoder can be converted to a 1 x 4 Demultiplexer where S1 and S0 will select a line to which data input is to be routed (see figure 71 (b))

                                                                Select S0 S0 Inputs

                                                                S1 D0 D1

                                                                D2

                                                                D3

                                                                Enable (a) Block Diagram of a 2 x 4 Decoder

                                                                Figure 71

                                                                S1 D0 D1

                                                                D2

                                                                D3

                                                                Inputs

                                                                Data Input (b) Block Diagram of a 1 x 4 Demulptiplexer

                                                                34

                                                                Logic Design amp Switching Theory 1 Lab Session 07 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                Figure 72 Circuit Diagram for 2 x 4 Decoder 1 x 4 Demultiplexer

                                                                Implementation and Observations Implement the 2 x 4 Decoder 1 x 4 Demultiplexer circuit (figure 72) on a bread board (prepare the pin diagram (use appendix A) and refer to laboratory session 01 for implementation procedure) and record the observations in the following table

                                                                Enable Data Input S1 S0 D0 D1 D2 D3

                                                                0 0 0 0 0 1 0 1 0 0 1 1 1 0 0 1 0 1 1 1 0 1 1 1

                                                                TESTING OF 74138 3 x 8 Decoder The 74138 IC has three inputs and eight output lines It has three enable inputs and for the IC to function all three inputs need to be enabled Function of various pins of this IC is described below

                                                                35

                                                                Logic Design amp Switching Theory 1 Lab Session 07 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                bull Y0 through Y7 Active low data outputs bull A B C Input select lines with C being the MSB bull G1 Active high enable Input bull G2Arsquo and G2Brsquo Active low enable Inputs bull VCC and GND Supply connections lines Circuit Diagram

                                                                Figure 73 Pin connections of 74138

                                                                Testing Procedure

                                                                bull Make connections as shown in the circuit diagram bull Apply different combinations of 1s and 0s at data inputs bull Observe the output and record your observations in the following table

                                                                Observations

                                                                C B A Y0 Y1 Y2 Y3 Y4 Y5 Y6 Y7 0 0 0 0 0 1 0 1 0 0 1 1 1 0 0 1 0 1 1 1 0 1 1 1

                                                                36

                                                                Logic Design amp Switching Theory 1 Lab Session 07 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                37

                                                                ACTIVITY ACTIVITY 1 What will be the binary values at the outputs Y0 through Y7 of 74138 if 1 What will be the binary values at the outputs Y0 through Y7 of 74138 if

                                                                bull All three enable pins are connected to ground bull All three enable pins are connected to ground __________________________________________________________________________________________________________________________________________ __________________________________________________________________________________________________________________________________________ _____________________________________________________________________ _____________________________________________________________________

                                                                bull All three enable pins are connected to VCC bull All three enable pins are connected to VCC _______________________________________________________________________________________________________________________________________________________________________________________________________________

                                                                _______________________________________________________________________________________________________________________________________________________________________________________________________________

                                                                2 Show connections for 74138 in order to use it as a 1 x 8 Demultiplexer 2 Show connections for 74138 in order to use it as a 1 x 8 Demultiplexer

                                                                3 Consider a 2 x 4 Decoder with two enable inputs (one active high - G and one active low ndash Grsquo) Draw the output wave-forms for D0 D1 D2 and D3 if the two select inputs are A and B (B being the MSB) All outputs are active low

                                                                Grsquo

                                                                G

                                                                A B

                                                                D0 D1 D2

                                                                D3

                                                                Logic Design amp Switching Theory 1 Lab Session 08 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                Lab Session 08 OBJECT

                                                                bull Designing of a 4 x 2 Priority Encoder bull Experimenting with 74148 IC

                                                                COMPONENTS AND APPARATUS REQUIRED

                                                                1 Following ICs and their Datasheets

                                                                bull 7408 Quad 2-input or 7421 Dual 4-input AND Gates bull 7432 Quad 2-input OR Gates bull 7404 Hex Inverter bull 74148 Encoder

                                                                2 Digital Trainer DT-01 or the following components Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches

                                                                THEORY

                                                                Encoder An Encoder is a digital function that produces a reverse operation from that of a decoder An Encoder has 2n (or less) input lines and n output lines The output lines generate the binary code for the 2n input variables Priority Encoder

                                                                A simple encoder may produce an erroneous output if more than one of its inputs is high A Priority Encoder is one that responds to just one input among those that may be simultaneously high in accordance with some priority system The most common priority system is based on the relative magnitudes of the inputs whichever decimal input is largest is the one that is encoded

                                                                DESIGN OF A 4 x 2 Priority Encoder

                                                                The following equations represent the outputs of a 4 x 2 priority encoder 32 DDA +=

                                                                321 DDDB += As can be seen from the equations that input D0 which has a binary code 00 is not used in any equation A binary code 00 at the output indicates two conditions Either D0 is selected or no input is selected In order to differentiate these two conditions we will provide an additional output Z to indicate if at least one of the inputs is a 1 The equation for Z will be

                                                                4321 DDDDZ = If Z is 0 then the binary code 00 at the output indicates that D0 is selected and if Z is 1 then it indicates that no input line is selected

                                                                38

                                                                Logic Design amp Switching Theory 1 Lab Session 08 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                Figure 81 Circuit Diagram for 4 x 2 Priority Encoder

                                                                it (figure 81) on a bread board (prepare the to laboratory session 01 for implementation

                                                                Implementation a Implement the 4 x 2 Priority Encoder circu

                                                                ram (use appendix A) and refer

                                                                nd Observations

                                                                pin diagprocedure) and record the observations in the following table

                                                                D3 D2 D1 D0 A B 0 0 0 1 0 0 1 x 0 1 x x 1 x x x

                                                                TESTING OF 74148 8 x 3 Octal Priority Encoder

                                                                imal digits There are nine of which three represents

                                                                ing any of the inputs is high

                                                                then it shows that line 0 is selected and if e inputs selected E0 and GS

                                                                cannot be in the same state provided that E1 is enabled

                                                                The 74148 is a priority encoder with active-Low input for dec

                                                                input) and five output linesinputs lines (including an enablethe binary code for the octal digit Function of various pins of this IC is described below

                                                                bull 0 through 7 Active low data inputs representing the octal digits A2 A1 A0 Active low output lines representing the binary code bullbull E1 Active low enable Input bull E0 Active low output indicating none of the inputs is high bull GS Active low output indicatbull VCC and GND Supply connections lines Therefore if GS A2 A1 and A0 are all low

                                                                then it shows that none of thE0 A2 A1 and A0 are all low

                                                                39

                                                                Logic Design amp Switching Theory 1 Lab Session 08 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                Circuit Diagram

                                                                Figure 82 Pin connections of 74148

                                                                Testing Procedure bull Make connections as sho

                                                                binations of 1s and 0s at data inputs d record your observations in the following table

                                                                GS E0

                                                                wn in the circuit diagram bull Apply different combull Observe the output an Observations

                                                                0 1 2 3 4 5 6 7 A2 A1 A0 1 1 1 1 1 1 1 1 x x x x x x x 0 x x x x x x 0 1 x x x x x 0 1 1 x x x x 0 1 1 1 x x x 0 1 1 1 1 x x 0 1 1 1 1 1 x 0 1 1 1 1 1 1 0 1 1 1 1 1 1 1

                                                                40

                                                                Logic Design amp Switching Theory 1 Lab Session 08 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                41

                                                                CTIVITY

                                                                Cascade the following two 74148 8 x 3 Priority Encoders to form 16 x 4 Priority

                                                                A 1

                                                                Encoder

                                                                Logic Design amp Switching Theory 1 Lab Session 09 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering `

                                                                Lab Session 09 OBJECT

                                                                Designing an Odd Parity Generator and Checker for a 3-bit Data COMPONENTS AND APPARATUS REQUIRED

                                                                1 Following ICs and their Datasheets

                                                                bull 7486 Quad 2-input Exclusive-OR Gates bull 7404 Hex Inverter

                                                                2 Digital Trainer DT-01 or the following components Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches

                                                                THEORY

                                                                Parity Generator When binary data is transmitted and processed it is ndash as are all electrical signals ndash susceptible to noise that can either alter or distort its contents 1s may be effectively changed to 0s and 0s to 1s To overcome this problem one or more bits are often added to the data as an aid in detecting errors caused by noise The most common of these is a Parity bit that signifies whether the total number of 1s in a code group is odd or even In an Odd Parity system the parity bit is made 0 or 1 as necessary to make the total number 1s odd (counting the parity bit itself) In an Even Parity system the parity bit is chosen to make the total number of 1s even Table 91 shows how parity bits would be added to BCD code group in both systems

                                                                Decimal BCD Value Parity Bit ABCD Odd Parity Even Parity

                                                                0 0000 1 0 1 0001 0 1 2 0010 0 1 3 0011 1 0 4 0100 0 1 5 0101 1 0 6 0110 1 0 7 0111 0 1 8 1000 0 1 9 1001 1 0

                                                                Table 91 Odd and Even Parity in BCD

                                                                When digital data is received a parity checking circuit generates an error signal if the total number of 1s is odd in an even parity system or if it is even in an odd parity system Parity check always detects a single error (one bit change from 0 to 1 or 1 to 0) but may not detect

                                                                42

                                                                Logic Design amp Switching Theory 1 Lab Session 09 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering ` two or more errors Odd parity is used more often than even parity because even parity does not detect a situation where all 0s are created due to short circuit or other fault condition DESIGN OF A 3-BIT ODD PARITY GENERATOR AND CHECKER Let x y and z be the three bits that constitute the message and are the input to the Odd Parity Generator Circuit Since it is an odd parity system the bit P is generated so as to make the total number of 1s odd (including P) The function P can be expressed as follows P = x oplus y Ο z or P = x Ο y oplus z Since the IC available is 7486 which is quad 2input XOR IC therefore we will convert XNOR also to XOR

                                                                P = x oplus y Ο z

                                                                P = ( x oplus y ) Ο z Since for even number of variables ______

                                                                XOR = XNOR Therefore ___________ _________

                                                                P = ( x oplus y ) oplus z = x oplus y oplus z This logical expression can be implemented with two XOR gates and an inverter (see figure 91)

                                                                Figure 91 Circuit Diagram for a 3-bit Parity Generator

                                                                The 3-bit message and the parity bit are transmitted to their destination where they are applied to a Parity Checker Circuit An error occurs during transmission if the parity of the four bits received is even since the binary information transmitted was originally odd The output C of the parity checker should be a 1 when an error occurs ie when the number of 1s in the four inputs is even Therefore the function C can be expressed as

                                                                C = x Ο y Ο z Ο P

                                                                Using the same logic applied for the conversion of the equation of P

                                                                PzyxC oplusoplusoplus= This logical expression can be implemented with three XOR gates and an inverter (see figure 92)

                                                                43

                                                                Logic Design amp Switching Theory 1 Lab Session 09 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering `

                                                                44

                                                                Figure 92 Circuit Diagram for a 3-bit Parity Checker Implementation and Observations Implement the 3-bit Parity Generator and Checker circuits (figure 91 and 92) on a bread board (prepare the pin diagram (use appendix A) and refer to laboratory session 01 for implementation procedure) and record the observations in the following table

                                                                x y z P x y z P C x y z P C 0 0 0 0 0 0 0 1 0 0 0 0 0 1 0 0 0 1 1 0 0 1 0 1 0 0 0 1 0 1 0 1 0 0 1 1 0 0 1 1 1 0 1 1 1 0 0 0 1 0 0 1 1 0 0 1 0 1 0 1 0 1 1 1 0 1 1 1 0 0 1 1 0 1 1 1 0 1 1 1 0 1 1 1 1 1 1 1

                                                                Odd Parity Generation Odd Parity Check ACTIVITY 1 Try using the parity checker of figure 92 as 3-bit parity generator Write the details here

                                                                _____________________________________________________________________________________________________________________________________________________________________________________________________________________ ______________________________________________________________________________________________________________________________________________ _______________________________________________________________________ ______________________________________________________________________________________________________________________________________________

                                                                Logic Design amp Switching Theory 1 Lab Session 10 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                Lab Session 10 OBJECT

                                                                Driving a seven segment display using 7447 7448 driver IC COMPONENTS AND APPARATUS REQUIRED

                                                                1 Following ICs and their Datasheets

                                                                bull Seven Segment Displays (Common Anode Common Cathode) bull 7447 7448 BCD to Seven Segment Driver

                                                                2 Digital Trainer DT-01 or the following components Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches

                                                                THEORY Seven Segment Displays A Seven Segment Display consists of seven light-emitting segments The segments are designated by letters a through g (see figure 101) By illuminating various combinations of segments the numerals 0 through 9 can be displayed Seven Segment Displays are commonly constructed with light-emitting diodes (LEDs) and with liquid-crystal displays (LCDs) LEDs generally provide greater illumination levels but require much greater power than LCDs An LED display can be a common-anode type or common cathode type In common anode type a high voltage is applied at the common terminal of the display and low voltage is applied at a segmentrsquos terminal for illumination In the common-cathode type a low voltage is applied at the common terminal of the display and high voltage is applied at a segmentrsquos terminal for illumination

                                                                Figure 101 Seven Segment Display

                                                                a f b g

                                                                e c d

                                                                7447 7448 BCD to Seven Segment Driver 7447 7448 IC is particularly used to drive Seven Segment Its input is a BCD number and output drives a seven segment display 7447 is used to drive common-anode displays whereas 7448 is used to drive common cathode displays 7447 7448 is a 16 pin IC Function of various pins of these ICs is described below

                                                                bull A B C D Inputs representing BCD digits (D being the MSB)

                                                                45

                                                                Logic Design amp Switching Theory 1 Lab Session 10 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering bull OA through OG Outputs to drive segments a through g of the display (Active low

                                                                in 7447 and active high in 7448) bull RBI Ripple Blanking Input Turns off all the segments if kept low provided that LT

                                                                is kept high and all other inputs (A B C D BI) are kept low Should be kept high otherwise

                                                                bull BI RBO Wire-AND logic serving as a Blanking Input and or Ripple Blanking Output

                                                                o BI Turns off all the segments if low o RBO Goes to a low level (response condition) along with other outputs when

                                                                RBI and inputs A B C and D are low with LT input at high level bull LT Lamp Test input Tests whether all segments are working or not Illuminates all

                                                                segments if kept low provided that BI is kept high Should be kept high otherwise bull VCC and GND Supply connections lines CIRCUIT DIAGRAM

                                                                Figure 102 Circuit diagram for 7447driving a common-anode display

                                                                IMPLEMENTATION AND OBSERVATIONS

                                                                bull Make connections as shown in the circuit diagram (refer to laboratory session 01 for implementation procedure)

                                                                bull Apply different combinations of 1s and 0s at data inputs bull Observe the output and record your observations in the following table

                                                                46

                                                                Logic Design amp Switching Theory 1 Lab Session 10 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                47

                                                                Decimal Digit

                                                                BCD Inputs Seven Segment Outputs D C B A a b c d e f g

                                                                0 0 0 0 0 1 0 0 0 1 2 0 0 1 0 3 0 0 1 1 4 0 1 0 0 5 0 1 0 1 6 0 1 1 0 7 0 1 1 1 8 1 0 0 0 9 1 0 0 1

                                                                ACTIVITY 1 Perform the Lamp Test for the designed circuit and write your observations

                                                                ____________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________

                                                                2 How can you use 7447 IC to drive a common-cathode display

                                                                ____________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________

                                                                3 What symbols appear in the seven segment display if inputs DCBA are

                                                                DCBA Symbol

                                                                1010

                                                                1011

                                                                1100

                                                                1101

                                                                1110

                                                                1111

                                                                Logic Design amp Switching Theory 1 Lab Session 11 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                48

                                                                Lab Session 11 OBJECT

                                                                Testing different modes of JK-FF COMPONENTS AND APPARATUS REQUIRED 1 Following ICs and their Datasheets

                                                                bull 7473 7476 JK Flip-Flop 2 Digital Trainer DT-01 or the following components

                                                                Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches

                                                                THEORY

                                                                Flip-Flop A flip-flop circuit can maintain a binary state indefinitely (as long as the power is delivered to the circuit) until directed by an input signal to switch states The major differences among various types of flip-flops are in the number of inputs they possess and in the manner in which the inputs affect the binary state

                                                                JK Flip-Flop JK flip flop is an edge triggered device A typical JK flip flop has three inputs J K and a clock input The flip-flop can be either positive or negative edge triggered The output Q is available in complemented form as well Beside the usual inputs and output most of the flip-flop IC also possess two asynchronous inputs namely Preset and Clear These inputs are usually active low If used Preset and Clear inputs keep the flip-flop in set and reset state respectively irrespective of the other inputs Both of these inputs cannot be used simultaneously otherwise they will bring the flip-flop in unstable state

                                                                Figure 111 Symbol for JK flip-flop

                                                                (a) positive-edge triggering (b) active low Preset (PR) and Clear (CLR) with positive-edge triggering

                                                                (c) active low Preset (PR) and Clear (CLR) with negative-edge triggering

                                                                Logic Design amp Switching Theory 1 Lab Session 11 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                49

                                                                TESTING OF 7473 7476 DUAL JK FLIP-FLOP

                                                                Both the ICs 7473 and 7476 are similar in functionality except for one difference The flip-flops in 7473 have only one type of active low asynchronous input which is the Clear input whereas the flip-flops in 7476 have both Preset and Clear inputs Both these ICs have negative edge triggered flip-flops

                                                                Circuit Diagram

                                                                Figure 112 Pin connections of 7476

                                                                Testing Procedure

                                                                bull Make connections as shown in the circuit diagram (figure 112) bull Apply different combinations of 1s and 0s at J and K inputs bull Observe the output and record your observations in the following table

                                                                Observations

                                                                J

                                                                K Q

                                                                0 0 0 1 1 0 1 1

                                                                ACTIVITY

                                                                1 Observe the output Q of JK flip-flop if the clock input is connected to VCC or GND instead of a clock source Write your observations here __________________________________________________________________________________________________________________________________________ _______________________________________________________________________________________________________________________________________________________________________________________________________________

                                                                Logic Design amp Switching Theory 1 Lab Session 12 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                50

                                                                Lab Session 12 OBJECT

                                                                Designing sequential circuit for the given state diagram using D flip-flop GIVEN STATE DIAGRAM

                                                                00

                                                                11

                                                                Figure 121 State Diagram COMPONENTS AND APPARATUS REQUIRED 1 Following ICs and their Datasheets

                                                                bull 7474 D Flip-Flop bull ICs of basic gates (AND OR NOT XOR etc) as required

                                                                2 Digital Trainer DT-01 or the following components Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches

                                                                THEORY

                                                                Sequential Circuits In Sequential Circuits the output not only depends on the present inputs but also on previous states of the circuit These circuits use memory elements (latches flip-flops) and the binary information stored in the memory elements at any given time defines the state of the sequential circuit Analysis of a Sequential Circuit The behavior of a sequential circuit is determined from the inputs the outputs and the states of its flip-flops Both the outputs and next state are a function of the inputs and the

                                                                10

                                                                01

                                                                00 11 10

                                                                00

                                                                00 11 10 00

                                                                Logic Design amp Switching Theory 1 Lab Session 12 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                51

                                                                present state The analysis of a sequential circuit form a state diagram comprises of the following bull Selecting a particular flip-flop to design the circuit bull Obtaining state table from the state diagram bull Finding input equations for the selected flip-flop bull Finding state equations (not required for the construction of circuit) bull Implementing the circuit using selected flip-flops and their input equations ANALYZING THE GIVEN STATE DIAGRAM D Flip-Flop D flip-flop is also called transparent flip-flop as it simply transfers the input data to the output For our design we require the graphical symbol and excitation table of D flip-flop (see figure 122)

                                                                Qt Qt+1 T 0 0 0 0 1 1 1 0 0 1 1 1

                                                                (b) Excitation table of D Flip-Flop

                                                                (a) Graphical Symbol

                                                                Figure 122 Characteristic equation of D flip-flop is Q(t+1) = D State Table The given state diagram has four states so we will need two D flip-flops (FF-0 FF-1) Form state table form the given state diagram and record the results in the following table

                                                                Present State Input Next State Output Input to FF-0 D0

                                                                Input to FF-1 D1 Q1t Q0t x Q1(t+1) Q0(t+1) z

                                                                Logic Design amp Switching Theory 1 Lab Session 12 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                52

                                                                Input Equations Using Karnaugh map the input equations D0 and D1 for the two flip-flops can be found

                                                                D0 D1 Q0x

                                                                Q1

                                                                _ _ Q0x

                                                                _ Q0x

                                                                Q0x

                                                                _ Q0x

                                                                Q0x

                                                                Q1

                                                                _ _ Q0x

                                                                _ Q0x

                                                                Q0x

                                                                _ Q0x

                                                                _ Q1

                                                                _ Q1

                                                                Q1

                                                                Q1

                                                                D0 = _________________ D1 = _________________

                                                                State Equations Using the characteristic equation of D flip-flop we can find the state equations Q0(t+1) and Q1(t+1) for the to flip flops Q0(t+1) = _______________________ Q1(t+1) = _______________________ _______________________ _______________________ _______________________ _______________________ Circuit Diagram

                                                                Logic Design amp Switching Theory 1 Lab Session 12 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                53

                                                                Implementation Procedure and Observations

                                                                1 Implement the circuit using digital ICs on a bread board (prepare the pin diagram (use appendix A) and refer to laboratory session 01 for procedure)

                                                                2 Make the clear inputs of the flip-flops low (to clear the flip-flops) The flip-flops will remain in clear state as long as the clear inputs are connected to low level

                                                                3 Connect output Q0 and the clock pulse to an oscilloscope 4 Apply 0 to the input x 5 Now make the clear inputs to high 6 Observe the waveform for the first 5 clock pulses and record it 7 Repeat steps 2 to 6 keeping x=1 in step 4 this time 8 Repeat steps 2 to 7 this time connecting Q1 instead of Q0 to the oscilloscope in step

                                                                3 Record your observations (Keep frequency of the clock pulse low (eg1Hz) so that the output waveforms can be observed easily)

                                                                1 2 3 4 5 Clock Pulse

                                                                Output Waveform for Q0 when x=0

                                                                Output Waveform for Q0 when x=1

                                                                Output Waveform for Q1 when x=0

                                                                Output Waveform for Q1 when x=1

                                                                Logic Design amp Switching Theory 1 Lab Session 13 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                Lab Session 13 OBJECT

                                                                Designing a modulo-5 asynchronous up-counter using JK-FF COMPONENTS AND APPARATUS REQUIRED

                                                                1 Following ICs and their Datasheets

                                                                bull 7400 Quad 2-input or 7410 Triple 3-input NAND Gates bull 7476 7473 JK Flip-Flop

                                                                2 Digital Trainer DT-01 or the following components Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches

                                                                THEORY

                                                                Digital Counters A digital counter is a set of flip-flops whose states change in response to pulses applied at the input to the counter The flip-flops are interconnected so that their combined state at any time is the binary equivalent of the total number of pulses that have occurred up to that time Every counter resets after a certain number of clock pulses Thus as it name implies a counter is used to count pulses An n stage counter can count up to a maximum of 2n states n is equal to the number of flip-flops required for the construction of counter

                                                                Modulus Counters The number of input pulses that causes a counter to reset to its initial count is called the modulus of the counter Thus the modulus equals to total number of distinct states (counts) including zero that a counter can store A binary counter with n stages is a modulo-2n (or mod-2n) counter The largest count a mod-N counter can achieve is N-1 ie a mod-N counter never reaches the binary number equal to its modulus N is always equal to or less than 2n Counters can be classified as bull Synchronous Counters which are clock driven All the flip-flops are driven by a

                                                                single clock bull Asynchronous Counters which are event driven Clock input is given to the first

                                                                flip-flop only Rest of the flip-flops are driven by their preceding flip-flops

                                                                DESIGN OF A MOD-5 ASYNCHRONOUS UP COUNTER The number of flip-flops required to construct a mod-5 counter is 3 because 5 should be less than or equal to 2n This counter will count from 0 to 4 a total of 5 distinct states Since a 3-stage counter can count up to 8 states at maximum a NAND gate is used to reset it after 5 clock pulses Figure 131 shows the logic diagram

                                                                54

                                                                Logic Design amp Switching Theory 1 Lab Session 13 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                55

                                                                Figure 131 A Mod-5 Asynchronous Up Counter

                                                                Implementation and Observations

                                                                Implement the mod-5 counter circuit (figure 131) on a bread board (prepare the pin diagram (use appendix A) and refer to laboratory session 01 for implementation procedure) and record the observations in the following table

                                                                Clock Pulse Q2 Q1 Q0

                                                                0 1 2 3 4 5 6 7

                                                                ACTIVITY

                                                                Draw the timing diagram for mod-5 counter designed in this laboratory session

                                                                Logic Design amp Switching Theory 1 Lab Session 14 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                Lab Session 14 OBJECT

                                                                Experimenting with 74194 4-bit bidirectional universal shift register COMPONENTS AND APPARATUS REQUIRED

                                                                1 Following ICs and their Datasheets

                                                                bull 74194 4-bit bidirectional universal shift register 2 Digital Trainer DT-01 or the following components

                                                                Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches

                                                                THEORY

                                                                Shift Registers

                                                                A Register is a set of flip-flops used to store binary data A register which is capable of shifting its binary information either to the right or left is called a shift register The logical configuration of a register consists of a chain of flip-flops connected in cascade with the output of one flip-flop connected to the input of next flip-flop All flip-flops receive a common clock pulse which causes the shift from one stage to the next

                                                                Bidirectional Shift Registers A bi-directional shift register is one whose bits can be shifted from left to right or from right to left

                                                                Universal Shift Registers A universal shift register is a bi-directional register whose input can be in either serial or parallel form and whose output can be in either serial or parallel form

                                                                74194 4-BIT BIDIRECTIONAL UNIVERSAL SHIFT REGISTER

                                                                The 74194 register provides parallel as well as serial loading in both directions Function of various pins of this IC is described below

                                                                bull A B C and D Active high inputs for parallel loading bull QA QB QC and QD Active high outputs bull S0 and S1 Active high mode control inputs The following table shows combinations

                                                                of S1 and S0 to enable various modes

                                                                S1 S0 Clock Action 0 0 x No change 0 1 uarr Shift right 1 0 uarr Shift left 1 1 uarr Parallel load

                                                                uarr shows the rising edge of the clock pulse

                                                                56

                                                                Logic Design amp Switching Theory 1 Lab Session 14 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering bull SR Active high serial input for right shifting bull SL Active high serial input for left shifting bull CLR Active low input Clears all the flip-flops of the register if set to 0 should be

                                                                kept high otherwise bull CLK Clock input bull VCC and GND Supply connections lines Thus A B C and D are inputs for parallel loading whereas SR and SL are inputs for serial loading with right or left shifting respectively S1 and S0 are used to select the loading mode Circuit Diagram

                                                                Figure 141 Pin connections of 74194 Testing Procedure

                                                                bull Make connections as shown in the circuit diagram bull Observe the output for the input combinations given in the following table

                                                                57

                                                                Logic Design amp Switching Theory 1 Lab Session 14 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                58

                                                                Observations

                                                                S1 S0 SL SR A B C D QA QB QC QD 0 0 0 1 0 0 0 0 0 1 1 0 0 0 0 1 1 0 0 0 0 0 1 0 1 1 0 0 0 0 1 1 0 0 1 1 0 1 0 0 0 1 1 1 0 1 0 1 1 0 1 0 0 1 1 0 1 1 1 0 0 1 1 1 1 1 0 0 1 1 1 1

                                                                ACTIVITY 1 Show connections of 74194 to convert it into a ring counter with right shifting

                                                                Logic Design amp Switching Theory 1 Lab Session 15 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                Lab Session 15

                                                                OBJECT

                                                                Experimenting with 74245 octal bus transceivers using parallel port PC interfacing COMPONENTS AND APPARATUS REQUIRED 1 Parallel Port Connectors (DB-25) with Cable 2 Personal Computer with Windows 98 and TurboC Compiler Installed 3 Following ICs and their Datasheets

                                                                bull 74245 Octal Bus Transceivers with 3-State Outputs 4 Digital Trainer DT-01 or the following components

                                                                Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches

                                                                THEORY

                                                                3-State Logic Sometimes it is necessary to isolate one part of circuit from the other part For this purpose some TTL ICs are designed with 3-state logic Such devices have three possible output states high low and high impedance The device can be put into high impedance state by a control signal applied to an appropriate pin When such a device is in high impedance state there is very high impedance at its output effectively isolating the device from whatever circuitry the output normally drives 74245 Octal Bus Transceivers A bus is any conducting path or set of paths having electrical connections to one or more devices 74245 octal bus transceivers are mainly used to control connectivity between two devices or circuits It also provides direction control for signal flow Function of various pin of this IC is given below

                                                                bull A1 through A8 Bus A bull B1 through B8 Bus B bull G΄ Active low enable input When high sets all the bus pins to high impedance state bull DIR Direction control for signal flow When set to high logic level transfers bus A

                                                                data to B bus When set to low logic level transfers bus B data to A bus bull VCC and GND Supply connections lines Serial and Parallel Port Connectors A Parallel Port can consist of only 25 pin port adapter called a DB-25 and a serial port can consist of either a 25 pin port adapter called a DB-25 or 9 pin adapter called a DB-9 port adapter Whether the port is a 9 pin or 25 pin it can accomplish all of the same tasks that serial port communications have been designed for

                                                                59

                                                                Logic Design amp Switching Theory 1 Lab Session 15 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                60

                                                                Each adapter can be a male type connector with pins or a female type adapter with tiny holes Generally a PRINTER port (called LPT1) on the back of a computer is female type adapter and we need to use MALE DB-25 pin cable on it for PRINTER connection or for parallel LAPLINK cable And a COM port on the back of a computer is male for the serial ports but it may not necessarily be Parallel Port Connector ndash DB-25 The DB-25 connector (named for its B-size D-shaped shell and 25 pins) is practically ubiquitous in the electronics industry The DB-25 connector is used for a variety of purposes Two common applications are RS-232EIA-232 (serial) connections and the parallel printer interface on the IBM PC The DB-25 connector is also used for SCSI connections Normally the parallel port is used for output to a printer or other device It sends data 8-bits or one byte at a time in parallel The other lines available on the DB-25 connector are a combination of status lines control lines and ground lines The status and control lines are used for handshaking commands and feedback when we are talking to a printer

                                                                Figure 152 DB-25 Female Figure 151 DB-25 Male

                                                                Figure 153 Pin Layout for DB-25 As can be seen form figure 153 there are four types of pins in this connector

                                                                bull Data pins (8 pins - D0 to D7) Active high bidirectional lines

                                                                Logic Design amp Switching Theory 1 Lab Session 15 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering bull Control pins (4 pins - C0 to C3) C0 C1 and C3 are active low whereas C2 is active

                                                                high These lines also are bidirectional bull Status pins (5 pins ndash S3 to S7) Only S7 is active low rest are active high input lines bull Ground pins (8 pins) Used as a reference signal for the low (below 05 volts) charge

                                                                Parallel Port Addresses A DB-25 connector at a parallel port has three address one for each kind of pins register data status and control The first or base address generally refers to data register Second address is for status register and the third one is for control register In Windows 98 the base address is usually found to be 278H 378H or 3BCH Now if 378H is the base address then it refers to the data register whereas addresses for status and control register are respectively 379H and 37AH For Windows 98 the base address can be found as follows 1 On your Desktop right-click on My Computer and select Properties 2 Click on the Device Manager tab and find LPT1 under Plug and Play BIOS 3 After selecting LPT1 click the Properties button 4 Next select the Resources tab and the address should then appear next to InputOutput

                                                                Range Accessing parallel port through C Language Programming There are multiple functions in C Language for accessing external ports The most commonly used are listed below

                                                                bull unsigned char inportb(int portid) inportb reads a byte from a hardware port

                                                                bull int inport(int portid) reads a word from a hardware port

                                                                bull void outportb(int portid unsigned char value) outputs a byte to a hardware port

                                                                bull void outport(int portid int value) outputs a word to a hardware port

                                                                portid refers to the port address whereas value refers to the data to be sent TESTING 74245 USING PARALLEL PORT PC INTERFACING At one end the parallel port connector will be connected to the PC via parallel port cable and another connector (to be plugged into the PC parallel port slot) At the other end it will be connected to the buffer IC 74245 Data lines of the connector will be used to transfer 8-bit data between the PC and the buffer Out of the 8-bits of 74245 4-bits will be used to enter data which will be displayed at the monitor through a C language

                                                                61

                                                                Logic Design amp Switching Theory 1 Lab Session 15 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering program The remaining 4-bits will receive data from PC as entered by the user via keyboard

                                                                Circuit Diagram

                                                                Figure 154 Interface of 74245 to PC via Parallel Port

                                                                Procedure

                                                                1 Connect the DB-25 connector to the PC at one end and solder it to the circuit board at the other end

                                                                2 Connect various pins of the connector and 74245 according to the circuit diagram shown in figure 152

                                                                3 Using the functions listed in the previous section write a program in C language to operate various pins of the buffer The user interface of the program should provide option to the user whether to send or receive data from the port

                                                                4 Set DIR switch to 1 5 Try sending some data bits to the port The result should be displayed at the LEDs 6 Set DIR switch to 0 7 Set some binary 4-bit value through the switches Try reading it via parallel port

                                                                C Language Program

                                                                A program to access parallel port for data transfers

                                                                use header file include ltstdiohgt main program void main() define variable

                                                                62

                                                                Logic Design amp Switching Theory 1 Lab Session 15 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering unsigned int data=0 char choice while(1) printing option menu clrscr() printf(This program will send or receive a BCD digit from the parallel portn) printf(nPress your choice numbern) printf(n1 Send Data) printf(n2 Receive Data) printf(n3 Exitn) choice = getch() sending entered digit to the port if(choice == 1) input BCD digit printf(nEnter BCD digit to be sent to the port) data = getche() masking the first four bits data = data amp 0x0f sending to the port outportb(0x378data) printf(nThe BCD digit c has been sent to the port data) printing on screen the data received from the port else if(choice == 2) receiving data from the port data = inportb(0x378) masking the last four bits data = data amp 0xf0 shifting first four bits to make them the last four bits datagtgt=4 printf(nThe BCD digit set at the port is c data) exit else if(choice == 3) break key pressed is not in the menu else printf(nEnter valid choice number) printf(nnPress any key to continue) getch()

                                                                63

                                                                Logic Design amp Switching Theory 1 Lab Session 15 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                ACTIVITY 1 In the above circuit DIR and G΄ inputs are hardwired Connect them to status or

                                                                control pins of the parallel port connector and control their function through your software program Circuit Diagram Program Code ______________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________

                                                                ___________________________________________________________________________________________________________________________________________________

                                                                64

                                                                Logic Design amp Switching Theory 1 Lab Session 15 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                65

                                                                _____________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ _____________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ _______________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ _________________________________________________ _________________________________________________

                                                                Logic Design amp Switching Theory 1 Appendix A NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                Appendix A

                                                                PIN DIAGRAMS OF THE ICS REQUIRED FOR THE LABORATORY SESSIONS Consult the TTLIC data book for internal diagrams and electrical characteristics of these ICs 7400 Quad 2-Input NAND 7402 Quad 2-Input NOR

                                                                7404 Hex Inverter 7408 Quad 2-Input AND

                                                                7410 Triple 3-Input NAND 7411 Triple 3-Input AND

                                                                7421 Dual 4-Input AND 7432 Quad 2-Input OR

                                                                66

                                                                Logic Design amp Switching Theory 1 Appendix A NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                BCD-to-Seven Segm 7448 BCD-to-Seven Segment 7447 ent

                                                                Decoder (15V OC) Decoder (2kΩ pull-up output)

                                                                7473 Dual JK Flip-Flop 7474 Dual D-Type Flip-Flop

                                                                7476 Dual JK Flop-Flop -Bit Binary Full Adder 7483 4 with Fast Carry

                                                                86 Quad 2-Inpu 74138 3-to-8 Line 74 t Exclusive OR Decoder Demultiplexer

                                                                67

                                                                Logic Design amp Switching Theory 1 Appendix A NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                68

                                                                74148 8-to-3 Line 16-to-1 Line Data

                                                                Priority Encoder 74150 Selector Multiplexer

                                                                74245 Oct nsceivers Universal Shift Register (PIPO) (3-State)

                                                                74194 4-Bit Bidirectional al Bus Tra

                                                                Logic Design amp Switching Theory 1 Appendix B NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                Appendix B

                                                                DEBOUNCING CIRCUITRY FOR MECHANICAL SWITCHES Mechanical switches form the interface between human beings and computers or other digital systems For example a keyboard is a matrix of switches used to supply alphanumeric data to a computer Whatever the switch design it is a potential source of problems due to contact bounce The contact bounce creates a sense of narrow pulses when a switch is opened or closed An example of device whose operation would be adversely affected by contact bounce is a digital counter used to count the number of times a switch is depressed Eliminating the effects of contact bounce is called debouncing When data is entered into a computer via a keyboard a software debounce is often used This type of debouncing is a program that causes the computer to sample the switch terminal (ie to input data from it) many times in succession during the interval of time that contact bounce occurs If the data is sensed to be 1s (or 0s) for a specific number of consecutive samples then it is assumed that contact bounce has ended and the last value sensed is valid Hardware debouncing is the use of electronic circuitry to eliminate the effects of contact bounce There are numerous versions of such circuitry including those that use monostable multivibrators (one-shots) but the most straightforward is simply an RS latch Figure B1 shows the circuit When the switch is in position 1 R = 0 and S = 1 so the latch is set and the output (Q) is 1 When the switch is in position 0 R = 1and S = 0 so the latch is reset and the output is 0 When the switch is moved form one position to the other the latch changes state and bouncing occurs at either the R or the S input The bouncing does not affect the latch after it has change state An RS latch will remain set for example when its R input is 0 and its S input is alternately changed form 1 to 0

                                                                Figure B1 Use of RS latch to debounce a mechanical switch

                                                                69

                                                                • 01-ldst-Outer title
                                                                  • Practical Workbook
                                                                  • Logic Design amp Switching Theory I
                                                                    • Dept of Computer amp Information Systems Engineering
                                                                      • NED University of Engineering amp Technology
                                                                      • Karachi ndash 75270 Pakistan
                                                                        • 02-ldst-inner Title
                                                                          • Practical Workbook
                                                                          • Logic Design amp Switching Theory I
                                                                            • Dept of Computer amp Information Systems Engineering
                                                                              • NED University of Engineering amp Technology
                                                                              • Karachi ndash 75270 Pakistan
                                                                                • 03-ldst-general info
                                                                                • 04-ldst-introduction
                                                                                • 05-Table of Contents
                                                                                  • CONTENTS
                                                                                    • Lab Session No Object Page No
                                                                                    • 1
                                                                                    • Also implementing and testing the given circuit on a bread board
                                                                                      • Working with Electronics Workbench
                                                                                        • Driving a seven segment display using 7447 7448 driver IC
                                                                                          • Designing a modulus-5 asynchronous up-counter using JK-FF
                                                                                            • Experimenting with 74194 4-bit bidirectional universal shift register
                                                                                                • 13
                                                                                                    • 06-ldst-Exp01
                                                                                                      • Lab Session 01
                                                                                                      • OBJECT
                                                                                                        • 1 Bread board
                                                                                                        • 2 5 V - power supply
                                                                                                        • 3 Multimeter
                                                                                                        • 4 Logic probe
                                                                                                        • 5 LEDs with resistors
                                                                                                        • 6 Connecting wires
                                                                                                        • 8 Following ICs and their datasheets
                                                                                                          • THEORY
                                                                                                            • Logic Gates
                                                                                                            • 1 The AND Gate ndash An AND gatersquos output is 1 if and only if all its inputs are 1 If A and B are two inputs to an AND gate then output F of the gate is given as F = AB
                                                                                                            • 2 The OR Gate - An OR gatersquos output is 1 if at least one of its input is 1 If A and B are two inputs to an OR gate then output F of the gate is given as F = A+B
                                                                                                            • 3 The NOT Gate (Inverter) ndash Its output is 1 when its input is 0 and its output is 0 when the input is 1 ie it complements a digital variable If A is the input to a NOT gate then output F of the gate is given as
                                                                                                            • 4 The NAND Gate ndash Its output is 1 if at least one of its input is 0 This gate performs the same logic as an AND gate followed by an inverter If A and B are two inputs to a NAND gate then output F of the gate is given as
                                                                                                              • 5 The NOR Gate - The output of a NOR gate is 1 if and only if all its inputs are 0 This gate performs the same logic function as an OR gate followed by an inverter If A and B are two inputs to a NAND gate then output F of the gate is given as
                                                                                                                  • DATA SHEETS
                                                                                                                    • Logic expression for the given logic diagram __________________________________
                                                                                                                        • 07-ldst-exp02
                                                                                                                          • Working with Electronics Workbench
                                                                                                                            • 08-ldst-exp03
                                                                                                                              • Designing Half and Full Adder Circuits
                                                                                                                                • COMPONENTS AND APPARATUS REQUIRED
                                                                                                                                  • 1 Following ICs and their Datasheets
                                                                                                                                  • 7408 Quad 2-input AND Gate
                                                                                                                                  • 2 Digital Trainer DT-01 or the following components
                                                                                                                                    • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                    • Connecting wires Switches
                                                                                                                                      • THEORY
                                                                                                                                          • IMPLEMENTATION AND OBSERVATIONS
                                                                                                                                            • 09-ldst-Exp04
                                                                                                                                              • Lab Session 04
                                                                                                                                              • 1 Digital ICs and their Datasheets
                                                                                                                                              • 7408 Quad 2-input AND Gate
                                                                                                                                              • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                • Connecting wires Switches
                                                                                                                                                • PROCEDURE
                                                                                                                                                • REDUCTION OF LOGIC EXPRESSION USING KARNAUGH MAP
                                                                                                                                                • OBSERVATIONS
                                                                                                                                                • RESULT
                                                                                                                                                    • 10-ldst-Exp05
                                                                                                                                                      • Lab Session 05
                                                                                                                                                      • 1 Following ICs and their Datasheets
                                                                                                                                                      • 7408 Quad 2-input AND Gate
                                                                                                                                                      • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                        • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                        • (100 Ω) Connecting wires Switches
                                                                                                                                                        • THEORY
                                                                                                                                                          • IMPLEMENTATION AND OBSERVATIONS
                                                                                                                                                            • 11-ldst-Exp06
                                                                                                                                                              • OBJECT
                                                                                                                                                              • 1 Following ICs and their Datasheets
                                                                                                                                                              • 7408 Quad 2-input AND Gates or 7411 Triple 3-input AND Gates
                                                                                                                                                              • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                • Connecting wires Switches
                                                                                                                                                                  • Figure 62 Circuit Diagram for 4 x 1 Multiplexer
                                                                                                                                                                  • Implementation and Observations
                                                                                                                                                                    • Circuit Diagram
                                                                                                                                                                      • ACTIVITY
                                                                                                                                                                        • 12-ldst-exp07
                                                                                                                                                                          • 1 Following ICs and their Datasheets
                                                                                                                                                                          • 7408 Quad 2-input or 7411 Triple 3-input AND Gates
                                                                                                                                                                          • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                            • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                            • Connecting wires Switches
                                                                                                                                                                              • THEORY
                                                                                                                                                                                  • Figure 72 Circuit Diagram for 2 x 4 Decoder 1 x 4 Demultiplexer
                                                                                                                                                                                  • Implementation and Observations
                                                                                                                                                                                    • Circuit Diagram
                                                                                                                                                                                      • ACTIVITY
                                                                                                                                                                                        • 13-ldst-Exp08
                                                                                                                                                                                          • OBJECT
                                                                                                                                                                                          • 1 Following ICs and their Datasheets
                                                                                                                                                                                          • 7408 Quad 2-input or 7421 Dual 4-input AND Gates
                                                                                                                                                                                          • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                            • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                            • Connecting wires Switches
                                                                                                                                                                                              • THEORY
                                                                                                                                                                                                  • Figure 81 Circuit Diagram for 4 x 2 Priority Encoder
                                                                                                                                                                                                  • Implementation and Observations
                                                                                                                                                                                                    • Therefore if GS A2 A1 and A0 are all low then it shows that line 0 is selected and if E0 A2 A1 and A0 are all low then it shows that none of the inputs selected E0 and GS cannot be in the same state provided that E1 is enabled
                                                                                                                                                                                                    • Circuit Diagram
                                                                                                                                                                                                      • ACTIVITY
                                                                                                                                                                                                        • 14-ldst-exp09
                                                                                                                                                                                                          • OBJECT
                                                                                                                                                                                                          • 1 Following ICs and their Datasheets
                                                                                                                                                                                                          • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                            • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                            • Connecting wires Switches
                                                                                                                                                                                                              • THEORY
                                                                                                                                                                                                                • Parity Generator
                                                                                                                                                                                                                  • Let x y and z be the three bits that constitute the message and are the input to the Odd Parity Generator Circuit Since it is an odd parity system the bit P is generated so as to make the total number of 1s odd (including P) The function P can be expressed as follows
                                                                                                                                                                                                                  • Figure 91 Circuit Diagram for a 3-bit Parity Generator
                                                                                                                                                                                                                    • C = x Ο y Ο z Ο P
                                                                                                                                                                                                                      • Implementation and Observations
                                                                                                                                                                                                                        • ACTIVITY
                                                                                                                                                                                                                            • 15-ldst-exp10
                                                                                                                                                                                                                              • Driving a seven segment display using 7447 7448 driver IC
                                                                                                                                                                                                                              • COMPONENTS AND APPARATUS REQUIRED
                                                                                                                                                                                                                              • 1 Following ICs and their Datasheets
                                                                                                                                                                                                                              • 7447 7448 BCD to Seven Segment Driver
                                                                                                                                                                                                                              • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                                • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches
                                                                                                                                                                                                                                  • THEORY
                                                                                                                                                                                                                                  • Seven Segment Displays
                                                                                                                                                                                                                                  • CIRCUIT DIAGRAM
                                                                                                                                                                                                                                  • Figure 102 Circuit diagram for 7447driving a common-anode display
                                                                                                                                                                                                                                      • IMPLEMENTATION AND OBSERVATIONS
                                                                                                                                                                                                                                        • Decimal Digit
                                                                                                                                                                                                                                        • BCD Inputs
                                                                                                                                                                                                                                        • Seven Segment Outputs
                                                                                                                                                                                                                                        • D
                                                                                                                                                                                                                                        • C
                                                                                                                                                                                                                                        • B
                                                                                                                                                                                                                                        • A
                                                                                                                                                                                                                                        • a
                                                                                                                                                                                                                                        • b
                                                                                                                                                                                                                                        • c
                                                                                                                                                                                                                                        • d
                                                                                                                                                                                                                                        • e
                                                                                                                                                                                                                                        • f
                                                                                                                                                                                                                                        • g
                                                                                                                                                                                                                                        • 0
                                                                                                                                                                                                                                        • 0
                                                                                                                                                                                                                                        • 0
                                                                                                                                                                                                                                        • 0
                                                                                                                                                                                                                                        • 0
                                                                                                                                                                                                                                        • 1
                                                                                                                                                                                                                                        • 0
                                                                                                                                                                                                                                        • 0
                                                                                                                                                                                                                                        • 0
                                                                                                                                                                                                                                        • 1
                                                                                                                                                                                                                                        • 2
                                                                                                                                                                                                                                        • 0
                                                                                                                                                                                                                                        • 0
                                                                                                                                                                                                                                        • 1
                                                                                                                                                                                                                                        • 0
                                                                                                                                                                                                                                        • 3
                                                                                                                                                                                                                                        • 0
                                                                                                                                                                                                                                        • 0
                                                                                                                                                                                                                                        • 1
                                                                                                                                                                                                                                        • 1
                                                                                                                                                                                                                                        • 4
                                                                                                                                                                                                                                        • 0
                                                                                                                                                                                                                                        • 1
                                                                                                                                                                                                                                        • 0
                                                                                                                                                                                                                                        • 0
                                                                                                                                                                                                                                        • 5
                                                                                                                                                                                                                                        • 0
                                                                                                                                                                                                                                        • 1
                                                                                                                                                                                                                                        • 0
                                                                                                                                                                                                                                        • 1
                                                                                                                                                                                                                                        • 6
                                                                                                                                                                                                                                        • 0
                                                                                                                                                                                                                                        • 1
                                                                                                                                                                                                                                        • 1
                                                                                                                                                                                                                                        • 0
                                                                                                                                                                                                                                        • 7
                                                                                                                                                                                                                                        • 0
                                                                                                                                                                                                                                        • 1
                                                                                                                                                                                                                                        • 1
                                                                                                                                                                                                                                        • 1
                                                                                                                                                                                                                                        • 8
                                                                                                                                                                                                                                        • 1
                                                                                                                                                                                                                                        • 0
                                                                                                                                                                                                                                        • 0
                                                                                                                                                                                                                                        • 0
                                                                                                                                                                                                                                        • 9
                                                                                                                                                                                                                                        • 1
                                                                                                                                                                                                                                        • 0
                                                                                                                                                                                                                                        • 0
                                                                                                                                                                                                                                        • 1
                                                                                                                                                                                                                                          • ACTIVITY
                                                                                                                                                                                                                                            • 16-ldst-exp11
                                                                                                                                                                                                                                              • Lab Session 11
                                                                                                                                                                                                                                                • OBJECT
                                                                                                                                                                                                                                                • COMPONENTS AND APPARATUS REQUIRED
                                                                                                                                                                                                                                                  • 1 Following ICs and their Datasheets
                                                                                                                                                                                                                                                  • 7473 7476 JK Flip-Flop
                                                                                                                                                                                                                                                  • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                                                    • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                                                                    • Connecting wires Switches
                                                                                                                                                                                                                                                      • THEORY
                                                                                                                                                                                                                                                          • Flip-Flop
                                                                                                                                                                                                                                                          • JK Flip-Flop
                                                                                                                                                                                                                                                            • Circuit Diagram
                                                                                                                                                                                                                                                              • Observations
                                                                                                                                                                                                                                                                • ACTIVITY
                                                                                                                                                                                                                                                                    • 17-ldst-exp12
                                                                                                                                                                                                                                                                      • Lab Session 12
                                                                                                                                                                                                                                                                        • OBJECT
                                                                                                                                                                                                                                                                        • GIVEN STATE DIAGRAM
                                                                                                                                                                                                                                                                        • Figure 121 State Diagram
                                                                                                                                                                                                                                                                        • COMPONENTS AND APPARATUS REQUIRED
                                                                                                                                                                                                                                                                          • 1 Following ICs and their Datasheets
                                                                                                                                                                                                                                                                          • 7474 D Flip-Flop
                                                                                                                                                                                                                                                                          • ICs of basic gates (AND OR NOT XOR etc) as required
                                                                                                                                                                                                                                                                          • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                                                                            • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                                                                                            • Connecting wires Switches
                                                                                                                                                                                                                                                                              • THEORY
                                                                                                                                                                                                                                                                                  • Sequential Circuits
                                                                                                                                                                                                                                                                                    • 18-ldst-exp13
                                                                                                                                                                                                                                                                                      • Lab Session 13
                                                                                                                                                                                                                                                                                        • Designing a modulo-5 asynchronous up-counter using JK-FF
                                                                                                                                                                                                                                                                                          • 1 Following ICs and their Datasheets
                                                                                                                                                                                                                                                                                          • 7400 Quad 2-input or 7410 Triple 3-input NAND Gates
                                                                                                                                                                                                                                                                                          • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                                                                                            • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                                                                                                            • Connecting wires Switches
                                                                                                                                                                                                                                                                                              • THEORY
                                                                                                                                                                                                                                                                                                  • Figure 131 A Mod-5 Asynchronous Up Counter
                                                                                                                                                                                                                                                                                                  • Implementation and Observations
                                                                                                                                                                                                                                                                                                    • ACTIVITY
                                                                                                                                                                                                                                                                                                        • 19-ldst-exp14
                                                                                                                                                                                                                                                                                                          • Experimenting with 74194 4-bit bidirectional universal shift register
                                                                                                                                                                                                                                                                                                          • 1 Following ICs and their Datasheets
                                                                                                                                                                                                                                                                                                          • 74194 4-bit bidirectional universal shift register
                                                                                                                                                                                                                                                                                                          • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                                                                                                            • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                                                                                                                            • Connecting wires Switches
                                                                                                                                                                                                                                                                                                              • THEORY
                                                                                                                                                                                                                                                                                                                • Shift Registers
                                                                                                                                                                                                                                                                                                                • Bidirectional Shift Registers
                                                                                                                                                                                                                                                                                                                • Universal Shift Registers
                                                                                                                                                                                                                                                                                                                  • S1
                                                                                                                                                                                                                                                                                                                    • Circuit Diagram
                                                                                                                                                                                                                                                                                                                    • ACTIVITY
                                                                                                                                                                                                                                                                                                                        • 20-ldst-exp15
                                                                                                                                                                                                                                                                                                                          • COMPONENTS AND APPARATUS REQUIRED
                                                                                                                                                                                                                                                                                                                          • 1 Parallel Port Connectors (DB-25) with Cable
                                                                                                                                                                                                                                                                                                                          • 2 Personal Computer with Windows 98 and TurboC Compiler Installed
                                                                                                                                                                                                                                                                                                                          • 3 Following ICs and their Datasheets
                                                                                                                                                                                                                                                                                                                          • 74245 Octal Bus Transceivers with 3-State Outputs
                                                                                                                                                                                                                                                                                                                          • 4 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                                                                                                                            • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                                                                                                                                              • Connecting wires Switches
                                                                                                                                                                                                                                                                                                                                • THEORY
                                                                                                                                                                                                                                                                                                                                • 3-State Logic
                                                                                                                                                                                                                                                                                                                                  • Serial and Parallel Port Connectors
                                                                                                                                                                                                                                                                                                                                  • Parallel Port Connector ndash DB-25
                                                                                                                                                                                                                                                                                                                                    • Accessing parallel port through C Language Programming
                                                                                                                                                                                                                                                                                                                                        • 21-ldst-appendixA
                                                                                                                                                                                                                                                                                                                                        • 22-ldst-appendixB
                                                                                                                                                                                                                                                                                                                                          • DEBOUNCING CIRCUITRY FOR MECHANICAL SWITCHES

                                                                  Logic Design amp Switching Theory 1 Lab Session 07 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                  Figure 72 Circuit Diagram for 2 x 4 Decoder 1 x 4 Demultiplexer

                                                                  Implementation and Observations Implement the 2 x 4 Decoder 1 x 4 Demultiplexer circuit (figure 72) on a bread board (prepare the pin diagram (use appendix A) and refer to laboratory session 01 for implementation procedure) and record the observations in the following table

                                                                  Enable Data Input S1 S0 D0 D1 D2 D3

                                                                  0 0 0 0 0 1 0 1 0 0 1 1 1 0 0 1 0 1 1 1 0 1 1 1

                                                                  TESTING OF 74138 3 x 8 Decoder The 74138 IC has three inputs and eight output lines It has three enable inputs and for the IC to function all three inputs need to be enabled Function of various pins of this IC is described below

                                                                  35

                                                                  Logic Design amp Switching Theory 1 Lab Session 07 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                  bull Y0 through Y7 Active low data outputs bull A B C Input select lines with C being the MSB bull G1 Active high enable Input bull G2Arsquo and G2Brsquo Active low enable Inputs bull VCC and GND Supply connections lines Circuit Diagram

                                                                  Figure 73 Pin connections of 74138

                                                                  Testing Procedure

                                                                  bull Make connections as shown in the circuit diagram bull Apply different combinations of 1s and 0s at data inputs bull Observe the output and record your observations in the following table

                                                                  Observations

                                                                  C B A Y0 Y1 Y2 Y3 Y4 Y5 Y6 Y7 0 0 0 0 0 1 0 1 0 0 1 1 1 0 0 1 0 1 1 1 0 1 1 1

                                                                  36

                                                                  Logic Design amp Switching Theory 1 Lab Session 07 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                  37

                                                                  ACTIVITY ACTIVITY 1 What will be the binary values at the outputs Y0 through Y7 of 74138 if 1 What will be the binary values at the outputs Y0 through Y7 of 74138 if

                                                                  bull All three enable pins are connected to ground bull All three enable pins are connected to ground __________________________________________________________________________________________________________________________________________ __________________________________________________________________________________________________________________________________________ _____________________________________________________________________ _____________________________________________________________________

                                                                  bull All three enable pins are connected to VCC bull All three enable pins are connected to VCC _______________________________________________________________________________________________________________________________________________________________________________________________________________

                                                                  _______________________________________________________________________________________________________________________________________________________________________________________________________________

                                                                  2 Show connections for 74138 in order to use it as a 1 x 8 Demultiplexer 2 Show connections for 74138 in order to use it as a 1 x 8 Demultiplexer

                                                                  3 Consider a 2 x 4 Decoder with two enable inputs (one active high - G and one active low ndash Grsquo) Draw the output wave-forms for D0 D1 D2 and D3 if the two select inputs are A and B (B being the MSB) All outputs are active low

                                                                  Grsquo

                                                                  G

                                                                  A B

                                                                  D0 D1 D2

                                                                  D3

                                                                  Logic Design amp Switching Theory 1 Lab Session 08 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                  Lab Session 08 OBJECT

                                                                  bull Designing of a 4 x 2 Priority Encoder bull Experimenting with 74148 IC

                                                                  COMPONENTS AND APPARATUS REQUIRED

                                                                  1 Following ICs and their Datasheets

                                                                  bull 7408 Quad 2-input or 7421 Dual 4-input AND Gates bull 7432 Quad 2-input OR Gates bull 7404 Hex Inverter bull 74148 Encoder

                                                                  2 Digital Trainer DT-01 or the following components Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches

                                                                  THEORY

                                                                  Encoder An Encoder is a digital function that produces a reverse operation from that of a decoder An Encoder has 2n (or less) input lines and n output lines The output lines generate the binary code for the 2n input variables Priority Encoder

                                                                  A simple encoder may produce an erroneous output if more than one of its inputs is high A Priority Encoder is one that responds to just one input among those that may be simultaneously high in accordance with some priority system The most common priority system is based on the relative magnitudes of the inputs whichever decimal input is largest is the one that is encoded

                                                                  DESIGN OF A 4 x 2 Priority Encoder

                                                                  The following equations represent the outputs of a 4 x 2 priority encoder 32 DDA +=

                                                                  321 DDDB += As can be seen from the equations that input D0 which has a binary code 00 is not used in any equation A binary code 00 at the output indicates two conditions Either D0 is selected or no input is selected In order to differentiate these two conditions we will provide an additional output Z to indicate if at least one of the inputs is a 1 The equation for Z will be

                                                                  4321 DDDDZ = If Z is 0 then the binary code 00 at the output indicates that D0 is selected and if Z is 1 then it indicates that no input line is selected

                                                                  38

                                                                  Logic Design amp Switching Theory 1 Lab Session 08 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                  Figure 81 Circuit Diagram for 4 x 2 Priority Encoder

                                                                  it (figure 81) on a bread board (prepare the to laboratory session 01 for implementation

                                                                  Implementation a Implement the 4 x 2 Priority Encoder circu

                                                                  ram (use appendix A) and refer

                                                                  nd Observations

                                                                  pin diagprocedure) and record the observations in the following table

                                                                  D3 D2 D1 D0 A B 0 0 0 1 0 0 1 x 0 1 x x 1 x x x

                                                                  TESTING OF 74148 8 x 3 Octal Priority Encoder

                                                                  imal digits There are nine of which three represents

                                                                  ing any of the inputs is high

                                                                  then it shows that line 0 is selected and if e inputs selected E0 and GS

                                                                  cannot be in the same state provided that E1 is enabled

                                                                  The 74148 is a priority encoder with active-Low input for dec

                                                                  input) and five output linesinputs lines (including an enablethe binary code for the octal digit Function of various pins of this IC is described below

                                                                  bull 0 through 7 Active low data inputs representing the octal digits A2 A1 A0 Active low output lines representing the binary code bullbull E1 Active low enable Input bull E0 Active low output indicating none of the inputs is high bull GS Active low output indicatbull VCC and GND Supply connections lines Therefore if GS A2 A1 and A0 are all low

                                                                  then it shows that none of thE0 A2 A1 and A0 are all low

                                                                  39

                                                                  Logic Design amp Switching Theory 1 Lab Session 08 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                  Circuit Diagram

                                                                  Figure 82 Pin connections of 74148

                                                                  Testing Procedure bull Make connections as sho

                                                                  binations of 1s and 0s at data inputs d record your observations in the following table

                                                                  GS E0

                                                                  wn in the circuit diagram bull Apply different combull Observe the output an Observations

                                                                  0 1 2 3 4 5 6 7 A2 A1 A0 1 1 1 1 1 1 1 1 x x x x x x x 0 x x x x x x 0 1 x x x x x 0 1 1 x x x x 0 1 1 1 x x x 0 1 1 1 1 x x 0 1 1 1 1 1 x 0 1 1 1 1 1 1 0 1 1 1 1 1 1 1

                                                                  40

                                                                  Logic Design amp Switching Theory 1 Lab Session 08 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                  41

                                                                  CTIVITY

                                                                  Cascade the following two 74148 8 x 3 Priority Encoders to form 16 x 4 Priority

                                                                  A 1

                                                                  Encoder

                                                                  Logic Design amp Switching Theory 1 Lab Session 09 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering `

                                                                  Lab Session 09 OBJECT

                                                                  Designing an Odd Parity Generator and Checker for a 3-bit Data COMPONENTS AND APPARATUS REQUIRED

                                                                  1 Following ICs and their Datasheets

                                                                  bull 7486 Quad 2-input Exclusive-OR Gates bull 7404 Hex Inverter

                                                                  2 Digital Trainer DT-01 or the following components Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches

                                                                  THEORY

                                                                  Parity Generator When binary data is transmitted and processed it is ndash as are all electrical signals ndash susceptible to noise that can either alter or distort its contents 1s may be effectively changed to 0s and 0s to 1s To overcome this problem one or more bits are often added to the data as an aid in detecting errors caused by noise The most common of these is a Parity bit that signifies whether the total number of 1s in a code group is odd or even In an Odd Parity system the parity bit is made 0 or 1 as necessary to make the total number 1s odd (counting the parity bit itself) In an Even Parity system the parity bit is chosen to make the total number of 1s even Table 91 shows how parity bits would be added to BCD code group in both systems

                                                                  Decimal BCD Value Parity Bit ABCD Odd Parity Even Parity

                                                                  0 0000 1 0 1 0001 0 1 2 0010 0 1 3 0011 1 0 4 0100 0 1 5 0101 1 0 6 0110 1 0 7 0111 0 1 8 1000 0 1 9 1001 1 0

                                                                  Table 91 Odd and Even Parity in BCD

                                                                  When digital data is received a parity checking circuit generates an error signal if the total number of 1s is odd in an even parity system or if it is even in an odd parity system Parity check always detects a single error (one bit change from 0 to 1 or 1 to 0) but may not detect

                                                                  42

                                                                  Logic Design amp Switching Theory 1 Lab Session 09 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering ` two or more errors Odd parity is used more often than even parity because even parity does not detect a situation where all 0s are created due to short circuit or other fault condition DESIGN OF A 3-BIT ODD PARITY GENERATOR AND CHECKER Let x y and z be the three bits that constitute the message and are the input to the Odd Parity Generator Circuit Since it is an odd parity system the bit P is generated so as to make the total number of 1s odd (including P) The function P can be expressed as follows P = x oplus y Ο z or P = x Ο y oplus z Since the IC available is 7486 which is quad 2input XOR IC therefore we will convert XNOR also to XOR

                                                                  P = x oplus y Ο z

                                                                  P = ( x oplus y ) Ο z Since for even number of variables ______

                                                                  XOR = XNOR Therefore ___________ _________

                                                                  P = ( x oplus y ) oplus z = x oplus y oplus z This logical expression can be implemented with two XOR gates and an inverter (see figure 91)

                                                                  Figure 91 Circuit Diagram for a 3-bit Parity Generator

                                                                  The 3-bit message and the parity bit are transmitted to their destination where they are applied to a Parity Checker Circuit An error occurs during transmission if the parity of the four bits received is even since the binary information transmitted was originally odd The output C of the parity checker should be a 1 when an error occurs ie when the number of 1s in the four inputs is even Therefore the function C can be expressed as

                                                                  C = x Ο y Ο z Ο P

                                                                  Using the same logic applied for the conversion of the equation of P

                                                                  PzyxC oplusoplusoplus= This logical expression can be implemented with three XOR gates and an inverter (see figure 92)

                                                                  43

                                                                  Logic Design amp Switching Theory 1 Lab Session 09 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering `

                                                                  44

                                                                  Figure 92 Circuit Diagram for a 3-bit Parity Checker Implementation and Observations Implement the 3-bit Parity Generator and Checker circuits (figure 91 and 92) on a bread board (prepare the pin diagram (use appendix A) and refer to laboratory session 01 for implementation procedure) and record the observations in the following table

                                                                  x y z P x y z P C x y z P C 0 0 0 0 0 0 0 1 0 0 0 0 0 1 0 0 0 1 1 0 0 1 0 1 0 0 0 1 0 1 0 1 0 0 1 1 0 0 1 1 1 0 1 1 1 0 0 0 1 0 0 1 1 0 0 1 0 1 0 1 0 1 1 1 0 1 1 1 0 0 1 1 0 1 1 1 0 1 1 1 0 1 1 1 1 1 1 1

                                                                  Odd Parity Generation Odd Parity Check ACTIVITY 1 Try using the parity checker of figure 92 as 3-bit parity generator Write the details here

                                                                  _____________________________________________________________________________________________________________________________________________________________________________________________________________________ ______________________________________________________________________________________________________________________________________________ _______________________________________________________________________ ______________________________________________________________________________________________________________________________________________

                                                                  Logic Design amp Switching Theory 1 Lab Session 10 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                  Lab Session 10 OBJECT

                                                                  Driving a seven segment display using 7447 7448 driver IC COMPONENTS AND APPARATUS REQUIRED

                                                                  1 Following ICs and their Datasheets

                                                                  bull Seven Segment Displays (Common Anode Common Cathode) bull 7447 7448 BCD to Seven Segment Driver

                                                                  2 Digital Trainer DT-01 or the following components Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches

                                                                  THEORY Seven Segment Displays A Seven Segment Display consists of seven light-emitting segments The segments are designated by letters a through g (see figure 101) By illuminating various combinations of segments the numerals 0 through 9 can be displayed Seven Segment Displays are commonly constructed with light-emitting diodes (LEDs) and with liquid-crystal displays (LCDs) LEDs generally provide greater illumination levels but require much greater power than LCDs An LED display can be a common-anode type or common cathode type In common anode type a high voltage is applied at the common terminal of the display and low voltage is applied at a segmentrsquos terminal for illumination In the common-cathode type a low voltage is applied at the common terminal of the display and high voltage is applied at a segmentrsquos terminal for illumination

                                                                  Figure 101 Seven Segment Display

                                                                  a f b g

                                                                  e c d

                                                                  7447 7448 BCD to Seven Segment Driver 7447 7448 IC is particularly used to drive Seven Segment Its input is a BCD number and output drives a seven segment display 7447 is used to drive common-anode displays whereas 7448 is used to drive common cathode displays 7447 7448 is a 16 pin IC Function of various pins of these ICs is described below

                                                                  bull A B C D Inputs representing BCD digits (D being the MSB)

                                                                  45

                                                                  Logic Design amp Switching Theory 1 Lab Session 10 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering bull OA through OG Outputs to drive segments a through g of the display (Active low

                                                                  in 7447 and active high in 7448) bull RBI Ripple Blanking Input Turns off all the segments if kept low provided that LT

                                                                  is kept high and all other inputs (A B C D BI) are kept low Should be kept high otherwise

                                                                  bull BI RBO Wire-AND logic serving as a Blanking Input and or Ripple Blanking Output

                                                                  o BI Turns off all the segments if low o RBO Goes to a low level (response condition) along with other outputs when

                                                                  RBI and inputs A B C and D are low with LT input at high level bull LT Lamp Test input Tests whether all segments are working or not Illuminates all

                                                                  segments if kept low provided that BI is kept high Should be kept high otherwise bull VCC and GND Supply connections lines CIRCUIT DIAGRAM

                                                                  Figure 102 Circuit diagram for 7447driving a common-anode display

                                                                  IMPLEMENTATION AND OBSERVATIONS

                                                                  bull Make connections as shown in the circuit diagram (refer to laboratory session 01 for implementation procedure)

                                                                  bull Apply different combinations of 1s and 0s at data inputs bull Observe the output and record your observations in the following table

                                                                  46

                                                                  Logic Design amp Switching Theory 1 Lab Session 10 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                  47

                                                                  Decimal Digit

                                                                  BCD Inputs Seven Segment Outputs D C B A a b c d e f g

                                                                  0 0 0 0 0 1 0 0 0 1 2 0 0 1 0 3 0 0 1 1 4 0 1 0 0 5 0 1 0 1 6 0 1 1 0 7 0 1 1 1 8 1 0 0 0 9 1 0 0 1

                                                                  ACTIVITY 1 Perform the Lamp Test for the designed circuit and write your observations

                                                                  ____________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________

                                                                  2 How can you use 7447 IC to drive a common-cathode display

                                                                  ____________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________

                                                                  3 What symbols appear in the seven segment display if inputs DCBA are

                                                                  DCBA Symbol

                                                                  1010

                                                                  1011

                                                                  1100

                                                                  1101

                                                                  1110

                                                                  1111

                                                                  Logic Design amp Switching Theory 1 Lab Session 11 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                  48

                                                                  Lab Session 11 OBJECT

                                                                  Testing different modes of JK-FF COMPONENTS AND APPARATUS REQUIRED 1 Following ICs and their Datasheets

                                                                  bull 7473 7476 JK Flip-Flop 2 Digital Trainer DT-01 or the following components

                                                                  Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches

                                                                  THEORY

                                                                  Flip-Flop A flip-flop circuit can maintain a binary state indefinitely (as long as the power is delivered to the circuit) until directed by an input signal to switch states The major differences among various types of flip-flops are in the number of inputs they possess and in the manner in which the inputs affect the binary state

                                                                  JK Flip-Flop JK flip flop is an edge triggered device A typical JK flip flop has three inputs J K and a clock input The flip-flop can be either positive or negative edge triggered The output Q is available in complemented form as well Beside the usual inputs and output most of the flip-flop IC also possess two asynchronous inputs namely Preset and Clear These inputs are usually active low If used Preset and Clear inputs keep the flip-flop in set and reset state respectively irrespective of the other inputs Both of these inputs cannot be used simultaneously otherwise they will bring the flip-flop in unstable state

                                                                  Figure 111 Symbol for JK flip-flop

                                                                  (a) positive-edge triggering (b) active low Preset (PR) and Clear (CLR) with positive-edge triggering

                                                                  (c) active low Preset (PR) and Clear (CLR) with negative-edge triggering

                                                                  Logic Design amp Switching Theory 1 Lab Session 11 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                  49

                                                                  TESTING OF 7473 7476 DUAL JK FLIP-FLOP

                                                                  Both the ICs 7473 and 7476 are similar in functionality except for one difference The flip-flops in 7473 have only one type of active low asynchronous input which is the Clear input whereas the flip-flops in 7476 have both Preset and Clear inputs Both these ICs have negative edge triggered flip-flops

                                                                  Circuit Diagram

                                                                  Figure 112 Pin connections of 7476

                                                                  Testing Procedure

                                                                  bull Make connections as shown in the circuit diagram (figure 112) bull Apply different combinations of 1s and 0s at J and K inputs bull Observe the output and record your observations in the following table

                                                                  Observations

                                                                  J

                                                                  K Q

                                                                  0 0 0 1 1 0 1 1

                                                                  ACTIVITY

                                                                  1 Observe the output Q of JK flip-flop if the clock input is connected to VCC or GND instead of a clock source Write your observations here __________________________________________________________________________________________________________________________________________ _______________________________________________________________________________________________________________________________________________________________________________________________________________

                                                                  Logic Design amp Switching Theory 1 Lab Session 12 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                  50

                                                                  Lab Session 12 OBJECT

                                                                  Designing sequential circuit for the given state diagram using D flip-flop GIVEN STATE DIAGRAM

                                                                  00

                                                                  11

                                                                  Figure 121 State Diagram COMPONENTS AND APPARATUS REQUIRED 1 Following ICs and their Datasheets

                                                                  bull 7474 D Flip-Flop bull ICs of basic gates (AND OR NOT XOR etc) as required

                                                                  2 Digital Trainer DT-01 or the following components Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches

                                                                  THEORY

                                                                  Sequential Circuits In Sequential Circuits the output not only depends on the present inputs but also on previous states of the circuit These circuits use memory elements (latches flip-flops) and the binary information stored in the memory elements at any given time defines the state of the sequential circuit Analysis of a Sequential Circuit The behavior of a sequential circuit is determined from the inputs the outputs and the states of its flip-flops Both the outputs and next state are a function of the inputs and the

                                                                  10

                                                                  01

                                                                  00 11 10

                                                                  00

                                                                  00 11 10 00

                                                                  Logic Design amp Switching Theory 1 Lab Session 12 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                  51

                                                                  present state The analysis of a sequential circuit form a state diagram comprises of the following bull Selecting a particular flip-flop to design the circuit bull Obtaining state table from the state diagram bull Finding input equations for the selected flip-flop bull Finding state equations (not required for the construction of circuit) bull Implementing the circuit using selected flip-flops and their input equations ANALYZING THE GIVEN STATE DIAGRAM D Flip-Flop D flip-flop is also called transparent flip-flop as it simply transfers the input data to the output For our design we require the graphical symbol and excitation table of D flip-flop (see figure 122)

                                                                  Qt Qt+1 T 0 0 0 0 1 1 1 0 0 1 1 1

                                                                  (b) Excitation table of D Flip-Flop

                                                                  (a) Graphical Symbol

                                                                  Figure 122 Characteristic equation of D flip-flop is Q(t+1) = D State Table The given state diagram has four states so we will need two D flip-flops (FF-0 FF-1) Form state table form the given state diagram and record the results in the following table

                                                                  Present State Input Next State Output Input to FF-0 D0

                                                                  Input to FF-1 D1 Q1t Q0t x Q1(t+1) Q0(t+1) z

                                                                  Logic Design amp Switching Theory 1 Lab Session 12 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                  52

                                                                  Input Equations Using Karnaugh map the input equations D0 and D1 for the two flip-flops can be found

                                                                  D0 D1 Q0x

                                                                  Q1

                                                                  _ _ Q0x

                                                                  _ Q0x

                                                                  Q0x

                                                                  _ Q0x

                                                                  Q0x

                                                                  Q1

                                                                  _ _ Q0x

                                                                  _ Q0x

                                                                  Q0x

                                                                  _ Q0x

                                                                  _ Q1

                                                                  _ Q1

                                                                  Q1

                                                                  Q1

                                                                  D0 = _________________ D1 = _________________

                                                                  State Equations Using the characteristic equation of D flip-flop we can find the state equations Q0(t+1) and Q1(t+1) for the to flip flops Q0(t+1) = _______________________ Q1(t+1) = _______________________ _______________________ _______________________ _______________________ _______________________ Circuit Diagram

                                                                  Logic Design amp Switching Theory 1 Lab Session 12 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                  53

                                                                  Implementation Procedure and Observations

                                                                  1 Implement the circuit using digital ICs on a bread board (prepare the pin diagram (use appendix A) and refer to laboratory session 01 for procedure)

                                                                  2 Make the clear inputs of the flip-flops low (to clear the flip-flops) The flip-flops will remain in clear state as long as the clear inputs are connected to low level

                                                                  3 Connect output Q0 and the clock pulse to an oscilloscope 4 Apply 0 to the input x 5 Now make the clear inputs to high 6 Observe the waveform for the first 5 clock pulses and record it 7 Repeat steps 2 to 6 keeping x=1 in step 4 this time 8 Repeat steps 2 to 7 this time connecting Q1 instead of Q0 to the oscilloscope in step

                                                                  3 Record your observations (Keep frequency of the clock pulse low (eg1Hz) so that the output waveforms can be observed easily)

                                                                  1 2 3 4 5 Clock Pulse

                                                                  Output Waveform for Q0 when x=0

                                                                  Output Waveform for Q0 when x=1

                                                                  Output Waveform for Q1 when x=0

                                                                  Output Waveform for Q1 when x=1

                                                                  Logic Design amp Switching Theory 1 Lab Session 13 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                  Lab Session 13 OBJECT

                                                                  Designing a modulo-5 asynchronous up-counter using JK-FF COMPONENTS AND APPARATUS REQUIRED

                                                                  1 Following ICs and their Datasheets

                                                                  bull 7400 Quad 2-input or 7410 Triple 3-input NAND Gates bull 7476 7473 JK Flip-Flop

                                                                  2 Digital Trainer DT-01 or the following components Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches

                                                                  THEORY

                                                                  Digital Counters A digital counter is a set of flip-flops whose states change in response to pulses applied at the input to the counter The flip-flops are interconnected so that their combined state at any time is the binary equivalent of the total number of pulses that have occurred up to that time Every counter resets after a certain number of clock pulses Thus as it name implies a counter is used to count pulses An n stage counter can count up to a maximum of 2n states n is equal to the number of flip-flops required for the construction of counter

                                                                  Modulus Counters The number of input pulses that causes a counter to reset to its initial count is called the modulus of the counter Thus the modulus equals to total number of distinct states (counts) including zero that a counter can store A binary counter with n stages is a modulo-2n (or mod-2n) counter The largest count a mod-N counter can achieve is N-1 ie a mod-N counter never reaches the binary number equal to its modulus N is always equal to or less than 2n Counters can be classified as bull Synchronous Counters which are clock driven All the flip-flops are driven by a

                                                                  single clock bull Asynchronous Counters which are event driven Clock input is given to the first

                                                                  flip-flop only Rest of the flip-flops are driven by their preceding flip-flops

                                                                  DESIGN OF A MOD-5 ASYNCHRONOUS UP COUNTER The number of flip-flops required to construct a mod-5 counter is 3 because 5 should be less than or equal to 2n This counter will count from 0 to 4 a total of 5 distinct states Since a 3-stage counter can count up to 8 states at maximum a NAND gate is used to reset it after 5 clock pulses Figure 131 shows the logic diagram

                                                                  54

                                                                  Logic Design amp Switching Theory 1 Lab Session 13 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                  55

                                                                  Figure 131 A Mod-5 Asynchronous Up Counter

                                                                  Implementation and Observations

                                                                  Implement the mod-5 counter circuit (figure 131) on a bread board (prepare the pin diagram (use appendix A) and refer to laboratory session 01 for implementation procedure) and record the observations in the following table

                                                                  Clock Pulse Q2 Q1 Q0

                                                                  0 1 2 3 4 5 6 7

                                                                  ACTIVITY

                                                                  Draw the timing diagram for mod-5 counter designed in this laboratory session

                                                                  Logic Design amp Switching Theory 1 Lab Session 14 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                  Lab Session 14 OBJECT

                                                                  Experimenting with 74194 4-bit bidirectional universal shift register COMPONENTS AND APPARATUS REQUIRED

                                                                  1 Following ICs and their Datasheets

                                                                  bull 74194 4-bit bidirectional universal shift register 2 Digital Trainer DT-01 or the following components

                                                                  Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches

                                                                  THEORY

                                                                  Shift Registers

                                                                  A Register is a set of flip-flops used to store binary data A register which is capable of shifting its binary information either to the right or left is called a shift register The logical configuration of a register consists of a chain of flip-flops connected in cascade with the output of one flip-flop connected to the input of next flip-flop All flip-flops receive a common clock pulse which causes the shift from one stage to the next

                                                                  Bidirectional Shift Registers A bi-directional shift register is one whose bits can be shifted from left to right or from right to left

                                                                  Universal Shift Registers A universal shift register is a bi-directional register whose input can be in either serial or parallel form and whose output can be in either serial or parallel form

                                                                  74194 4-BIT BIDIRECTIONAL UNIVERSAL SHIFT REGISTER

                                                                  The 74194 register provides parallel as well as serial loading in both directions Function of various pins of this IC is described below

                                                                  bull A B C and D Active high inputs for parallel loading bull QA QB QC and QD Active high outputs bull S0 and S1 Active high mode control inputs The following table shows combinations

                                                                  of S1 and S0 to enable various modes

                                                                  S1 S0 Clock Action 0 0 x No change 0 1 uarr Shift right 1 0 uarr Shift left 1 1 uarr Parallel load

                                                                  uarr shows the rising edge of the clock pulse

                                                                  56

                                                                  Logic Design amp Switching Theory 1 Lab Session 14 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering bull SR Active high serial input for right shifting bull SL Active high serial input for left shifting bull CLR Active low input Clears all the flip-flops of the register if set to 0 should be

                                                                  kept high otherwise bull CLK Clock input bull VCC and GND Supply connections lines Thus A B C and D are inputs for parallel loading whereas SR and SL are inputs for serial loading with right or left shifting respectively S1 and S0 are used to select the loading mode Circuit Diagram

                                                                  Figure 141 Pin connections of 74194 Testing Procedure

                                                                  bull Make connections as shown in the circuit diagram bull Observe the output for the input combinations given in the following table

                                                                  57

                                                                  Logic Design amp Switching Theory 1 Lab Session 14 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                  58

                                                                  Observations

                                                                  S1 S0 SL SR A B C D QA QB QC QD 0 0 0 1 0 0 0 0 0 1 1 0 0 0 0 1 1 0 0 0 0 0 1 0 1 1 0 0 0 0 1 1 0 0 1 1 0 1 0 0 0 1 1 1 0 1 0 1 1 0 1 0 0 1 1 0 1 1 1 0 0 1 1 1 1 1 0 0 1 1 1 1

                                                                  ACTIVITY 1 Show connections of 74194 to convert it into a ring counter with right shifting

                                                                  Logic Design amp Switching Theory 1 Lab Session 15 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                  Lab Session 15

                                                                  OBJECT

                                                                  Experimenting with 74245 octal bus transceivers using parallel port PC interfacing COMPONENTS AND APPARATUS REQUIRED 1 Parallel Port Connectors (DB-25) with Cable 2 Personal Computer with Windows 98 and TurboC Compiler Installed 3 Following ICs and their Datasheets

                                                                  bull 74245 Octal Bus Transceivers with 3-State Outputs 4 Digital Trainer DT-01 or the following components

                                                                  Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches

                                                                  THEORY

                                                                  3-State Logic Sometimes it is necessary to isolate one part of circuit from the other part For this purpose some TTL ICs are designed with 3-state logic Such devices have three possible output states high low and high impedance The device can be put into high impedance state by a control signal applied to an appropriate pin When such a device is in high impedance state there is very high impedance at its output effectively isolating the device from whatever circuitry the output normally drives 74245 Octal Bus Transceivers A bus is any conducting path or set of paths having electrical connections to one or more devices 74245 octal bus transceivers are mainly used to control connectivity between two devices or circuits It also provides direction control for signal flow Function of various pin of this IC is given below

                                                                  bull A1 through A8 Bus A bull B1 through B8 Bus B bull G΄ Active low enable input When high sets all the bus pins to high impedance state bull DIR Direction control for signal flow When set to high logic level transfers bus A

                                                                  data to B bus When set to low logic level transfers bus B data to A bus bull VCC and GND Supply connections lines Serial and Parallel Port Connectors A Parallel Port can consist of only 25 pin port adapter called a DB-25 and a serial port can consist of either a 25 pin port adapter called a DB-25 or 9 pin adapter called a DB-9 port adapter Whether the port is a 9 pin or 25 pin it can accomplish all of the same tasks that serial port communications have been designed for

                                                                  59

                                                                  Logic Design amp Switching Theory 1 Lab Session 15 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                  60

                                                                  Each adapter can be a male type connector with pins or a female type adapter with tiny holes Generally a PRINTER port (called LPT1) on the back of a computer is female type adapter and we need to use MALE DB-25 pin cable on it for PRINTER connection or for parallel LAPLINK cable And a COM port on the back of a computer is male for the serial ports but it may not necessarily be Parallel Port Connector ndash DB-25 The DB-25 connector (named for its B-size D-shaped shell and 25 pins) is practically ubiquitous in the electronics industry The DB-25 connector is used for a variety of purposes Two common applications are RS-232EIA-232 (serial) connections and the parallel printer interface on the IBM PC The DB-25 connector is also used for SCSI connections Normally the parallel port is used for output to a printer or other device It sends data 8-bits or one byte at a time in parallel The other lines available on the DB-25 connector are a combination of status lines control lines and ground lines The status and control lines are used for handshaking commands and feedback when we are talking to a printer

                                                                  Figure 152 DB-25 Female Figure 151 DB-25 Male

                                                                  Figure 153 Pin Layout for DB-25 As can be seen form figure 153 there are four types of pins in this connector

                                                                  bull Data pins (8 pins - D0 to D7) Active high bidirectional lines

                                                                  Logic Design amp Switching Theory 1 Lab Session 15 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering bull Control pins (4 pins - C0 to C3) C0 C1 and C3 are active low whereas C2 is active

                                                                  high These lines also are bidirectional bull Status pins (5 pins ndash S3 to S7) Only S7 is active low rest are active high input lines bull Ground pins (8 pins) Used as a reference signal for the low (below 05 volts) charge

                                                                  Parallel Port Addresses A DB-25 connector at a parallel port has three address one for each kind of pins register data status and control The first or base address generally refers to data register Second address is for status register and the third one is for control register In Windows 98 the base address is usually found to be 278H 378H or 3BCH Now if 378H is the base address then it refers to the data register whereas addresses for status and control register are respectively 379H and 37AH For Windows 98 the base address can be found as follows 1 On your Desktop right-click on My Computer and select Properties 2 Click on the Device Manager tab and find LPT1 under Plug and Play BIOS 3 After selecting LPT1 click the Properties button 4 Next select the Resources tab and the address should then appear next to InputOutput

                                                                  Range Accessing parallel port through C Language Programming There are multiple functions in C Language for accessing external ports The most commonly used are listed below

                                                                  bull unsigned char inportb(int portid) inportb reads a byte from a hardware port

                                                                  bull int inport(int portid) reads a word from a hardware port

                                                                  bull void outportb(int portid unsigned char value) outputs a byte to a hardware port

                                                                  bull void outport(int portid int value) outputs a word to a hardware port

                                                                  portid refers to the port address whereas value refers to the data to be sent TESTING 74245 USING PARALLEL PORT PC INTERFACING At one end the parallel port connector will be connected to the PC via parallel port cable and another connector (to be plugged into the PC parallel port slot) At the other end it will be connected to the buffer IC 74245 Data lines of the connector will be used to transfer 8-bit data between the PC and the buffer Out of the 8-bits of 74245 4-bits will be used to enter data which will be displayed at the monitor through a C language

                                                                  61

                                                                  Logic Design amp Switching Theory 1 Lab Session 15 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering program The remaining 4-bits will receive data from PC as entered by the user via keyboard

                                                                  Circuit Diagram

                                                                  Figure 154 Interface of 74245 to PC via Parallel Port

                                                                  Procedure

                                                                  1 Connect the DB-25 connector to the PC at one end and solder it to the circuit board at the other end

                                                                  2 Connect various pins of the connector and 74245 according to the circuit diagram shown in figure 152

                                                                  3 Using the functions listed in the previous section write a program in C language to operate various pins of the buffer The user interface of the program should provide option to the user whether to send or receive data from the port

                                                                  4 Set DIR switch to 1 5 Try sending some data bits to the port The result should be displayed at the LEDs 6 Set DIR switch to 0 7 Set some binary 4-bit value through the switches Try reading it via parallel port

                                                                  C Language Program

                                                                  A program to access parallel port for data transfers

                                                                  use header file include ltstdiohgt main program void main() define variable

                                                                  62

                                                                  Logic Design amp Switching Theory 1 Lab Session 15 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering unsigned int data=0 char choice while(1) printing option menu clrscr() printf(This program will send or receive a BCD digit from the parallel portn) printf(nPress your choice numbern) printf(n1 Send Data) printf(n2 Receive Data) printf(n3 Exitn) choice = getch() sending entered digit to the port if(choice == 1) input BCD digit printf(nEnter BCD digit to be sent to the port) data = getche() masking the first four bits data = data amp 0x0f sending to the port outportb(0x378data) printf(nThe BCD digit c has been sent to the port data) printing on screen the data received from the port else if(choice == 2) receiving data from the port data = inportb(0x378) masking the last four bits data = data amp 0xf0 shifting first four bits to make them the last four bits datagtgt=4 printf(nThe BCD digit set at the port is c data) exit else if(choice == 3) break key pressed is not in the menu else printf(nEnter valid choice number) printf(nnPress any key to continue) getch()

                                                                  63

                                                                  Logic Design amp Switching Theory 1 Lab Session 15 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                  ACTIVITY 1 In the above circuit DIR and G΄ inputs are hardwired Connect them to status or

                                                                  control pins of the parallel port connector and control their function through your software program Circuit Diagram Program Code ______________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________

                                                                  ___________________________________________________________________________________________________________________________________________________

                                                                  64

                                                                  Logic Design amp Switching Theory 1 Lab Session 15 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                  65

                                                                  _____________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ _____________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ _______________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ _________________________________________________ _________________________________________________

                                                                  Logic Design amp Switching Theory 1 Appendix A NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                  Appendix A

                                                                  PIN DIAGRAMS OF THE ICS REQUIRED FOR THE LABORATORY SESSIONS Consult the TTLIC data book for internal diagrams and electrical characteristics of these ICs 7400 Quad 2-Input NAND 7402 Quad 2-Input NOR

                                                                  7404 Hex Inverter 7408 Quad 2-Input AND

                                                                  7410 Triple 3-Input NAND 7411 Triple 3-Input AND

                                                                  7421 Dual 4-Input AND 7432 Quad 2-Input OR

                                                                  66

                                                                  Logic Design amp Switching Theory 1 Appendix A NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                  BCD-to-Seven Segm 7448 BCD-to-Seven Segment 7447 ent

                                                                  Decoder (15V OC) Decoder (2kΩ pull-up output)

                                                                  7473 Dual JK Flip-Flop 7474 Dual D-Type Flip-Flop

                                                                  7476 Dual JK Flop-Flop -Bit Binary Full Adder 7483 4 with Fast Carry

                                                                  86 Quad 2-Inpu 74138 3-to-8 Line 74 t Exclusive OR Decoder Demultiplexer

                                                                  67

                                                                  Logic Design amp Switching Theory 1 Appendix A NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                  68

                                                                  74148 8-to-3 Line 16-to-1 Line Data

                                                                  Priority Encoder 74150 Selector Multiplexer

                                                                  74245 Oct nsceivers Universal Shift Register (PIPO) (3-State)

                                                                  74194 4-Bit Bidirectional al Bus Tra

                                                                  Logic Design amp Switching Theory 1 Appendix B NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                  Appendix B

                                                                  DEBOUNCING CIRCUITRY FOR MECHANICAL SWITCHES Mechanical switches form the interface between human beings and computers or other digital systems For example a keyboard is a matrix of switches used to supply alphanumeric data to a computer Whatever the switch design it is a potential source of problems due to contact bounce The contact bounce creates a sense of narrow pulses when a switch is opened or closed An example of device whose operation would be adversely affected by contact bounce is a digital counter used to count the number of times a switch is depressed Eliminating the effects of contact bounce is called debouncing When data is entered into a computer via a keyboard a software debounce is often used This type of debouncing is a program that causes the computer to sample the switch terminal (ie to input data from it) many times in succession during the interval of time that contact bounce occurs If the data is sensed to be 1s (or 0s) for a specific number of consecutive samples then it is assumed that contact bounce has ended and the last value sensed is valid Hardware debouncing is the use of electronic circuitry to eliminate the effects of contact bounce There are numerous versions of such circuitry including those that use monostable multivibrators (one-shots) but the most straightforward is simply an RS latch Figure B1 shows the circuit When the switch is in position 1 R = 0 and S = 1 so the latch is set and the output (Q) is 1 When the switch is in position 0 R = 1and S = 0 so the latch is reset and the output is 0 When the switch is moved form one position to the other the latch changes state and bouncing occurs at either the R or the S input The bouncing does not affect the latch after it has change state An RS latch will remain set for example when its R input is 0 and its S input is alternately changed form 1 to 0

                                                                  Figure B1 Use of RS latch to debounce a mechanical switch

                                                                  69

                                                                  • 01-ldst-Outer title
                                                                    • Practical Workbook
                                                                    • Logic Design amp Switching Theory I
                                                                      • Dept of Computer amp Information Systems Engineering
                                                                        • NED University of Engineering amp Technology
                                                                        • Karachi ndash 75270 Pakistan
                                                                          • 02-ldst-inner Title
                                                                            • Practical Workbook
                                                                            • Logic Design amp Switching Theory I
                                                                              • Dept of Computer amp Information Systems Engineering
                                                                                • NED University of Engineering amp Technology
                                                                                • Karachi ndash 75270 Pakistan
                                                                                  • 03-ldst-general info
                                                                                  • 04-ldst-introduction
                                                                                  • 05-Table of Contents
                                                                                    • CONTENTS
                                                                                      • Lab Session No Object Page No
                                                                                      • 1
                                                                                      • Also implementing and testing the given circuit on a bread board
                                                                                        • Working with Electronics Workbench
                                                                                          • Driving a seven segment display using 7447 7448 driver IC
                                                                                            • Designing a modulus-5 asynchronous up-counter using JK-FF
                                                                                              • Experimenting with 74194 4-bit bidirectional universal shift register
                                                                                                  • 13
                                                                                                      • 06-ldst-Exp01
                                                                                                        • Lab Session 01
                                                                                                        • OBJECT
                                                                                                          • 1 Bread board
                                                                                                          • 2 5 V - power supply
                                                                                                          • 3 Multimeter
                                                                                                          • 4 Logic probe
                                                                                                          • 5 LEDs with resistors
                                                                                                          • 6 Connecting wires
                                                                                                          • 8 Following ICs and their datasheets
                                                                                                            • THEORY
                                                                                                              • Logic Gates
                                                                                                              • 1 The AND Gate ndash An AND gatersquos output is 1 if and only if all its inputs are 1 If A and B are two inputs to an AND gate then output F of the gate is given as F = AB
                                                                                                              • 2 The OR Gate - An OR gatersquos output is 1 if at least one of its input is 1 If A and B are two inputs to an OR gate then output F of the gate is given as F = A+B
                                                                                                              • 3 The NOT Gate (Inverter) ndash Its output is 1 when its input is 0 and its output is 0 when the input is 1 ie it complements a digital variable If A is the input to a NOT gate then output F of the gate is given as
                                                                                                              • 4 The NAND Gate ndash Its output is 1 if at least one of its input is 0 This gate performs the same logic as an AND gate followed by an inverter If A and B are two inputs to a NAND gate then output F of the gate is given as
                                                                                                                • 5 The NOR Gate - The output of a NOR gate is 1 if and only if all its inputs are 0 This gate performs the same logic function as an OR gate followed by an inverter If A and B are two inputs to a NAND gate then output F of the gate is given as
                                                                                                                    • DATA SHEETS
                                                                                                                      • Logic expression for the given logic diagram __________________________________
                                                                                                                          • 07-ldst-exp02
                                                                                                                            • Working with Electronics Workbench
                                                                                                                              • 08-ldst-exp03
                                                                                                                                • Designing Half and Full Adder Circuits
                                                                                                                                  • COMPONENTS AND APPARATUS REQUIRED
                                                                                                                                    • 1 Following ICs and their Datasheets
                                                                                                                                    • 7408 Quad 2-input AND Gate
                                                                                                                                    • 2 Digital Trainer DT-01 or the following components
                                                                                                                                      • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                      • Connecting wires Switches
                                                                                                                                        • THEORY
                                                                                                                                            • IMPLEMENTATION AND OBSERVATIONS
                                                                                                                                              • 09-ldst-Exp04
                                                                                                                                                • Lab Session 04
                                                                                                                                                • 1 Digital ICs and their Datasheets
                                                                                                                                                • 7408 Quad 2-input AND Gate
                                                                                                                                                • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                  • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                  • Connecting wires Switches
                                                                                                                                                  • PROCEDURE
                                                                                                                                                  • REDUCTION OF LOGIC EXPRESSION USING KARNAUGH MAP
                                                                                                                                                  • OBSERVATIONS
                                                                                                                                                  • RESULT
                                                                                                                                                      • 10-ldst-Exp05
                                                                                                                                                        • Lab Session 05
                                                                                                                                                        • 1 Following ICs and their Datasheets
                                                                                                                                                        • 7408 Quad 2-input AND Gate
                                                                                                                                                        • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                          • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                          • (100 Ω) Connecting wires Switches
                                                                                                                                                          • THEORY
                                                                                                                                                            • IMPLEMENTATION AND OBSERVATIONS
                                                                                                                                                              • 11-ldst-Exp06
                                                                                                                                                                • OBJECT
                                                                                                                                                                • 1 Following ICs and their Datasheets
                                                                                                                                                                • 7408 Quad 2-input AND Gates or 7411 Triple 3-input AND Gates
                                                                                                                                                                • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                  • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                  • Connecting wires Switches
                                                                                                                                                                    • Figure 62 Circuit Diagram for 4 x 1 Multiplexer
                                                                                                                                                                    • Implementation and Observations
                                                                                                                                                                      • Circuit Diagram
                                                                                                                                                                        • ACTIVITY
                                                                                                                                                                          • 12-ldst-exp07
                                                                                                                                                                            • 1 Following ICs and their Datasheets
                                                                                                                                                                            • 7408 Quad 2-input or 7411 Triple 3-input AND Gates
                                                                                                                                                                            • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                              • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                              • Connecting wires Switches
                                                                                                                                                                                • THEORY
                                                                                                                                                                                    • Figure 72 Circuit Diagram for 2 x 4 Decoder 1 x 4 Demultiplexer
                                                                                                                                                                                    • Implementation and Observations
                                                                                                                                                                                      • Circuit Diagram
                                                                                                                                                                                        • ACTIVITY
                                                                                                                                                                                          • 13-ldst-Exp08
                                                                                                                                                                                            • OBJECT
                                                                                                                                                                                            • 1 Following ICs and their Datasheets
                                                                                                                                                                                            • 7408 Quad 2-input or 7421 Dual 4-input AND Gates
                                                                                                                                                                                            • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                              • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                              • Connecting wires Switches
                                                                                                                                                                                                • THEORY
                                                                                                                                                                                                    • Figure 81 Circuit Diagram for 4 x 2 Priority Encoder
                                                                                                                                                                                                    • Implementation and Observations
                                                                                                                                                                                                      • Therefore if GS A2 A1 and A0 are all low then it shows that line 0 is selected and if E0 A2 A1 and A0 are all low then it shows that none of the inputs selected E0 and GS cannot be in the same state provided that E1 is enabled
                                                                                                                                                                                                      • Circuit Diagram
                                                                                                                                                                                                        • ACTIVITY
                                                                                                                                                                                                          • 14-ldst-exp09
                                                                                                                                                                                                            • OBJECT
                                                                                                                                                                                                            • 1 Following ICs and their Datasheets
                                                                                                                                                                                                            • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                              • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                              • Connecting wires Switches
                                                                                                                                                                                                                • THEORY
                                                                                                                                                                                                                  • Parity Generator
                                                                                                                                                                                                                    • Let x y and z be the three bits that constitute the message and are the input to the Odd Parity Generator Circuit Since it is an odd parity system the bit P is generated so as to make the total number of 1s odd (including P) The function P can be expressed as follows
                                                                                                                                                                                                                    • Figure 91 Circuit Diagram for a 3-bit Parity Generator
                                                                                                                                                                                                                      • C = x Ο y Ο z Ο P
                                                                                                                                                                                                                        • Implementation and Observations
                                                                                                                                                                                                                          • ACTIVITY
                                                                                                                                                                                                                              • 15-ldst-exp10
                                                                                                                                                                                                                                • Driving a seven segment display using 7447 7448 driver IC
                                                                                                                                                                                                                                • COMPONENTS AND APPARATUS REQUIRED
                                                                                                                                                                                                                                • 1 Following ICs and their Datasheets
                                                                                                                                                                                                                                • 7447 7448 BCD to Seven Segment Driver
                                                                                                                                                                                                                                • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                                  • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches
                                                                                                                                                                                                                                    • THEORY
                                                                                                                                                                                                                                    • Seven Segment Displays
                                                                                                                                                                                                                                    • CIRCUIT DIAGRAM
                                                                                                                                                                                                                                    • Figure 102 Circuit diagram for 7447driving a common-anode display
                                                                                                                                                                                                                                        • IMPLEMENTATION AND OBSERVATIONS
                                                                                                                                                                                                                                          • Decimal Digit
                                                                                                                                                                                                                                          • BCD Inputs
                                                                                                                                                                                                                                          • Seven Segment Outputs
                                                                                                                                                                                                                                          • D
                                                                                                                                                                                                                                          • C
                                                                                                                                                                                                                                          • B
                                                                                                                                                                                                                                          • A
                                                                                                                                                                                                                                          • a
                                                                                                                                                                                                                                          • b
                                                                                                                                                                                                                                          • c
                                                                                                                                                                                                                                          • d
                                                                                                                                                                                                                                          • e
                                                                                                                                                                                                                                          • f
                                                                                                                                                                                                                                          • g
                                                                                                                                                                                                                                          • 0
                                                                                                                                                                                                                                          • 0
                                                                                                                                                                                                                                          • 0
                                                                                                                                                                                                                                          • 0
                                                                                                                                                                                                                                          • 0
                                                                                                                                                                                                                                          • 1
                                                                                                                                                                                                                                          • 0
                                                                                                                                                                                                                                          • 0
                                                                                                                                                                                                                                          • 0
                                                                                                                                                                                                                                          • 1
                                                                                                                                                                                                                                          • 2
                                                                                                                                                                                                                                          • 0
                                                                                                                                                                                                                                          • 0
                                                                                                                                                                                                                                          • 1
                                                                                                                                                                                                                                          • 0
                                                                                                                                                                                                                                          • 3
                                                                                                                                                                                                                                          • 0
                                                                                                                                                                                                                                          • 0
                                                                                                                                                                                                                                          • 1
                                                                                                                                                                                                                                          • 1
                                                                                                                                                                                                                                          • 4
                                                                                                                                                                                                                                          • 0
                                                                                                                                                                                                                                          • 1
                                                                                                                                                                                                                                          • 0
                                                                                                                                                                                                                                          • 0
                                                                                                                                                                                                                                          • 5
                                                                                                                                                                                                                                          • 0
                                                                                                                                                                                                                                          • 1
                                                                                                                                                                                                                                          • 0
                                                                                                                                                                                                                                          • 1
                                                                                                                                                                                                                                          • 6
                                                                                                                                                                                                                                          • 0
                                                                                                                                                                                                                                          • 1
                                                                                                                                                                                                                                          • 1
                                                                                                                                                                                                                                          • 0
                                                                                                                                                                                                                                          • 7
                                                                                                                                                                                                                                          • 0
                                                                                                                                                                                                                                          • 1
                                                                                                                                                                                                                                          • 1
                                                                                                                                                                                                                                          • 1
                                                                                                                                                                                                                                          • 8
                                                                                                                                                                                                                                          • 1
                                                                                                                                                                                                                                          • 0
                                                                                                                                                                                                                                          • 0
                                                                                                                                                                                                                                          • 0
                                                                                                                                                                                                                                          • 9
                                                                                                                                                                                                                                          • 1
                                                                                                                                                                                                                                          • 0
                                                                                                                                                                                                                                          • 0
                                                                                                                                                                                                                                          • 1
                                                                                                                                                                                                                                            • ACTIVITY
                                                                                                                                                                                                                                              • 16-ldst-exp11
                                                                                                                                                                                                                                                • Lab Session 11
                                                                                                                                                                                                                                                  • OBJECT
                                                                                                                                                                                                                                                  • COMPONENTS AND APPARATUS REQUIRED
                                                                                                                                                                                                                                                    • 1 Following ICs and their Datasheets
                                                                                                                                                                                                                                                    • 7473 7476 JK Flip-Flop
                                                                                                                                                                                                                                                    • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                                                      • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                                                                      • Connecting wires Switches
                                                                                                                                                                                                                                                        • THEORY
                                                                                                                                                                                                                                                            • Flip-Flop
                                                                                                                                                                                                                                                            • JK Flip-Flop
                                                                                                                                                                                                                                                              • Circuit Diagram
                                                                                                                                                                                                                                                                • Observations
                                                                                                                                                                                                                                                                  • ACTIVITY
                                                                                                                                                                                                                                                                      • 17-ldst-exp12
                                                                                                                                                                                                                                                                        • Lab Session 12
                                                                                                                                                                                                                                                                          • OBJECT
                                                                                                                                                                                                                                                                          • GIVEN STATE DIAGRAM
                                                                                                                                                                                                                                                                          • Figure 121 State Diagram
                                                                                                                                                                                                                                                                          • COMPONENTS AND APPARATUS REQUIRED
                                                                                                                                                                                                                                                                            • 1 Following ICs and their Datasheets
                                                                                                                                                                                                                                                                            • 7474 D Flip-Flop
                                                                                                                                                                                                                                                                            • ICs of basic gates (AND OR NOT XOR etc) as required
                                                                                                                                                                                                                                                                            • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                                                                              • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                                                                                              • Connecting wires Switches
                                                                                                                                                                                                                                                                                • THEORY
                                                                                                                                                                                                                                                                                    • Sequential Circuits
                                                                                                                                                                                                                                                                                      • 18-ldst-exp13
                                                                                                                                                                                                                                                                                        • Lab Session 13
                                                                                                                                                                                                                                                                                          • Designing a modulo-5 asynchronous up-counter using JK-FF
                                                                                                                                                                                                                                                                                            • 1 Following ICs and their Datasheets
                                                                                                                                                                                                                                                                                            • 7400 Quad 2-input or 7410 Triple 3-input NAND Gates
                                                                                                                                                                                                                                                                                            • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                                                                                              • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                                                                                                              • Connecting wires Switches
                                                                                                                                                                                                                                                                                                • THEORY
                                                                                                                                                                                                                                                                                                    • Figure 131 A Mod-5 Asynchronous Up Counter
                                                                                                                                                                                                                                                                                                    • Implementation and Observations
                                                                                                                                                                                                                                                                                                      • ACTIVITY
                                                                                                                                                                                                                                                                                                          • 19-ldst-exp14
                                                                                                                                                                                                                                                                                                            • Experimenting with 74194 4-bit bidirectional universal shift register
                                                                                                                                                                                                                                                                                                            • 1 Following ICs and their Datasheets
                                                                                                                                                                                                                                                                                                            • 74194 4-bit bidirectional universal shift register
                                                                                                                                                                                                                                                                                                            • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                                                                                                              • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                                                                                                                              • Connecting wires Switches
                                                                                                                                                                                                                                                                                                                • THEORY
                                                                                                                                                                                                                                                                                                                  • Shift Registers
                                                                                                                                                                                                                                                                                                                  • Bidirectional Shift Registers
                                                                                                                                                                                                                                                                                                                  • Universal Shift Registers
                                                                                                                                                                                                                                                                                                                    • S1
                                                                                                                                                                                                                                                                                                                      • Circuit Diagram
                                                                                                                                                                                                                                                                                                                      • ACTIVITY
                                                                                                                                                                                                                                                                                                                          • 20-ldst-exp15
                                                                                                                                                                                                                                                                                                                            • COMPONENTS AND APPARATUS REQUIRED
                                                                                                                                                                                                                                                                                                                            • 1 Parallel Port Connectors (DB-25) with Cable
                                                                                                                                                                                                                                                                                                                            • 2 Personal Computer with Windows 98 and TurboC Compiler Installed
                                                                                                                                                                                                                                                                                                                            • 3 Following ICs and their Datasheets
                                                                                                                                                                                                                                                                                                                            • 74245 Octal Bus Transceivers with 3-State Outputs
                                                                                                                                                                                                                                                                                                                            • 4 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                                                                                                                              • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                                                                                                                                                • Connecting wires Switches
                                                                                                                                                                                                                                                                                                                                  • THEORY
                                                                                                                                                                                                                                                                                                                                  • 3-State Logic
                                                                                                                                                                                                                                                                                                                                    • Serial and Parallel Port Connectors
                                                                                                                                                                                                                                                                                                                                    • Parallel Port Connector ndash DB-25
                                                                                                                                                                                                                                                                                                                                      • Accessing parallel port through C Language Programming
                                                                                                                                                                                                                                                                                                                                          • 21-ldst-appendixA
                                                                                                                                                                                                                                                                                                                                          • 22-ldst-appendixB
                                                                                                                                                                                                                                                                                                                                            • DEBOUNCING CIRCUITRY FOR MECHANICAL SWITCHES

                                                                    Logic Design amp Switching Theory 1 Lab Session 07 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                    bull Y0 through Y7 Active low data outputs bull A B C Input select lines with C being the MSB bull G1 Active high enable Input bull G2Arsquo and G2Brsquo Active low enable Inputs bull VCC and GND Supply connections lines Circuit Diagram

                                                                    Figure 73 Pin connections of 74138

                                                                    Testing Procedure

                                                                    bull Make connections as shown in the circuit diagram bull Apply different combinations of 1s and 0s at data inputs bull Observe the output and record your observations in the following table

                                                                    Observations

                                                                    C B A Y0 Y1 Y2 Y3 Y4 Y5 Y6 Y7 0 0 0 0 0 1 0 1 0 0 1 1 1 0 0 1 0 1 1 1 0 1 1 1

                                                                    36

                                                                    Logic Design amp Switching Theory 1 Lab Session 07 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                    37

                                                                    ACTIVITY ACTIVITY 1 What will be the binary values at the outputs Y0 through Y7 of 74138 if 1 What will be the binary values at the outputs Y0 through Y7 of 74138 if

                                                                    bull All three enable pins are connected to ground bull All three enable pins are connected to ground __________________________________________________________________________________________________________________________________________ __________________________________________________________________________________________________________________________________________ _____________________________________________________________________ _____________________________________________________________________

                                                                    bull All three enable pins are connected to VCC bull All three enable pins are connected to VCC _______________________________________________________________________________________________________________________________________________________________________________________________________________

                                                                    _______________________________________________________________________________________________________________________________________________________________________________________________________________

                                                                    2 Show connections for 74138 in order to use it as a 1 x 8 Demultiplexer 2 Show connections for 74138 in order to use it as a 1 x 8 Demultiplexer

                                                                    3 Consider a 2 x 4 Decoder with two enable inputs (one active high - G and one active low ndash Grsquo) Draw the output wave-forms for D0 D1 D2 and D3 if the two select inputs are A and B (B being the MSB) All outputs are active low

                                                                    Grsquo

                                                                    G

                                                                    A B

                                                                    D0 D1 D2

                                                                    D3

                                                                    Logic Design amp Switching Theory 1 Lab Session 08 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                    Lab Session 08 OBJECT

                                                                    bull Designing of a 4 x 2 Priority Encoder bull Experimenting with 74148 IC

                                                                    COMPONENTS AND APPARATUS REQUIRED

                                                                    1 Following ICs and their Datasheets

                                                                    bull 7408 Quad 2-input or 7421 Dual 4-input AND Gates bull 7432 Quad 2-input OR Gates bull 7404 Hex Inverter bull 74148 Encoder

                                                                    2 Digital Trainer DT-01 or the following components Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches

                                                                    THEORY

                                                                    Encoder An Encoder is a digital function that produces a reverse operation from that of a decoder An Encoder has 2n (or less) input lines and n output lines The output lines generate the binary code for the 2n input variables Priority Encoder

                                                                    A simple encoder may produce an erroneous output if more than one of its inputs is high A Priority Encoder is one that responds to just one input among those that may be simultaneously high in accordance with some priority system The most common priority system is based on the relative magnitudes of the inputs whichever decimal input is largest is the one that is encoded

                                                                    DESIGN OF A 4 x 2 Priority Encoder

                                                                    The following equations represent the outputs of a 4 x 2 priority encoder 32 DDA +=

                                                                    321 DDDB += As can be seen from the equations that input D0 which has a binary code 00 is not used in any equation A binary code 00 at the output indicates two conditions Either D0 is selected or no input is selected In order to differentiate these two conditions we will provide an additional output Z to indicate if at least one of the inputs is a 1 The equation for Z will be

                                                                    4321 DDDDZ = If Z is 0 then the binary code 00 at the output indicates that D0 is selected and if Z is 1 then it indicates that no input line is selected

                                                                    38

                                                                    Logic Design amp Switching Theory 1 Lab Session 08 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                    Figure 81 Circuit Diagram for 4 x 2 Priority Encoder

                                                                    it (figure 81) on a bread board (prepare the to laboratory session 01 for implementation

                                                                    Implementation a Implement the 4 x 2 Priority Encoder circu

                                                                    ram (use appendix A) and refer

                                                                    nd Observations

                                                                    pin diagprocedure) and record the observations in the following table

                                                                    D3 D2 D1 D0 A B 0 0 0 1 0 0 1 x 0 1 x x 1 x x x

                                                                    TESTING OF 74148 8 x 3 Octal Priority Encoder

                                                                    imal digits There are nine of which three represents

                                                                    ing any of the inputs is high

                                                                    then it shows that line 0 is selected and if e inputs selected E0 and GS

                                                                    cannot be in the same state provided that E1 is enabled

                                                                    The 74148 is a priority encoder with active-Low input for dec

                                                                    input) and five output linesinputs lines (including an enablethe binary code for the octal digit Function of various pins of this IC is described below

                                                                    bull 0 through 7 Active low data inputs representing the octal digits A2 A1 A0 Active low output lines representing the binary code bullbull E1 Active low enable Input bull E0 Active low output indicating none of the inputs is high bull GS Active low output indicatbull VCC and GND Supply connections lines Therefore if GS A2 A1 and A0 are all low

                                                                    then it shows that none of thE0 A2 A1 and A0 are all low

                                                                    39

                                                                    Logic Design amp Switching Theory 1 Lab Session 08 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                    Circuit Diagram

                                                                    Figure 82 Pin connections of 74148

                                                                    Testing Procedure bull Make connections as sho

                                                                    binations of 1s and 0s at data inputs d record your observations in the following table

                                                                    GS E0

                                                                    wn in the circuit diagram bull Apply different combull Observe the output an Observations

                                                                    0 1 2 3 4 5 6 7 A2 A1 A0 1 1 1 1 1 1 1 1 x x x x x x x 0 x x x x x x 0 1 x x x x x 0 1 1 x x x x 0 1 1 1 x x x 0 1 1 1 1 x x 0 1 1 1 1 1 x 0 1 1 1 1 1 1 0 1 1 1 1 1 1 1

                                                                    40

                                                                    Logic Design amp Switching Theory 1 Lab Session 08 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                    41

                                                                    CTIVITY

                                                                    Cascade the following two 74148 8 x 3 Priority Encoders to form 16 x 4 Priority

                                                                    A 1

                                                                    Encoder

                                                                    Logic Design amp Switching Theory 1 Lab Session 09 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering `

                                                                    Lab Session 09 OBJECT

                                                                    Designing an Odd Parity Generator and Checker for a 3-bit Data COMPONENTS AND APPARATUS REQUIRED

                                                                    1 Following ICs and their Datasheets

                                                                    bull 7486 Quad 2-input Exclusive-OR Gates bull 7404 Hex Inverter

                                                                    2 Digital Trainer DT-01 or the following components Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches

                                                                    THEORY

                                                                    Parity Generator When binary data is transmitted and processed it is ndash as are all electrical signals ndash susceptible to noise that can either alter or distort its contents 1s may be effectively changed to 0s and 0s to 1s To overcome this problem one or more bits are often added to the data as an aid in detecting errors caused by noise The most common of these is a Parity bit that signifies whether the total number of 1s in a code group is odd or even In an Odd Parity system the parity bit is made 0 or 1 as necessary to make the total number 1s odd (counting the parity bit itself) In an Even Parity system the parity bit is chosen to make the total number of 1s even Table 91 shows how parity bits would be added to BCD code group in both systems

                                                                    Decimal BCD Value Parity Bit ABCD Odd Parity Even Parity

                                                                    0 0000 1 0 1 0001 0 1 2 0010 0 1 3 0011 1 0 4 0100 0 1 5 0101 1 0 6 0110 1 0 7 0111 0 1 8 1000 0 1 9 1001 1 0

                                                                    Table 91 Odd and Even Parity in BCD

                                                                    When digital data is received a parity checking circuit generates an error signal if the total number of 1s is odd in an even parity system or if it is even in an odd parity system Parity check always detects a single error (one bit change from 0 to 1 or 1 to 0) but may not detect

                                                                    42

                                                                    Logic Design amp Switching Theory 1 Lab Session 09 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering ` two or more errors Odd parity is used more often than even parity because even parity does not detect a situation where all 0s are created due to short circuit or other fault condition DESIGN OF A 3-BIT ODD PARITY GENERATOR AND CHECKER Let x y and z be the three bits that constitute the message and are the input to the Odd Parity Generator Circuit Since it is an odd parity system the bit P is generated so as to make the total number of 1s odd (including P) The function P can be expressed as follows P = x oplus y Ο z or P = x Ο y oplus z Since the IC available is 7486 which is quad 2input XOR IC therefore we will convert XNOR also to XOR

                                                                    P = x oplus y Ο z

                                                                    P = ( x oplus y ) Ο z Since for even number of variables ______

                                                                    XOR = XNOR Therefore ___________ _________

                                                                    P = ( x oplus y ) oplus z = x oplus y oplus z This logical expression can be implemented with two XOR gates and an inverter (see figure 91)

                                                                    Figure 91 Circuit Diagram for a 3-bit Parity Generator

                                                                    The 3-bit message and the parity bit are transmitted to their destination where they are applied to a Parity Checker Circuit An error occurs during transmission if the parity of the four bits received is even since the binary information transmitted was originally odd The output C of the parity checker should be a 1 when an error occurs ie when the number of 1s in the four inputs is even Therefore the function C can be expressed as

                                                                    C = x Ο y Ο z Ο P

                                                                    Using the same logic applied for the conversion of the equation of P

                                                                    PzyxC oplusoplusoplus= This logical expression can be implemented with three XOR gates and an inverter (see figure 92)

                                                                    43

                                                                    Logic Design amp Switching Theory 1 Lab Session 09 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering `

                                                                    44

                                                                    Figure 92 Circuit Diagram for a 3-bit Parity Checker Implementation and Observations Implement the 3-bit Parity Generator and Checker circuits (figure 91 and 92) on a bread board (prepare the pin diagram (use appendix A) and refer to laboratory session 01 for implementation procedure) and record the observations in the following table

                                                                    x y z P x y z P C x y z P C 0 0 0 0 0 0 0 1 0 0 0 0 0 1 0 0 0 1 1 0 0 1 0 1 0 0 0 1 0 1 0 1 0 0 1 1 0 0 1 1 1 0 1 1 1 0 0 0 1 0 0 1 1 0 0 1 0 1 0 1 0 1 1 1 0 1 1 1 0 0 1 1 0 1 1 1 0 1 1 1 0 1 1 1 1 1 1 1

                                                                    Odd Parity Generation Odd Parity Check ACTIVITY 1 Try using the parity checker of figure 92 as 3-bit parity generator Write the details here

                                                                    _____________________________________________________________________________________________________________________________________________________________________________________________________________________ ______________________________________________________________________________________________________________________________________________ _______________________________________________________________________ ______________________________________________________________________________________________________________________________________________

                                                                    Logic Design amp Switching Theory 1 Lab Session 10 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                    Lab Session 10 OBJECT

                                                                    Driving a seven segment display using 7447 7448 driver IC COMPONENTS AND APPARATUS REQUIRED

                                                                    1 Following ICs and their Datasheets

                                                                    bull Seven Segment Displays (Common Anode Common Cathode) bull 7447 7448 BCD to Seven Segment Driver

                                                                    2 Digital Trainer DT-01 or the following components Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches

                                                                    THEORY Seven Segment Displays A Seven Segment Display consists of seven light-emitting segments The segments are designated by letters a through g (see figure 101) By illuminating various combinations of segments the numerals 0 through 9 can be displayed Seven Segment Displays are commonly constructed with light-emitting diodes (LEDs) and with liquid-crystal displays (LCDs) LEDs generally provide greater illumination levels but require much greater power than LCDs An LED display can be a common-anode type or common cathode type In common anode type a high voltage is applied at the common terminal of the display and low voltage is applied at a segmentrsquos terminal for illumination In the common-cathode type a low voltage is applied at the common terminal of the display and high voltage is applied at a segmentrsquos terminal for illumination

                                                                    Figure 101 Seven Segment Display

                                                                    a f b g

                                                                    e c d

                                                                    7447 7448 BCD to Seven Segment Driver 7447 7448 IC is particularly used to drive Seven Segment Its input is a BCD number and output drives a seven segment display 7447 is used to drive common-anode displays whereas 7448 is used to drive common cathode displays 7447 7448 is a 16 pin IC Function of various pins of these ICs is described below

                                                                    bull A B C D Inputs representing BCD digits (D being the MSB)

                                                                    45

                                                                    Logic Design amp Switching Theory 1 Lab Session 10 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering bull OA through OG Outputs to drive segments a through g of the display (Active low

                                                                    in 7447 and active high in 7448) bull RBI Ripple Blanking Input Turns off all the segments if kept low provided that LT

                                                                    is kept high and all other inputs (A B C D BI) are kept low Should be kept high otherwise

                                                                    bull BI RBO Wire-AND logic serving as a Blanking Input and or Ripple Blanking Output

                                                                    o BI Turns off all the segments if low o RBO Goes to a low level (response condition) along with other outputs when

                                                                    RBI and inputs A B C and D are low with LT input at high level bull LT Lamp Test input Tests whether all segments are working or not Illuminates all

                                                                    segments if kept low provided that BI is kept high Should be kept high otherwise bull VCC and GND Supply connections lines CIRCUIT DIAGRAM

                                                                    Figure 102 Circuit diagram for 7447driving a common-anode display

                                                                    IMPLEMENTATION AND OBSERVATIONS

                                                                    bull Make connections as shown in the circuit diagram (refer to laboratory session 01 for implementation procedure)

                                                                    bull Apply different combinations of 1s and 0s at data inputs bull Observe the output and record your observations in the following table

                                                                    46

                                                                    Logic Design amp Switching Theory 1 Lab Session 10 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                    47

                                                                    Decimal Digit

                                                                    BCD Inputs Seven Segment Outputs D C B A a b c d e f g

                                                                    0 0 0 0 0 1 0 0 0 1 2 0 0 1 0 3 0 0 1 1 4 0 1 0 0 5 0 1 0 1 6 0 1 1 0 7 0 1 1 1 8 1 0 0 0 9 1 0 0 1

                                                                    ACTIVITY 1 Perform the Lamp Test for the designed circuit and write your observations

                                                                    ____________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________

                                                                    2 How can you use 7447 IC to drive a common-cathode display

                                                                    ____________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________

                                                                    3 What symbols appear in the seven segment display if inputs DCBA are

                                                                    DCBA Symbol

                                                                    1010

                                                                    1011

                                                                    1100

                                                                    1101

                                                                    1110

                                                                    1111

                                                                    Logic Design amp Switching Theory 1 Lab Session 11 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                    48

                                                                    Lab Session 11 OBJECT

                                                                    Testing different modes of JK-FF COMPONENTS AND APPARATUS REQUIRED 1 Following ICs and their Datasheets

                                                                    bull 7473 7476 JK Flip-Flop 2 Digital Trainer DT-01 or the following components

                                                                    Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches

                                                                    THEORY

                                                                    Flip-Flop A flip-flop circuit can maintain a binary state indefinitely (as long as the power is delivered to the circuit) until directed by an input signal to switch states The major differences among various types of flip-flops are in the number of inputs they possess and in the manner in which the inputs affect the binary state

                                                                    JK Flip-Flop JK flip flop is an edge triggered device A typical JK flip flop has three inputs J K and a clock input The flip-flop can be either positive or negative edge triggered The output Q is available in complemented form as well Beside the usual inputs and output most of the flip-flop IC also possess two asynchronous inputs namely Preset and Clear These inputs are usually active low If used Preset and Clear inputs keep the flip-flop in set and reset state respectively irrespective of the other inputs Both of these inputs cannot be used simultaneously otherwise they will bring the flip-flop in unstable state

                                                                    Figure 111 Symbol for JK flip-flop

                                                                    (a) positive-edge triggering (b) active low Preset (PR) and Clear (CLR) with positive-edge triggering

                                                                    (c) active low Preset (PR) and Clear (CLR) with negative-edge triggering

                                                                    Logic Design amp Switching Theory 1 Lab Session 11 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                    49

                                                                    TESTING OF 7473 7476 DUAL JK FLIP-FLOP

                                                                    Both the ICs 7473 and 7476 are similar in functionality except for one difference The flip-flops in 7473 have only one type of active low asynchronous input which is the Clear input whereas the flip-flops in 7476 have both Preset and Clear inputs Both these ICs have negative edge triggered flip-flops

                                                                    Circuit Diagram

                                                                    Figure 112 Pin connections of 7476

                                                                    Testing Procedure

                                                                    bull Make connections as shown in the circuit diagram (figure 112) bull Apply different combinations of 1s and 0s at J and K inputs bull Observe the output and record your observations in the following table

                                                                    Observations

                                                                    J

                                                                    K Q

                                                                    0 0 0 1 1 0 1 1

                                                                    ACTIVITY

                                                                    1 Observe the output Q of JK flip-flop if the clock input is connected to VCC or GND instead of a clock source Write your observations here __________________________________________________________________________________________________________________________________________ _______________________________________________________________________________________________________________________________________________________________________________________________________________

                                                                    Logic Design amp Switching Theory 1 Lab Session 12 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                    50

                                                                    Lab Session 12 OBJECT

                                                                    Designing sequential circuit for the given state diagram using D flip-flop GIVEN STATE DIAGRAM

                                                                    00

                                                                    11

                                                                    Figure 121 State Diagram COMPONENTS AND APPARATUS REQUIRED 1 Following ICs and their Datasheets

                                                                    bull 7474 D Flip-Flop bull ICs of basic gates (AND OR NOT XOR etc) as required

                                                                    2 Digital Trainer DT-01 or the following components Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches

                                                                    THEORY

                                                                    Sequential Circuits In Sequential Circuits the output not only depends on the present inputs but also on previous states of the circuit These circuits use memory elements (latches flip-flops) and the binary information stored in the memory elements at any given time defines the state of the sequential circuit Analysis of a Sequential Circuit The behavior of a sequential circuit is determined from the inputs the outputs and the states of its flip-flops Both the outputs and next state are a function of the inputs and the

                                                                    10

                                                                    01

                                                                    00 11 10

                                                                    00

                                                                    00 11 10 00

                                                                    Logic Design amp Switching Theory 1 Lab Session 12 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                    51

                                                                    present state The analysis of a sequential circuit form a state diagram comprises of the following bull Selecting a particular flip-flop to design the circuit bull Obtaining state table from the state diagram bull Finding input equations for the selected flip-flop bull Finding state equations (not required for the construction of circuit) bull Implementing the circuit using selected flip-flops and their input equations ANALYZING THE GIVEN STATE DIAGRAM D Flip-Flop D flip-flop is also called transparent flip-flop as it simply transfers the input data to the output For our design we require the graphical symbol and excitation table of D flip-flop (see figure 122)

                                                                    Qt Qt+1 T 0 0 0 0 1 1 1 0 0 1 1 1

                                                                    (b) Excitation table of D Flip-Flop

                                                                    (a) Graphical Symbol

                                                                    Figure 122 Characteristic equation of D flip-flop is Q(t+1) = D State Table The given state diagram has four states so we will need two D flip-flops (FF-0 FF-1) Form state table form the given state diagram and record the results in the following table

                                                                    Present State Input Next State Output Input to FF-0 D0

                                                                    Input to FF-1 D1 Q1t Q0t x Q1(t+1) Q0(t+1) z

                                                                    Logic Design amp Switching Theory 1 Lab Session 12 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                    52

                                                                    Input Equations Using Karnaugh map the input equations D0 and D1 for the two flip-flops can be found

                                                                    D0 D1 Q0x

                                                                    Q1

                                                                    _ _ Q0x

                                                                    _ Q0x

                                                                    Q0x

                                                                    _ Q0x

                                                                    Q0x

                                                                    Q1

                                                                    _ _ Q0x

                                                                    _ Q0x

                                                                    Q0x

                                                                    _ Q0x

                                                                    _ Q1

                                                                    _ Q1

                                                                    Q1

                                                                    Q1

                                                                    D0 = _________________ D1 = _________________

                                                                    State Equations Using the characteristic equation of D flip-flop we can find the state equations Q0(t+1) and Q1(t+1) for the to flip flops Q0(t+1) = _______________________ Q1(t+1) = _______________________ _______________________ _______________________ _______________________ _______________________ Circuit Diagram

                                                                    Logic Design amp Switching Theory 1 Lab Session 12 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                    53

                                                                    Implementation Procedure and Observations

                                                                    1 Implement the circuit using digital ICs on a bread board (prepare the pin diagram (use appendix A) and refer to laboratory session 01 for procedure)

                                                                    2 Make the clear inputs of the flip-flops low (to clear the flip-flops) The flip-flops will remain in clear state as long as the clear inputs are connected to low level

                                                                    3 Connect output Q0 and the clock pulse to an oscilloscope 4 Apply 0 to the input x 5 Now make the clear inputs to high 6 Observe the waveform for the first 5 clock pulses and record it 7 Repeat steps 2 to 6 keeping x=1 in step 4 this time 8 Repeat steps 2 to 7 this time connecting Q1 instead of Q0 to the oscilloscope in step

                                                                    3 Record your observations (Keep frequency of the clock pulse low (eg1Hz) so that the output waveforms can be observed easily)

                                                                    1 2 3 4 5 Clock Pulse

                                                                    Output Waveform for Q0 when x=0

                                                                    Output Waveform for Q0 when x=1

                                                                    Output Waveform for Q1 when x=0

                                                                    Output Waveform for Q1 when x=1

                                                                    Logic Design amp Switching Theory 1 Lab Session 13 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                    Lab Session 13 OBJECT

                                                                    Designing a modulo-5 asynchronous up-counter using JK-FF COMPONENTS AND APPARATUS REQUIRED

                                                                    1 Following ICs and their Datasheets

                                                                    bull 7400 Quad 2-input or 7410 Triple 3-input NAND Gates bull 7476 7473 JK Flip-Flop

                                                                    2 Digital Trainer DT-01 or the following components Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches

                                                                    THEORY

                                                                    Digital Counters A digital counter is a set of flip-flops whose states change in response to pulses applied at the input to the counter The flip-flops are interconnected so that their combined state at any time is the binary equivalent of the total number of pulses that have occurred up to that time Every counter resets after a certain number of clock pulses Thus as it name implies a counter is used to count pulses An n stage counter can count up to a maximum of 2n states n is equal to the number of flip-flops required for the construction of counter

                                                                    Modulus Counters The number of input pulses that causes a counter to reset to its initial count is called the modulus of the counter Thus the modulus equals to total number of distinct states (counts) including zero that a counter can store A binary counter with n stages is a modulo-2n (or mod-2n) counter The largest count a mod-N counter can achieve is N-1 ie a mod-N counter never reaches the binary number equal to its modulus N is always equal to or less than 2n Counters can be classified as bull Synchronous Counters which are clock driven All the flip-flops are driven by a

                                                                    single clock bull Asynchronous Counters which are event driven Clock input is given to the first

                                                                    flip-flop only Rest of the flip-flops are driven by their preceding flip-flops

                                                                    DESIGN OF A MOD-5 ASYNCHRONOUS UP COUNTER The number of flip-flops required to construct a mod-5 counter is 3 because 5 should be less than or equal to 2n This counter will count from 0 to 4 a total of 5 distinct states Since a 3-stage counter can count up to 8 states at maximum a NAND gate is used to reset it after 5 clock pulses Figure 131 shows the logic diagram

                                                                    54

                                                                    Logic Design amp Switching Theory 1 Lab Session 13 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                    55

                                                                    Figure 131 A Mod-5 Asynchronous Up Counter

                                                                    Implementation and Observations

                                                                    Implement the mod-5 counter circuit (figure 131) on a bread board (prepare the pin diagram (use appendix A) and refer to laboratory session 01 for implementation procedure) and record the observations in the following table

                                                                    Clock Pulse Q2 Q1 Q0

                                                                    0 1 2 3 4 5 6 7

                                                                    ACTIVITY

                                                                    Draw the timing diagram for mod-5 counter designed in this laboratory session

                                                                    Logic Design amp Switching Theory 1 Lab Session 14 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                    Lab Session 14 OBJECT

                                                                    Experimenting with 74194 4-bit bidirectional universal shift register COMPONENTS AND APPARATUS REQUIRED

                                                                    1 Following ICs and their Datasheets

                                                                    bull 74194 4-bit bidirectional universal shift register 2 Digital Trainer DT-01 or the following components

                                                                    Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches

                                                                    THEORY

                                                                    Shift Registers

                                                                    A Register is a set of flip-flops used to store binary data A register which is capable of shifting its binary information either to the right or left is called a shift register The logical configuration of a register consists of a chain of flip-flops connected in cascade with the output of one flip-flop connected to the input of next flip-flop All flip-flops receive a common clock pulse which causes the shift from one stage to the next

                                                                    Bidirectional Shift Registers A bi-directional shift register is one whose bits can be shifted from left to right or from right to left

                                                                    Universal Shift Registers A universal shift register is a bi-directional register whose input can be in either serial or parallel form and whose output can be in either serial or parallel form

                                                                    74194 4-BIT BIDIRECTIONAL UNIVERSAL SHIFT REGISTER

                                                                    The 74194 register provides parallel as well as serial loading in both directions Function of various pins of this IC is described below

                                                                    bull A B C and D Active high inputs for parallel loading bull QA QB QC and QD Active high outputs bull S0 and S1 Active high mode control inputs The following table shows combinations

                                                                    of S1 and S0 to enable various modes

                                                                    S1 S0 Clock Action 0 0 x No change 0 1 uarr Shift right 1 0 uarr Shift left 1 1 uarr Parallel load

                                                                    uarr shows the rising edge of the clock pulse

                                                                    56

                                                                    Logic Design amp Switching Theory 1 Lab Session 14 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering bull SR Active high serial input for right shifting bull SL Active high serial input for left shifting bull CLR Active low input Clears all the flip-flops of the register if set to 0 should be

                                                                    kept high otherwise bull CLK Clock input bull VCC and GND Supply connections lines Thus A B C and D are inputs for parallel loading whereas SR and SL are inputs for serial loading with right or left shifting respectively S1 and S0 are used to select the loading mode Circuit Diagram

                                                                    Figure 141 Pin connections of 74194 Testing Procedure

                                                                    bull Make connections as shown in the circuit diagram bull Observe the output for the input combinations given in the following table

                                                                    57

                                                                    Logic Design amp Switching Theory 1 Lab Session 14 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                    58

                                                                    Observations

                                                                    S1 S0 SL SR A B C D QA QB QC QD 0 0 0 1 0 0 0 0 0 1 1 0 0 0 0 1 1 0 0 0 0 0 1 0 1 1 0 0 0 0 1 1 0 0 1 1 0 1 0 0 0 1 1 1 0 1 0 1 1 0 1 0 0 1 1 0 1 1 1 0 0 1 1 1 1 1 0 0 1 1 1 1

                                                                    ACTIVITY 1 Show connections of 74194 to convert it into a ring counter with right shifting

                                                                    Logic Design amp Switching Theory 1 Lab Session 15 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                    Lab Session 15

                                                                    OBJECT

                                                                    Experimenting with 74245 octal bus transceivers using parallel port PC interfacing COMPONENTS AND APPARATUS REQUIRED 1 Parallel Port Connectors (DB-25) with Cable 2 Personal Computer with Windows 98 and TurboC Compiler Installed 3 Following ICs and their Datasheets

                                                                    bull 74245 Octal Bus Transceivers with 3-State Outputs 4 Digital Trainer DT-01 or the following components

                                                                    Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches

                                                                    THEORY

                                                                    3-State Logic Sometimes it is necessary to isolate one part of circuit from the other part For this purpose some TTL ICs are designed with 3-state logic Such devices have three possible output states high low and high impedance The device can be put into high impedance state by a control signal applied to an appropriate pin When such a device is in high impedance state there is very high impedance at its output effectively isolating the device from whatever circuitry the output normally drives 74245 Octal Bus Transceivers A bus is any conducting path or set of paths having electrical connections to one or more devices 74245 octal bus transceivers are mainly used to control connectivity between two devices or circuits It also provides direction control for signal flow Function of various pin of this IC is given below

                                                                    bull A1 through A8 Bus A bull B1 through B8 Bus B bull G΄ Active low enable input When high sets all the bus pins to high impedance state bull DIR Direction control for signal flow When set to high logic level transfers bus A

                                                                    data to B bus When set to low logic level transfers bus B data to A bus bull VCC and GND Supply connections lines Serial and Parallel Port Connectors A Parallel Port can consist of only 25 pin port adapter called a DB-25 and a serial port can consist of either a 25 pin port adapter called a DB-25 or 9 pin adapter called a DB-9 port adapter Whether the port is a 9 pin or 25 pin it can accomplish all of the same tasks that serial port communications have been designed for

                                                                    59

                                                                    Logic Design amp Switching Theory 1 Lab Session 15 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                    60

                                                                    Each adapter can be a male type connector with pins or a female type adapter with tiny holes Generally a PRINTER port (called LPT1) on the back of a computer is female type adapter and we need to use MALE DB-25 pin cable on it for PRINTER connection or for parallel LAPLINK cable And a COM port on the back of a computer is male for the serial ports but it may not necessarily be Parallel Port Connector ndash DB-25 The DB-25 connector (named for its B-size D-shaped shell and 25 pins) is practically ubiquitous in the electronics industry The DB-25 connector is used for a variety of purposes Two common applications are RS-232EIA-232 (serial) connections and the parallel printer interface on the IBM PC The DB-25 connector is also used for SCSI connections Normally the parallel port is used for output to a printer or other device It sends data 8-bits or one byte at a time in parallel The other lines available on the DB-25 connector are a combination of status lines control lines and ground lines The status and control lines are used for handshaking commands and feedback when we are talking to a printer

                                                                    Figure 152 DB-25 Female Figure 151 DB-25 Male

                                                                    Figure 153 Pin Layout for DB-25 As can be seen form figure 153 there are four types of pins in this connector

                                                                    bull Data pins (8 pins - D0 to D7) Active high bidirectional lines

                                                                    Logic Design amp Switching Theory 1 Lab Session 15 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering bull Control pins (4 pins - C0 to C3) C0 C1 and C3 are active low whereas C2 is active

                                                                    high These lines also are bidirectional bull Status pins (5 pins ndash S3 to S7) Only S7 is active low rest are active high input lines bull Ground pins (8 pins) Used as a reference signal for the low (below 05 volts) charge

                                                                    Parallel Port Addresses A DB-25 connector at a parallel port has three address one for each kind of pins register data status and control The first or base address generally refers to data register Second address is for status register and the third one is for control register In Windows 98 the base address is usually found to be 278H 378H or 3BCH Now if 378H is the base address then it refers to the data register whereas addresses for status and control register are respectively 379H and 37AH For Windows 98 the base address can be found as follows 1 On your Desktop right-click on My Computer and select Properties 2 Click on the Device Manager tab and find LPT1 under Plug and Play BIOS 3 After selecting LPT1 click the Properties button 4 Next select the Resources tab and the address should then appear next to InputOutput

                                                                    Range Accessing parallel port through C Language Programming There are multiple functions in C Language for accessing external ports The most commonly used are listed below

                                                                    bull unsigned char inportb(int portid) inportb reads a byte from a hardware port

                                                                    bull int inport(int portid) reads a word from a hardware port

                                                                    bull void outportb(int portid unsigned char value) outputs a byte to a hardware port

                                                                    bull void outport(int portid int value) outputs a word to a hardware port

                                                                    portid refers to the port address whereas value refers to the data to be sent TESTING 74245 USING PARALLEL PORT PC INTERFACING At one end the parallel port connector will be connected to the PC via parallel port cable and another connector (to be plugged into the PC parallel port slot) At the other end it will be connected to the buffer IC 74245 Data lines of the connector will be used to transfer 8-bit data between the PC and the buffer Out of the 8-bits of 74245 4-bits will be used to enter data which will be displayed at the monitor through a C language

                                                                    61

                                                                    Logic Design amp Switching Theory 1 Lab Session 15 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering program The remaining 4-bits will receive data from PC as entered by the user via keyboard

                                                                    Circuit Diagram

                                                                    Figure 154 Interface of 74245 to PC via Parallel Port

                                                                    Procedure

                                                                    1 Connect the DB-25 connector to the PC at one end and solder it to the circuit board at the other end

                                                                    2 Connect various pins of the connector and 74245 according to the circuit diagram shown in figure 152

                                                                    3 Using the functions listed in the previous section write a program in C language to operate various pins of the buffer The user interface of the program should provide option to the user whether to send or receive data from the port

                                                                    4 Set DIR switch to 1 5 Try sending some data bits to the port The result should be displayed at the LEDs 6 Set DIR switch to 0 7 Set some binary 4-bit value through the switches Try reading it via parallel port

                                                                    C Language Program

                                                                    A program to access parallel port for data transfers

                                                                    use header file include ltstdiohgt main program void main() define variable

                                                                    62

                                                                    Logic Design amp Switching Theory 1 Lab Session 15 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering unsigned int data=0 char choice while(1) printing option menu clrscr() printf(This program will send or receive a BCD digit from the parallel portn) printf(nPress your choice numbern) printf(n1 Send Data) printf(n2 Receive Data) printf(n3 Exitn) choice = getch() sending entered digit to the port if(choice == 1) input BCD digit printf(nEnter BCD digit to be sent to the port) data = getche() masking the first four bits data = data amp 0x0f sending to the port outportb(0x378data) printf(nThe BCD digit c has been sent to the port data) printing on screen the data received from the port else if(choice == 2) receiving data from the port data = inportb(0x378) masking the last four bits data = data amp 0xf0 shifting first four bits to make them the last four bits datagtgt=4 printf(nThe BCD digit set at the port is c data) exit else if(choice == 3) break key pressed is not in the menu else printf(nEnter valid choice number) printf(nnPress any key to continue) getch()

                                                                    63

                                                                    Logic Design amp Switching Theory 1 Lab Session 15 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                    ACTIVITY 1 In the above circuit DIR and G΄ inputs are hardwired Connect them to status or

                                                                    control pins of the parallel port connector and control their function through your software program Circuit Diagram Program Code ______________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________

                                                                    ___________________________________________________________________________________________________________________________________________________

                                                                    64

                                                                    Logic Design amp Switching Theory 1 Lab Session 15 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                    65

                                                                    _____________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ _____________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ _______________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ _________________________________________________ _________________________________________________

                                                                    Logic Design amp Switching Theory 1 Appendix A NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                    Appendix A

                                                                    PIN DIAGRAMS OF THE ICS REQUIRED FOR THE LABORATORY SESSIONS Consult the TTLIC data book for internal diagrams and electrical characteristics of these ICs 7400 Quad 2-Input NAND 7402 Quad 2-Input NOR

                                                                    7404 Hex Inverter 7408 Quad 2-Input AND

                                                                    7410 Triple 3-Input NAND 7411 Triple 3-Input AND

                                                                    7421 Dual 4-Input AND 7432 Quad 2-Input OR

                                                                    66

                                                                    Logic Design amp Switching Theory 1 Appendix A NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                    BCD-to-Seven Segm 7448 BCD-to-Seven Segment 7447 ent

                                                                    Decoder (15V OC) Decoder (2kΩ pull-up output)

                                                                    7473 Dual JK Flip-Flop 7474 Dual D-Type Flip-Flop

                                                                    7476 Dual JK Flop-Flop -Bit Binary Full Adder 7483 4 with Fast Carry

                                                                    86 Quad 2-Inpu 74138 3-to-8 Line 74 t Exclusive OR Decoder Demultiplexer

                                                                    67

                                                                    Logic Design amp Switching Theory 1 Appendix A NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                    68

                                                                    74148 8-to-3 Line 16-to-1 Line Data

                                                                    Priority Encoder 74150 Selector Multiplexer

                                                                    74245 Oct nsceivers Universal Shift Register (PIPO) (3-State)

                                                                    74194 4-Bit Bidirectional al Bus Tra

                                                                    Logic Design amp Switching Theory 1 Appendix B NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                    Appendix B

                                                                    DEBOUNCING CIRCUITRY FOR MECHANICAL SWITCHES Mechanical switches form the interface between human beings and computers or other digital systems For example a keyboard is a matrix of switches used to supply alphanumeric data to a computer Whatever the switch design it is a potential source of problems due to contact bounce The contact bounce creates a sense of narrow pulses when a switch is opened or closed An example of device whose operation would be adversely affected by contact bounce is a digital counter used to count the number of times a switch is depressed Eliminating the effects of contact bounce is called debouncing When data is entered into a computer via a keyboard a software debounce is often used This type of debouncing is a program that causes the computer to sample the switch terminal (ie to input data from it) many times in succession during the interval of time that contact bounce occurs If the data is sensed to be 1s (or 0s) for a specific number of consecutive samples then it is assumed that contact bounce has ended and the last value sensed is valid Hardware debouncing is the use of electronic circuitry to eliminate the effects of contact bounce There are numerous versions of such circuitry including those that use monostable multivibrators (one-shots) but the most straightforward is simply an RS latch Figure B1 shows the circuit When the switch is in position 1 R = 0 and S = 1 so the latch is set and the output (Q) is 1 When the switch is in position 0 R = 1and S = 0 so the latch is reset and the output is 0 When the switch is moved form one position to the other the latch changes state and bouncing occurs at either the R or the S input The bouncing does not affect the latch after it has change state An RS latch will remain set for example when its R input is 0 and its S input is alternately changed form 1 to 0

                                                                    Figure B1 Use of RS latch to debounce a mechanical switch

                                                                    69

                                                                    • 01-ldst-Outer title
                                                                      • Practical Workbook
                                                                      • Logic Design amp Switching Theory I
                                                                        • Dept of Computer amp Information Systems Engineering
                                                                          • NED University of Engineering amp Technology
                                                                          • Karachi ndash 75270 Pakistan
                                                                            • 02-ldst-inner Title
                                                                              • Practical Workbook
                                                                              • Logic Design amp Switching Theory I
                                                                                • Dept of Computer amp Information Systems Engineering
                                                                                  • NED University of Engineering amp Technology
                                                                                  • Karachi ndash 75270 Pakistan
                                                                                    • 03-ldst-general info
                                                                                    • 04-ldst-introduction
                                                                                    • 05-Table of Contents
                                                                                      • CONTENTS
                                                                                        • Lab Session No Object Page No
                                                                                        • 1
                                                                                        • Also implementing and testing the given circuit on a bread board
                                                                                          • Working with Electronics Workbench
                                                                                            • Driving a seven segment display using 7447 7448 driver IC
                                                                                              • Designing a modulus-5 asynchronous up-counter using JK-FF
                                                                                                • Experimenting with 74194 4-bit bidirectional universal shift register
                                                                                                    • 13
                                                                                                        • 06-ldst-Exp01
                                                                                                          • Lab Session 01
                                                                                                          • OBJECT
                                                                                                            • 1 Bread board
                                                                                                            • 2 5 V - power supply
                                                                                                            • 3 Multimeter
                                                                                                            • 4 Logic probe
                                                                                                            • 5 LEDs with resistors
                                                                                                            • 6 Connecting wires
                                                                                                            • 8 Following ICs and their datasheets
                                                                                                              • THEORY
                                                                                                                • Logic Gates
                                                                                                                • 1 The AND Gate ndash An AND gatersquos output is 1 if and only if all its inputs are 1 If A and B are two inputs to an AND gate then output F of the gate is given as F = AB
                                                                                                                • 2 The OR Gate - An OR gatersquos output is 1 if at least one of its input is 1 If A and B are two inputs to an OR gate then output F of the gate is given as F = A+B
                                                                                                                • 3 The NOT Gate (Inverter) ndash Its output is 1 when its input is 0 and its output is 0 when the input is 1 ie it complements a digital variable If A is the input to a NOT gate then output F of the gate is given as
                                                                                                                • 4 The NAND Gate ndash Its output is 1 if at least one of its input is 0 This gate performs the same logic as an AND gate followed by an inverter If A and B are two inputs to a NAND gate then output F of the gate is given as
                                                                                                                  • 5 The NOR Gate - The output of a NOR gate is 1 if and only if all its inputs are 0 This gate performs the same logic function as an OR gate followed by an inverter If A and B are two inputs to a NAND gate then output F of the gate is given as
                                                                                                                      • DATA SHEETS
                                                                                                                        • Logic expression for the given logic diagram __________________________________
                                                                                                                            • 07-ldst-exp02
                                                                                                                              • Working with Electronics Workbench
                                                                                                                                • 08-ldst-exp03
                                                                                                                                  • Designing Half and Full Adder Circuits
                                                                                                                                    • COMPONENTS AND APPARATUS REQUIRED
                                                                                                                                      • 1 Following ICs and their Datasheets
                                                                                                                                      • 7408 Quad 2-input AND Gate
                                                                                                                                      • 2 Digital Trainer DT-01 or the following components
                                                                                                                                        • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                        • Connecting wires Switches
                                                                                                                                          • THEORY
                                                                                                                                              • IMPLEMENTATION AND OBSERVATIONS
                                                                                                                                                • 09-ldst-Exp04
                                                                                                                                                  • Lab Session 04
                                                                                                                                                  • 1 Digital ICs and their Datasheets
                                                                                                                                                  • 7408 Quad 2-input AND Gate
                                                                                                                                                  • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                    • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                    • Connecting wires Switches
                                                                                                                                                    • PROCEDURE
                                                                                                                                                    • REDUCTION OF LOGIC EXPRESSION USING KARNAUGH MAP
                                                                                                                                                    • OBSERVATIONS
                                                                                                                                                    • RESULT
                                                                                                                                                        • 10-ldst-Exp05
                                                                                                                                                          • Lab Session 05
                                                                                                                                                          • 1 Following ICs and their Datasheets
                                                                                                                                                          • 7408 Quad 2-input AND Gate
                                                                                                                                                          • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                            • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                            • (100 Ω) Connecting wires Switches
                                                                                                                                                            • THEORY
                                                                                                                                                              • IMPLEMENTATION AND OBSERVATIONS
                                                                                                                                                                • 11-ldst-Exp06
                                                                                                                                                                  • OBJECT
                                                                                                                                                                  • 1 Following ICs and their Datasheets
                                                                                                                                                                  • 7408 Quad 2-input AND Gates or 7411 Triple 3-input AND Gates
                                                                                                                                                                  • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                    • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                    • Connecting wires Switches
                                                                                                                                                                      • Figure 62 Circuit Diagram for 4 x 1 Multiplexer
                                                                                                                                                                      • Implementation and Observations
                                                                                                                                                                        • Circuit Diagram
                                                                                                                                                                          • ACTIVITY
                                                                                                                                                                            • 12-ldst-exp07
                                                                                                                                                                              • 1 Following ICs and their Datasheets
                                                                                                                                                                              • 7408 Quad 2-input or 7411 Triple 3-input AND Gates
                                                                                                                                                                              • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                • Connecting wires Switches
                                                                                                                                                                                  • THEORY
                                                                                                                                                                                      • Figure 72 Circuit Diagram for 2 x 4 Decoder 1 x 4 Demultiplexer
                                                                                                                                                                                      • Implementation and Observations
                                                                                                                                                                                        • Circuit Diagram
                                                                                                                                                                                          • ACTIVITY
                                                                                                                                                                                            • 13-ldst-Exp08
                                                                                                                                                                                              • OBJECT
                                                                                                                                                                                              • 1 Following ICs and their Datasheets
                                                                                                                                                                                              • 7408 Quad 2-input or 7421 Dual 4-input AND Gates
                                                                                                                                                                                              • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                • Connecting wires Switches
                                                                                                                                                                                                  • THEORY
                                                                                                                                                                                                      • Figure 81 Circuit Diagram for 4 x 2 Priority Encoder
                                                                                                                                                                                                      • Implementation and Observations
                                                                                                                                                                                                        • Therefore if GS A2 A1 and A0 are all low then it shows that line 0 is selected and if E0 A2 A1 and A0 are all low then it shows that none of the inputs selected E0 and GS cannot be in the same state provided that E1 is enabled
                                                                                                                                                                                                        • Circuit Diagram
                                                                                                                                                                                                          • ACTIVITY
                                                                                                                                                                                                            • 14-ldst-exp09
                                                                                                                                                                                                              • OBJECT
                                                                                                                                                                                                              • 1 Following ICs and their Datasheets
                                                                                                                                                                                                              • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                                • Connecting wires Switches
                                                                                                                                                                                                                  • THEORY
                                                                                                                                                                                                                    • Parity Generator
                                                                                                                                                                                                                      • Let x y and z be the three bits that constitute the message and are the input to the Odd Parity Generator Circuit Since it is an odd parity system the bit P is generated so as to make the total number of 1s odd (including P) The function P can be expressed as follows
                                                                                                                                                                                                                      • Figure 91 Circuit Diagram for a 3-bit Parity Generator
                                                                                                                                                                                                                        • C = x Ο y Ο z Ο P
                                                                                                                                                                                                                          • Implementation and Observations
                                                                                                                                                                                                                            • ACTIVITY
                                                                                                                                                                                                                                • 15-ldst-exp10
                                                                                                                                                                                                                                  • Driving a seven segment display using 7447 7448 driver IC
                                                                                                                                                                                                                                  • COMPONENTS AND APPARATUS REQUIRED
                                                                                                                                                                                                                                  • 1 Following ICs and their Datasheets
                                                                                                                                                                                                                                  • 7447 7448 BCD to Seven Segment Driver
                                                                                                                                                                                                                                  • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                                    • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches
                                                                                                                                                                                                                                      • THEORY
                                                                                                                                                                                                                                      • Seven Segment Displays
                                                                                                                                                                                                                                      • CIRCUIT DIAGRAM
                                                                                                                                                                                                                                      • Figure 102 Circuit diagram for 7447driving a common-anode display
                                                                                                                                                                                                                                          • IMPLEMENTATION AND OBSERVATIONS
                                                                                                                                                                                                                                            • Decimal Digit
                                                                                                                                                                                                                                            • BCD Inputs
                                                                                                                                                                                                                                            • Seven Segment Outputs
                                                                                                                                                                                                                                            • D
                                                                                                                                                                                                                                            • C
                                                                                                                                                                                                                                            • B
                                                                                                                                                                                                                                            • A
                                                                                                                                                                                                                                            • a
                                                                                                                                                                                                                                            • b
                                                                                                                                                                                                                                            • c
                                                                                                                                                                                                                                            • d
                                                                                                                                                                                                                                            • e
                                                                                                                                                                                                                                            • f
                                                                                                                                                                                                                                            • g
                                                                                                                                                                                                                                            • 0
                                                                                                                                                                                                                                            • 0
                                                                                                                                                                                                                                            • 0
                                                                                                                                                                                                                                            • 0
                                                                                                                                                                                                                                            • 0
                                                                                                                                                                                                                                            • 1
                                                                                                                                                                                                                                            • 0
                                                                                                                                                                                                                                            • 0
                                                                                                                                                                                                                                            • 0
                                                                                                                                                                                                                                            • 1
                                                                                                                                                                                                                                            • 2
                                                                                                                                                                                                                                            • 0
                                                                                                                                                                                                                                            • 0
                                                                                                                                                                                                                                            • 1
                                                                                                                                                                                                                                            • 0
                                                                                                                                                                                                                                            • 3
                                                                                                                                                                                                                                            • 0
                                                                                                                                                                                                                                            • 0
                                                                                                                                                                                                                                            • 1
                                                                                                                                                                                                                                            • 1
                                                                                                                                                                                                                                            • 4
                                                                                                                                                                                                                                            • 0
                                                                                                                                                                                                                                            • 1
                                                                                                                                                                                                                                            • 0
                                                                                                                                                                                                                                            • 0
                                                                                                                                                                                                                                            • 5
                                                                                                                                                                                                                                            • 0
                                                                                                                                                                                                                                            • 1
                                                                                                                                                                                                                                            • 0
                                                                                                                                                                                                                                            • 1
                                                                                                                                                                                                                                            • 6
                                                                                                                                                                                                                                            • 0
                                                                                                                                                                                                                                            • 1
                                                                                                                                                                                                                                            • 1
                                                                                                                                                                                                                                            • 0
                                                                                                                                                                                                                                            • 7
                                                                                                                                                                                                                                            • 0
                                                                                                                                                                                                                                            • 1
                                                                                                                                                                                                                                            • 1
                                                                                                                                                                                                                                            • 1
                                                                                                                                                                                                                                            • 8
                                                                                                                                                                                                                                            • 1
                                                                                                                                                                                                                                            • 0
                                                                                                                                                                                                                                            • 0
                                                                                                                                                                                                                                            • 0
                                                                                                                                                                                                                                            • 9
                                                                                                                                                                                                                                            • 1
                                                                                                                                                                                                                                            • 0
                                                                                                                                                                                                                                            • 0
                                                                                                                                                                                                                                            • 1
                                                                                                                                                                                                                                              • ACTIVITY
                                                                                                                                                                                                                                                • 16-ldst-exp11
                                                                                                                                                                                                                                                  • Lab Session 11
                                                                                                                                                                                                                                                    • OBJECT
                                                                                                                                                                                                                                                    • COMPONENTS AND APPARATUS REQUIRED
                                                                                                                                                                                                                                                      • 1 Following ICs and their Datasheets
                                                                                                                                                                                                                                                      • 7473 7476 JK Flip-Flop
                                                                                                                                                                                                                                                      • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                                                        • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                                                                        • Connecting wires Switches
                                                                                                                                                                                                                                                          • THEORY
                                                                                                                                                                                                                                                              • Flip-Flop
                                                                                                                                                                                                                                                              • JK Flip-Flop
                                                                                                                                                                                                                                                                • Circuit Diagram
                                                                                                                                                                                                                                                                  • Observations
                                                                                                                                                                                                                                                                    • ACTIVITY
                                                                                                                                                                                                                                                                        • 17-ldst-exp12
                                                                                                                                                                                                                                                                          • Lab Session 12
                                                                                                                                                                                                                                                                            • OBJECT
                                                                                                                                                                                                                                                                            • GIVEN STATE DIAGRAM
                                                                                                                                                                                                                                                                            • Figure 121 State Diagram
                                                                                                                                                                                                                                                                            • COMPONENTS AND APPARATUS REQUIRED
                                                                                                                                                                                                                                                                              • 1 Following ICs and their Datasheets
                                                                                                                                                                                                                                                                              • 7474 D Flip-Flop
                                                                                                                                                                                                                                                                              • ICs of basic gates (AND OR NOT XOR etc) as required
                                                                                                                                                                                                                                                                              • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                                                                                • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                                                                                                • Connecting wires Switches
                                                                                                                                                                                                                                                                                  • THEORY
                                                                                                                                                                                                                                                                                      • Sequential Circuits
                                                                                                                                                                                                                                                                                        • 18-ldst-exp13
                                                                                                                                                                                                                                                                                          • Lab Session 13
                                                                                                                                                                                                                                                                                            • Designing a modulo-5 asynchronous up-counter using JK-FF
                                                                                                                                                                                                                                                                                              • 1 Following ICs and their Datasheets
                                                                                                                                                                                                                                                                                              • 7400 Quad 2-input or 7410 Triple 3-input NAND Gates
                                                                                                                                                                                                                                                                                              • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                                                                                                • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                                                                                                                • Connecting wires Switches
                                                                                                                                                                                                                                                                                                  • THEORY
                                                                                                                                                                                                                                                                                                      • Figure 131 A Mod-5 Asynchronous Up Counter
                                                                                                                                                                                                                                                                                                      • Implementation and Observations
                                                                                                                                                                                                                                                                                                        • ACTIVITY
                                                                                                                                                                                                                                                                                                            • 19-ldst-exp14
                                                                                                                                                                                                                                                                                                              • Experimenting with 74194 4-bit bidirectional universal shift register
                                                                                                                                                                                                                                                                                                              • 1 Following ICs and their Datasheets
                                                                                                                                                                                                                                                                                                              • 74194 4-bit bidirectional universal shift register
                                                                                                                                                                                                                                                                                                              • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                                                                                                                • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                                                                                                                                • Connecting wires Switches
                                                                                                                                                                                                                                                                                                                  • THEORY
                                                                                                                                                                                                                                                                                                                    • Shift Registers
                                                                                                                                                                                                                                                                                                                    • Bidirectional Shift Registers
                                                                                                                                                                                                                                                                                                                    • Universal Shift Registers
                                                                                                                                                                                                                                                                                                                      • S1
                                                                                                                                                                                                                                                                                                                        • Circuit Diagram
                                                                                                                                                                                                                                                                                                                        • ACTIVITY
                                                                                                                                                                                                                                                                                                                            • 20-ldst-exp15
                                                                                                                                                                                                                                                                                                                              • COMPONENTS AND APPARATUS REQUIRED
                                                                                                                                                                                                                                                                                                                              • 1 Parallel Port Connectors (DB-25) with Cable
                                                                                                                                                                                                                                                                                                                              • 2 Personal Computer with Windows 98 and TurboC Compiler Installed
                                                                                                                                                                                                                                                                                                                              • 3 Following ICs and their Datasheets
                                                                                                                                                                                                                                                                                                                              • 74245 Octal Bus Transceivers with 3-State Outputs
                                                                                                                                                                                                                                                                                                                              • 4 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                                                                                                                                • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                                                                                                                                                  • Connecting wires Switches
                                                                                                                                                                                                                                                                                                                                    • THEORY
                                                                                                                                                                                                                                                                                                                                    • 3-State Logic
                                                                                                                                                                                                                                                                                                                                      • Serial and Parallel Port Connectors
                                                                                                                                                                                                                                                                                                                                      • Parallel Port Connector ndash DB-25
                                                                                                                                                                                                                                                                                                                                        • Accessing parallel port through C Language Programming
                                                                                                                                                                                                                                                                                                                                            • 21-ldst-appendixA
                                                                                                                                                                                                                                                                                                                                            • 22-ldst-appendixB
                                                                                                                                                                                                                                                                                                                                              • DEBOUNCING CIRCUITRY FOR MECHANICAL SWITCHES

                                                                      Logic Design amp Switching Theory 1 Lab Session 07 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                      37

                                                                      ACTIVITY ACTIVITY 1 What will be the binary values at the outputs Y0 through Y7 of 74138 if 1 What will be the binary values at the outputs Y0 through Y7 of 74138 if

                                                                      bull All three enable pins are connected to ground bull All three enable pins are connected to ground __________________________________________________________________________________________________________________________________________ __________________________________________________________________________________________________________________________________________ _____________________________________________________________________ _____________________________________________________________________

                                                                      bull All three enable pins are connected to VCC bull All three enable pins are connected to VCC _______________________________________________________________________________________________________________________________________________________________________________________________________________

                                                                      _______________________________________________________________________________________________________________________________________________________________________________________________________________

                                                                      2 Show connections for 74138 in order to use it as a 1 x 8 Demultiplexer 2 Show connections for 74138 in order to use it as a 1 x 8 Demultiplexer

                                                                      3 Consider a 2 x 4 Decoder with two enable inputs (one active high - G and one active low ndash Grsquo) Draw the output wave-forms for D0 D1 D2 and D3 if the two select inputs are A and B (B being the MSB) All outputs are active low

                                                                      Grsquo

                                                                      G

                                                                      A B

                                                                      D0 D1 D2

                                                                      D3

                                                                      Logic Design amp Switching Theory 1 Lab Session 08 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                      Lab Session 08 OBJECT

                                                                      bull Designing of a 4 x 2 Priority Encoder bull Experimenting with 74148 IC

                                                                      COMPONENTS AND APPARATUS REQUIRED

                                                                      1 Following ICs and their Datasheets

                                                                      bull 7408 Quad 2-input or 7421 Dual 4-input AND Gates bull 7432 Quad 2-input OR Gates bull 7404 Hex Inverter bull 74148 Encoder

                                                                      2 Digital Trainer DT-01 or the following components Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches

                                                                      THEORY

                                                                      Encoder An Encoder is a digital function that produces a reverse operation from that of a decoder An Encoder has 2n (or less) input lines and n output lines The output lines generate the binary code for the 2n input variables Priority Encoder

                                                                      A simple encoder may produce an erroneous output if more than one of its inputs is high A Priority Encoder is one that responds to just one input among those that may be simultaneously high in accordance with some priority system The most common priority system is based on the relative magnitudes of the inputs whichever decimal input is largest is the one that is encoded

                                                                      DESIGN OF A 4 x 2 Priority Encoder

                                                                      The following equations represent the outputs of a 4 x 2 priority encoder 32 DDA +=

                                                                      321 DDDB += As can be seen from the equations that input D0 which has a binary code 00 is not used in any equation A binary code 00 at the output indicates two conditions Either D0 is selected or no input is selected In order to differentiate these two conditions we will provide an additional output Z to indicate if at least one of the inputs is a 1 The equation for Z will be

                                                                      4321 DDDDZ = If Z is 0 then the binary code 00 at the output indicates that D0 is selected and if Z is 1 then it indicates that no input line is selected

                                                                      38

                                                                      Logic Design amp Switching Theory 1 Lab Session 08 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                      Figure 81 Circuit Diagram for 4 x 2 Priority Encoder

                                                                      it (figure 81) on a bread board (prepare the to laboratory session 01 for implementation

                                                                      Implementation a Implement the 4 x 2 Priority Encoder circu

                                                                      ram (use appendix A) and refer

                                                                      nd Observations

                                                                      pin diagprocedure) and record the observations in the following table

                                                                      D3 D2 D1 D0 A B 0 0 0 1 0 0 1 x 0 1 x x 1 x x x

                                                                      TESTING OF 74148 8 x 3 Octal Priority Encoder

                                                                      imal digits There are nine of which three represents

                                                                      ing any of the inputs is high

                                                                      then it shows that line 0 is selected and if e inputs selected E0 and GS

                                                                      cannot be in the same state provided that E1 is enabled

                                                                      The 74148 is a priority encoder with active-Low input for dec

                                                                      input) and five output linesinputs lines (including an enablethe binary code for the octal digit Function of various pins of this IC is described below

                                                                      bull 0 through 7 Active low data inputs representing the octal digits A2 A1 A0 Active low output lines representing the binary code bullbull E1 Active low enable Input bull E0 Active low output indicating none of the inputs is high bull GS Active low output indicatbull VCC and GND Supply connections lines Therefore if GS A2 A1 and A0 are all low

                                                                      then it shows that none of thE0 A2 A1 and A0 are all low

                                                                      39

                                                                      Logic Design amp Switching Theory 1 Lab Session 08 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                      Circuit Diagram

                                                                      Figure 82 Pin connections of 74148

                                                                      Testing Procedure bull Make connections as sho

                                                                      binations of 1s and 0s at data inputs d record your observations in the following table

                                                                      GS E0

                                                                      wn in the circuit diagram bull Apply different combull Observe the output an Observations

                                                                      0 1 2 3 4 5 6 7 A2 A1 A0 1 1 1 1 1 1 1 1 x x x x x x x 0 x x x x x x 0 1 x x x x x 0 1 1 x x x x 0 1 1 1 x x x 0 1 1 1 1 x x 0 1 1 1 1 1 x 0 1 1 1 1 1 1 0 1 1 1 1 1 1 1

                                                                      40

                                                                      Logic Design amp Switching Theory 1 Lab Session 08 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                      41

                                                                      CTIVITY

                                                                      Cascade the following two 74148 8 x 3 Priority Encoders to form 16 x 4 Priority

                                                                      A 1

                                                                      Encoder

                                                                      Logic Design amp Switching Theory 1 Lab Session 09 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering `

                                                                      Lab Session 09 OBJECT

                                                                      Designing an Odd Parity Generator and Checker for a 3-bit Data COMPONENTS AND APPARATUS REQUIRED

                                                                      1 Following ICs and their Datasheets

                                                                      bull 7486 Quad 2-input Exclusive-OR Gates bull 7404 Hex Inverter

                                                                      2 Digital Trainer DT-01 or the following components Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches

                                                                      THEORY

                                                                      Parity Generator When binary data is transmitted and processed it is ndash as are all electrical signals ndash susceptible to noise that can either alter or distort its contents 1s may be effectively changed to 0s and 0s to 1s To overcome this problem one or more bits are often added to the data as an aid in detecting errors caused by noise The most common of these is a Parity bit that signifies whether the total number of 1s in a code group is odd or even In an Odd Parity system the parity bit is made 0 or 1 as necessary to make the total number 1s odd (counting the parity bit itself) In an Even Parity system the parity bit is chosen to make the total number of 1s even Table 91 shows how parity bits would be added to BCD code group in both systems

                                                                      Decimal BCD Value Parity Bit ABCD Odd Parity Even Parity

                                                                      0 0000 1 0 1 0001 0 1 2 0010 0 1 3 0011 1 0 4 0100 0 1 5 0101 1 0 6 0110 1 0 7 0111 0 1 8 1000 0 1 9 1001 1 0

                                                                      Table 91 Odd and Even Parity in BCD

                                                                      When digital data is received a parity checking circuit generates an error signal if the total number of 1s is odd in an even parity system or if it is even in an odd parity system Parity check always detects a single error (one bit change from 0 to 1 or 1 to 0) but may not detect

                                                                      42

                                                                      Logic Design amp Switching Theory 1 Lab Session 09 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering ` two or more errors Odd parity is used more often than even parity because even parity does not detect a situation where all 0s are created due to short circuit or other fault condition DESIGN OF A 3-BIT ODD PARITY GENERATOR AND CHECKER Let x y and z be the three bits that constitute the message and are the input to the Odd Parity Generator Circuit Since it is an odd parity system the bit P is generated so as to make the total number of 1s odd (including P) The function P can be expressed as follows P = x oplus y Ο z or P = x Ο y oplus z Since the IC available is 7486 which is quad 2input XOR IC therefore we will convert XNOR also to XOR

                                                                      P = x oplus y Ο z

                                                                      P = ( x oplus y ) Ο z Since for even number of variables ______

                                                                      XOR = XNOR Therefore ___________ _________

                                                                      P = ( x oplus y ) oplus z = x oplus y oplus z This logical expression can be implemented with two XOR gates and an inverter (see figure 91)

                                                                      Figure 91 Circuit Diagram for a 3-bit Parity Generator

                                                                      The 3-bit message and the parity bit are transmitted to their destination where they are applied to a Parity Checker Circuit An error occurs during transmission if the parity of the four bits received is even since the binary information transmitted was originally odd The output C of the parity checker should be a 1 when an error occurs ie when the number of 1s in the four inputs is even Therefore the function C can be expressed as

                                                                      C = x Ο y Ο z Ο P

                                                                      Using the same logic applied for the conversion of the equation of P

                                                                      PzyxC oplusoplusoplus= This logical expression can be implemented with three XOR gates and an inverter (see figure 92)

                                                                      43

                                                                      Logic Design amp Switching Theory 1 Lab Session 09 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering `

                                                                      44

                                                                      Figure 92 Circuit Diagram for a 3-bit Parity Checker Implementation and Observations Implement the 3-bit Parity Generator and Checker circuits (figure 91 and 92) on a bread board (prepare the pin diagram (use appendix A) and refer to laboratory session 01 for implementation procedure) and record the observations in the following table

                                                                      x y z P x y z P C x y z P C 0 0 0 0 0 0 0 1 0 0 0 0 0 1 0 0 0 1 1 0 0 1 0 1 0 0 0 1 0 1 0 1 0 0 1 1 0 0 1 1 1 0 1 1 1 0 0 0 1 0 0 1 1 0 0 1 0 1 0 1 0 1 1 1 0 1 1 1 0 0 1 1 0 1 1 1 0 1 1 1 0 1 1 1 1 1 1 1

                                                                      Odd Parity Generation Odd Parity Check ACTIVITY 1 Try using the parity checker of figure 92 as 3-bit parity generator Write the details here

                                                                      _____________________________________________________________________________________________________________________________________________________________________________________________________________________ ______________________________________________________________________________________________________________________________________________ _______________________________________________________________________ ______________________________________________________________________________________________________________________________________________

                                                                      Logic Design amp Switching Theory 1 Lab Session 10 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                      Lab Session 10 OBJECT

                                                                      Driving a seven segment display using 7447 7448 driver IC COMPONENTS AND APPARATUS REQUIRED

                                                                      1 Following ICs and their Datasheets

                                                                      bull Seven Segment Displays (Common Anode Common Cathode) bull 7447 7448 BCD to Seven Segment Driver

                                                                      2 Digital Trainer DT-01 or the following components Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches

                                                                      THEORY Seven Segment Displays A Seven Segment Display consists of seven light-emitting segments The segments are designated by letters a through g (see figure 101) By illuminating various combinations of segments the numerals 0 through 9 can be displayed Seven Segment Displays are commonly constructed with light-emitting diodes (LEDs) and with liquid-crystal displays (LCDs) LEDs generally provide greater illumination levels but require much greater power than LCDs An LED display can be a common-anode type or common cathode type In common anode type a high voltage is applied at the common terminal of the display and low voltage is applied at a segmentrsquos terminal for illumination In the common-cathode type a low voltage is applied at the common terminal of the display and high voltage is applied at a segmentrsquos terminal for illumination

                                                                      Figure 101 Seven Segment Display

                                                                      a f b g

                                                                      e c d

                                                                      7447 7448 BCD to Seven Segment Driver 7447 7448 IC is particularly used to drive Seven Segment Its input is a BCD number and output drives a seven segment display 7447 is used to drive common-anode displays whereas 7448 is used to drive common cathode displays 7447 7448 is a 16 pin IC Function of various pins of these ICs is described below

                                                                      bull A B C D Inputs representing BCD digits (D being the MSB)

                                                                      45

                                                                      Logic Design amp Switching Theory 1 Lab Session 10 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering bull OA through OG Outputs to drive segments a through g of the display (Active low

                                                                      in 7447 and active high in 7448) bull RBI Ripple Blanking Input Turns off all the segments if kept low provided that LT

                                                                      is kept high and all other inputs (A B C D BI) are kept low Should be kept high otherwise

                                                                      bull BI RBO Wire-AND logic serving as a Blanking Input and or Ripple Blanking Output

                                                                      o BI Turns off all the segments if low o RBO Goes to a low level (response condition) along with other outputs when

                                                                      RBI and inputs A B C and D are low with LT input at high level bull LT Lamp Test input Tests whether all segments are working or not Illuminates all

                                                                      segments if kept low provided that BI is kept high Should be kept high otherwise bull VCC and GND Supply connections lines CIRCUIT DIAGRAM

                                                                      Figure 102 Circuit diagram for 7447driving a common-anode display

                                                                      IMPLEMENTATION AND OBSERVATIONS

                                                                      bull Make connections as shown in the circuit diagram (refer to laboratory session 01 for implementation procedure)

                                                                      bull Apply different combinations of 1s and 0s at data inputs bull Observe the output and record your observations in the following table

                                                                      46

                                                                      Logic Design amp Switching Theory 1 Lab Session 10 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                      47

                                                                      Decimal Digit

                                                                      BCD Inputs Seven Segment Outputs D C B A a b c d e f g

                                                                      0 0 0 0 0 1 0 0 0 1 2 0 0 1 0 3 0 0 1 1 4 0 1 0 0 5 0 1 0 1 6 0 1 1 0 7 0 1 1 1 8 1 0 0 0 9 1 0 0 1

                                                                      ACTIVITY 1 Perform the Lamp Test for the designed circuit and write your observations

                                                                      ____________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________

                                                                      2 How can you use 7447 IC to drive a common-cathode display

                                                                      ____________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________

                                                                      3 What symbols appear in the seven segment display if inputs DCBA are

                                                                      DCBA Symbol

                                                                      1010

                                                                      1011

                                                                      1100

                                                                      1101

                                                                      1110

                                                                      1111

                                                                      Logic Design amp Switching Theory 1 Lab Session 11 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                      48

                                                                      Lab Session 11 OBJECT

                                                                      Testing different modes of JK-FF COMPONENTS AND APPARATUS REQUIRED 1 Following ICs and their Datasheets

                                                                      bull 7473 7476 JK Flip-Flop 2 Digital Trainer DT-01 or the following components

                                                                      Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches

                                                                      THEORY

                                                                      Flip-Flop A flip-flop circuit can maintain a binary state indefinitely (as long as the power is delivered to the circuit) until directed by an input signal to switch states The major differences among various types of flip-flops are in the number of inputs they possess and in the manner in which the inputs affect the binary state

                                                                      JK Flip-Flop JK flip flop is an edge triggered device A typical JK flip flop has three inputs J K and a clock input The flip-flop can be either positive or negative edge triggered The output Q is available in complemented form as well Beside the usual inputs and output most of the flip-flop IC also possess two asynchronous inputs namely Preset and Clear These inputs are usually active low If used Preset and Clear inputs keep the flip-flop in set and reset state respectively irrespective of the other inputs Both of these inputs cannot be used simultaneously otherwise they will bring the flip-flop in unstable state

                                                                      Figure 111 Symbol for JK flip-flop

                                                                      (a) positive-edge triggering (b) active low Preset (PR) and Clear (CLR) with positive-edge triggering

                                                                      (c) active low Preset (PR) and Clear (CLR) with negative-edge triggering

                                                                      Logic Design amp Switching Theory 1 Lab Session 11 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                      49

                                                                      TESTING OF 7473 7476 DUAL JK FLIP-FLOP

                                                                      Both the ICs 7473 and 7476 are similar in functionality except for one difference The flip-flops in 7473 have only one type of active low asynchronous input which is the Clear input whereas the flip-flops in 7476 have both Preset and Clear inputs Both these ICs have negative edge triggered flip-flops

                                                                      Circuit Diagram

                                                                      Figure 112 Pin connections of 7476

                                                                      Testing Procedure

                                                                      bull Make connections as shown in the circuit diagram (figure 112) bull Apply different combinations of 1s and 0s at J and K inputs bull Observe the output and record your observations in the following table

                                                                      Observations

                                                                      J

                                                                      K Q

                                                                      0 0 0 1 1 0 1 1

                                                                      ACTIVITY

                                                                      1 Observe the output Q of JK flip-flop if the clock input is connected to VCC or GND instead of a clock source Write your observations here __________________________________________________________________________________________________________________________________________ _______________________________________________________________________________________________________________________________________________________________________________________________________________

                                                                      Logic Design amp Switching Theory 1 Lab Session 12 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                      50

                                                                      Lab Session 12 OBJECT

                                                                      Designing sequential circuit for the given state diagram using D flip-flop GIVEN STATE DIAGRAM

                                                                      00

                                                                      11

                                                                      Figure 121 State Diagram COMPONENTS AND APPARATUS REQUIRED 1 Following ICs and their Datasheets

                                                                      bull 7474 D Flip-Flop bull ICs of basic gates (AND OR NOT XOR etc) as required

                                                                      2 Digital Trainer DT-01 or the following components Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches

                                                                      THEORY

                                                                      Sequential Circuits In Sequential Circuits the output not only depends on the present inputs but also on previous states of the circuit These circuits use memory elements (latches flip-flops) and the binary information stored in the memory elements at any given time defines the state of the sequential circuit Analysis of a Sequential Circuit The behavior of a sequential circuit is determined from the inputs the outputs and the states of its flip-flops Both the outputs and next state are a function of the inputs and the

                                                                      10

                                                                      01

                                                                      00 11 10

                                                                      00

                                                                      00 11 10 00

                                                                      Logic Design amp Switching Theory 1 Lab Session 12 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                      51

                                                                      present state The analysis of a sequential circuit form a state diagram comprises of the following bull Selecting a particular flip-flop to design the circuit bull Obtaining state table from the state diagram bull Finding input equations for the selected flip-flop bull Finding state equations (not required for the construction of circuit) bull Implementing the circuit using selected flip-flops and their input equations ANALYZING THE GIVEN STATE DIAGRAM D Flip-Flop D flip-flop is also called transparent flip-flop as it simply transfers the input data to the output For our design we require the graphical symbol and excitation table of D flip-flop (see figure 122)

                                                                      Qt Qt+1 T 0 0 0 0 1 1 1 0 0 1 1 1

                                                                      (b) Excitation table of D Flip-Flop

                                                                      (a) Graphical Symbol

                                                                      Figure 122 Characteristic equation of D flip-flop is Q(t+1) = D State Table The given state diagram has four states so we will need two D flip-flops (FF-0 FF-1) Form state table form the given state diagram and record the results in the following table

                                                                      Present State Input Next State Output Input to FF-0 D0

                                                                      Input to FF-1 D1 Q1t Q0t x Q1(t+1) Q0(t+1) z

                                                                      Logic Design amp Switching Theory 1 Lab Session 12 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                      52

                                                                      Input Equations Using Karnaugh map the input equations D0 and D1 for the two flip-flops can be found

                                                                      D0 D1 Q0x

                                                                      Q1

                                                                      _ _ Q0x

                                                                      _ Q0x

                                                                      Q0x

                                                                      _ Q0x

                                                                      Q0x

                                                                      Q1

                                                                      _ _ Q0x

                                                                      _ Q0x

                                                                      Q0x

                                                                      _ Q0x

                                                                      _ Q1

                                                                      _ Q1

                                                                      Q1

                                                                      Q1

                                                                      D0 = _________________ D1 = _________________

                                                                      State Equations Using the characteristic equation of D flip-flop we can find the state equations Q0(t+1) and Q1(t+1) for the to flip flops Q0(t+1) = _______________________ Q1(t+1) = _______________________ _______________________ _______________________ _______________________ _______________________ Circuit Diagram

                                                                      Logic Design amp Switching Theory 1 Lab Session 12 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                      53

                                                                      Implementation Procedure and Observations

                                                                      1 Implement the circuit using digital ICs on a bread board (prepare the pin diagram (use appendix A) and refer to laboratory session 01 for procedure)

                                                                      2 Make the clear inputs of the flip-flops low (to clear the flip-flops) The flip-flops will remain in clear state as long as the clear inputs are connected to low level

                                                                      3 Connect output Q0 and the clock pulse to an oscilloscope 4 Apply 0 to the input x 5 Now make the clear inputs to high 6 Observe the waveform for the first 5 clock pulses and record it 7 Repeat steps 2 to 6 keeping x=1 in step 4 this time 8 Repeat steps 2 to 7 this time connecting Q1 instead of Q0 to the oscilloscope in step

                                                                      3 Record your observations (Keep frequency of the clock pulse low (eg1Hz) so that the output waveforms can be observed easily)

                                                                      1 2 3 4 5 Clock Pulse

                                                                      Output Waveform for Q0 when x=0

                                                                      Output Waveform for Q0 when x=1

                                                                      Output Waveform for Q1 when x=0

                                                                      Output Waveform for Q1 when x=1

                                                                      Logic Design amp Switching Theory 1 Lab Session 13 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                      Lab Session 13 OBJECT

                                                                      Designing a modulo-5 asynchronous up-counter using JK-FF COMPONENTS AND APPARATUS REQUIRED

                                                                      1 Following ICs and their Datasheets

                                                                      bull 7400 Quad 2-input or 7410 Triple 3-input NAND Gates bull 7476 7473 JK Flip-Flop

                                                                      2 Digital Trainer DT-01 or the following components Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches

                                                                      THEORY

                                                                      Digital Counters A digital counter is a set of flip-flops whose states change in response to pulses applied at the input to the counter The flip-flops are interconnected so that their combined state at any time is the binary equivalent of the total number of pulses that have occurred up to that time Every counter resets after a certain number of clock pulses Thus as it name implies a counter is used to count pulses An n stage counter can count up to a maximum of 2n states n is equal to the number of flip-flops required for the construction of counter

                                                                      Modulus Counters The number of input pulses that causes a counter to reset to its initial count is called the modulus of the counter Thus the modulus equals to total number of distinct states (counts) including zero that a counter can store A binary counter with n stages is a modulo-2n (or mod-2n) counter The largest count a mod-N counter can achieve is N-1 ie a mod-N counter never reaches the binary number equal to its modulus N is always equal to or less than 2n Counters can be classified as bull Synchronous Counters which are clock driven All the flip-flops are driven by a

                                                                      single clock bull Asynchronous Counters which are event driven Clock input is given to the first

                                                                      flip-flop only Rest of the flip-flops are driven by their preceding flip-flops

                                                                      DESIGN OF A MOD-5 ASYNCHRONOUS UP COUNTER The number of flip-flops required to construct a mod-5 counter is 3 because 5 should be less than or equal to 2n This counter will count from 0 to 4 a total of 5 distinct states Since a 3-stage counter can count up to 8 states at maximum a NAND gate is used to reset it after 5 clock pulses Figure 131 shows the logic diagram

                                                                      54

                                                                      Logic Design amp Switching Theory 1 Lab Session 13 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                      55

                                                                      Figure 131 A Mod-5 Asynchronous Up Counter

                                                                      Implementation and Observations

                                                                      Implement the mod-5 counter circuit (figure 131) on a bread board (prepare the pin diagram (use appendix A) and refer to laboratory session 01 for implementation procedure) and record the observations in the following table

                                                                      Clock Pulse Q2 Q1 Q0

                                                                      0 1 2 3 4 5 6 7

                                                                      ACTIVITY

                                                                      Draw the timing diagram for mod-5 counter designed in this laboratory session

                                                                      Logic Design amp Switching Theory 1 Lab Session 14 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                      Lab Session 14 OBJECT

                                                                      Experimenting with 74194 4-bit bidirectional universal shift register COMPONENTS AND APPARATUS REQUIRED

                                                                      1 Following ICs and their Datasheets

                                                                      bull 74194 4-bit bidirectional universal shift register 2 Digital Trainer DT-01 or the following components

                                                                      Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches

                                                                      THEORY

                                                                      Shift Registers

                                                                      A Register is a set of flip-flops used to store binary data A register which is capable of shifting its binary information either to the right or left is called a shift register The logical configuration of a register consists of a chain of flip-flops connected in cascade with the output of one flip-flop connected to the input of next flip-flop All flip-flops receive a common clock pulse which causes the shift from one stage to the next

                                                                      Bidirectional Shift Registers A bi-directional shift register is one whose bits can be shifted from left to right or from right to left

                                                                      Universal Shift Registers A universal shift register is a bi-directional register whose input can be in either serial or parallel form and whose output can be in either serial or parallel form

                                                                      74194 4-BIT BIDIRECTIONAL UNIVERSAL SHIFT REGISTER

                                                                      The 74194 register provides parallel as well as serial loading in both directions Function of various pins of this IC is described below

                                                                      bull A B C and D Active high inputs for parallel loading bull QA QB QC and QD Active high outputs bull S0 and S1 Active high mode control inputs The following table shows combinations

                                                                      of S1 and S0 to enable various modes

                                                                      S1 S0 Clock Action 0 0 x No change 0 1 uarr Shift right 1 0 uarr Shift left 1 1 uarr Parallel load

                                                                      uarr shows the rising edge of the clock pulse

                                                                      56

                                                                      Logic Design amp Switching Theory 1 Lab Session 14 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering bull SR Active high serial input for right shifting bull SL Active high serial input for left shifting bull CLR Active low input Clears all the flip-flops of the register if set to 0 should be

                                                                      kept high otherwise bull CLK Clock input bull VCC and GND Supply connections lines Thus A B C and D are inputs for parallel loading whereas SR and SL are inputs for serial loading with right or left shifting respectively S1 and S0 are used to select the loading mode Circuit Diagram

                                                                      Figure 141 Pin connections of 74194 Testing Procedure

                                                                      bull Make connections as shown in the circuit diagram bull Observe the output for the input combinations given in the following table

                                                                      57

                                                                      Logic Design amp Switching Theory 1 Lab Session 14 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                      58

                                                                      Observations

                                                                      S1 S0 SL SR A B C D QA QB QC QD 0 0 0 1 0 0 0 0 0 1 1 0 0 0 0 1 1 0 0 0 0 0 1 0 1 1 0 0 0 0 1 1 0 0 1 1 0 1 0 0 0 1 1 1 0 1 0 1 1 0 1 0 0 1 1 0 1 1 1 0 0 1 1 1 1 1 0 0 1 1 1 1

                                                                      ACTIVITY 1 Show connections of 74194 to convert it into a ring counter with right shifting

                                                                      Logic Design amp Switching Theory 1 Lab Session 15 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                      Lab Session 15

                                                                      OBJECT

                                                                      Experimenting with 74245 octal bus transceivers using parallel port PC interfacing COMPONENTS AND APPARATUS REQUIRED 1 Parallel Port Connectors (DB-25) with Cable 2 Personal Computer with Windows 98 and TurboC Compiler Installed 3 Following ICs and their Datasheets

                                                                      bull 74245 Octal Bus Transceivers with 3-State Outputs 4 Digital Trainer DT-01 or the following components

                                                                      Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches

                                                                      THEORY

                                                                      3-State Logic Sometimes it is necessary to isolate one part of circuit from the other part For this purpose some TTL ICs are designed with 3-state logic Such devices have three possible output states high low and high impedance The device can be put into high impedance state by a control signal applied to an appropriate pin When such a device is in high impedance state there is very high impedance at its output effectively isolating the device from whatever circuitry the output normally drives 74245 Octal Bus Transceivers A bus is any conducting path or set of paths having electrical connections to one or more devices 74245 octal bus transceivers are mainly used to control connectivity between two devices or circuits It also provides direction control for signal flow Function of various pin of this IC is given below

                                                                      bull A1 through A8 Bus A bull B1 through B8 Bus B bull G΄ Active low enable input When high sets all the bus pins to high impedance state bull DIR Direction control for signal flow When set to high logic level transfers bus A

                                                                      data to B bus When set to low logic level transfers bus B data to A bus bull VCC and GND Supply connections lines Serial and Parallel Port Connectors A Parallel Port can consist of only 25 pin port adapter called a DB-25 and a serial port can consist of either a 25 pin port adapter called a DB-25 or 9 pin adapter called a DB-9 port adapter Whether the port is a 9 pin or 25 pin it can accomplish all of the same tasks that serial port communications have been designed for

                                                                      59

                                                                      Logic Design amp Switching Theory 1 Lab Session 15 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                      60

                                                                      Each adapter can be a male type connector with pins or a female type adapter with tiny holes Generally a PRINTER port (called LPT1) on the back of a computer is female type adapter and we need to use MALE DB-25 pin cable on it for PRINTER connection or for parallel LAPLINK cable And a COM port on the back of a computer is male for the serial ports but it may not necessarily be Parallel Port Connector ndash DB-25 The DB-25 connector (named for its B-size D-shaped shell and 25 pins) is practically ubiquitous in the electronics industry The DB-25 connector is used for a variety of purposes Two common applications are RS-232EIA-232 (serial) connections and the parallel printer interface on the IBM PC The DB-25 connector is also used for SCSI connections Normally the parallel port is used for output to a printer or other device It sends data 8-bits or one byte at a time in parallel The other lines available on the DB-25 connector are a combination of status lines control lines and ground lines The status and control lines are used for handshaking commands and feedback when we are talking to a printer

                                                                      Figure 152 DB-25 Female Figure 151 DB-25 Male

                                                                      Figure 153 Pin Layout for DB-25 As can be seen form figure 153 there are four types of pins in this connector

                                                                      bull Data pins (8 pins - D0 to D7) Active high bidirectional lines

                                                                      Logic Design amp Switching Theory 1 Lab Session 15 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering bull Control pins (4 pins - C0 to C3) C0 C1 and C3 are active low whereas C2 is active

                                                                      high These lines also are bidirectional bull Status pins (5 pins ndash S3 to S7) Only S7 is active low rest are active high input lines bull Ground pins (8 pins) Used as a reference signal for the low (below 05 volts) charge

                                                                      Parallel Port Addresses A DB-25 connector at a parallel port has three address one for each kind of pins register data status and control The first or base address generally refers to data register Second address is for status register and the third one is for control register In Windows 98 the base address is usually found to be 278H 378H or 3BCH Now if 378H is the base address then it refers to the data register whereas addresses for status and control register are respectively 379H and 37AH For Windows 98 the base address can be found as follows 1 On your Desktop right-click on My Computer and select Properties 2 Click on the Device Manager tab and find LPT1 under Plug and Play BIOS 3 After selecting LPT1 click the Properties button 4 Next select the Resources tab and the address should then appear next to InputOutput

                                                                      Range Accessing parallel port through C Language Programming There are multiple functions in C Language for accessing external ports The most commonly used are listed below

                                                                      bull unsigned char inportb(int portid) inportb reads a byte from a hardware port

                                                                      bull int inport(int portid) reads a word from a hardware port

                                                                      bull void outportb(int portid unsigned char value) outputs a byte to a hardware port

                                                                      bull void outport(int portid int value) outputs a word to a hardware port

                                                                      portid refers to the port address whereas value refers to the data to be sent TESTING 74245 USING PARALLEL PORT PC INTERFACING At one end the parallel port connector will be connected to the PC via parallel port cable and another connector (to be plugged into the PC parallel port slot) At the other end it will be connected to the buffer IC 74245 Data lines of the connector will be used to transfer 8-bit data between the PC and the buffer Out of the 8-bits of 74245 4-bits will be used to enter data which will be displayed at the monitor through a C language

                                                                      61

                                                                      Logic Design amp Switching Theory 1 Lab Session 15 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering program The remaining 4-bits will receive data from PC as entered by the user via keyboard

                                                                      Circuit Diagram

                                                                      Figure 154 Interface of 74245 to PC via Parallel Port

                                                                      Procedure

                                                                      1 Connect the DB-25 connector to the PC at one end and solder it to the circuit board at the other end

                                                                      2 Connect various pins of the connector and 74245 according to the circuit diagram shown in figure 152

                                                                      3 Using the functions listed in the previous section write a program in C language to operate various pins of the buffer The user interface of the program should provide option to the user whether to send or receive data from the port

                                                                      4 Set DIR switch to 1 5 Try sending some data bits to the port The result should be displayed at the LEDs 6 Set DIR switch to 0 7 Set some binary 4-bit value through the switches Try reading it via parallel port

                                                                      C Language Program

                                                                      A program to access parallel port for data transfers

                                                                      use header file include ltstdiohgt main program void main() define variable

                                                                      62

                                                                      Logic Design amp Switching Theory 1 Lab Session 15 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering unsigned int data=0 char choice while(1) printing option menu clrscr() printf(This program will send or receive a BCD digit from the parallel portn) printf(nPress your choice numbern) printf(n1 Send Data) printf(n2 Receive Data) printf(n3 Exitn) choice = getch() sending entered digit to the port if(choice == 1) input BCD digit printf(nEnter BCD digit to be sent to the port) data = getche() masking the first four bits data = data amp 0x0f sending to the port outportb(0x378data) printf(nThe BCD digit c has been sent to the port data) printing on screen the data received from the port else if(choice == 2) receiving data from the port data = inportb(0x378) masking the last four bits data = data amp 0xf0 shifting first four bits to make them the last four bits datagtgt=4 printf(nThe BCD digit set at the port is c data) exit else if(choice == 3) break key pressed is not in the menu else printf(nEnter valid choice number) printf(nnPress any key to continue) getch()

                                                                      63

                                                                      Logic Design amp Switching Theory 1 Lab Session 15 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                      ACTIVITY 1 In the above circuit DIR and G΄ inputs are hardwired Connect them to status or

                                                                      control pins of the parallel port connector and control their function through your software program Circuit Diagram Program Code ______________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________

                                                                      ___________________________________________________________________________________________________________________________________________________

                                                                      64

                                                                      Logic Design amp Switching Theory 1 Lab Session 15 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                      65

                                                                      _____________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ _____________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ _______________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ _________________________________________________ _________________________________________________

                                                                      Logic Design amp Switching Theory 1 Appendix A NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                      Appendix A

                                                                      PIN DIAGRAMS OF THE ICS REQUIRED FOR THE LABORATORY SESSIONS Consult the TTLIC data book for internal diagrams and electrical characteristics of these ICs 7400 Quad 2-Input NAND 7402 Quad 2-Input NOR

                                                                      7404 Hex Inverter 7408 Quad 2-Input AND

                                                                      7410 Triple 3-Input NAND 7411 Triple 3-Input AND

                                                                      7421 Dual 4-Input AND 7432 Quad 2-Input OR

                                                                      66

                                                                      Logic Design amp Switching Theory 1 Appendix A NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                      BCD-to-Seven Segm 7448 BCD-to-Seven Segment 7447 ent

                                                                      Decoder (15V OC) Decoder (2kΩ pull-up output)

                                                                      7473 Dual JK Flip-Flop 7474 Dual D-Type Flip-Flop

                                                                      7476 Dual JK Flop-Flop -Bit Binary Full Adder 7483 4 with Fast Carry

                                                                      86 Quad 2-Inpu 74138 3-to-8 Line 74 t Exclusive OR Decoder Demultiplexer

                                                                      67

                                                                      Logic Design amp Switching Theory 1 Appendix A NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                      68

                                                                      74148 8-to-3 Line 16-to-1 Line Data

                                                                      Priority Encoder 74150 Selector Multiplexer

                                                                      74245 Oct nsceivers Universal Shift Register (PIPO) (3-State)

                                                                      74194 4-Bit Bidirectional al Bus Tra

                                                                      Logic Design amp Switching Theory 1 Appendix B NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                      Appendix B

                                                                      DEBOUNCING CIRCUITRY FOR MECHANICAL SWITCHES Mechanical switches form the interface between human beings and computers or other digital systems For example a keyboard is a matrix of switches used to supply alphanumeric data to a computer Whatever the switch design it is a potential source of problems due to contact bounce The contact bounce creates a sense of narrow pulses when a switch is opened or closed An example of device whose operation would be adversely affected by contact bounce is a digital counter used to count the number of times a switch is depressed Eliminating the effects of contact bounce is called debouncing When data is entered into a computer via a keyboard a software debounce is often used This type of debouncing is a program that causes the computer to sample the switch terminal (ie to input data from it) many times in succession during the interval of time that contact bounce occurs If the data is sensed to be 1s (or 0s) for a specific number of consecutive samples then it is assumed that contact bounce has ended and the last value sensed is valid Hardware debouncing is the use of electronic circuitry to eliminate the effects of contact bounce There are numerous versions of such circuitry including those that use monostable multivibrators (one-shots) but the most straightforward is simply an RS latch Figure B1 shows the circuit When the switch is in position 1 R = 0 and S = 1 so the latch is set and the output (Q) is 1 When the switch is in position 0 R = 1and S = 0 so the latch is reset and the output is 0 When the switch is moved form one position to the other the latch changes state and bouncing occurs at either the R or the S input The bouncing does not affect the latch after it has change state An RS latch will remain set for example when its R input is 0 and its S input is alternately changed form 1 to 0

                                                                      Figure B1 Use of RS latch to debounce a mechanical switch

                                                                      69

                                                                      • 01-ldst-Outer title
                                                                        • Practical Workbook
                                                                        • Logic Design amp Switching Theory I
                                                                          • Dept of Computer amp Information Systems Engineering
                                                                            • NED University of Engineering amp Technology
                                                                            • Karachi ndash 75270 Pakistan
                                                                              • 02-ldst-inner Title
                                                                                • Practical Workbook
                                                                                • Logic Design amp Switching Theory I
                                                                                  • Dept of Computer amp Information Systems Engineering
                                                                                    • NED University of Engineering amp Technology
                                                                                    • Karachi ndash 75270 Pakistan
                                                                                      • 03-ldst-general info
                                                                                      • 04-ldst-introduction
                                                                                      • 05-Table of Contents
                                                                                        • CONTENTS
                                                                                          • Lab Session No Object Page No
                                                                                          • 1
                                                                                          • Also implementing and testing the given circuit on a bread board
                                                                                            • Working with Electronics Workbench
                                                                                              • Driving a seven segment display using 7447 7448 driver IC
                                                                                                • Designing a modulus-5 asynchronous up-counter using JK-FF
                                                                                                  • Experimenting with 74194 4-bit bidirectional universal shift register
                                                                                                      • 13
                                                                                                          • 06-ldst-Exp01
                                                                                                            • Lab Session 01
                                                                                                            • OBJECT
                                                                                                              • 1 Bread board
                                                                                                              • 2 5 V - power supply
                                                                                                              • 3 Multimeter
                                                                                                              • 4 Logic probe
                                                                                                              • 5 LEDs with resistors
                                                                                                              • 6 Connecting wires
                                                                                                              • 8 Following ICs and their datasheets
                                                                                                                • THEORY
                                                                                                                  • Logic Gates
                                                                                                                  • 1 The AND Gate ndash An AND gatersquos output is 1 if and only if all its inputs are 1 If A and B are two inputs to an AND gate then output F of the gate is given as F = AB
                                                                                                                  • 2 The OR Gate - An OR gatersquos output is 1 if at least one of its input is 1 If A and B are two inputs to an OR gate then output F of the gate is given as F = A+B
                                                                                                                  • 3 The NOT Gate (Inverter) ndash Its output is 1 when its input is 0 and its output is 0 when the input is 1 ie it complements a digital variable If A is the input to a NOT gate then output F of the gate is given as
                                                                                                                  • 4 The NAND Gate ndash Its output is 1 if at least one of its input is 0 This gate performs the same logic as an AND gate followed by an inverter If A and B are two inputs to a NAND gate then output F of the gate is given as
                                                                                                                    • 5 The NOR Gate - The output of a NOR gate is 1 if and only if all its inputs are 0 This gate performs the same logic function as an OR gate followed by an inverter If A and B are two inputs to a NAND gate then output F of the gate is given as
                                                                                                                        • DATA SHEETS
                                                                                                                          • Logic expression for the given logic diagram __________________________________
                                                                                                                              • 07-ldst-exp02
                                                                                                                                • Working with Electronics Workbench
                                                                                                                                  • 08-ldst-exp03
                                                                                                                                    • Designing Half and Full Adder Circuits
                                                                                                                                      • COMPONENTS AND APPARATUS REQUIRED
                                                                                                                                        • 1 Following ICs and their Datasheets
                                                                                                                                        • 7408 Quad 2-input AND Gate
                                                                                                                                        • 2 Digital Trainer DT-01 or the following components
                                                                                                                                          • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                          • Connecting wires Switches
                                                                                                                                            • THEORY
                                                                                                                                                • IMPLEMENTATION AND OBSERVATIONS
                                                                                                                                                  • 09-ldst-Exp04
                                                                                                                                                    • Lab Session 04
                                                                                                                                                    • 1 Digital ICs and their Datasheets
                                                                                                                                                    • 7408 Quad 2-input AND Gate
                                                                                                                                                    • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                      • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                      • Connecting wires Switches
                                                                                                                                                      • PROCEDURE
                                                                                                                                                      • REDUCTION OF LOGIC EXPRESSION USING KARNAUGH MAP
                                                                                                                                                      • OBSERVATIONS
                                                                                                                                                      • RESULT
                                                                                                                                                          • 10-ldst-Exp05
                                                                                                                                                            • Lab Session 05
                                                                                                                                                            • 1 Following ICs and their Datasheets
                                                                                                                                                            • 7408 Quad 2-input AND Gate
                                                                                                                                                            • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                              • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                              • (100 Ω) Connecting wires Switches
                                                                                                                                                              • THEORY
                                                                                                                                                                • IMPLEMENTATION AND OBSERVATIONS
                                                                                                                                                                  • 11-ldst-Exp06
                                                                                                                                                                    • OBJECT
                                                                                                                                                                    • 1 Following ICs and their Datasheets
                                                                                                                                                                    • 7408 Quad 2-input AND Gates or 7411 Triple 3-input AND Gates
                                                                                                                                                                    • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                      • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                      • Connecting wires Switches
                                                                                                                                                                        • Figure 62 Circuit Diagram for 4 x 1 Multiplexer
                                                                                                                                                                        • Implementation and Observations
                                                                                                                                                                          • Circuit Diagram
                                                                                                                                                                            • ACTIVITY
                                                                                                                                                                              • 12-ldst-exp07
                                                                                                                                                                                • 1 Following ICs and their Datasheets
                                                                                                                                                                                • 7408 Quad 2-input or 7411 Triple 3-input AND Gates
                                                                                                                                                                                • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                  • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                  • Connecting wires Switches
                                                                                                                                                                                    • THEORY
                                                                                                                                                                                        • Figure 72 Circuit Diagram for 2 x 4 Decoder 1 x 4 Demultiplexer
                                                                                                                                                                                        • Implementation and Observations
                                                                                                                                                                                          • Circuit Diagram
                                                                                                                                                                                            • ACTIVITY
                                                                                                                                                                                              • 13-ldst-Exp08
                                                                                                                                                                                                • OBJECT
                                                                                                                                                                                                • 1 Following ICs and their Datasheets
                                                                                                                                                                                                • 7408 Quad 2-input or 7421 Dual 4-input AND Gates
                                                                                                                                                                                                • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                  • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                  • Connecting wires Switches
                                                                                                                                                                                                    • THEORY
                                                                                                                                                                                                        • Figure 81 Circuit Diagram for 4 x 2 Priority Encoder
                                                                                                                                                                                                        • Implementation and Observations
                                                                                                                                                                                                          • Therefore if GS A2 A1 and A0 are all low then it shows that line 0 is selected and if E0 A2 A1 and A0 are all low then it shows that none of the inputs selected E0 and GS cannot be in the same state provided that E1 is enabled
                                                                                                                                                                                                          • Circuit Diagram
                                                                                                                                                                                                            • ACTIVITY
                                                                                                                                                                                                              • 14-ldst-exp09
                                                                                                                                                                                                                • OBJECT
                                                                                                                                                                                                                • 1 Following ICs and their Datasheets
                                                                                                                                                                                                                • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                  • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                                  • Connecting wires Switches
                                                                                                                                                                                                                    • THEORY
                                                                                                                                                                                                                      • Parity Generator
                                                                                                                                                                                                                        • Let x y and z be the three bits that constitute the message and are the input to the Odd Parity Generator Circuit Since it is an odd parity system the bit P is generated so as to make the total number of 1s odd (including P) The function P can be expressed as follows
                                                                                                                                                                                                                        • Figure 91 Circuit Diagram for a 3-bit Parity Generator
                                                                                                                                                                                                                          • C = x Ο y Ο z Ο P
                                                                                                                                                                                                                            • Implementation and Observations
                                                                                                                                                                                                                              • ACTIVITY
                                                                                                                                                                                                                                  • 15-ldst-exp10
                                                                                                                                                                                                                                    • Driving a seven segment display using 7447 7448 driver IC
                                                                                                                                                                                                                                    • COMPONENTS AND APPARATUS REQUIRED
                                                                                                                                                                                                                                    • 1 Following ICs and their Datasheets
                                                                                                                                                                                                                                    • 7447 7448 BCD to Seven Segment Driver
                                                                                                                                                                                                                                    • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                                      • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches
                                                                                                                                                                                                                                        • THEORY
                                                                                                                                                                                                                                        • Seven Segment Displays
                                                                                                                                                                                                                                        • CIRCUIT DIAGRAM
                                                                                                                                                                                                                                        • Figure 102 Circuit diagram for 7447driving a common-anode display
                                                                                                                                                                                                                                            • IMPLEMENTATION AND OBSERVATIONS
                                                                                                                                                                                                                                              • Decimal Digit
                                                                                                                                                                                                                                              • BCD Inputs
                                                                                                                                                                                                                                              • Seven Segment Outputs
                                                                                                                                                                                                                                              • D
                                                                                                                                                                                                                                              • C
                                                                                                                                                                                                                                              • B
                                                                                                                                                                                                                                              • A
                                                                                                                                                                                                                                              • a
                                                                                                                                                                                                                                              • b
                                                                                                                                                                                                                                              • c
                                                                                                                                                                                                                                              • d
                                                                                                                                                                                                                                              • e
                                                                                                                                                                                                                                              • f
                                                                                                                                                                                                                                              • g
                                                                                                                                                                                                                                              • 0
                                                                                                                                                                                                                                              • 0
                                                                                                                                                                                                                                              • 0
                                                                                                                                                                                                                                              • 0
                                                                                                                                                                                                                                              • 0
                                                                                                                                                                                                                                              • 1
                                                                                                                                                                                                                                              • 0
                                                                                                                                                                                                                                              • 0
                                                                                                                                                                                                                                              • 0
                                                                                                                                                                                                                                              • 1
                                                                                                                                                                                                                                              • 2
                                                                                                                                                                                                                                              • 0
                                                                                                                                                                                                                                              • 0
                                                                                                                                                                                                                                              • 1
                                                                                                                                                                                                                                              • 0
                                                                                                                                                                                                                                              • 3
                                                                                                                                                                                                                                              • 0
                                                                                                                                                                                                                                              • 0
                                                                                                                                                                                                                                              • 1
                                                                                                                                                                                                                                              • 1
                                                                                                                                                                                                                                              • 4
                                                                                                                                                                                                                                              • 0
                                                                                                                                                                                                                                              • 1
                                                                                                                                                                                                                                              • 0
                                                                                                                                                                                                                                              • 0
                                                                                                                                                                                                                                              • 5
                                                                                                                                                                                                                                              • 0
                                                                                                                                                                                                                                              • 1
                                                                                                                                                                                                                                              • 0
                                                                                                                                                                                                                                              • 1
                                                                                                                                                                                                                                              • 6
                                                                                                                                                                                                                                              • 0
                                                                                                                                                                                                                                              • 1
                                                                                                                                                                                                                                              • 1
                                                                                                                                                                                                                                              • 0
                                                                                                                                                                                                                                              • 7
                                                                                                                                                                                                                                              • 0
                                                                                                                                                                                                                                              • 1
                                                                                                                                                                                                                                              • 1
                                                                                                                                                                                                                                              • 1
                                                                                                                                                                                                                                              • 8
                                                                                                                                                                                                                                              • 1
                                                                                                                                                                                                                                              • 0
                                                                                                                                                                                                                                              • 0
                                                                                                                                                                                                                                              • 0
                                                                                                                                                                                                                                              • 9
                                                                                                                                                                                                                                              • 1
                                                                                                                                                                                                                                              • 0
                                                                                                                                                                                                                                              • 0
                                                                                                                                                                                                                                              • 1
                                                                                                                                                                                                                                                • ACTIVITY
                                                                                                                                                                                                                                                  • 16-ldst-exp11
                                                                                                                                                                                                                                                    • Lab Session 11
                                                                                                                                                                                                                                                      • OBJECT
                                                                                                                                                                                                                                                      • COMPONENTS AND APPARATUS REQUIRED
                                                                                                                                                                                                                                                        • 1 Following ICs and their Datasheets
                                                                                                                                                                                                                                                        • 7473 7476 JK Flip-Flop
                                                                                                                                                                                                                                                        • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                                                          • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                                                                          • Connecting wires Switches
                                                                                                                                                                                                                                                            • THEORY
                                                                                                                                                                                                                                                                • Flip-Flop
                                                                                                                                                                                                                                                                • JK Flip-Flop
                                                                                                                                                                                                                                                                  • Circuit Diagram
                                                                                                                                                                                                                                                                    • Observations
                                                                                                                                                                                                                                                                      • ACTIVITY
                                                                                                                                                                                                                                                                          • 17-ldst-exp12
                                                                                                                                                                                                                                                                            • Lab Session 12
                                                                                                                                                                                                                                                                              • OBJECT
                                                                                                                                                                                                                                                                              • GIVEN STATE DIAGRAM
                                                                                                                                                                                                                                                                              • Figure 121 State Diagram
                                                                                                                                                                                                                                                                              • COMPONENTS AND APPARATUS REQUIRED
                                                                                                                                                                                                                                                                                • 1 Following ICs and their Datasheets
                                                                                                                                                                                                                                                                                • 7474 D Flip-Flop
                                                                                                                                                                                                                                                                                • ICs of basic gates (AND OR NOT XOR etc) as required
                                                                                                                                                                                                                                                                                • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                                                                                  • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                                                                                                  • Connecting wires Switches
                                                                                                                                                                                                                                                                                    • THEORY
                                                                                                                                                                                                                                                                                        • Sequential Circuits
                                                                                                                                                                                                                                                                                          • 18-ldst-exp13
                                                                                                                                                                                                                                                                                            • Lab Session 13
                                                                                                                                                                                                                                                                                              • Designing a modulo-5 asynchronous up-counter using JK-FF
                                                                                                                                                                                                                                                                                                • 1 Following ICs and their Datasheets
                                                                                                                                                                                                                                                                                                • 7400 Quad 2-input or 7410 Triple 3-input NAND Gates
                                                                                                                                                                                                                                                                                                • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                                                                                                  • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                                                                                                                  • Connecting wires Switches
                                                                                                                                                                                                                                                                                                    • THEORY
                                                                                                                                                                                                                                                                                                        • Figure 131 A Mod-5 Asynchronous Up Counter
                                                                                                                                                                                                                                                                                                        • Implementation and Observations
                                                                                                                                                                                                                                                                                                          • ACTIVITY
                                                                                                                                                                                                                                                                                                              • 19-ldst-exp14
                                                                                                                                                                                                                                                                                                                • Experimenting with 74194 4-bit bidirectional universal shift register
                                                                                                                                                                                                                                                                                                                • 1 Following ICs and their Datasheets
                                                                                                                                                                                                                                                                                                                • 74194 4-bit bidirectional universal shift register
                                                                                                                                                                                                                                                                                                                • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                                                                                                                  • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                                                                                                                                  • Connecting wires Switches
                                                                                                                                                                                                                                                                                                                    • THEORY
                                                                                                                                                                                                                                                                                                                      • Shift Registers
                                                                                                                                                                                                                                                                                                                      • Bidirectional Shift Registers
                                                                                                                                                                                                                                                                                                                      • Universal Shift Registers
                                                                                                                                                                                                                                                                                                                        • S1
                                                                                                                                                                                                                                                                                                                          • Circuit Diagram
                                                                                                                                                                                                                                                                                                                          • ACTIVITY
                                                                                                                                                                                                                                                                                                                              • 20-ldst-exp15
                                                                                                                                                                                                                                                                                                                                • COMPONENTS AND APPARATUS REQUIRED
                                                                                                                                                                                                                                                                                                                                • 1 Parallel Port Connectors (DB-25) with Cable
                                                                                                                                                                                                                                                                                                                                • 2 Personal Computer with Windows 98 and TurboC Compiler Installed
                                                                                                                                                                                                                                                                                                                                • 3 Following ICs and their Datasheets
                                                                                                                                                                                                                                                                                                                                • 74245 Octal Bus Transceivers with 3-State Outputs
                                                                                                                                                                                                                                                                                                                                • 4 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                                                                                                                                  • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                                                                                                                                                    • Connecting wires Switches
                                                                                                                                                                                                                                                                                                                                      • THEORY
                                                                                                                                                                                                                                                                                                                                      • 3-State Logic
                                                                                                                                                                                                                                                                                                                                        • Serial and Parallel Port Connectors
                                                                                                                                                                                                                                                                                                                                        • Parallel Port Connector ndash DB-25
                                                                                                                                                                                                                                                                                                                                          • Accessing parallel port through C Language Programming
                                                                                                                                                                                                                                                                                                                                              • 21-ldst-appendixA
                                                                                                                                                                                                                                                                                                                                              • 22-ldst-appendixB
                                                                                                                                                                                                                                                                                                                                                • DEBOUNCING CIRCUITRY FOR MECHANICAL SWITCHES

                                                                        Logic Design amp Switching Theory 1 Lab Session 08 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                        Lab Session 08 OBJECT

                                                                        bull Designing of a 4 x 2 Priority Encoder bull Experimenting with 74148 IC

                                                                        COMPONENTS AND APPARATUS REQUIRED

                                                                        1 Following ICs and their Datasheets

                                                                        bull 7408 Quad 2-input or 7421 Dual 4-input AND Gates bull 7432 Quad 2-input OR Gates bull 7404 Hex Inverter bull 74148 Encoder

                                                                        2 Digital Trainer DT-01 or the following components Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches

                                                                        THEORY

                                                                        Encoder An Encoder is a digital function that produces a reverse operation from that of a decoder An Encoder has 2n (or less) input lines and n output lines The output lines generate the binary code for the 2n input variables Priority Encoder

                                                                        A simple encoder may produce an erroneous output if more than one of its inputs is high A Priority Encoder is one that responds to just one input among those that may be simultaneously high in accordance with some priority system The most common priority system is based on the relative magnitudes of the inputs whichever decimal input is largest is the one that is encoded

                                                                        DESIGN OF A 4 x 2 Priority Encoder

                                                                        The following equations represent the outputs of a 4 x 2 priority encoder 32 DDA +=

                                                                        321 DDDB += As can be seen from the equations that input D0 which has a binary code 00 is not used in any equation A binary code 00 at the output indicates two conditions Either D0 is selected or no input is selected In order to differentiate these two conditions we will provide an additional output Z to indicate if at least one of the inputs is a 1 The equation for Z will be

                                                                        4321 DDDDZ = If Z is 0 then the binary code 00 at the output indicates that D0 is selected and if Z is 1 then it indicates that no input line is selected

                                                                        38

                                                                        Logic Design amp Switching Theory 1 Lab Session 08 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                        Figure 81 Circuit Diagram for 4 x 2 Priority Encoder

                                                                        it (figure 81) on a bread board (prepare the to laboratory session 01 for implementation

                                                                        Implementation a Implement the 4 x 2 Priority Encoder circu

                                                                        ram (use appendix A) and refer

                                                                        nd Observations

                                                                        pin diagprocedure) and record the observations in the following table

                                                                        D3 D2 D1 D0 A B 0 0 0 1 0 0 1 x 0 1 x x 1 x x x

                                                                        TESTING OF 74148 8 x 3 Octal Priority Encoder

                                                                        imal digits There are nine of which three represents

                                                                        ing any of the inputs is high

                                                                        then it shows that line 0 is selected and if e inputs selected E0 and GS

                                                                        cannot be in the same state provided that E1 is enabled

                                                                        The 74148 is a priority encoder with active-Low input for dec

                                                                        input) and five output linesinputs lines (including an enablethe binary code for the octal digit Function of various pins of this IC is described below

                                                                        bull 0 through 7 Active low data inputs representing the octal digits A2 A1 A0 Active low output lines representing the binary code bullbull E1 Active low enable Input bull E0 Active low output indicating none of the inputs is high bull GS Active low output indicatbull VCC and GND Supply connections lines Therefore if GS A2 A1 and A0 are all low

                                                                        then it shows that none of thE0 A2 A1 and A0 are all low

                                                                        39

                                                                        Logic Design amp Switching Theory 1 Lab Session 08 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                        Circuit Diagram

                                                                        Figure 82 Pin connections of 74148

                                                                        Testing Procedure bull Make connections as sho

                                                                        binations of 1s and 0s at data inputs d record your observations in the following table

                                                                        GS E0

                                                                        wn in the circuit diagram bull Apply different combull Observe the output an Observations

                                                                        0 1 2 3 4 5 6 7 A2 A1 A0 1 1 1 1 1 1 1 1 x x x x x x x 0 x x x x x x 0 1 x x x x x 0 1 1 x x x x 0 1 1 1 x x x 0 1 1 1 1 x x 0 1 1 1 1 1 x 0 1 1 1 1 1 1 0 1 1 1 1 1 1 1

                                                                        40

                                                                        Logic Design amp Switching Theory 1 Lab Session 08 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                        41

                                                                        CTIVITY

                                                                        Cascade the following two 74148 8 x 3 Priority Encoders to form 16 x 4 Priority

                                                                        A 1

                                                                        Encoder

                                                                        Logic Design amp Switching Theory 1 Lab Session 09 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering `

                                                                        Lab Session 09 OBJECT

                                                                        Designing an Odd Parity Generator and Checker for a 3-bit Data COMPONENTS AND APPARATUS REQUIRED

                                                                        1 Following ICs and their Datasheets

                                                                        bull 7486 Quad 2-input Exclusive-OR Gates bull 7404 Hex Inverter

                                                                        2 Digital Trainer DT-01 or the following components Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches

                                                                        THEORY

                                                                        Parity Generator When binary data is transmitted and processed it is ndash as are all electrical signals ndash susceptible to noise that can either alter or distort its contents 1s may be effectively changed to 0s and 0s to 1s To overcome this problem one or more bits are often added to the data as an aid in detecting errors caused by noise The most common of these is a Parity bit that signifies whether the total number of 1s in a code group is odd or even In an Odd Parity system the parity bit is made 0 or 1 as necessary to make the total number 1s odd (counting the parity bit itself) In an Even Parity system the parity bit is chosen to make the total number of 1s even Table 91 shows how parity bits would be added to BCD code group in both systems

                                                                        Decimal BCD Value Parity Bit ABCD Odd Parity Even Parity

                                                                        0 0000 1 0 1 0001 0 1 2 0010 0 1 3 0011 1 0 4 0100 0 1 5 0101 1 0 6 0110 1 0 7 0111 0 1 8 1000 0 1 9 1001 1 0

                                                                        Table 91 Odd and Even Parity in BCD

                                                                        When digital data is received a parity checking circuit generates an error signal if the total number of 1s is odd in an even parity system or if it is even in an odd parity system Parity check always detects a single error (one bit change from 0 to 1 or 1 to 0) but may not detect

                                                                        42

                                                                        Logic Design amp Switching Theory 1 Lab Session 09 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering ` two or more errors Odd parity is used more often than even parity because even parity does not detect a situation where all 0s are created due to short circuit or other fault condition DESIGN OF A 3-BIT ODD PARITY GENERATOR AND CHECKER Let x y and z be the three bits that constitute the message and are the input to the Odd Parity Generator Circuit Since it is an odd parity system the bit P is generated so as to make the total number of 1s odd (including P) The function P can be expressed as follows P = x oplus y Ο z or P = x Ο y oplus z Since the IC available is 7486 which is quad 2input XOR IC therefore we will convert XNOR also to XOR

                                                                        P = x oplus y Ο z

                                                                        P = ( x oplus y ) Ο z Since for even number of variables ______

                                                                        XOR = XNOR Therefore ___________ _________

                                                                        P = ( x oplus y ) oplus z = x oplus y oplus z This logical expression can be implemented with two XOR gates and an inverter (see figure 91)

                                                                        Figure 91 Circuit Diagram for a 3-bit Parity Generator

                                                                        The 3-bit message and the parity bit are transmitted to their destination where they are applied to a Parity Checker Circuit An error occurs during transmission if the parity of the four bits received is even since the binary information transmitted was originally odd The output C of the parity checker should be a 1 when an error occurs ie when the number of 1s in the four inputs is even Therefore the function C can be expressed as

                                                                        C = x Ο y Ο z Ο P

                                                                        Using the same logic applied for the conversion of the equation of P

                                                                        PzyxC oplusoplusoplus= This logical expression can be implemented with three XOR gates and an inverter (see figure 92)

                                                                        43

                                                                        Logic Design amp Switching Theory 1 Lab Session 09 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering `

                                                                        44

                                                                        Figure 92 Circuit Diagram for a 3-bit Parity Checker Implementation and Observations Implement the 3-bit Parity Generator and Checker circuits (figure 91 and 92) on a bread board (prepare the pin diagram (use appendix A) and refer to laboratory session 01 for implementation procedure) and record the observations in the following table

                                                                        x y z P x y z P C x y z P C 0 0 0 0 0 0 0 1 0 0 0 0 0 1 0 0 0 1 1 0 0 1 0 1 0 0 0 1 0 1 0 1 0 0 1 1 0 0 1 1 1 0 1 1 1 0 0 0 1 0 0 1 1 0 0 1 0 1 0 1 0 1 1 1 0 1 1 1 0 0 1 1 0 1 1 1 0 1 1 1 0 1 1 1 1 1 1 1

                                                                        Odd Parity Generation Odd Parity Check ACTIVITY 1 Try using the parity checker of figure 92 as 3-bit parity generator Write the details here

                                                                        _____________________________________________________________________________________________________________________________________________________________________________________________________________________ ______________________________________________________________________________________________________________________________________________ _______________________________________________________________________ ______________________________________________________________________________________________________________________________________________

                                                                        Logic Design amp Switching Theory 1 Lab Session 10 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                        Lab Session 10 OBJECT

                                                                        Driving a seven segment display using 7447 7448 driver IC COMPONENTS AND APPARATUS REQUIRED

                                                                        1 Following ICs and their Datasheets

                                                                        bull Seven Segment Displays (Common Anode Common Cathode) bull 7447 7448 BCD to Seven Segment Driver

                                                                        2 Digital Trainer DT-01 or the following components Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches

                                                                        THEORY Seven Segment Displays A Seven Segment Display consists of seven light-emitting segments The segments are designated by letters a through g (see figure 101) By illuminating various combinations of segments the numerals 0 through 9 can be displayed Seven Segment Displays are commonly constructed with light-emitting diodes (LEDs) and with liquid-crystal displays (LCDs) LEDs generally provide greater illumination levels but require much greater power than LCDs An LED display can be a common-anode type or common cathode type In common anode type a high voltage is applied at the common terminal of the display and low voltage is applied at a segmentrsquos terminal for illumination In the common-cathode type a low voltage is applied at the common terminal of the display and high voltage is applied at a segmentrsquos terminal for illumination

                                                                        Figure 101 Seven Segment Display

                                                                        a f b g

                                                                        e c d

                                                                        7447 7448 BCD to Seven Segment Driver 7447 7448 IC is particularly used to drive Seven Segment Its input is a BCD number and output drives a seven segment display 7447 is used to drive common-anode displays whereas 7448 is used to drive common cathode displays 7447 7448 is a 16 pin IC Function of various pins of these ICs is described below

                                                                        bull A B C D Inputs representing BCD digits (D being the MSB)

                                                                        45

                                                                        Logic Design amp Switching Theory 1 Lab Session 10 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering bull OA through OG Outputs to drive segments a through g of the display (Active low

                                                                        in 7447 and active high in 7448) bull RBI Ripple Blanking Input Turns off all the segments if kept low provided that LT

                                                                        is kept high and all other inputs (A B C D BI) are kept low Should be kept high otherwise

                                                                        bull BI RBO Wire-AND logic serving as a Blanking Input and or Ripple Blanking Output

                                                                        o BI Turns off all the segments if low o RBO Goes to a low level (response condition) along with other outputs when

                                                                        RBI and inputs A B C and D are low with LT input at high level bull LT Lamp Test input Tests whether all segments are working or not Illuminates all

                                                                        segments if kept low provided that BI is kept high Should be kept high otherwise bull VCC and GND Supply connections lines CIRCUIT DIAGRAM

                                                                        Figure 102 Circuit diagram for 7447driving a common-anode display

                                                                        IMPLEMENTATION AND OBSERVATIONS

                                                                        bull Make connections as shown in the circuit diagram (refer to laboratory session 01 for implementation procedure)

                                                                        bull Apply different combinations of 1s and 0s at data inputs bull Observe the output and record your observations in the following table

                                                                        46

                                                                        Logic Design amp Switching Theory 1 Lab Session 10 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                        47

                                                                        Decimal Digit

                                                                        BCD Inputs Seven Segment Outputs D C B A a b c d e f g

                                                                        0 0 0 0 0 1 0 0 0 1 2 0 0 1 0 3 0 0 1 1 4 0 1 0 0 5 0 1 0 1 6 0 1 1 0 7 0 1 1 1 8 1 0 0 0 9 1 0 0 1

                                                                        ACTIVITY 1 Perform the Lamp Test for the designed circuit and write your observations

                                                                        ____________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________

                                                                        2 How can you use 7447 IC to drive a common-cathode display

                                                                        ____________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________

                                                                        3 What symbols appear in the seven segment display if inputs DCBA are

                                                                        DCBA Symbol

                                                                        1010

                                                                        1011

                                                                        1100

                                                                        1101

                                                                        1110

                                                                        1111

                                                                        Logic Design amp Switching Theory 1 Lab Session 11 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                        48

                                                                        Lab Session 11 OBJECT

                                                                        Testing different modes of JK-FF COMPONENTS AND APPARATUS REQUIRED 1 Following ICs and their Datasheets

                                                                        bull 7473 7476 JK Flip-Flop 2 Digital Trainer DT-01 or the following components

                                                                        Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches

                                                                        THEORY

                                                                        Flip-Flop A flip-flop circuit can maintain a binary state indefinitely (as long as the power is delivered to the circuit) until directed by an input signal to switch states The major differences among various types of flip-flops are in the number of inputs they possess and in the manner in which the inputs affect the binary state

                                                                        JK Flip-Flop JK flip flop is an edge triggered device A typical JK flip flop has three inputs J K and a clock input The flip-flop can be either positive or negative edge triggered The output Q is available in complemented form as well Beside the usual inputs and output most of the flip-flop IC also possess two asynchronous inputs namely Preset and Clear These inputs are usually active low If used Preset and Clear inputs keep the flip-flop in set and reset state respectively irrespective of the other inputs Both of these inputs cannot be used simultaneously otherwise they will bring the flip-flop in unstable state

                                                                        Figure 111 Symbol for JK flip-flop

                                                                        (a) positive-edge triggering (b) active low Preset (PR) and Clear (CLR) with positive-edge triggering

                                                                        (c) active low Preset (PR) and Clear (CLR) with negative-edge triggering

                                                                        Logic Design amp Switching Theory 1 Lab Session 11 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                        49

                                                                        TESTING OF 7473 7476 DUAL JK FLIP-FLOP

                                                                        Both the ICs 7473 and 7476 are similar in functionality except for one difference The flip-flops in 7473 have only one type of active low asynchronous input which is the Clear input whereas the flip-flops in 7476 have both Preset and Clear inputs Both these ICs have negative edge triggered flip-flops

                                                                        Circuit Diagram

                                                                        Figure 112 Pin connections of 7476

                                                                        Testing Procedure

                                                                        bull Make connections as shown in the circuit diagram (figure 112) bull Apply different combinations of 1s and 0s at J and K inputs bull Observe the output and record your observations in the following table

                                                                        Observations

                                                                        J

                                                                        K Q

                                                                        0 0 0 1 1 0 1 1

                                                                        ACTIVITY

                                                                        1 Observe the output Q of JK flip-flop if the clock input is connected to VCC or GND instead of a clock source Write your observations here __________________________________________________________________________________________________________________________________________ _______________________________________________________________________________________________________________________________________________________________________________________________________________

                                                                        Logic Design amp Switching Theory 1 Lab Session 12 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                        50

                                                                        Lab Session 12 OBJECT

                                                                        Designing sequential circuit for the given state diagram using D flip-flop GIVEN STATE DIAGRAM

                                                                        00

                                                                        11

                                                                        Figure 121 State Diagram COMPONENTS AND APPARATUS REQUIRED 1 Following ICs and their Datasheets

                                                                        bull 7474 D Flip-Flop bull ICs of basic gates (AND OR NOT XOR etc) as required

                                                                        2 Digital Trainer DT-01 or the following components Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches

                                                                        THEORY

                                                                        Sequential Circuits In Sequential Circuits the output not only depends on the present inputs but also on previous states of the circuit These circuits use memory elements (latches flip-flops) and the binary information stored in the memory elements at any given time defines the state of the sequential circuit Analysis of a Sequential Circuit The behavior of a sequential circuit is determined from the inputs the outputs and the states of its flip-flops Both the outputs and next state are a function of the inputs and the

                                                                        10

                                                                        01

                                                                        00 11 10

                                                                        00

                                                                        00 11 10 00

                                                                        Logic Design amp Switching Theory 1 Lab Session 12 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                        51

                                                                        present state The analysis of a sequential circuit form a state diagram comprises of the following bull Selecting a particular flip-flop to design the circuit bull Obtaining state table from the state diagram bull Finding input equations for the selected flip-flop bull Finding state equations (not required for the construction of circuit) bull Implementing the circuit using selected flip-flops and their input equations ANALYZING THE GIVEN STATE DIAGRAM D Flip-Flop D flip-flop is also called transparent flip-flop as it simply transfers the input data to the output For our design we require the graphical symbol and excitation table of D flip-flop (see figure 122)

                                                                        Qt Qt+1 T 0 0 0 0 1 1 1 0 0 1 1 1

                                                                        (b) Excitation table of D Flip-Flop

                                                                        (a) Graphical Symbol

                                                                        Figure 122 Characteristic equation of D flip-flop is Q(t+1) = D State Table The given state diagram has four states so we will need two D flip-flops (FF-0 FF-1) Form state table form the given state diagram and record the results in the following table

                                                                        Present State Input Next State Output Input to FF-0 D0

                                                                        Input to FF-1 D1 Q1t Q0t x Q1(t+1) Q0(t+1) z

                                                                        Logic Design amp Switching Theory 1 Lab Session 12 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                        52

                                                                        Input Equations Using Karnaugh map the input equations D0 and D1 for the two flip-flops can be found

                                                                        D0 D1 Q0x

                                                                        Q1

                                                                        _ _ Q0x

                                                                        _ Q0x

                                                                        Q0x

                                                                        _ Q0x

                                                                        Q0x

                                                                        Q1

                                                                        _ _ Q0x

                                                                        _ Q0x

                                                                        Q0x

                                                                        _ Q0x

                                                                        _ Q1

                                                                        _ Q1

                                                                        Q1

                                                                        Q1

                                                                        D0 = _________________ D1 = _________________

                                                                        State Equations Using the characteristic equation of D flip-flop we can find the state equations Q0(t+1) and Q1(t+1) for the to flip flops Q0(t+1) = _______________________ Q1(t+1) = _______________________ _______________________ _______________________ _______________________ _______________________ Circuit Diagram

                                                                        Logic Design amp Switching Theory 1 Lab Session 12 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                        53

                                                                        Implementation Procedure and Observations

                                                                        1 Implement the circuit using digital ICs on a bread board (prepare the pin diagram (use appendix A) and refer to laboratory session 01 for procedure)

                                                                        2 Make the clear inputs of the flip-flops low (to clear the flip-flops) The flip-flops will remain in clear state as long as the clear inputs are connected to low level

                                                                        3 Connect output Q0 and the clock pulse to an oscilloscope 4 Apply 0 to the input x 5 Now make the clear inputs to high 6 Observe the waveform for the first 5 clock pulses and record it 7 Repeat steps 2 to 6 keeping x=1 in step 4 this time 8 Repeat steps 2 to 7 this time connecting Q1 instead of Q0 to the oscilloscope in step

                                                                        3 Record your observations (Keep frequency of the clock pulse low (eg1Hz) so that the output waveforms can be observed easily)

                                                                        1 2 3 4 5 Clock Pulse

                                                                        Output Waveform for Q0 when x=0

                                                                        Output Waveform for Q0 when x=1

                                                                        Output Waveform for Q1 when x=0

                                                                        Output Waveform for Q1 when x=1

                                                                        Logic Design amp Switching Theory 1 Lab Session 13 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                        Lab Session 13 OBJECT

                                                                        Designing a modulo-5 asynchronous up-counter using JK-FF COMPONENTS AND APPARATUS REQUIRED

                                                                        1 Following ICs and their Datasheets

                                                                        bull 7400 Quad 2-input or 7410 Triple 3-input NAND Gates bull 7476 7473 JK Flip-Flop

                                                                        2 Digital Trainer DT-01 or the following components Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches

                                                                        THEORY

                                                                        Digital Counters A digital counter is a set of flip-flops whose states change in response to pulses applied at the input to the counter The flip-flops are interconnected so that their combined state at any time is the binary equivalent of the total number of pulses that have occurred up to that time Every counter resets after a certain number of clock pulses Thus as it name implies a counter is used to count pulses An n stage counter can count up to a maximum of 2n states n is equal to the number of flip-flops required for the construction of counter

                                                                        Modulus Counters The number of input pulses that causes a counter to reset to its initial count is called the modulus of the counter Thus the modulus equals to total number of distinct states (counts) including zero that a counter can store A binary counter with n stages is a modulo-2n (or mod-2n) counter The largest count a mod-N counter can achieve is N-1 ie a mod-N counter never reaches the binary number equal to its modulus N is always equal to or less than 2n Counters can be classified as bull Synchronous Counters which are clock driven All the flip-flops are driven by a

                                                                        single clock bull Asynchronous Counters which are event driven Clock input is given to the first

                                                                        flip-flop only Rest of the flip-flops are driven by their preceding flip-flops

                                                                        DESIGN OF A MOD-5 ASYNCHRONOUS UP COUNTER The number of flip-flops required to construct a mod-5 counter is 3 because 5 should be less than or equal to 2n This counter will count from 0 to 4 a total of 5 distinct states Since a 3-stage counter can count up to 8 states at maximum a NAND gate is used to reset it after 5 clock pulses Figure 131 shows the logic diagram

                                                                        54

                                                                        Logic Design amp Switching Theory 1 Lab Session 13 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                        55

                                                                        Figure 131 A Mod-5 Asynchronous Up Counter

                                                                        Implementation and Observations

                                                                        Implement the mod-5 counter circuit (figure 131) on a bread board (prepare the pin diagram (use appendix A) and refer to laboratory session 01 for implementation procedure) and record the observations in the following table

                                                                        Clock Pulse Q2 Q1 Q0

                                                                        0 1 2 3 4 5 6 7

                                                                        ACTIVITY

                                                                        Draw the timing diagram for mod-5 counter designed in this laboratory session

                                                                        Logic Design amp Switching Theory 1 Lab Session 14 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                        Lab Session 14 OBJECT

                                                                        Experimenting with 74194 4-bit bidirectional universal shift register COMPONENTS AND APPARATUS REQUIRED

                                                                        1 Following ICs and their Datasheets

                                                                        bull 74194 4-bit bidirectional universal shift register 2 Digital Trainer DT-01 or the following components

                                                                        Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches

                                                                        THEORY

                                                                        Shift Registers

                                                                        A Register is a set of flip-flops used to store binary data A register which is capable of shifting its binary information either to the right or left is called a shift register The logical configuration of a register consists of a chain of flip-flops connected in cascade with the output of one flip-flop connected to the input of next flip-flop All flip-flops receive a common clock pulse which causes the shift from one stage to the next

                                                                        Bidirectional Shift Registers A bi-directional shift register is one whose bits can be shifted from left to right or from right to left

                                                                        Universal Shift Registers A universal shift register is a bi-directional register whose input can be in either serial or parallel form and whose output can be in either serial or parallel form

                                                                        74194 4-BIT BIDIRECTIONAL UNIVERSAL SHIFT REGISTER

                                                                        The 74194 register provides parallel as well as serial loading in both directions Function of various pins of this IC is described below

                                                                        bull A B C and D Active high inputs for parallel loading bull QA QB QC and QD Active high outputs bull S0 and S1 Active high mode control inputs The following table shows combinations

                                                                        of S1 and S0 to enable various modes

                                                                        S1 S0 Clock Action 0 0 x No change 0 1 uarr Shift right 1 0 uarr Shift left 1 1 uarr Parallel load

                                                                        uarr shows the rising edge of the clock pulse

                                                                        56

                                                                        Logic Design amp Switching Theory 1 Lab Session 14 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering bull SR Active high serial input for right shifting bull SL Active high serial input for left shifting bull CLR Active low input Clears all the flip-flops of the register if set to 0 should be

                                                                        kept high otherwise bull CLK Clock input bull VCC and GND Supply connections lines Thus A B C and D are inputs for parallel loading whereas SR and SL are inputs for serial loading with right or left shifting respectively S1 and S0 are used to select the loading mode Circuit Diagram

                                                                        Figure 141 Pin connections of 74194 Testing Procedure

                                                                        bull Make connections as shown in the circuit diagram bull Observe the output for the input combinations given in the following table

                                                                        57

                                                                        Logic Design amp Switching Theory 1 Lab Session 14 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                        58

                                                                        Observations

                                                                        S1 S0 SL SR A B C D QA QB QC QD 0 0 0 1 0 0 0 0 0 1 1 0 0 0 0 1 1 0 0 0 0 0 1 0 1 1 0 0 0 0 1 1 0 0 1 1 0 1 0 0 0 1 1 1 0 1 0 1 1 0 1 0 0 1 1 0 1 1 1 0 0 1 1 1 1 1 0 0 1 1 1 1

                                                                        ACTIVITY 1 Show connections of 74194 to convert it into a ring counter with right shifting

                                                                        Logic Design amp Switching Theory 1 Lab Session 15 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                        Lab Session 15

                                                                        OBJECT

                                                                        Experimenting with 74245 octal bus transceivers using parallel port PC interfacing COMPONENTS AND APPARATUS REQUIRED 1 Parallel Port Connectors (DB-25) with Cable 2 Personal Computer with Windows 98 and TurboC Compiler Installed 3 Following ICs and their Datasheets

                                                                        bull 74245 Octal Bus Transceivers with 3-State Outputs 4 Digital Trainer DT-01 or the following components

                                                                        Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches

                                                                        THEORY

                                                                        3-State Logic Sometimes it is necessary to isolate one part of circuit from the other part For this purpose some TTL ICs are designed with 3-state logic Such devices have three possible output states high low and high impedance The device can be put into high impedance state by a control signal applied to an appropriate pin When such a device is in high impedance state there is very high impedance at its output effectively isolating the device from whatever circuitry the output normally drives 74245 Octal Bus Transceivers A bus is any conducting path or set of paths having electrical connections to one or more devices 74245 octal bus transceivers are mainly used to control connectivity between two devices or circuits It also provides direction control for signal flow Function of various pin of this IC is given below

                                                                        bull A1 through A8 Bus A bull B1 through B8 Bus B bull G΄ Active low enable input When high sets all the bus pins to high impedance state bull DIR Direction control for signal flow When set to high logic level transfers bus A

                                                                        data to B bus When set to low logic level transfers bus B data to A bus bull VCC and GND Supply connections lines Serial and Parallel Port Connectors A Parallel Port can consist of only 25 pin port adapter called a DB-25 and a serial port can consist of either a 25 pin port adapter called a DB-25 or 9 pin adapter called a DB-9 port adapter Whether the port is a 9 pin or 25 pin it can accomplish all of the same tasks that serial port communications have been designed for

                                                                        59

                                                                        Logic Design amp Switching Theory 1 Lab Session 15 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                        60

                                                                        Each adapter can be a male type connector with pins or a female type adapter with tiny holes Generally a PRINTER port (called LPT1) on the back of a computer is female type adapter and we need to use MALE DB-25 pin cable on it for PRINTER connection or for parallel LAPLINK cable And a COM port on the back of a computer is male for the serial ports but it may not necessarily be Parallel Port Connector ndash DB-25 The DB-25 connector (named for its B-size D-shaped shell and 25 pins) is practically ubiquitous in the electronics industry The DB-25 connector is used for a variety of purposes Two common applications are RS-232EIA-232 (serial) connections and the parallel printer interface on the IBM PC The DB-25 connector is also used for SCSI connections Normally the parallel port is used for output to a printer or other device It sends data 8-bits or one byte at a time in parallel The other lines available on the DB-25 connector are a combination of status lines control lines and ground lines The status and control lines are used for handshaking commands and feedback when we are talking to a printer

                                                                        Figure 152 DB-25 Female Figure 151 DB-25 Male

                                                                        Figure 153 Pin Layout for DB-25 As can be seen form figure 153 there are four types of pins in this connector

                                                                        bull Data pins (8 pins - D0 to D7) Active high bidirectional lines

                                                                        Logic Design amp Switching Theory 1 Lab Session 15 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering bull Control pins (4 pins - C0 to C3) C0 C1 and C3 are active low whereas C2 is active

                                                                        high These lines also are bidirectional bull Status pins (5 pins ndash S3 to S7) Only S7 is active low rest are active high input lines bull Ground pins (8 pins) Used as a reference signal for the low (below 05 volts) charge

                                                                        Parallel Port Addresses A DB-25 connector at a parallel port has three address one for each kind of pins register data status and control The first or base address generally refers to data register Second address is for status register and the third one is for control register In Windows 98 the base address is usually found to be 278H 378H or 3BCH Now if 378H is the base address then it refers to the data register whereas addresses for status and control register are respectively 379H and 37AH For Windows 98 the base address can be found as follows 1 On your Desktop right-click on My Computer and select Properties 2 Click on the Device Manager tab and find LPT1 under Plug and Play BIOS 3 After selecting LPT1 click the Properties button 4 Next select the Resources tab and the address should then appear next to InputOutput

                                                                        Range Accessing parallel port through C Language Programming There are multiple functions in C Language for accessing external ports The most commonly used are listed below

                                                                        bull unsigned char inportb(int portid) inportb reads a byte from a hardware port

                                                                        bull int inport(int portid) reads a word from a hardware port

                                                                        bull void outportb(int portid unsigned char value) outputs a byte to a hardware port

                                                                        bull void outport(int portid int value) outputs a word to a hardware port

                                                                        portid refers to the port address whereas value refers to the data to be sent TESTING 74245 USING PARALLEL PORT PC INTERFACING At one end the parallel port connector will be connected to the PC via parallel port cable and another connector (to be plugged into the PC parallel port slot) At the other end it will be connected to the buffer IC 74245 Data lines of the connector will be used to transfer 8-bit data between the PC and the buffer Out of the 8-bits of 74245 4-bits will be used to enter data which will be displayed at the monitor through a C language

                                                                        61

                                                                        Logic Design amp Switching Theory 1 Lab Session 15 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering program The remaining 4-bits will receive data from PC as entered by the user via keyboard

                                                                        Circuit Diagram

                                                                        Figure 154 Interface of 74245 to PC via Parallel Port

                                                                        Procedure

                                                                        1 Connect the DB-25 connector to the PC at one end and solder it to the circuit board at the other end

                                                                        2 Connect various pins of the connector and 74245 according to the circuit diagram shown in figure 152

                                                                        3 Using the functions listed in the previous section write a program in C language to operate various pins of the buffer The user interface of the program should provide option to the user whether to send or receive data from the port

                                                                        4 Set DIR switch to 1 5 Try sending some data bits to the port The result should be displayed at the LEDs 6 Set DIR switch to 0 7 Set some binary 4-bit value through the switches Try reading it via parallel port

                                                                        C Language Program

                                                                        A program to access parallel port for data transfers

                                                                        use header file include ltstdiohgt main program void main() define variable

                                                                        62

                                                                        Logic Design amp Switching Theory 1 Lab Session 15 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering unsigned int data=0 char choice while(1) printing option menu clrscr() printf(This program will send or receive a BCD digit from the parallel portn) printf(nPress your choice numbern) printf(n1 Send Data) printf(n2 Receive Data) printf(n3 Exitn) choice = getch() sending entered digit to the port if(choice == 1) input BCD digit printf(nEnter BCD digit to be sent to the port) data = getche() masking the first four bits data = data amp 0x0f sending to the port outportb(0x378data) printf(nThe BCD digit c has been sent to the port data) printing on screen the data received from the port else if(choice == 2) receiving data from the port data = inportb(0x378) masking the last four bits data = data amp 0xf0 shifting first four bits to make them the last four bits datagtgt=4 printf(nThe BCD digit set at the port is c data) exit else if(choice == 3) break key pressed is not in the menu else printf(nEnter valid choice number) printf(nnPress any key to continue) getch()

                                                                        63

                                                                        Logic Design amp Switching Theory 1 Lab Session 15 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                        ACTIVITY 1 In the above circuit DIR and G΄ inputs are hardwired Connect them to status or

                                                                        control pins of the parallel port connector and control their function through your software program Circuit Diagram Program Code ______________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________

                                                                        ___________________________________________________________________________________________________________________________________________________

                                                                        64

                                                                        Logic Design amp Switching Theory 1 Lab Session 15 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                        65

                                                                        _____________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ _____________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ _______________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ _________________________________________________ _________________________________________________

                                                                        Logic Design amp Switching Theory 1 Appendix A NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                        Appendix A

                                                                        PIN DIAGRAMS OF THE ICS REQUIRED FOR THE LABORATORY SESSIONS Consult the TTLIC data book for internal diagrams and electrical characteristics of these ICs 7400 Quad 2-Input NAND 7402 Quad 2-Input NOR

                                                                        7404 Hex Inverter 7408 Quad 2-Input AND

                                                                        7410 Triple 3-Input NAND 7411 Triple 3-Input AND

                                                                        7421 Dual 4-Input AND 7432 Quad 2-Input OR

                                                                        66

                                                                        Logic Design amp Switching Theory 1 Appendix A NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                        BCD-to-Seven Segm 7448 BCD-to-Seven Segment 7447 ent

                                                                        Decoder (15V OC) Decoder (2kΩ pull-up output)

                                                                        7473 Dual JK Flip-Flop 7474 Dual D-Type Flip-Flop

                                                                        7476 Dual JK Flop-Flop -Bit Binary Full Adder 7483 4 with Fast Carry

                                                                        86 Quad 2-Inpu 74138 3-to-8 Line 74 t Exclusive OR Decoder Demultiplexer

                                                                        67

                                                                        Logic Design amp Switching Theory 1 Appendix A NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                        68

                                                                        74148 8-to-3 Line 16-to-1 Line Data

                                                                        Priority Encoder 74150 Selector Multiplexer

                                                                        74245 Oct nsceivers Universal Shift Register (PIPO) (3-State)

                                                                        74194 4-Bit Bidirectional al Bus Tra

                                                                        Logic Design amp Switching Theory 1 Appendix B NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                        Appendix B

                                                                        DEBOUNCING CIRCUITRY FOR MECHANICAL SWITCHES Mechanical switches form the interface between human beings and computers or other digital systems For example a keyboard is a matrix of switches used to supply alphanumeric data to a computer Whatever the switch design it is a potential source of problems due to contact bounce The contact bounce creates a sense of narrow pulses when a switch is opened or closed An example of device whose operation would be adversely affected by contact bounce is a digital counter used to count the number of times a switch is depressed Eliminating the effects of contact bounce is called debouncing When data is entered into a computer via a keyboard a software debounce is often used This type of debouncing is a program that causes the computer to sample the switch terminal (ie to input data from it) many times in succession during the interval of time that contact bounce occurs If the data is sensed to be 1s (or 0s) for a specific number of consecutive samples then it is assumed that contact bounce has ended and the last value sensed is valid Hardware debouncing is the use of electronic circuitry to eliminate the effects of contact bounce There are numerous versions of such circuitry including those that use monostable multivibrators (one-shots) but the most straightforward is simply an RS latch Figure B1 shows the circuit When the switch is in position 1 R = 0 and S = 1 so the latch is set and the output (Q) is 1 When the switch is in position 0 R = 1and S = 0 so the latch is reset and the output is 0 When the switch is moved form one position to the other the latch changes state and bouncing occurs at either the R or the S input The bouncing does not affect the latch after it has change state An RS latch will remain set for example when its R input is 0 and its S input is alternately changed form 1 to 0

                                                                        Figure B1 Use of RS latch to debounce a mechanical switch

                                                                        69

                                                                        • 01-ldst-Outer title
                                                                          • Practical Workbook
                                                                          • Logic Design amp Switching Theory I
                                                                            • Dept of Computer amp Information Systems Engineering
                                                                              • NED University of Engineering amp Technology
                                                                              • Karachi ndash 75270 Pakistan
                                                                                • 02-ldst-inner Title
                                                                                  • Practical Workbook
                                                                                  • Logic Design amp Switching Theory I
                                                                                    • Dept of Computer amp Information Systems Engineering
                                                                                      • NED University of Engineering amp Technology
                                                                                      • Karachi ndash 75270 Pakistan
                                                                                        • 03-ldst-general info
                                                                                        • 04-ldst-introduction
                                                                                        • 05-Table of Contents
                                                                                          • CONTENTS
                                                                                            • Lab Session No Object Page No
                                                                                            • 1
                                                                                            • Also implementing and testing the given circuit on a bread board
                                                                                              • Working with Electronics Workbench
                                                                                                • Driving a seven segment display using 7447 7448 driver IC
                                                                                                  • Designing a modulus-5 asynchronous up-counter using JK-FF
                                                                                                    • Experimenting with 74194 4-bit bidirectional universal shift register
                                                                                                        • 13
                                                                                                            • 06-ldst-Exp01
                                                                                                              • Lab Session 01
                                                                                                              • OBJECT
                                                                                                                • 1 Bread board
                                                                                                                • 2 5 V - power supply
                                                                                                                • 3 Multimeter
                                                                                                                • 4 Logic probe
                                                                                                                • 5 LEDs with resistors
                                                                                                                • 6 Connecting wires
                                                                                                                • 8 Following ICs and their datasheets
                                                                                                                  • THEORY
                                                                                                                    • Logic Gates
                                                                                                                    • 1 The AND Gate ndash An AND gatersquos output is 1 if and only if all its inputs are 1 If A and B are two inputs to an AND gate then output F of the gate is given as F = AB
                                                                                                                    • 2 The OR Gate - An OR gatersquos output is 1 if at least one of its input is 1 If A and B are two inputs to an OR gate then output F of the gate is given as F = A+B
                                                                                                                    • 3 The NOT Gate (Inverter) ndash Its output is 1 when its input is 0 and its output is 0 when the input is 1 ie it complements a digital variable If A is the input to a NOT gate then output F of the gate is given as
                                                                                                                    • 4 The NAND Gate ndash Its output is 1 if at least one of its input is 0 This gate performs the same logic as an AND gate followed by an inverter If A and B are two inputs to a NAND gate then output F of the gate is given as
                                                                                                                      • 5 The NOR Gate - The output of a NOR gate is 1 if and only if all its inputs are 0 This gate performs the same logic function as an OR gate followed by an inverter If A and B are two inputs to a NAND gate then output F of the gate is given as
                                                                                                                          • DATA SHEETS
                                                                                                                            • Logic expression for the given logic diagram __________________________________
                                                                                                                                • 07-ldst-exp02
                                                                                                                                  • Working with Electronics Workbench
                                                                                                                                    • 08-ldst-exp03
                                                                                                                                      • Designing Half and Full Adder Circuits
                                                                                                                                        • COMPONENTS AND APPARATUS REQUIRED
                                                                                                                                          • 1 Following ICs and their Datasheets
                                                                                                                                          • 7408 Quad 2-input AND Gate
                                                                                                                                          • 2 Digital Trainer DT-01 or the following components
                                                                                                                                            • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                            • Connecting wires Switches
                                                                                                                                              • THEORY
                                                                                                                                                  • IMPLEMENTATION AND OBSERVATIONS
                                                                                                                                                    • 09-ldst-Exp04
                                                                                                                                                      • Lab Session 04
                                                                                                                                                      • 1 Digital ICs and their Datasheets
                                                                                                                                                      • 7408 Quad 2-input AND Gate
                                                                                                                                                      • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                        • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                        • Connecting wires Switches
                                                                                                                                                        • PROCEDURE
                                                                                                                                                        • REDUCTION OF LOGIC EXPRESSION USING KARNAUGH MAP
                                                                                                                                                        • OBSERVATIONS
                                                                                                                                                        • RESULT
                                                                                                                                                            • 10-ldst-Exp05
                                                                                                                                                              • Lab Session 05
                                                                                                                                                              • 1 Following ICs and their Datasheets
                                                                                                                                                              • 7408 Quad 2-input AND Gate
                                                                                                                                                              • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                • (100 Ω) Connecting wires Switches
                                                                                                                                                                • THEORY
                                                                                                                                                                  • IMPLEMENTATION AND OBSERVATIONS
                                                                                                                                                                    • 11-ldst-Exp06
                                                                                                                                                                      • OBJECT
                                                                                                                                                                      • 1 Following ICs and their Datasheets
                                                                                                                                                                      • 7408 Quad 2-input AND Gates or 7411 Triple 3-input AND Gates
                                                                                                                                                                      • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                        • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                        • Connecting wires Switches
                                                                                                                                                                          • Figure 62 Circuit Diagram for 4 x 1 Multiplexer
                                                                                                                                                                          • Implementation and Observations
                                                                                                                                                                            • Circuit Diagram
                                                                                                                                                                              • ACTIVITY
                                                                                                                                                                                • 12-ldst-exp07
                                                                                                                                                                                  • 1 Following ICs and their Datasheets
                                                                                                                                                                                  • 7408 Quad 2-input or 7411 Triple 3-input AND Gates
                                                                                                                                                                                  • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                    • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                    • Connecting wires Switches
                                                                                                                                                                                      • THEORY
                                                                                                                                                                                          • Figure 72 Circuit Diagram for 2 x 4 Decoder 1 x 4 Demultiplexer
                                                                                                                                                                                          • Implementation and Observations
                                                                                                                                                                                            • Circuit Diagram
                                                                                                                                                                                              • ACTIVITY
                                                                                                                                                                                                • 13-ldst-Exp08
                                                                                                                                                                                                  • OBJECT
                                                                                                                                                                                                  • 1 Following ICs and their Datasheets
                                                                                                                                                                                                  • 7408 Quad 2-input or 7421 Dual 4-input AND Gates
                                                                                                                                                                                                  • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                    • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                    • Connecting wires Switches
                                                                                                                                                                                                      • THEORY
                                                                                                                                                                                                          • Figure 81 Circuit Diagram for 4 x 2 Priority Encoder
                                                                                                                                                                                                          • Implementation and Observations
                                                                                                                                                                                                            • Therefore if GS A2 A1 and A0 are all low then it shows that line 0 is selected and if E0 A2 A1 and A0 are all low then it shows that none of the inputs selected E0 and GS cannot be in the same state provided that E1 is enabled
                                                                                                                                                                                                            • Circuit Diagram
                                                                                                                                                                                                              • ACTIVITY
                                                                                                                                                                                                                • 14-ldst-exp09
                                                                                                                                                                                                                  • OBJECT
                                                                                                                                                                                                                  • 1 Following ICs and their Datasheets
                                                                                                                                                                                                                  • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                    • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                                    • Connecting wires Switches
                                                                                                                                                                                                                      • THEORY
                                                                                                                                                                                                                        • Parity Generator
                                                                                                                                                                                                                          • Let x y and z be the three bits that constitute the message and are the input to the Odd Parity Generator Circuit Since it is an odd parity system the bit P is generated so as to make the total number of 1s odd (including P) The function P can be expressed as follows
                                                                                                                                                                                                                          • Figure 91 Circuit Diagram for a 3-bit Parity Generator
                                                                                                                                                                                                                            • C = x Ο y Ο z Ο P
                                                                                                                                                                                                                              • Implementation and Observations
                                                                                                                                                                                                                                • ACTIVITY
                                                                                                                                                                                                                                    • 15-ldst-exp10
                                                                                                                                                                                                                                      • Driving a seven segment display using 7447 7448 driver IC
                                                                                                                                                                                                                                      • COMPONENTS AND APPARATUS REQUIRED
                                                                                                                                                                                                                                      • 1 Following ICs and their Datasheets
                                                                                                                                                                                                                                      • 7447 7448 BCD to Seven Segment Driver
                                                                                                                                                                                                                                      • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                                        • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches
                                                                                                                                                                                                                                          • THEORY
                                                                                                                                                                                                                                          • Seven Segment Displays
                                                                                                                                                                                                                                          • CIRCUIT DIAGRAM
                                                                                                                                                                                                                                          • Figure 102 Circuit diagram for 7447driving a common-anode display
                                                                                                                                                                                                                                              • IMPLEMENTATION AND OBSERVATIONS
                                                                                                                                                                                                                                                • Decimal Digit
                                                                                                                                                                                                                                                • BCD Inputs
                                                                                                                                                                                                                                                • Seven Segment Outputs
                                                                                                                                                                                                                                                • D
                                                                                                                                                                                                                                                • C
                                                                                                                                                                                                                                                • B
                                                                                                                                                                                                                                                • A
                                                                                                                                                                                                                                                • a
                                                                                                                                                                                                                                                • b
                                                                                                                                                                                                                                                • c
                                                                                                                                                                                                                                                • d
                                                                                                                                                                                                                                                • e
                                                                                                                                                                                                                                                • f
                                                                                                                                                                                                                                                • g
                                                                                                                                                                                                                                                • 0
                                                                                                                                                                                                                                                • 0
                                                                                                                                                                                                                                                • 0
                                                                                                                                                                                                                                                • 0
                                                                                                                                                                                                                                                • 0
                                                                                                                                                                                                                                                • 1
                                                                                                                                                                                                                                                • 0
                                                                                                                                                                                                                                                • 0
                                                                                                                                                                                                                                                • 0
                                                                                                                                                                                                                                                • 1
                                                                                                                                                                                                                                                • 2
                                                                                                                                                                                                                                                • 0
                                                                                                                                                                                                                                                • 0
                                                                                                                                                                                                                                                • 1
                                                                                                                                                                                                                                                • 0
                                                                                                                                                                                                                                                • 3
                                                                                                                                                                                                                                                • 0
                                                                                                                                                                                                                                                • 0
                                                                                                                                                                                                                                                • 1
                                                                                                                                                                                                                                                • 1
                                                                                                                                                                                                                                                • 4
                                                                                                                                                                                                                                                • 0
                                                                                                                                                                                                                                                • 1
                                                                                                                                                                                                                                                • 0
                                                                                                                                                                                                                                                • 0
                                                                                                                                                                                                                                                • 5
                                                                                                                                                                                                                                                • 0
                                                                                                                                                                                                                                                • 1
                                                                                                                                                                                                                                                • 0
                                                                                                                                                                                                                                                • 1
                                                                                                                                                                                                                                                • 6
                                                                                                                                                                                                                                                • 0
                                                                                                                                                                                                                                                • 1
                                                                                                                                                                                                                                                • 1
                                                                                                                                                                                                                                                • 0
                                                                                                                                                                                                                                                • 7
                                                                                                                                                                                                                                                • 0
                                                                                                                                                                                                                                                • 1
                                                                                                                                                                                                                                                • 1
                                                                                                                                                                                                                                                • 1
                                                                                                                                                                                                                                                • 8
                                                                                                                                                                                                                                                • 1
                                                                                                                                                                                                                                                • 0
                                                                                                                                                                                                                                                • 0
                                                                                                                                                                                                                                                • 0
                                                                                                                                                                                                                                                • 9
                                                                                                                                                                                                                                                • 1
                                                                                                                                                                                                                                                • 0
                                                                                                                                                                                                                                                • 0
                                                                                                                                                                                                                                                • 1
                                                                                                                                                                                                                                                  • ACTIVITY
                                                                                                                                                                                                                                                    • 16-ldst-exp11
                                                                                                                                                                                                                                                      • Lab Session 11
                                                                                                                                                                                                                                                        • OBJECT
                                                                                                                                                                                                                                                        • COMPONENTS AND APPARATUS REQUIRED
                                                                                                                                                                                                                                                          • 1 Following ICs and their Datasheets
                                                                                                                                                                                                                                                          • 7473 7476 JK Flip-Flop
                                                                                                                                                                                                                                                          • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                                                            • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                                                                            • Connecting wires Switches
                                                                                                                                                                                                                                                              • THEORY
                                                                                                                                                                                                                                                                  • Flip-Flop
                                                                                                                                                                                                                                                                  • JK Flip-Flop
                                                                                                                                                                                                                                                                    • Circuit Diagram
                                                                                                                                                                                                                                                                      • Observations
                                                                                                                                                                                                                                                                        • ACTIVITY
                                                                                                                                                                                                                                                                            • 17-ldst-exp12
                                                                                                                                                                                                                                                                              • Lab Session 12
                                                                                                                                                                                                                                                                                • OBJECT
                                                                                                                                                                                                                                                                                • GIVEN STATE DIAGRAM
                                                                                                                                                                                                                                                                                • Figure 121 State Diagram
                                                                                                                                                                                                                                                                                • COMPONENTS AND APPARATUS REQUIRED
                                                                                                                                                                                                                                                                                  • 1 Following ICs and their Datasheets
                                                                                                                                                                                                                                                                                  • 7474 D Flip-Flop
                                                                                                                                                                                                                                                                                  • ICs of basic gates (AND OR NOT XOR etc) as required
                                                                                                                                                                                                                                                                                  • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                                                                                    • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                                                                                                    • Connecting wires Switches
                                                                                                                                                                                                                                                                                      • THEORY
                                                                                                                                                                                                                                                                                          • Sequential Circuits
                                                                                                                                                                                                                                                                                            • 18-ldst-exp13
                                                                                                                                                                                                                                                                                              • Lab Session 13
                                                                                                                                                                                                                                                                                                • Designing a modulo-5 asynchronous up-counter using JK-FF
                                                                                                                                                                                                                                                                                                  • 1 Following ICs and their Datasheets
                                                                                                                                                                                                                                                                                                  • 7400 Quad 2-input or 7410 Triple 3-input NAND Gates
                                                                                                                                                                                                                                                                                                  • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                                                                                                    • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                                                                                                                    • Connecting wires Switches
                                                                                                                                                                                                                                                                                                      • THEORY
                                                                                                                                                                                                                                                                                                          • Figure 131 A Mod-5 Asynchronous Up Counter
                                                                                                                                                                                                                                                                                                          • Implementation and Observations
                                                                                                                                                                                                                                                                                                            • ACTIVITY
                                                                                                                                                                                                                                                                                                                • 19-ldst-exp14
                                                                                                                                                                                                                                                                                                                  • Experimenting with 74194 4-bit bidirectional universal shift register
                                                                                                                                                                                                                                                                                                                  • 1 Following ICs and their Datasheets
                                                                                                                                                                                                                                                                                                                  • 74194 4-bit bidirectional universal shift register
                                                                                                                                                                                                                                                                                                                  • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                                                                                                                    • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                                                                                                                                    • Connecting wires Switches
                                                                                                                                                                                                                                                                                                                      • THEORY
                                                                                                                                                                                                                                                                                                                        • Shift Registers
                                                                                                                                                                                                                                                                                                                        • Bidirectional Shift Registers
                                                                                                                                                                                                                                                                                                                        • Universal Shift Registers
                                                                                                                                                                                                                                                                                                                          • S1
                                                                                                                                                                                                                                                                                                                            • Circuit Diagram
                                                                                                                                                                                                                                                                                                                            • ACTIVITY
                                                                                                                                                                                                                                                                                                                                • 20-ldst-exp15
                                                                                                                                                                                                                                                                                                                                  • COMPONENTS AND APPARATUS REQUIRED
                                                                                                                                                                                                                                                                                                                                  • 1 Parallel Port Connectors (DB-25) with Cable
                                                                                                                                                                                                                                                                                                                                  • 2 Personal Computer with Windows 98 and TurboC Compiler Installed
                                                                                                                                                                                                                                                                                                                                  • 3 Following ICs and their Datasheets
                                                                                                                                                                                                                                                                                                                                  • 74245 Octal Bus Transceivers with 3-State Outputs
                                                                                                                                                                                                                                                                                                                                  • 4 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                                                                                                                                    • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                                                                                                                                                      • Connecting wires Switches
                                                                                                                                                                                                                                                                                                                                        • THEORY
                                                                                                                                                                                                                                                                                                                                        • 3-State Logic
                                                                                                                                                                                                                                                                                                                                          • Serial and Parallel Port Connectors
                                                                                                                                                                                                                                                                                                                                          • Parallel Port Connector ndash DB-25
                                                                                                                                                                                                                                                                                                                                            • Accessing parallel port through C Language Programming
                                                                                                                                                                                                                                                                                                                                                • 21-ldst-appendixA
                                                                                                                                                                                                                                                                                                                                                • 22-ldst-appendixB
                                                                                                                                                                                                                                                                                                                                                  • DEBOUNCING CIRCUITRY FOR MECHANICAL SWITCHES

                                                                          Logic Design amp Switching Theory 1 Lab Session 08 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                          Figure 81 Circuit Diagram for 4 x 2 Priority Encoder

                                                                          it (figure 81) on a bread board (prepare the to laboratory session 01 for implementation

                                                                          Implementation a Implement the 4 x 2 Priority Encoder circu

                                                                          ram (use appendix A) and refer

                                                                          nd Observations

                                                                          pin diagprocedure) and record the observations in the following table

                                                                          D3 D2 D1 D0 A B 0 0 0 1 0 0 1 x 0 1 x x 1 x x x

                                                                          TESTING OF 74148 8 x 3 Octal Priority Encoder

                                                                          imal digits There are nine of which three represents

                                                                          ing any of the inputs is high

                                                                          then it shows that line 0 is selected and if e inputs selected E0 and GS

                                                                          cannot be in the same state provided that E1 is enabled

                                                                          The 74148 is a priority encoder with active-Low input for dec

                                                                          input) and five output linesinputs lines (including an enablethe binary code for the octal digit Function of various pins of this IC is described below

                                                                          bull 0 through 7 Active low data inputs representing the octal digits A2 A1 A0 Active low output lines representing the binary code bullbull E1 Active low enable Input bull E0 Active low output indicating none of the inputs is high bull GS Active low output indicatbull VCC and GND Supply connections lines Therefore if GS A2 A1 and A0 are all low

                                                                          then it shows that none of thE0 A2 A1 and A0 are all low

                                                                          39

                                                                          Logic Design amp Switching Theory 1 Lab Session 08 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                          Circuit Diagram

                                                                          Figure 82 Pin connections of 74148

                                                                          Testing Procedure bull Make connections as sho

                                                                          binations of 1s and 0s at data inputs d record your observations in the following table

                                                                          GS E0

                                                                          wn in the circuit diagram bull Apply different combull Observe the output an Observations

                                                                          0 1 2 3 4 5 6 7 A2 A1 A0 1 1 1 1 1 1 1 1 x x x x x x x 0 x x x x x x 0 1 x x x x x 0 1 1 x x x x 0 1 1 1 x x x 0 1 1 1 1 x x 0 1 1 1 1 1 x 0 1 1 1 1 1 1 0 1 1 1 1 1 1 1

                                                                          40

                                                                          Logic Design amp Switching Theory 1 Lab Session 08 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                          41

                                                                          CTIVITY

                                                                          Cascade the following two 74148 8 x 3 Priority Encoders to form 16 x 4 Priority

                                                                          A 1

                                                                          Encoder

                                                                          Logic Design amp Switching Theory 1 Lab Session 09 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering `

                                                                          Lab Session 09 OBJECT

                                                                          Designing an Odd Parity Generator and Checker for a 3-bit Data COMPONENTS AND APPARATUS REQUIRED

                                                                          1 Following ICs and their Datasheets

                                                                          bull 7486 Quad 2-input Exclusive-OR Gates bull 7404 Hex Inverter

                                                                          2 Digital Trainer DT-01 or the following components Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches

                                                                          THEORY

                                                                          Parity Generator When binary data is transmitted and processed it is ndash as are all electrical signals ndash susceptible to noise that can either alter or distort its contents 1s may be effectively changed to 0s and 0s to 1s To overcome this problem one or more bits are often added to the data as an aid in detecting errors caused by noise The most common of these is a Parity bit that signifies whether the total number of 1s in a code group is odd or even In an Odd Parity system the parity bit is made 0 or 1 as necessary to make the total number 1s odd (counting the parity bit itself) In an Even Parity system the parity bit is chosen to make the total number of 1s even Table 91 shows how parity bits would be added to BCD code group in both systems

                                                                          Decimal BCD Value Parity Bit ABCD Odd Parity Even Parity

                                                                          0 0000 1 0 1 0001 0 1 2 0010 0 1 3 0011 1 0 4 0100 0 1 5 0101 1 0 6 0110 1 0 7 0111 0 1 8 1000 0 1 9 1001 1 0

                                                                          Table 91 Odd and Even Parity in BCD

                                                                          When digital data is received a parity checking circuit generates an error signal if the total number of 1s is odd in an even parity system or if it is even in an odd parity system Parity check always detects a single error (one bit change from 0 to 1 or 1 to 0) but may not detect

                                                                          42

                                                                          Logic Design amp Switching Theory 1 Lab Session 09 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering ` two or more errors Odd parity is used more often than even parity because even parity does not detect a situation where all 0s are created due to short circuit or other fault condition DESIGN OF A 3-BIT ODD PARITY GENERATOR AND CHECKER Let x y and z be the three bits that constitute the message and are the input to the Odd Parity Generator Circuit Since it is an odd parity system the bit P is generated so as to make the total number of 1s odd (including P) The function P can be expressed as follows P = x oplus y Ο z or P = x Ο y oplus z Since the IC available is 7486 which is quad 2input XOR IC therefore we will convert XNOR also to XOR

                                                                          P = x oplus y Ο z

                                                                          P = ( x oplus y ) Ο z Since for even number of variables ______

                                                                          XOR = XNOR Therefore ___________ _________

                                                                          P = ( x oplus y ) oplus z = x oplus y oplus z This logical expression can be implemented with two XOR gates and an inverter (see figure 91)

                                                                          Figure 91 Circuit Diagram for a 3-bit Parity Generator

                                                                          The 3-bit message and the parity bit are transmitted to their destination where they are applied to a Parity Checker Circuit An error occurs during transmission if the parity of the four bits received is even since the binary information transmitted was originally odd The output C of the parity checker should be a 1 when an error occurs ie when the number of 1s in the four inputs is even Therefore the function C can be expressed as

                                                                          C = x Ο y Ο z Ο P

                                                                          Using the same logic applied for the conversion of the equation of P

                                                                          PzyxC oplusoplusoplus= This logical expression can be implemented with three XOR gates and an inverter (see figure 92)

                                                                          43

                                                                          Logic Design amp Switching Theory 1 Lab Session 09 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering `

                                                                          44

                                                                          Figure 92 Circuit Diagram for a 3-bit Parity Checker Implementation and Observations Implement the 3-bit Parity Generator and Checker circuits (figure 91 and 92) on a bread board (prepare the pin diagram (use appendix A) and refer to laboratory session 01 for implementation procedure) and record the observations in the following table

                                                                          x y z P x y z P C x y z P C 0 0 0 0 0 0 0 1 0 0 0 0 0 1 0 0 0 1 1 0 0 1 0 1 0 0 0 1 0 1 0 1 0 0 1 1 0 0 1 1 1 0 1 1 1 0 0 0 1 0 0 1 1 0 0 1 0 1 0 1 0 1 1 1 0 1 1 1 0 0 1 1 0 1 1 1 0 1 1 1 0 1 1 1 1 1 1 1

                                                                          Odd Parity Generation Odd Parity Check ACTIVITY 1 Try using the parity checker of figure 92 as 3-bit parity generator Write the details here

                                                                          _____________________________________________________________________________________________________________________________________________________________________________________________________________________ ______________________________________________________________________________________________________________________________________________ _______________________________________________________________________ ______________________________________________________________________________________________________________________________________________

                                                                          Logic Design amp Switching Theory 1 Lab Session 10 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                          Lab Session 10 OBJECT

                                                                          Driving a seven segment display using 7447 7448 driver IC COMPONENTS AND APPARATUS REQUIRED

                                                                          1 Following ICs and their Datasheets

                                                                          bull Seven Segment Displays (Common Anode Common Cathode) bull 7447 7448 BCD to Seven Segment Driver

                                                                          2 Digital Trainer DT-01 or the following components Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches

                                                                          THEORY Seven Segment Displays A Seven Segment Display consists of seven light-emitting segments The segments are designated by letters a through g (see figure 101) By illuminating various combinations of segments the numerals 0 through 9 can be displayed Seven Segment Displays are commonly constructed with light-emitting diodes (LEDs) and with liquid-crystal displays (LCDs) LEDs generally provide greater illumination levels but require much greater power than LCDs An LED display can be a common-anode type or common cathode type In common anode type a high voltage is applied at the common terminal of the display and low voltage is applied at a segmentrsquos terminal for illumination In the common-cathode type a low voltage is applied at the common terminal of the display and high voltage is applied at a segmentrsquos terminal for illumination

                                                                          Figure 101 Seven Segment Display

                                                                          a f b g

                                                                          e c d

                                                                          7447 7448 BCD to Seven Segment Driver 7447 7448 IC is particularly used to drive Seven Segment Its input is a BCD number and output drives a seven segment display 7447 is used to drive common-anode displays whereas 7448 is used to drive common cathode displays 7447 7448 is a 16 pin IC Function of various pins of these ICs is described below

                                                                          bull A B C D Inputs representing BCD digits (D being the MSB)

                                                                          45

                                                                          Logic Design amp Switching Theory 1 Lab Session 10 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering bull OA through OG Outputs to drive segments a through g of the display (Active low

                                                                          in 7447 and active high in 7448) bull RBI Ripple Blanking Input Turns off all the segments if kept low provided that LT

                                                                          is kept high and all other inputs (A B C D BI) are kept low Should be kept high otherwise

                                                                          bull BI RBO Wire-AND logic serving as a Blanking Input and or Ripple Blanking Output

                                                                          o BI Turns off all the segments if low o RBO Goes to a low level (response condition) along with other outputs when

                                                                          RBI and inputs A B C and D are low with LT input at high level bull LT Lamp Test input Tests whether all segments are working or not Illuminates all

                                                                          segments if kept low provided that BI is kept high Should be kept high otherwise bull VCC and GND Supply connections lines CIRCUIT DIAGRAM

                                                                          Figure 102 Circuit diagram for 7447driving a common-anode display

                                                                          IMPLEMENTATION AND OBSERVATIONS

                                                                          bull Make connections as shown in the circuit diagram (refer to laboratory session 01 for implementation procedure)

                                                                          bull Apply different combinations of 1s and 0s at data inputs bull Observe the output and record your observations in the following table

                                                                          46

                                                                          Logic Design amp Switching Theory 1 Lab Session 10 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                          47

                                                                          Decimal Digit

                                                                          BCD Inputs Seven Segment Outputs D C B A a b c d e f g

                                                                          0 0 0 0 0 1 0 0 0 1 2 0 0 1 0 3 0 0 1 1 4 0 1 0 0 5 0 1 0 1 6 0 1 1 0 7 0 1 1 1 8 1 0 0 0 9 1 0 0 1

                                                                          ACTIVITY 1 Perform the Lamp Test for the designed circuit and write your observations

                                                                          ____________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________

                                                                          2 How can you use 7447 IC to drive a common-cathode display

                                                                          ____________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________

                                                                          3 What symbols appear in the seven segment display if inputs DCBA are

                                                                          DCBA Symbol

                                                                          1010

                                                                          1011

                                                                          1100

                                                                          1101

                                                                          1110

                                                                          1111

                                                                          Logic Design amp Switching Theory 1 Lab Session 11 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                          48

                                                                          Lab Session 11 OBJECT

                                                                          Testing different modes of JK-FF COMPONENTS AND APPARATUS REQUIRED 1 Following ICs and their Datasheets

                                                                          bull 7473 7476 JK Flip-Flop 2 Digital Trainer DT-01 or the following components

                                                                          Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches

                                                                          THEORY

                                                                          Flip-Flop A flip-flop circuit can maintain a binary state indefinitely (as long as the power is delivered to the circuit) until directed by an input signal to switch states The major differences among various types of flip-flops are in the number of inputs they possess and in the manner in which the inputs affect the binary state

                                                                          JK Flip-Flop JK flip flop is an edge triggered device A typical JK flip flop has three inputs J K and a clock input The flip-flop can be either positive or negative edge triggered The output Q is available in complemented form as well Beside the usual inputs and output most of the flip-flop IC also possess two asynchronous inputs namely Preset and Clear These inputs are usually active low If used Preset and Clear inputs keep the flip-flop in set and reset state respectively irrespective of the other inputs Both of these inputs cannot be used simultaneously otherwise they will bring the flip-flop in unstable state

                                                                          Figure 111 Symbol for JK flip-flop

                                                                          (a) positive-edge triggering (b) active low Preset (PR) and Clear (CLR) with positive-edge triggering

                                                                          (c) active low Preset (PR) and Clear (CLR) with negative-edge triggering

                                                                          Logic Design amp Switching Theory 1 Lab Session 11 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                          49

                                                                          TESTING OF 7473 7476 DUAL JK FLIP-FLOP

                                                                          Both the ICs 7473 and 7476 are similar in functionality except for one difference The flip-flops in 7473 have only one type of active low asynchronous input which is the Clear input whereas the flip-flops in 7476 have both Preset and Clear inputs Both these ICs have negative edge triggered flip-flops

                                                                          Circuit Diagram

                                                                          Figure 112 Pin connections of 7476

                                                                          Testing Procedure

                                                                          bull Make connections as shown in the circuit diagram (figure 112) bull Apply different combinations of 1s and 0s at J and K inputs bull Observe the output and record your observations in the following table

                                                                          Observations

                                                                          J

                                                                          K Q

                                                                          0 0 0 1 1 0 1 1

                                                                          ACTIVITY

                                                                          1 Observe the output Q of JK flip-flop if the clock input is connected to VCC or GND instead of a clock source Write your observations here __________________________________________________________________________________________________________________________________________ _______________________________________________________________________________________________________________________________________________________________________________________________________________

                                                                          Logic Design amp Switching Theory 1 Lab Session 12 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                          50

                                                                          Lab Session 12 OBJECT

                                                                          Designing sequential circuit for the given state diagram using D flip-flop GIVEN STATE DIAGRAM

                                                                          00

                                                                          11

                                                                          Figure 121 State Diagram COMPONENTS AND APPARATUS REQUIRED 1 Following ICs and their Datasheets

                                                                          bull 7474 D Flip-Flop bull ICs of basic gates (AND OR NOT XOR etc) as required

                                                                          2 Digital Trainer DT-01 or the following components Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches

                                                                          THEORY

                                                                          Sequential Circuits In Sequential Circuits the output not only depends on the present inputs but also on previous states of the circuit These circuits use memory elements (latches flip-flops) and the binary information stored in the memory elements at any given time defines the state of the sequential circuit Analysis of a Sequential Circuit The behavior of a sequential circuit is determined from the inputs the outputs and the states of its flip-flops Both the outputs and next state are a function of the inputs and the

                                                                          10

                                                                          01

                                                                          00 11 10

                                                                          00

                                                                          00 11 10 00

                                                                          Logic Design amp Switching Theory 1 Lab Session 12 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                          51

                                                                          present state The analysis of a sequential circuit form a state diagram comprises of the following bull Selecting a particular flip-flop to design the circuit bull Obtaining state table from the state diagram bull Finding input equations for the selected flip-flop bull Finding state equations (not required for the construction of circuit) bull Implementing the circuit using selected flip-flops and their input equations ANALYZING THE GIVEN STATE DIAGRAM D Flip-Flop D flip-flop is also called transparent flip-flop as it simply transfers the input data to the output For our design we require the graphical symbol and excitation table of D flip-flop (see figure 122)

                                                                          Qt Qt+1 T 0 0 0 0 1 1 1 0 0 1 1 1

                                                                          (b) Excitation table of D Flip-Flop

                                                                          (a) Graphical Symbol

                                                                          Figure 122 Characteristic equation of D flip-flop is Q(t+1) = D State Table The given state diagram has four states so we will need two D flip-flops (FF-0 FF-1) Form state table form the given state diagram and record the results in the following table

                                                                          Present State Input Next State Output Input to FF-0 D0

                                                                          Input to FF-1 D1 Q1t Q0t x Q1(t+1) Q0(t+1) z

                                                                          Logic Design amp Switching Theory 1 Lab Session 12 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                          52

                                                                          Input Equations Using Karnaugh map the input equations D0 and D1 for the two flip-flops can be found

                                                                          D0 D1 Q0x

                                                                          Q1

                                                                          _ _ Q0x

                                                                          _ Q0x

                                                                          Q0x

                                                                          _ Q0x

                                                                          Q0x

                                                                          Q1

                                                                          _ _ Q0x

                                                                          _ Q0x

                                                                          Q0x

                                                                          _ Q0x

                                                                          _ Q1

                                                                          _ Q1

                                                                          Q1

                                                                          Q1

                                                                          D0 = _________________ D1 = _________________

                                                                          State Equations Using the characteristic equation of D flip-flop we can find the state equations Q0(t+1) and Q1(t+1) for the to flip flops Q0(t+1) = _______________________ Q1(t+1) = _______________________ _______________________ _______________________ _______________________ _______________________ Circuit Diagram

                                                                          Logic Design amp Switching Theory 1 Lab Session 12 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                          53

                                                                          Implementation Procedure and Observations

                                                                          1 Implement the circuit using digital ICs on a bread board (prepare the pin diagram (use appendix A) and refer to laboratory session 01 for procedure)

                                                                          2 Make the clear inputs of the flip-flops low (to clear the flip-flops) The flip-flops will remain in clear state as long as the clear inputs are connected to low level

                                                                          3 Connect output Q0 and the clock pulse to an oscilloscope 4 Apply 0 to the input x 5 Now make the clear inputs to high 6 Observe the waveform for the first 5 clock pulses and record it 7 Repeat steps 2 to 6 keeping x=1 in step 4 this time 8 Repeat steps 2 to 7 this time connecting Q1 instead of Q0 to the oscilloscope in step

                                                                          3 Record your observations (Keep frequency of the clock pulse low (eg1Hz) so that the output waveforms can be observed easily)

                                                                          1 2 3 4 5 Clock Pulse

                                                                          Output Waveform for Q0 when x=0

                                                                          Output Waveform for Q0 when x=1

                                                                          Output Waveform for Q1 when x=0

                                                                          Output Waveform for Q1 when x=1

                                                                          Logic Design amp Switching Theory 1 Lab Session 13 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                          Lab Session 13 OBJECT

                                                                          Designing a modulo-5 asynchronous up-counter using JK-FF COMPONENTS AND APPARATUS REQUIRED

                                                                          1 Following ICs and their Datasheets

                                                                          bull 7400 Quad 2-input or 7410 Triple 3-input NAND Gates bull 7476 7473 JK Flip-Flop

                                                                          2 Digital Trainer DT-01 or the following components Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches

                                                                          THEORY

                                                                          Digital Counters A digital counter is a set of flip-flops whose states change in response to pulses applied at the input to the counter The flip-flops are interconnected so that their combined state at any time is the binary equivalent of the total number of pulses that have occurred up to that time Every counter resets after a certain number of clock pulses Thus as it name implies a counter is used to count pulses An n stage counter can count up to a maximum of 2n states n is equal to the number of flip-flops required for the construction of counter

                                                                          Modulus Counters The number of input pulses that causes a counter to reset to its initial count is called the modulus of the counter Thus the modulus equals to total number of distinct states (counts) including zero that a counter can store A binary counter with n stages is a modulo-2n (or mod-2n) counter The largest count a mod-N counter can achieve is N-1 ie a mod-N counter never reaches the binary number equal to its modulus N is always equal to or less than 2n Counters can be classified as bull Synchronous Counters which are clock driven All the flip-flops are driven by a

                                                                          single clock bull Asynchronous Counters which are event driven Clock input is given to the first

                                                                          flip-flop only Rest of the flip-flops are driven by their preceding flip-flops

                                                                          DESIGN OF A MOD-5 ASYNCHRONOUS UP COUNTER The number of flip-flops required to construct a mod-5 counter is 3 because 5 should be less than or equal to 2n This counter will count from 0 to 4 a total of 5 distinct states Since a 3-stage counter can count up to 8 states at maximum a NAND gate is used to reset it after 5 clock pulses Figure 131 shows the logic diagram

                                                                          54

                                                                          Logic Design amp Switching Theory 1 Lab Session 13 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                          55

                                                                          Figure 131 A Mod-5 Asynchronous Up Counter

                                                                          Implementation and Observations

                                                                          Implement the mod-5 counter circuit (figure 131) on a bread board (prepare the pin diagram (use appendix A) and refer to laboratory session 01 for implementation procedure) and record the observations in the following table

                                                                          Clock Pulse Q2 Q1 Q0

                                                                          0 1 2 3 4 5 6 7

                                                                          ACTIVITY

                                                                          Draw the timing diagram for mod-5 counter designed in this laboratory session

                                                                          Logic Design amp Switching Theory 1 Lab Session 14 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                          Lab Session 14 OBJECT

                                                                          Experimenting with 74194 4-bit bidirectional universal shift register COMPONENTS AND APPARATUS REQUIRED

                                                                          1 Following ICs and their Datasheets

                                                                          bull 74194 4-bit bidirectional universal shift register 2 Digital Trainer DT-01 or the following components

                                                                          Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches

                                                                          THEORY

                                                                          Shift Registers

                                                                          A Register is a set of flip-flops used to store binary data A register which is capable of shifting its binary information either to the right or left is called a shift register The logical configuration of a register consists of a chain of flip-flops connected in cascade with the output of one flip-flop connected to the input of next flip-flop All flip-flops receive a common clock pulse which causes the shift from one stage to the next

                                                                          Bidirectional Shift Registers A bi-directional shift register is one whose bits can be shifted from left to right or from right to left

                                                                          Universal Shift Registers A universal shift register is a bi-directional register whose input can be in either serial or parallel form and whose output can be in either serial or parallel form

                                                                          74194 4-BIT BIDIRECTIONAL UNIVERSAL SHIFT REGISTER

                                                                          The 74194 register provides parallel as well as serial loading in both directions Function of various pins of this IC is described below

                                                                          bull A B C and D Active high inputs for parallel loading bull QA QB QC and QD Active high outputs bull S0 and S1 Active high mode control inputs The following table shows combinations

                                                                          of S1 and S0 to enable various modes

                                                                          S1 S0 Clock Action 0 0 x No change 0 1 uarr Shift right 1 0 uarr Shift left 1 1 uarr Parallel load

                                                                          uarr shows the rising edge of the clock pulse

                                                                          56

                                                                          Logic Design amp Switching Theory 1 Lab Session 14 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering bull SR Active high serial input for right shifting bull SL Active high serial input for left shifting bull CLR Active low input Clears all the flip-flops of the register if set to 0 should be

                                                                          kept high otherwise bull CLK Clock input bull VCC and GND Supply connections lines Thus A B C and D are inputs for parallel loading whereas SR and SL are inputs for serial loading with right or left shifting respectively S1 and S0 are used to select the loading mode Circuit Diagram

                                                                          Figure 141 Pin connections of 74194 Testing Procedure

                                                                          bull Make connections as shown in the circuit diagram bull Observe the output for the input combinations given in the following table

                                                                          57

                                                                          Logic Design amp Switching Theory 1 Lab Session 14 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                          58

                                                                          Observations

                                                                          S1 S0 SL SR A B C D QA QB QC QD 0 0 0 1 0 0 0 0 0 1 1 0 0 0 0 1 1 0 0 0 0 0 1 0 1 1 0 0 0 0 1 1 0 0 1 1 0 1 0 0 0 1 1 1 0 1 0 1 1 0 1 0 0 1 1 0 1 1 1 0 0 1 1 1 1 1 0 0 1 1 1 1

                                                                          ACTIVITY 1 Show connections of 74194 to convert it into a ring counter with right shifting

                                                                          Logic Design amp Switching Theory 1 Lab Session 15 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                          Lab Session 15

                                                                          OBJECT

                                                                          Experimenting with 74245 octal bus transceivers using parallel port PC interfacing COMPONENTS AND APPARATUS REQUIRED 1 Parallel Port Connectors (DB-25) with Cable 2 Personal Computer with Windows 98 and TurboC Compiler Installed 3 Following ICs and their Datasheets

                                                                          bull 74245 Octal Bus Transceivers with 3-State Outputs 4 Digital Trainer DT-01 or the following components

                                                                          Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches

                                                                          THEORY

                                                                          3-State Logic Sometimes it is necessary to isolate one part of circuit from the other part For this purpose some TTL ICs are designed with 3-state logic Such devices have three possible output states high low and high impedance The device can be put into high impedance state by a control signal applied to an appropriate pin When such a device is in high impedance state there is very high impedance at its output effectively isolating the device from whatever circuitry the output normally drives 74245 Octal Bus Transceivers A bus is any conducting path or set of paths having electrical connections to one or more devices 74245 octal bus transceivers are mainly used to control connectivity between two devices or circuits It also provides direction control for signal flow Function of various pin of this IC is given below

                                                                          bull A1 through A8 Bus A bull B1 through B8 Bus B bull G΄ Active low enable input When high sets all the bus pins to high impedance state bull DIR Direction control for signal flow When set to high logic level transfers bus A

                                                                          data to B bus When set to low logic level transfers bus B data to A bus bull VCC and GND Supply connections lines Serial and Parallel Port Connectors A Parallel Port can consist of only 25 pin port adapter called a DB-25 and a serial port can consist of either a 25 pin port adapter called a DB-25 or 9 pin adapter called a DB-9 port adapter Whether the port is a 9 pin or 25 pin it can accomplish all of the same tasks that serial port communications have been designed for

                                                                          59

                                                                          Logic Design amp Switching Theory 1 Lab Session 15 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                          60

                                                                          Each adapter can be a male type connector with pins or a female type adapter with tiny holes Generally a PRINTER port (called LPT1) on the back of a computer is female type adapter and we need to use MALE DB-25 pin cable on it for PRINTER connection or for parallel LAPLINK cable And a COM port on the back of a computer is male for the serial ports but it may not necessarily be Parallel Port Connector ndash DB-25 The DB-25 connector (named for its B-size D-shaped shell and 25 pins) is practically ubiquitous in the electronics industry The DB-25 connector is used for a variety of purposes Two common applications are RS-232EIA-232 (serial) connections and the parallel printer interface on the IBM PC The DB-25 connector is also used for SCSI connections Normally the parallel port is used for output to a printer or other device It sends data 8-bits or one byte at a time in parallel The other lines available on the DB-25 connector are a combination of status lines control lines and ground lines The status and control lines are used for handshaking commands and feedback when we are talking to a printer

                                                                          Figure 152 DB-25 Female Figure 151 DB-25 Male

                                                                          Figure 153 Pin Layout for DB-25 As can be seen form figure 153 there are four types of pins in this connector

                                                                          bull Data pins (8 pins - D0 to D7) Active high bidirectional lines

                                                                          Logic Design amp Switching Theory 1 Lab Session 15 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering bull Control pins (4 pins - C0 to C3) C0 C1 and C3 are active low whereas C2 is active

                                                                          high These lines also are bidirectional bull Status pins (5 pins ndash S3 to S7) Only S7 is active low rest are active high input lines bull Ground pins (8 pins) Used as a reference signal for the low (below 05 volts) charge

                                                                          Parallel Port Addresses A DB-25 connector at a parallel port has three address one for each kind of pins register data status and control The first or base address generally refers to data register Second address is for status register and the third one is for control register In Windows 98 the base address is usually found to be 278H 378H or 3BCH Now if 378H is the base address then it refers to the data register whereas addresses for status and control register are respectively 379H and 37AH For Windows 98 the base address can be found as follows 1 On your Desktop right-click on My Computer and select Properties 2 Click on the Device Manager tab and find LPT1 under Plug and Play BIOS 3 After selecting LPT1 click the Properties button 4 Next select the Resources tab and the address should then appear next to InputOutput

                                                                          Range Accessing parallel port through C Language Programming There are multiple functions in C Language for accessing external ports The most commonly used are listed below

                                                                          bull unsigned char inportb(int portid) inportb reads a byte from a hardware port

                                                                          bull int inport(int portid) reads a word from a hardware port

                                                                          bull void outportb(int portid unsigned char value) outputs a byte to a hardware port

                                                                          bull void outport(int portid int value) outputs a word to a hardware port

                                                                          portid refers to the port address whereas value refers to the data to be sent TESTING 74245 USING PARALLEL PORT PC INTERFACING At one end the parallel port connector will be connected to the PC via parallel port cable and another connector (to be plugged into the PC parallel port slot) At the other end it will be connected to the buffer IC 74245 Data lines of the connector will be used to transfer 8-bit data between the PC and the buffer Out of the 8-bits of 74245 4-bits will be used to enter data which will be displayed at the monitor through a C language

                                                                          61

                                                                          Logic Design amp Switching Theory 1 Lab Session 15 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering program The remaining 4-bits will receive data from PC as entered by the user via keyboard

                                                                          Circuit Diagram

                                                                          Figure 154 Interface of 74245 to PC via Parallel Port

                                                                          Procedure

                                                                          1 Connect the DB-25 connector to the PC at one end and solder it to the circuit board at the other end

                                                                          2 Connect various pins of the connector and 74245 according to the circuit diagram shown in figure 152

                                                                          3 Using the functions listed in the previous section write a program in C language to operate various pins of the buffer The user interface of the program should provide option to the user whether to send or receive data from the port

                                                                          4 Set DIR switch to 1 5 Try sending some data bits to the port The result should be displayed at the LEDs 6 Set DIR switch to 0 7 Set some binary 4-bit value through the switches Try reading it via parallel port

                                                                          C Language Program

                                                                          A program to access parallel port for data transfers

                                                                          use header file include ltstdiohgt main program void main() define variable

                                                                          62

                                                                          Logic Design amp Switching Theory 1 Lab Session 15 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering unsigned int data=0 char choice while(1) printing option menu clrscr() printf(This program will send or receive a BCD digit from the parallel portn) printf(nPress your choice numbern) printf(n1 Send Data) printf(n2 Receive Data) printf(n3 Exitn) choice = getch() sending entered digit to the port if(choice == 1) input BCD digit printf(nEnter BCD digit to be sent to the port) data = getche() masking the first four bits data = data amp 0x0f sending to the port outportb(0x378data) printf(nThe BCD digit c has been sent to the port data) printing on screen the data received from the port else if(choice == 2) receiving data from the port data = inportb(0x378) masking the last four bits data = data amp 0xf0 shifting first four bits to make them the last four bits datagtgt=4 printf(nThe BCD digit set at the port is c data) exit else if(choice == 3) break key pressed is not in the menu else printf(nEnter valid choice number) printf(nnPress any key to continue) getch()

                                                                          63

                                                                          Logic Design amp Switching Theory 1 Lab Session 15 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                          ACTIVITY 1 In the above circuit DIR and G΄ inputs are hardwired Connect them to status or

                                                                          control pins of the parallel port connector and control their function through your software program Circuit Diagram Program Code ______________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________

                                                                          ___________________________________________________________________________________________________________________________________________________

                                                                          64

                                                                          Logic Design amp Switching Theory 1 Lab Session 15 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                          65

                                                                          _____________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ _____________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ _______________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ _________________________________________________ _________________________________________________

                                                                          Logic Design amp Switching Theory 1 Appendix A NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                          Appendix A

                                                                          PIN DIAGRAMS OF THE ICS REQUIRED FOR THE LABORATORY SESSIONS Consult the TTLIC data book for internal diagrams and electrical characteristics of these ICs 7400 Quad 2-Input NAND 7402 Quad 2-Input NOR

                                                                          7404 Hex Inverter 7408 Quad 2-Input AND

                                                                          7410 Triple 3-Input NAND 7411 Triple 3-Input AND

                                                                          7421 Dual 4-Input AND 7432 Quad 2-Input OR

                                                                          66

                                                                          Logic Design amp Switching Theory 1 Appendix A NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                          BCD-to-Seven Segm 7448 BCD-to-Seven Segment 7447 ent

                                                                          Decoder (15V OC) Decoder (2kΩ pull-up output)

                                                                          7473 Dual JK Flip-Flop 7474 Dual D-Type Flip-Flop

                                                                          7476 Dual JK Flop-Flop -Bit Binary Full Adder 7483 4 with Fast Carry

                                                                          86 Quad 2-Inpu 74138 3-to-8 Line 74 t Exclusive OR Decoder Demultiplexer

                                                                          67

                                                                          Logic Design amp Switching Theory 1 Appendix A NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                          68

                                                                          74148 8-to-3 Line 16-to-1 Line Data

                                                                          Priority Encoder 74150 Selector Multiplexer

                                                                          74245 Oct nsceivers Universal Shift Register (PIPO) (3-State)

                                                                          74194 4-Bit Bidirectional al Bus Tra

                                                                          Logic Design amp Switching Theory 1 Appendix B NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                          Appendix B

                                                                          DEBOUNCING CIRCUITRY FOR MECHANICAL SWITCHES Mechanical switches form the interface between human beings and computers or other digital systems For example a keyboard is a matrix of switches used to supply alphanumeric data to a computer Whatever the switch design it is a potential source of problems due to contact bounce The contact bounce creates a sense of narrow pulses when a switch is opened or closed An example of device whose operation would be adversely affected by contact bounce is a digital counter used to count the number of times a switch is depressed Eliminating the effects of contact bounce is called debouncing When data is entered into a computer via a keyboard a software debounce is often used This type of debouncing is a program that causes the computer to sample the switch terminal (ie to input data from it) many times in succession during the interval of time that contact bounce occurs If the data is sensed to be 1s (or 0s) for a specific number of consecutive samples then it is assumed that contact bounce has ended and the last value sensed is valid Hardware debouncing is the use of electronic circuitry to eliminate the effects of contact bounce There are numerous versions of such circuitry including those that use monostable multivibrators (one-shots) but the most straightforward is simply an RS latch Figure B1 shows the circuit When the switch is in position 1 R = 0 and S = 1 so the latch is set and the output (Q) is 1 When the switch is in position 0 R = 1and S = 0 so the latch is reset and the output is 0 When the switch is moved form one position to the other the latch changes state and bouncing occurs at either the R or the S input The bouncing does not affect the latch after it has change state An RS latch will remain set for example when its R input is 0 and its S input is alternately changed form 1 to 0

                                                                          Figure B1 Use of RS latch to debounce a mechanical switch

                                                                          69

                                                                          • 01-ldst-Outer title
                                                                            • Practical Workbook
                                                                            • Logic Design amp Switching Theory I
                                                                              • Dept of Computer amp Information Systems Engineering
                                                                                • NED University of Engineering amp Technology
                                                                                • Karachi ndash 75270 Pakistan
                                                                                  • 02-ldst-inner Title
                                                                                    • Practical Workbook
                                                                                    • Logic Design amp Switching Theory I
                                                                                      • Dept of Computer amp Information Systems Engineering
                                                                                        • NED University of Engineering amp Technology
                                                                                        • Karachi ndash 75270 Pakistan
                                                                                          • 03-ldst-general info
                                                                                          • 04-ldst-introduction
                                                                                          • 05-Table of Contents
                                                                                            • CONTENTS
                                                                                              • Lab Session No Object Page No
                                                                                              • 1
                                                                                              • Also implementing and testing the given circuit on a bread board
                                                                                                • Working with Electronics Workbench
                                                                                                  • Driving a seven segment display using 7447 7448 driver IC
                                                                                                    • Designing a modulus-5 asynchronous up-counter using JK-FF
                                                                                                      • Experimenting with 74194 4-bit bidirectional universal shift register
                                                                                                          • 13
                                                                                                              • 06-ldst-Exp01
                                                                                                                • Lab Session 01
                                                                                                                • OBJECT
                                                                                                                  • 1 Bread board
                                                                                                                  • 2 5 V - power supply
                                                                                                                  • 3 Multimeter
                                                                                                                  • 4 Logic probe
                                                                                                                  • 5 LEDs with resistors
                                                                                                                  • 6 Connecting wires
                                                                                                                  • 8 Following ICs and their datasheets
                                                                                                                    • THEORY
                                                                                                                      • Logic Gates
                                                                                                                      • 1 The AND Gate ndash An AND gatersquos output is 1 if and only if all its inputs are 1 If A and B are two inputs to an AND gate then output F of the gate is given as F = AB
                                                                                                                      • 2 The OR Gate - An OR gatersquos output is 1 if at least one of its input is 1 If A and B are two inputs to an OR gate then output F of the gate is given as F = A+B
                                                                                                                      • 3 The NOT Gate (Inverter) ndash Its output is 1 when its input is 0 and its output is 0 when the input is 1 ie it complements a digital variable If A is the input to a NOT gate then output F of the gate is given as
                                                                                                                      • 4 The NAND Gate ndash Its output is 1 if at least one of its input is 0 This gate performs the same logic as an AND gate followed by an inverter If A and B are two inputs to a NAND gate then output F of the gate is given as
                                                                                                                        • 5 The NOR Gate - The output of a NOR gate is 1 if and only if all its inputs are 0 This gate performs the same logic function as an OR gate followed by an inverter If A and B are two inputs to a NAND gate then output F of the gate is given as
                                                                                                                            • DATA SHEETS
                                                                                                                              • Logic expression for the given logic diagram __________________________________
                                                                                                                                  • 07-ldst-exp02
                                                                                                                                    • Working with Electronics Workbench
                                                                                                                                      • 08-ldst-exp03
                                                                                                                                        • Designing Half and Full Adder Circuits
                                                                                                                                          • COMPONENTS AND APPARATUS REQUIRED
                                                                                                                                            • 1 Following ICs and their Datasheets
                                                                                                                                            • 7408 Quad 2-input AND Gate
                                                                                                                                            • 2 Digital Trainer DT-01 or the following components
                                                                                                                                              • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                              • Connecting wires Switches
                                                                                                                                                • THEORY
                                                                                                                                                    • IMPLEMENTATION AND OBSERVATIONS
                                                                                                                                                      • 09-ldst-Exp04
                                                                                                                                                        • Lab Session 04
                                                                                                                                                        • 1 Digital ICs and their Datasheets
                                                                                                                                                        • 7408 Quad 2-input AND Gate
                                                                                                                                                        • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                          • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                          • Connecting wires Switches
                                                                                                                                                          • PROCEDURE
                                                                                                                                                          • REDUCTION OF LOGIC EXPRESSION USING KARNAUGH MAP
                                                                                                                                                          • OBSERVATIONS
                                                                                                                                                          • RESULT
                                                                                                                                                              • 10-ldst-Exp05
                                                                                                                                                                • Lab Session 05
                                                                                                                                                                • 1 Following ICs and their Datasheets
                                                                                                                                                                • 7408 Quad 2-input AND Gate
                                                                                                                                                                • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                  • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                  • (100 Ω) Connecting wires Switches
                                                                                                                                                                  • THEORY
                                                                                                                                                                    • IMPLEMENTATION AND OBSERVATIONS
                                                                                                                                                                      • 11-ldst-Exp06
                                                                                                                                                                        • OBJECT
                                                                                                                                                                        • 1 Following ICs and their Datasheets
                                                                                                                                                                        • 7408 Quad 2-input AND Gates or 7411 Triple 3-input AND Gates
                                                                                                                                                                        • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                          • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                          • Connecting wires Switches
                                                                                                                                                                            • Figure 62 Circuit Diagram for 4 x 1 Multiplexer
                                                                                                                                                                            • Implementation and Observations
                                                                                                                                                                              • Circuit Diagram
                                                                                                                                                                                • ACTIVITY
                                                                                                                                                                                  • 12-ldst-exp07
                                                                                                                                                                                    • 1 Following ICs and their Datasheets
                                                                                                                                                                                    • 7408 Quad 2-input or 7411 Triple 3-input AND Gates
                                                                                                                                                                                    • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                      • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                      • Connecting wires Switches
                                                                                                                                                                                        • THEORY
                                                                                                                                                                                            • Figure 72 Circuit Diagram for 2 x 4 Decoder 1 x 4 Demultiplexer
                                                                                                                                                                                            • Implementation and Observations
                                                                                                                                                                                              • Circuit Diagram
                                                                                                                                                                                                • ACTIVITY
                                                                                                                                                                                                  • 13-ldst-Exp08
                                                                                                                                                                                                    • OBJECT
                                                                                                                                                                                                    • 1 Following ICs and their Datasheets
                                                                                                                                                                                                    • 7408 Quad 2-input or 7421 Dual 4-input AND Gates
                                                                                                                                                                                                    • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                      • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                      • Connecting wires Switches
                                                                                                                                                                                                        • THEORY
                                                                                                                                                                                                            • Figure 81 Circuit Diagram for 4 x 2 Priority Encoder
                                                                                                                                                                                                            • Implementation and Observations
                                                                                                                                                                                                              • Therefore if GS A2 A1 and A0 are all low then it shows that line 0 is selected and if E0 A2 A1 and A0 are all low then it shows that none of the inputs selected E0 and GS cannot be in the same state provided that E1 is enabled
                                                                                                                                                                                                              • Circuit Diagram
                                                                                                                                                                                                                • ACTIVITY
                                                                                                                                                                                                                  • 14-ldst-exp09
                                                                                                                                                                                                                    • OBJECT
                                                                                                                                                                                                                    • 1 Following ICs and their Datasheets
                                                                                                                                                                                                                    • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                      • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                                      • Connecting wires Switches
                                                                                                                                                                                                                        • THEORY
                                                                                                                                                                                                                          • Parity Generator
                                                                                                                                                                                                                            • Let x y and z be the three bits that constitute the message and are the input to the Odd Parity Generator Circuit Since it is an odd parity system the bit P is generated so as to make the total number of 1s odd (including P) The function P can be expressed as follows
                                                                                                                                                                                                                            • Figure 91 Circuit Diagram for a 3-bit Parity Generator
                                                                                                                                                                                                                              • C = x Ο y Ο z Ο P
                                                                                                                                                                                                                                • Implementation and Observations
                                                                                                                                                                                                                                  • ACTIVITY
                                                                                                                                                                                                                                      • 15-ldst-exp10
                                                                                                                                                                                                                                        • Driving a seven segment display using 7447 7448 driver IC
                                                                                                                                                                                                                                        • COMPONENTS AND APPARATUS REQUIRED
                                                                                                                                                                                                                                        • 1 Following ICs and their Datasheets
                                                                                                                                                                                                                                        • 7447 7448 BCD to Seven Segment Driver
                                                                                                                                                                                                                                        • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                                          • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches
                                                                                                                                                                                                                                            • THEORY
                                                                                                                                                                                                                                            • Seven Segment Displays
                                                                                                                                                                                                                                            • CIRCUIT DIAGRAM
                                                                                                                                                                                                                                            • Figure 102 Circuit diagram for 7447driving a common-anode display
                                                                                                                                                                                                                                                • IMPLEMENTATION AND OBSERVATIONS
                                                                                                                                                                                                                                                  • Decimal Digit
                                                                                                                                                                                                                                                  • BCD Inputs
                                                                                                                                                                                                                                                  • Seven Segment Outputs
                                                                                                                                                                                                                                                  • D
                                                                                                                                                                                                                                                  • C
                                                                                                                                                                                                                                                  • B
                                                                                                                                                                                                                                                  • A
                                                                                                                                                                                                                                                  • a
                                                                                                                                                                                                                                                  • b
                                                                                                                                                                                                                                                  • c
                                                                                                                                                                                                                                                  • d
                                                                                                                                                                                                                                                  • e
                                                                                                                                                                                                                                                  • f
                                                                                                                                                                                                                                                  • g
                                                                                                                                                                                                                                                  • 0
                                                                                                                                                                                                                                                  • 0
                                                                                                                                                                                                                                                  • 0
                                                                                                                                                                                                                                                  • 0
                                                                                                                                                                                                                                                  • 0
                                                                                                                                                                                                                                                  • 1
                                                                                                                                                                                                                                                  • 0
                                                                                                                                                                                                                                                  • 0
                                                                                                                                                                                                                                                  • 0
                                                                                                                                                                                                                                                  • 1
                                                                                                                                                                                                                                                  • 2
                                                                                                                                                                                                                                                  • 0
                                                                                                                                                                                                                                                  • 0
                                                                                                                                                                                                                                                  • 1
                                                                                                                                                                                                                                                  • 0
                                                                                                                                                                                                                                                  • 3
                                                                                                                                                                                                                                                  • 0
                                                                                                                                                                                                                                                  • 0
                                                                                                                                                                                                                                                  • 1
                                                                                                                                                                                                                                                  • 1
                                                                                                                                                                                                                                                  • 4
                                                                                                                                                                                                                                                  • 0
                                                                                                                                                                                                                                                  • 1
                                                                                                                                                                                                                                                  • 0
                                                                                                                                                                                                                                                  • 0
                                                                                                                                                                                                                                                  • 5
                                                                                                                                                                                                                                                  • 0
                                                                                                                                                                                                                                                  • 1
                                                                                                                                                                                                                                                  • 0
                                                                                                                                                                                                                                                  • 1
                                                                                                                                                                                                                                                  • 6
                                                                                                                                                                                                                                                  • 0
                                                                                                                                                                                                                                                  • 1
                                                                                                                                                                                                                                                  • 1
                                                                                                                                                                                                                                                  • 0
                                                                                                                                                                                                                                                  • 7
                                                                                                                                                                                                                                                  • 0
                                                                                                                                                                                                                                                  • 1
                                                                                                                                                                                                                                                  • 1
                                                                                                                                                                                                                                                  • 1
                                                                                                                                                                                                                                                  • 8
                                                                                                                                                                                                                                                  • 1
                                                                                                                                                                                                                                                  • 0
                                                                                                                                                                                                                                                  • 0
                                                                                                                                                                                                                                                  • 0
                                                                                                                                                                                                                                                  • 9
                                                                                                                                                                                                                                                  • 1
                                                                                                                                                                                                                                                  • 0
                                                                                                                                                                                                                                                  • 0
                                                                                                                                                                                                                                                  • 1
                                                                                                                                                                                                                                                    • ACTIVITY
                                                                                                                                                                                                                                                      • 16-ldst-exp11
                                                                                                                                                                                                                                                        • Lab Session 11
                                                                                                                                                                                                                                                          • OBJECT
                                                                                                                                                                                                                                                          • COMPONENTS AND APPARATUS REQUIRED
                                                                                                                                                                                                                                                            • 1 Following ICs and their Datasheets
                                                                                                                                                                                                                                                            • 7473 7476 JK Flip-Flop
                                                                                                                                                                                                                                                            • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                                                              • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                                                                              • Connecting wires Switches
                                                                                                                                                                                                                                                                • THEORY
                                                                                                                                                                                                                                                                    • Flip-Flop
                                                                                                                                                                                                                                                                    • JK Flip-Flop
                                                                                                                                                                                                                                                                      • Circuit Diagram
                                                                                                                                                                                                                                                                        • Observations
                                                                                                                                                                                                                                                                          • ACTIVITY
                                                                                                                                                                                                                                                                              • 17-ldst-exp12
                                                                                                                                                                                                                                                                                • Lab Session 12
                                                                                                                                                                                                                                                                                  • OBJECT
                                                                                                                                                                                                                                                                                  • GIVEN STATE DIAGRAM
                                                                                                                                                                                                                                                                                  • Figure 121 State Diagram
                                                                                                                                                                                                                                                                                  • COMPONENTS AND APPARATUS REQUIRED
                                                                                                                                                                                                                                                                                    • 1 Following ICs and their Datasheets
                                                                                                                                                                                                                                                                                    • 7474 D Flip-Flop
                                                                                                                                                                                                                                                                                    • ICs of basic gates (AND OR NOT XOR etc) as required
                                                                                                                                                                                                                                                                                    • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                                                                                      • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                                                                                                      • Connecting wires Switches
                                                                                                                                                                                                                                                                                        • THEORY
                                                                                                                                                                                                                                                                                            • Sequential Circuits
                                                                                                                                                                                                                                                                                              • 18-ldst-exp13
                                                                                                                                                                                                                                                                                                • Lab Session 13
                                                                                                                                                                                                                                                                                                  • Designing a modulo-5 asynchronous up-counter using JK-FF
                                                                                                                                                                                                                                                                                                    • 1 Following ICs and their Datasheets
                                                                                                                                                                                                                                                                                                    • 7400 Quad 2-input or 7410 Triple 3-input NAND Gates
                                                                                                                                                                                                                                                                                                    • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                                                                                                      • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                                                                                                                      • Connecting wires Switches
                                                                                                                                                                                                                                                                                                        • THEORY
                                                                                                                                                                                                                                                                                                            • Figure 131 A Mod-5 Asynchronous Up Counter
                                                                                                                                                                                                                                                                                                            • Implementation and Observations
                                                                                                                                                                                                                                                                                                              • ACTIVITY
                                                                                                                                                                                                                                                                                                                  • 19-ldst-exp14
                                                                                                                                                                                                                                                                                                                    • Experimenting with 74194 4-bit bidirectional universal shift register
                                                                                                                                                                                                                                                                                                                    • 1 Following ICs and their Datasheets
                                                                                                                                                                                                                                                                                                                    • 74194 4-bit bidirectional universal shift register
                                                                                                                                                                                                                                                                                                                    • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                                                                                                                      • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                                                                                                                                      • Connecting wires Switches
                                                                                                                                                                                                                                                                                                                        • THEORY
                                                                                                                                                                                                                                                                                                                          • Shift Registers
                                                                                                                                                                                                                                                                                                                          • Bidirectional Shift Registers
                                                                                                                                                                                                                                                                                                                          • Universal Shift Registers
                                                                                                                                                                                                                                                                                                                            • S1
                                                                                                                                                                                                                                                                                                                              • Circuit Diagram
                                                                                                                                                                                                                                                                                                                              • ACTIVITY
                                                                                                                                                                                                                                                                                                                                  • 20-ldst-exp15
                                                                                                                                                                                                                                                                                                                                    • COMPONENTS AND APPARATUS REQUIRED
                                                                                                                                                                                                                                                                                                                                    • 1 Parallel Port Connectors (DB-25) with Cable
                                                                                                                                                                                                                                                                                                                                    • 2 Personal Computer with Windows 98 and TurboC Compiler Installed
                                                                                                                                                                                                                                                                                                                                    • 3 Following ICs and their Datasheets
                                                                                                                                                                                                                                                                                                                                    • 74245 Octal Bus Transceivers with 3-State Outputs
                                                                                                                                                                                                                                                                                                                                    • 4 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                                                                                                                                      • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                                                                                                                                                        • Connecting wires Switches
                                                                                                                                                                                                                                                                                                                                          • THEORY
                                                                                                                                                                                                                                                                                                                                          • 3-State Logic
                                                                                                                                                                                                                                                                                                                                            • Serial and Parallel Port Connectors
                                                                                                                                                                                                                                                                                                                                            • Parallel Port Connector ndash DB-25
                                                                                                                                                                                                                                                                                                                                              • Accessing parallel port through C Language Programming
                                                                                                                                                                                                                                                                                                                                                  • 21-ldst-appendixA
                                                                                                                                                                                                                                                                                                                                                  • 22-ldst-appendixB
                                                                                                                                                                                                                                                                                                                                                    • DEBOUNCING CIRCUITRY FOR MECHANICAL SWITCHES

                                                                            Logic Design amp Switching Theory 1 Lab Session 08 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                            Circuit Diagram

                                                                            Figure 82 Pin connections of 74148

                                                                            Testing Procedure bull Make connections as sho

                                                                            binations of 1s and 0s at data inputs d record your observations in the following table

                                                                            GS E0

                                                                            wn in the circuit diagram bull Apply different combull Observe the output an Observations

                                                                            0 1 2 3 4 5 6 7 A2 A1 A0 1 1 1 1 1 1 1 1 x x x x x x x 0 x x x x x x 0 1 x x x x x 0 1 1 x x x x 0 1 1 1 x x x 0 1 1 1 1 x x 0 1 1 1 1 1 x 0 1 1 1 1 1 1 0 1 1 1 1 1 1 1

                                                                            40

                                                                            Logic Design amp Switching Theory 1 Lab Session 08 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                            41

                                                                            CTIVITY

                                                                            Cascade the following two 74148 8 x 3 Priority Encoders to form 16 x 4 Priority

                                                                            A 1

                                                                            Encoder

                                                                            Logic Design amp Switching Theory 1 Lab Session 09 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering `

                                                                            Lab Session 09 OBJECT

                                                                            Designing an Odd Parity Generator and Checker for a 3-bit Data COMPONENTS AND APPARATUS REQUIRED

                                                                            1 Following ICs and their Datasheets

                                                                            bull 7486 Quad 2-input Exclusive-OR Gates bull 7404 Hex Inverter

                                                                            2 Digital Trainer DT-01 or the following components Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches

                                                                            THEORY

                                                                            Parity Generator When binary data is transmitted and processed it is ndash as are all electrical signals ndash susceptible to noise that can either alter or distort its contents 1s may be effectively changed to 0s and 0s to 1s To overcome this problem one or more bits are often added to the data as an aid in detecting errors caused by noise The most common of these is a Parity bit that signifies whether the total number of 1s in a code group is odd or even In an Odd Parity system the parity bit is made 0 or 1 as necessary to make the total number 1s odd (counting the parity bit itself) In an Even Parity system the parity bit is chosen to make the total number of 1s even Table 91 shows how parity bits would be added to BCD code group in both systems

                                                                            Decimal BCD Value Parity Bit ABCD Odd Parity Even Parity

                                                                            0 0000 1 0 1 0001 0 1 2 0010 0 1 3 0011 1 0 4 0100 0 1 5 0101 1 0 6 0110 1 0 7 0111 0 1 8 1000 0 1 9 1001 1 0

                                                                            Table 91 Odd and Even Parity in BCD

                                                                            When digital data is received a parity checking circuit generates an error signal if the total number of 1s is odd in an even parity system or if it is even in an odd parity system Parity check always detects a single error (one bit change from 0 to 1 or 1 to 0) but may not detect

                                                                            42

                                                                            Logic Design amp Switching Theory 1 Lab Session 09 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering ` two or more errors Odd parity is used more often than even parity because even parity does not detect a situation where all 0s are created due to short circuit or other fault condition DESIGN OF A 3-BIT ODD PARITY GENERATOR AND CHECKER Let x y and z be the three bits that constitute the message and are the input to the Odd Parity Generator Circuit Since it is an odd parity system the bit P is generated so as to make the total number of 1s odd (including P) The function P can be expressed as follows P = x oplus y Ο z or P = x Ο y oplus z Since the IC available is 7486 which is quad 2input XOR IC therefore we will convert XNOR also to XOR

                                                                            P = x oplus y Ο z

                                                                            P = ( x oplus y ) Ο z Since for even number of variables ______

                                                                            XOR = XNOR Therefore ___________ _________

                                                                            P = ( x oplus y ) oplus z = x oplus y oplus z This logical expression can be implemented with two XOR gates and an inverter (see figure 91)

                                                                            Figure 91 Circuit Diagram for a 3-bit Parity Generator

                                                                            The 3-bit message and the parity bit are transmitted to their destination where they are applied to a Parity Checker Circuit An error occurs during transmission if the parity of the four bits received is even since the binary information transmitted was originally odd The output C of the parity checker should be a 1 when an error occurs ie when the number of 1s in the four inputs is even Therefore the function C can be expressed as

                                                                            C = x Ο y Ο z Ο P

                                                                            Using the same logic applied for the conversion of the equation of P

                                                                            PzyxC oplusoplusoplus= This logical expression can be implemented with three XOR gates and an inverter (see figure 92)

                                                                            43

                                                                            Logic Design amp Switching Theory 1 Lab Session 09 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering `

                                                                            44

                                                                            Figure 92 Circuit Diagram for a 3-bit Parity Checker Implementation and Observations Implement the 3-bit Parity Generator and Checker circuits (figure 91 and 92) on a bread board (prepare the pin diagram (use appendix A) and refer to laboratory session 01 for implementation procedure) and record the observations in the following table

                                                                            x y z P x y z P C x y z P C 0 0 0 0 0 0 0 1 0 0 0 0 0 1 0 0 0 1 1 0 0 1 0 1 0 0 0 1 0 1 0 1 0 0 1 1 0 0 1 1 1 0 1 1 1 0 0 0 1 0 0 1 1 0 0 1 0 1 0 1 0 1 1 1 0 1 1 1 0 0 1 1 0 1 1 1 0 1 1 1 0 1 1 1 1 1 1 1

                                                                            Odd Parity Generation Odd Parity Check ACTIVITY 1 Try using the parity checker of figure 92 as 3-bit parity generator Write the details here

                                                                            _____________________________________________________________________________________________________________________________________________________________________________________________________________________ ______________________________________________________________________________________________________________________________________________ _______________________________________________________________________ ______________________________________________________________________________________________________________________________________________

                                                                            Logic Design amp Switching Theory 1 Lab Session 10 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                            Lab Session 10 OBJECT

                                                                            Driving a seven segment display using 7447 7448 driver IC COMPONENTS AND APPARATUS REQUIRED

                                                                            1 Following ICs and their Datasheets

                                                                            bull Seven Segment Displays (Common Anode Common Cathode) bull 7447 7448 BCD to Seven Segment Driver

                                                                            2 Digital Trainer DT-01 or the following components Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches

                                                                            THEORY Seven Segment Displays A Seven Segment Display consists of seven light-emitting segments The segments are designated by letters a through g (see figure 101) By illuminating various combinations of segments the numerals 0 through 9 can be displayed Seven Segment Displays are commonly constructed with light-emitting diodes (LEDs) and with liquid-crystal displays (LCDs) LEDs generally provide greater illumination levels but require much greater power than LCDs An LED display can be a common-anode type or common cathode type In common anode type a high voltage is applied at the common terminal of the display and low voltage is applied at a segmentrsquos terminal for illumination In the common-cathode type a low voltage is applied at the common terminal of the display and high voltage is applied at a segmentrsquos terminal for illumination

                                                                            Figure 101 Seven Segment Display

                                                                            a f b g

                                                                            e c d

                                                                            7447 7448 BCD to Seven Segment Driver 7447 7448 IC is particularly used to drive Seven Segment Its input is a BCD number and output drives a seven segment display 7447 is used to drive common-anode displays whereas 7448 is used to drive common cathode displays 7447 7448 is a 16 pin IC Function of various pins of these ICs is described below

                                                                            bull A B C D Inputs representing BCD digits (D being the MSB)

                                                                            45

                                                                            Logic Design amp Switching Theory 1 Lab Session 10 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering bull OA through OG Outputs to drive segments a through g of the display (Active low

                                                                            in 7447 and active high in 7448) bull RBI Ripple Blanking Input Turns off all the segments if kept low provided that LT

                                                                            is kept high and all other inputs (A B C D BI) are kept low Should be kept high otherwise

                                                                            bull BI RBO Wire-AND logic serving as a Blanking Input and or Ripple Blanking Output

                                                                            o BI Turns off all the segments if low o RBO Goes to a low level (response condition) along with other outputs when

                                                                            RBI and inputs A B C and D are low with LT input at high level bull LT Lamp Test input Tests whether all segments are working or not Illuminates all

                                                                            segments if kept low provided that BI is kept high Should be kept high otherwise bull VCC and GND Supply connections lines CIRCUIT DIAGRAM

                                                                            Figure 102 Circuit diagram for 7447driving a common-anode display

                                                                            IMPLEMENTATION AND OBSERVATIONS

                                                                            bull Make connections as shown in the circuit diagram (refer to laboratory session 01 for implementation procedure)

                                                                            bull Apply different combinations of 1s and 0s at data inputs bull Observe the output and record your observations in the following table

                                                                            46

                                                                            Logic Design amp Switching Theory 1 Lab Session 10 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                            47

                                                                            Decimal Digit

                                                                            BCD Inputs Seven Segment Outputs D C B A a b c d e f g

                                                                            0 0 0 0 0 1 0 0 0 1 2 0 0 1 0 3 0 0 1 1 4 0 1 0 0 5 0 1 0 1 6 0 1 1 0 7 0 1 1 1 8 1 0 0 0 9 1 0 0 1

                                                                            ACTIVITY 1 Perform the Lamp Test for the designed circuit and write your observations

                                                                            ____________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________

                                                                            2 How can you use 7447 IC to drive a common-cathode display

                                                                            ____________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________

                                                                            3 What symbols appear in the seven segment display if inputs DCBA are

                                                                            DCBA Symbol

                                                                            1010

                                                                            1011

                                                                            1100

                                                                            1101

                                                                            1110

                                                                            1111

                                                                            Logic Design amp Switching Theory 1 Lab Session 11 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                            48

                                                                            Lab Session 11 OBJECT

                                                                            Testing different modes of JK-FF COMPONENTS AND APPARATUS REQUIRED 1 Following ICs and their Datasheets

                                                                            bull 7473 7476 JK Flip-Flop 2 Digital Trainer DT-01 or the following components

                                                                            Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches

                                                                            THEORY

                                                                            Flip-Flop A flip-flop circuit can maintain a binary state indefinitely (as long as the power is delivered to the circuit) until directed by an input signal to switch states The major differences among various types of flip-flops are in the number of inputs they possess and in the manner in which the inputs affect the binary state

                                                                            JK Flip-Flop JK flip flop is an edge triggered device A typical JK flip flop has three inputs J K and a clock input The flip-flop can be either positive or negative edge triggered The output Q is available in complemented form as well Beside the usual inputs and output most of the flip-flop IC also possess two asynchronous inputs namely Preset and Clear These inputs are usually active low If used Preset and Clear inputs keep the flip-flop in set and reset state respectively irrespective of the other inputs Both of these inputs cannot be used simultaneously otherwise they will bring the flip-flop in unstable state

                                                                            Figure 111 Symbol for JK flip-flop

                                                                            (a) positive-edge triggering (b) active low Preset (PR) and Clear (CLR) with positive-edge triggering

                                                                            (c) active low Preset (PR) and Clear (CLR) with negative-edge triggering

                                                                            Logic Design amp Switching Theory 1 Lab Session 11 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                            49

                                                                            TESTING OF 7473 7476 DUAL JK FLIP-FLOP

                                                                            Both the ICs 7473 and 7476 are similar in functionality except for one difference The flip-flops in 7473 have only one type of active low asynchronous input which is the Clear input whereas the flip-flops in 7476 have both Preset and Clear inputs Both these ICs have negative edge triggered flip-flops

                                                                            Circuit Diagram

                                                                            Figure 112 Pin connections of 7476

                                                                            Testing Procedure

                                                                            bull Make connections as shown in the circuit diagram (figure 112) bull Apply different combinations of 1s and 0s at J and K inputs bull Observe the output and record your observations in the following table

                                                                            Observations

                                                                            J

                                                                            K Q

                                                                            0 0 0 1 1 0 1 1

                                                                            ACTIVITY

                                                                            1 Observe the output Q of JK flip-flop if the clock input is connected to VCC or GND instead of a clock source Write your observations here __________________________________________________________________________________________________________________________________________ _______________________________________________________________________________________________________________________________________________________________________________________________________________

                                                                            Logic Design amp Switching Theory 1 Lab Session 12 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                            50

                                                                            Lab Session 12 OBJECT

                                                                            Designing sequential circuit for the given state diagram using D flip-flop GIVEN STATE DIAGRAM

                                                                            00

                                                                            11

                                                                            Figure 121 State Diagram COMPONENTS AND APPARATUS REQUIRED 1 Following ICs and their Datasheets

                                                                            bull 7474 D Flip-Flop bull ICs of basic gates (AND OR NOT XOR etc) as required

                                                                            2 Digital Trainer DT-01 or the following components Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches

                                                                            THEORY

                                                                            Sequential Circuits In Sequential Circuits the output not only depends on the present inputs but also on previous states of the circuit These circuits use memory elements (latches flip-flops) and the binary information stored in the memory elements at any given time defines the state of the sequential circuit Analysis of a Sequential Circuit The behavior of a sequential circuit is determined from the inputs the outputs and the states of its flip-flops Both the outputs and next state are a function of the inputs and the

                                                                            10

                                                                            01

                                                                            00 11 10

                                                                            00

                                                                            00 11 10 00

                                                                            Logic Design amp Switching Theory 1 Lab Session 12 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                            51

                                                                            present state The analysis of a sequential circuit form a state diagram comprises of the following bull Selecting a particular flip-flop to design the circuit bull Obtaining state table from the state diagram bull Finding input equations for the selected flip-flop bull Finding state equations (not required for the construction of circuit) bull Implementing the circuit using selected flip-flops and their input equations ANALYZING THE GIVEN STATE DIAGRAM D Flip-Flop D flip-flop is also called transparent flip-flop as it simply transfers the input data to the output For our design we require the graphical symbol and excitation table of D flip-flop (see figure 122)

                                                                            Qt Qt+1 T 0 0 0 0 1 1 1 0 0 1 1 1

                                                                            (b) Excitation table of D Flip-Flop

                                                                            (a) Graphical Symbol

                                                                            Figure 122 Characteristic equation of D flip-flop is Q(t+1) = D State Table The given state diagram has four states so we will need two D flip-flops (FF-0 FF-1) Form state table form the given state diagram and record the results in the following table

                                                                            Present State Input Next State Output Input to FF-0 D0

                                                                            Input to FF-1 D1 Q1t Q0t x Q1(t+1) Q0(t+1) z

                                                                            Logic Design amp Switching Theory 1 Lab Session 12 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                            52

                                                                            Input Equations Using Karnaugh map the input equations D0 and D1 for the two flip-flops can be found

                                                                            D0 D1 Q0x

                                                                            Q1

                                                                            _ _ Q0x

                                                                            _ Q0x

                                                                            Q0x

                                                                            _ Q0x

                                                                            Q0x

                                                                            Q1

                                                                            _ _ Q0x

                                                                            _ Q0x

                                                                            Q0x

                                                                            _ Q0x

                                                                            _ Q1

                                                                            _ Q1

                                                                            Q1

                                                                            Q1

                                                                            D0 = _________________ D1 = _________________

                                                                            State Equations Using the characteristic equation of D flip-flop we can find the state equations Q0(t+1) and Q1(t+1) for the to flip flops Q0(t+1) = _______________________ Q1(t+1) = _______________________ _______________________ _______________________ _______________________ _______________________ Circuit Diagram

                                                                            Logic Design amp Switching Theory 1 Lab Session 12 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                            53

                                                                            Implementation Procedure and Observations

                                                                            1 Implement the circuit using digital ICs on a bread board (prepare the pin diagram (use appendix A) and refer to laboratory session 01 for procedure)

                                                                            2 Make the clear inputs of the flip-flops low (to clear the flip-flops) The flip-flops will remain in clear state as long as the clear inputs are connected to low level

                                                                            3 Connect output Q0 and the clock pulse to an oscilloscope 4 Apply 0 to the input x 5 Now make the clear inputs to high 6 Observe the waveform for the first 5 clock pulses and record it 7 Repeat steps 2 to 6 keeping x=1 in step 4 this time 8 Repeat steps 2 to 7 this time connecting Q1 instead of Q0 to the oscilloscope in step

                                                                            3 Record your observations (Keep frequency of the clock pulse low (eg1Hz) so that the output waveforms can be observed easily)

                                                                            1 2 3 4 5 Clock Pulse

                                                                            Output Waveform for Q0 when x=0

                                                                            Output Waveform for Q0 when x=1

                                                                            Output Waveform for Q1 when x=0

                                                                            Output Waveform for Q1 when x=1

                                                                            Logic Design amp Switching Theory 1 Lab Session 13 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                            Lab Session 13 OBJECT

                                                                            Designing a modulo-5 asynchronous up-counter using JK-FF COMPONENTS AND APPARATUS REQUIRED

                                                                            1 Following ICs and their Datasheets

                                                                            bull 7400 Quad 2-input or 7410 Triple 3-input NAND Gates bull 7476 7473 JK Flip-Flop

                                                                            2 Digital Trainer DT-01 or the following components Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches

                                                                            THEORY

                                                                            Digital Counters A digital counter is a set of flip-flops whose states change in response to pulses applied at the input to the counter The flip-flops are interconnected so that their combined state at any time is the binary equivalent of the total number of pulses that have occurred up to that time Every counter resets after a certain number of clock pulses Thus as it name implies a counter is used to count pulses An n stage counter can count up to a maximum of 2n states n is equal to the number of flip-flops required for the construction of counter

                                                                            Modulus Counters The number of input pulses that causes a counter to reset to its initial count is called the modulus of the counter Thus the modulus equals to total number of distinct states (counts) including zero that a counter can store A binary counter with n stages is a modulo-2n (or mod-2n) counter The largest count a mod-N counter can achieve is N-1 ie a mod-N counter never reaches the binary number equal to its modulus N is always equal to or less than 2n Counters can be classified as bull Synchronous Counters which are clock driven All the flip-flops are driven by a

                                                                            single clock bull Asynchronous Counters which are event driven Clock input is given to the first

                                                                            flip-flop only Rest of the flip-flops are driven by their preceding flip-flops

                                                                            DESIGN OF A MOD-5 ASYNCHRONOUS UP COUNTER The number of flip-flops required to construct a mod-5 counter is 3 because 5 should be less than or equal to 2n This counter will count from 0 to 4 a total of 5 distinct states Since a 3-stage counter can count up to 8 states at maximum a NAND gate is used to reset it after 5 clock pulses Figure 131 shows the logic diagram

                                                                            54

                                                                            Logic Design amp Switching Theory 1 Lab Session 13 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                            55

                                                                            Figure 131 A Mod-5 Asynchronous Up Counter

                                                                            Implementation and Observations

                                                                            Implement the mod-5 counter circuit (figure 131) on a bread board (prepare the pin diagram (use appendix A) and refer to laboratory session 01 for implementation procedure) and record the observations in the following table

                                                                            Clock Pulse Q2 Q1 Q0

                                                                            0 1 2 3 4 5 6 7

                                                                            ACTIVITY

                                                                            Draw the timing diagram for mod-5 counter designed in this laboratory session

                                                                            Logic Design amp Switching Theory 1 Lab Session 14 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                            Lab Session 14 OBJECT

                                                                            Experimenting with 74194 4-bit bidirectional universal shift register COMPONENTS AND APPARATUS REQUIRED

                                                                            1 Following ICs and their Datasheets

                                                                            bull 74194 4-bit bidirectional universal shift register 2 Digital Trainer DT-01 or the following components

                                                                            Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches

                                                                            THEORY

                                                                            Shift Registers

                                                                            A Register is a set of flip-flops used to store binary data A register which is capable of shifting its binary information either to the right or left is called a shift register The logical configuration of a register consists of a chain of flip-flops connected in cascade with the output of one flip-flop connected to the input of next flip-flop All flip-flops receive a common clock pulse which causes the shift from one stage to the next

                                                                            Bidirectional Shift Registers A bi-directional shift register is one whose bits can be shifted from left to right or from right to left

                                                                            Universal Shift Registers A universal shift register is a bi-directional register whose input can be in either serial or parallel form and whose output can be in either serial or parallel form

                                                                            74194 4-BIT BIDIRECTIONAL UNIVERSAL SHIFT REGISTER

                                                                            The 74194 register provides parallel as well as serial loading in both directions Function of various pins of this IC is described below

                                                                            bull A B C and D Active high inputs for parallel loading bull QA QB QC and QD Active high outputs bull S0 and S1 Active high mode control inputs The following table shows combinations

                                                                            of S1 and S0 to enable various modes

                                                                            S1 S0 Clock Action 0 0 x No change 0 1 uarr Shift right 1 0 uarr Shift left 1 1 uarr Parallel load

                                                                            uarr shows the rising edge of the clock pulse

                                                                            56

                                                                            Logic Design amp Switching Theory 1 Lab Session 14 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering bull SR Active high serial input for right shifting bull SL Active high serial input for left shifting bull CLR Active low input Clears all the flip-flops of the register if set to 0 should be

                                                                            kept high otherwise bull CLK Clock input bull VCC and GND Supply connections lines Thus A B C and D are inputs for parallel loading whereas SR and SL are inputs for serial loading with right or left shifting respectively S1 and S0 are used to select the loading mode Circuit Diagram

                                                                            Figure 141 Pin connections of 74194 Testing Procedure

                                                                            bull Make connections as shown in the circuit diagram bull Observe the output for the input combinations given in the following table

                                                                            57

                                                                            Logic Design amp Switching Theory 1 Lab Session 14 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                            58

                                                                            Observations

                                                                            S1 S0 SL SR A B C D QA QB QC QD 0 0 0 1 0 0 0 0 0 1 1 0 0 0 0 1 1 0 0 0 0 0 1 0 1 1 0 0 0 0 1 1 0 0 1 1 0 1 0 0 0 1 1 1 0 1 0 1 1 0 1 0 0 1 1 0 1 1 1 0 0 1 1 1 1 1 0 0 1 1 1 1

                                                                            ACTIVITY 1 Show connections of 74194 to convert it into a ring counter with right shifting

                                                                            Logic Design amp Switching Theory 1 Lab Session 15 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                            Lab Session 15

                                                                            OBJECT

                                                                            Experimenting with 74245 octal bus transceivers using parallel port PC interfacing COMPONENTS AND APPARATUS REQUIRED 1 Parallel Port Connectors (DB-25) with Cable 2 Personal Computer with Windows 98 and TurboC Compiler Installed 3 Following ICs and their Datasheets

                                                                            bull 74245 Octal Bus Transceivers with 3-State Outputs 4 Digital Trainer DT-01 or the following components

                                                                            Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches

                                                                            THEORY

                                                                            3-State Logic Sometimes it is necessary to isolate one part of circuit from the other part For this purpose some TTL ICs are designed with 3-state logic Such devices have three possible output states high low and high impedance The device can be put into high impedance state by a control signal applied to an appropriate pin When such a device is in high impedance state there is very high impedance at its output effectively isolating the device from whatever circuitry the output normally drives 74245 Octal Bus Transceivers A bus is any conducting path or set of paths having electrical connections to one or more devices 74245 octal bus transceivers are mainly used to control connectivity between two devices or circuits It also provides direction control for signal flow Function of various pin of this IC is given below

                                                                            bull A1 through A8 Bus A bull B1 through B8 Bus B bull G΄ Active low enable input When high sets all the bus pins to high impedance state bull DIR Direction control for signal flow When set to high logic level transfers bus A

                                                                            data to B bus When set to low logic level transfers bus B data to A bus bull VCC and GND Supply connections lines Serial and Parallel Port Connectors A Parallel Port can consist of only 25 pin port adapter called a DB-25 and a serial port can consist of either a 25 pin port adapter called a DB-25 or 9 pin adapter called a DB-9 port adapter Whether the port is a 9 pin or 25 pin it can accomplish all of the same tasks that serial port communications have been designed for

                                                                            59

                                                                            Logic Design amp Switching Theory 1 Lab Session 15 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                            60

                                                                            Each adapter can be a male type connector with pins or a female type adapter with tiny holes Generally a PRINTER port (called LPT1) on the back of a computer is female type adapter and we need to use MALE DB-25 pin cable on it for PRINTER connection or for parallel LAPLINK cable And a COM port on the back of a computer is male for the serial ports but it may not necessarily be Parallel Port Connector ndash DB-25 The DB-25 connector (named for its B-size D-shaped shell and 25 pins) is practically ubiquitous in the electronics industry The DB-25 connector is used for a variety of purposes Two common applications are RS-232EIA-232 (serial) connections and the parallel printer interface on the IBM PC The DB-25 connector is also used for SCSI connections Normally the parallel port is used for output to a printer or other device It sends data 8-bits or one byte at a time in parallel The other lines available on the DB-25 connector are a combination of status lines control lines and ground lines The status and control lines are used for handshaking commands and feedback when we are talking to a printer

                                                                            Figure 152 DB-25 Female Figure 151 DB-25 Male

                                                                            Figure 153 Pin Layout for DB-25 As can be seen form figure 153 there are four types of pins in this connector

                                                                            bull Data pins (8 pins - D0 to D7) Active high bidirectional lines

                                                                            Logic Design amp Switching Theory 1 Lab Session 15 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering bull Control pins (4 pins - C0 to C3) C0 C1 and C3 are active low whereas C2 is active

                                                                            high These lines also are bidirectional bull Status pins (5 pins ndash S3 to S7) Only S7 is active low rest are active high input lines bull Ground pins (8 pins) Used as a reference signal for the low (below 05 volts) charge

                                                                            Parallel Port Addresses A DB-25 connector at a parallel port has three address one for each kind of pins register data status and control The first or base address generally refers to data register Second address is for status register and the third one is for control register In Windows 98 the base address is usually found to be 278H 378H or 3BCH Now if 378H is the base address then it refers to the data register whereas addresses for status and control register are respectively 379H and 37AH For Windows 98 the base address can be found as follows 1 On your Desktop right-click on My Computer and select Properties 2 Click on the Device Manager tab and find LPT1 under Plug and Play BIOS 3 After selecting LPT1 click the Properties button 4 Next select the Resources tab and the address should then appear next to InputOutput

                                                                            Range Accessing parallel port through C Language Programming There are multiple functions in C Language for accessing external ports The most commonly used are listed below

                                                                            bull unsigned char inportb(int portid) inportb reads a byte from a hardware port

                                                                            bull int inport(int portid) reads a word from a hardware port

                                                                            bull void outportb(int portid unsigned char value) outputs a byte to a hardware port

                                                                            bull void outport(int portid int value) outputs a word to a hardware port

                                                                            portid refers to the port address whereas value refers to the data to be sent TESTING 74245 USING PARALLEL PORT PC INTERFACING At one end the parallel port connector will be connected to the PC via parallel port cable and another connector (to be plugged into the PC parallel port slot) At the other end it will be connected to the buffer IC 74245 Data lines of the connector will be used to transfer 8-bit data between the PC and the buffer Out of the 8-bits of 74245 4-bits will be used to enter data which will be displayed at the monitor through a C language

                                                                            61

                                                                            Logic Design amp Switching Theory 1 Lab Session 15 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering program The remaining 4-bits will receive data from PC as entered by the user via keyboard

                                                                            Circuit Diagram

                                                                            Figure 154 Interface of 74245 to PC via Parallel Port

                                                                            Procedure

                                                                            1 Connect the DB-25 connector to the PC at one end and solder it to the circuit board at the other end

                                                                            2 Connect various pins of the connector and 74245 according to the circuit diagram shown in figure 152

                                                                            3 Using the functions listed in the previous section write a program in C language to operate various pins of the buffer The user interface of the program should provide option to the user whether to send or receive data from the port

                                                                            4 Set DIR switch to 1 5 Try sending some data bits to the port The result should be displayed at the LEDs 6 Set DIR switch to 0 7 Set some binary 4-bit value through the switches Try reading it via parallel port

                                                                            C Language Program

                                                                            A program to access parallel port for data transfers

                                                                            use header file include ltstdiohgt main program void main() define variable

                                                                            62

                                                                            Logic Design amp Switching Theory 1 Lab Session 15 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering unsigned int data=0 char choice while(1) printing option menu clrscr() printf(This program will send or receive a BCD digit from the parallel portn) printf(nPress your choice numbern) printf(n1 Send Data) printf(n2 Receive Data) printf(n3 Exitn) choice = getch() sending entered digit to the port if(choice == 1) input BCD digit printf(nEnter BCD digit to be sent to the port) data = getche() masking the first four bits data = data amp 0x0f sending to the port outportb(0x378data) printf(nThe BCD digit c has been sent to the port data) printing on screen the data received from the port else if(choice == 2) receiving data from the port data = inportb(0x378) masking the last four bits data = data amp 0xf0 shifting first four bits to make them the last four bits datagtgt=4 printf(nThe BCD digit set at the port is c data) exit else if(choice == 3) break key pressed is not in the menu else printf(nEnter valid choice number) printf(nnPress any key to continue) getch()

                                                                            63

                                                                            Logic Design amp Switching Theory 1 Lab Session 15 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                            ACTIVITY 1 In the above circuit DIR and G΄ inputs are hardwired Connect them to status or

                                                                            control pins of the parallel port connector and control their function through your software program Circuit Diagram Program Code ______________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________

                                                                            ___________________________________________________________________________________________________________________________________________________

                                                                            64

                                                                            Logic Design amp Switching Theory 1 Lab Session 15 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                            65

                                                                            _____________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ _____________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ _______________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ _________________________________________________ _________________________________________________

                                                                            Logic Design amp Switching Theory 1 Appendix A NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                            Appendix A

                                                                            PIN DIAGRAMS OF THE ICS REQUIRED FOR THE LABORATORY SESSIONS Consult the TTLIC data book for internal diagrams and electrical characteristics of these ICs 7400 Quad 2-Input NAND 7402 Quad 2-Input NOR

                                                                            7404 Hex Inverter 7408 Quad 2-Input AND

                                                                            7410 Triple 3-Input NAND 7411 Triple 3-Input AND

                                                                            7421 Dual 4-Input AND 7432 Quad 2-Input OR

                                                                            66

                                                                            Logic Design amp Switching Theory 1 Appendix A NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                            BCD-to-Seven Segm 7448 BCD-to-Seven Segment 7447 ent

                                                                            Decoder (15V OC) Decoder (2kΩ pull-up output)

                                                                            7473 Dual JK Flip-Flop 7474 Dual D-Type Flip-Flop

                                                                            7476 Dual JK Flop-Flop -Bit Binary Full Adder 7483 4 with Fast Carry

                                                                            86 Quad 2-Inpu 74138 3-to-8 Line 74 t Exclusive OR Decoder Demultiplexer

                                                                            67

                                                                            Logic Design amp Switching Theory 1 Appendix A NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                            68

                                                                            74148 8-to-3 Line 16-to-1 Line Data

                                                                            Priority Encoder 74150 Selector Multiplexer

                                                                            74245 Oct nsceivers Universal Shift Register (PIPO) (3-State)

                                                                            74194 4-Bit Bidirectional al Bus Tra

                                                                            Logic Design amp Switching Theory 1 Appendix B NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                            Appendix B

                                                                            DEBOUNCING CIRCUITRY FOR MECHANICAL SWITCHES Mechanical switches form the interface between human beings and computers or other digital systems For example a keyboard is a matrix of switches used to supply alphanumeric data to a computer Whatever the switch design it is a potential source of problems due to contact bounce The contact bounce creates a sense of narrow pulses when a switch is opened or closed An example of device whose operation would be adversely affected by contact bounce is a digital counter used to count the number of times a switch is depressed Eliminating the effects of contact bounce is called debouncing When data is entered into a computer via a keyboard a software debounce is often used This type of debouncing is a program that causes the computer to sample the switch terminal (ie to input data from it) many times in succession during the interval of time that contact bounce occurs If the data is sensed to be 1s (or 0s) for a specific number of consecutive samples then it is assumed that contact bounce has ended and the last value sensed is valid Hardware debouncing is the use of electronic circuitry to eliminate the effects of contact bounce There are numerous versions of such circuitry including those that use monostable multivibrators (one-shots) but the most straightforward is simply an RS latch Figure B1 shows the circuit When the switch is in position 1 R = 0 and S = 1 so the latch is set and the output (Q) is 1 When the switch is in position 0 R = 1and S = 0 so the latch is reset and the output is 0 When the switch is moved form one position to the other the latch changes state and bouncing occurs at either the R or the S input The bouncing does not affect the latch after it has change state An RS latch will remain set for example when its R input is 0 and its S input is alternately changed form 1 to 0

                                                                            Figure B1 Use of RS latch to debounce a mechanical switch

                                                                            69

                                                                            • 01-ldst-Outer title
                                                                              • Practical Workbook
                                                                              • Logic Design amp Switching Theory I
                                                                                • Dept of Computer amp Information Systems Engineering
                                                                                  • NED University of Engineering amp Technology
                                                                                  • Karachi ndash 75270 Pakistan
                                                                                    • 02-ldst-inner Title
                                                                                      • Practical Workbook
                                                                                      • Logic Design amp Switching Theory I
                                                                                        • Dept of Computer amp Information Systems Engineering
                                                                                          • NED University of Engineering amp Technology
                                                                                          • Karachi ndash 75270 Pakistan
                                                                                            • 03-ldst-general info
                                                                                            • 04-ldst-introduction
                                                                                            • 05-Table of Contents
                                                                                              • CONTENTS
                                                                                                • Lab Session No Object Page No
                                                                                                • 1
                                                                                                • Also implementing and testing the given circuit on a bread board
                                                                                                  • Working with Electronics Workbench
                                                                                                    • Driving a seven segment display using 7447 7448 driver IC
                                                                                                      • Designing a modulus-5 asynchronous up-counter using JK-FF
                                                                                                        • Experimenting with 74194 4-bit bidirectional universal shift register
                                                                                                            • 13
                                                                                                                • 06-ldst-Exp01
                                                                                                                  • Lab Session 01
                                                                                                                  • OBJECT
                                                                                                                    • 1 Bread board
                                                                                                                    • 2 5 V - power supply
                                                                                                                    • 3 Multimeter
                                                                                                                    • 4 Logic probe
                                                                                                                    • 5 LEDs with resistors
                                                                                                                    • 6 Connecting wires
                                                                                                                    • 8 Following ICs and their datasheets
                                                                                                                      • THEORY
                                                                                                                        • Logic Gates
                                                                                                                        • 1 The AND Gate ndash An AND gatersquos output is 1 if and only if all its inputs are 1 If A and B are two inputs to an AND gate then output F of the gate is given as F = AB
                                                                                                                        • 2 The OR Gate - An OR gatersquos output is 1 if at least one of its input is 1 If A and B are two inputs to an OR gate then output F of the gate is given as F = A+B
                                                                                                                        • 3 The NOT Gate (Inverter) ndash Its output is 1 when its input is 0 and its output is 0 when the input is 1 ie it complements a digital variable If A is the input to a NOT gate then output F of the gate is given as
                                                                                                                        • 4 The NAND Gate ndash Its output is 1 if at least one of its input is 0 This gate performs the same logic as an AND gate followed by an inverter If A and B are two inputs to a NAND gate then output F of the gate is given as
                                                                                                                          • 5 The NOR Gate - The output of a NOR gate is 1 if and only if all its inputs are 0 This gate performs the same logic function as an OR gate followed by an inverter If A and B are two inputs to a NAND gate then output F of the gate is given as
                                                                                                                              • DATA SHEETS
                                                                                                                                • Logic expression for the given logic diagram __________________________________
                                                                                                                                    • 07-ldst-exp02
                                                                                                                                      • Working with Electronics Workbench
                                                                                                                                        • 08-ldst-exp03
                                                                                                                                          • Designing Half and Full Adder Circuits
                                                                                                                                            • COMPONENTS AND APPARATUS REQUIRED
                                                                                                                                              • 1 Following ICs and their Datasheets
                                                                                                                                              • 7408 Quad 2-input AND Gate
                                                                                                                                              • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                • Connecting wires Switches
                                                                                                                                                  • THEORY
                                                                                                                                                      • IMPLEMENTATION AND OBSERVATIONS
                                                                                                                                                        • 09-ldst-Exp04
                                                                                                                                                          • Lab Session 04
                                                                                                                                                          • 1 Digital ICs and their Datasheets
                                                                                                                                                          • 7408 Quad 2-input AND Gate
                                                                                                                                                          • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                            • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                            • Connecting wires Switches
                                                                                                                                                            • PROCEDURE
                                                                                                                                                            • REDUCTION OF LOGIC EXPRESSION USING KARNAUGH MAP
                                                                                                                                                            • OBSERVATIONS
                                                                                                                                                            • RESULT
                                                                                                                                                                • 10-ldst-Exp05
                                                                                                                                                                  • Lab Session 05
                                                                                                                                                                  • 1 Following ICs and their Datasheets
                                                                                                                                                                  • 7408 Quad 2-input AND Gate
                                                                                                                                                                  • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                    • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                    • (100 Ω) Connecting wires Switches
                                                                                                                                                                    • THEORY
                                                                                                                                                                      • IMPLEMENTATION AND OBSERVATIONS
                                                                                                                                                                        • 11-ldst-Exp06
                                                                                                                                                                          • OBJECT
                                                                                                                                                                          • 1 Following ICs and their Datasheets
                                                                                                                                                                          • 7408 Quad 2-input AND Gates or 7411 Triple 3-input AND Gates
                                                                                                                                                                          • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                            • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                            • Connecting wires Switches
                                                                                                                                                                              • Figure 62 Circuit Diagram for 4 x 1 Multiplexer
                                                                                                                                                                              • Implementation and Observations
                                                                                                                                                                                • Circuit Diagram
                                                                                                                                                                                  • ACTIVITY
                                                                                                                                                                                    • 12-ldst-exp07
                                                                                                                                                                                      • 1 Following ICs and their Datasheets
                                                                                                                                                                                      • 7408 Quad 2-input or 7411 Triple 3-input AND Gates
                                                                                                                                                                                      • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                        • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                        • Connecting wires Switches
                                                                                                                                                                                          • THEORY
                                                                                                                                                                                              • Figure 72 Circuit Diagram for 2 x 4 Decoder 1 x 4 Demultiplexer
                                                                                                                                                                                              • Implementation and Observations
                                                                                                                                                                                                • Circuit Diagram
                                                                                                                                                                                                  • ACTIVITY
                                                                                                                                                                                                    • 13-ldst-Exp08
                                                                                                                                                                                                      • OBJECT
                                                                                                                                                                                                      • 1 Following ICs and their Datasheets
                                                                                                                                                                                                      • 7408 Quad 2-input or 7421 Dual 4-input AND Gates
                                                                                                                                                                                                      • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                        • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                        • Connecting wires Switches
                                                                                                                                                                                                          • THEORY
                                                                                                                                                                                                              • Figure 81 Circuit Diagram for 4 x 2 Priority Encoder
                                                                                                                                                                                                              • Implementation and Observations
                                                                                                                                                                                                                • Therefore if GS A2 A1 and A0 are all low then it shows that line 0 is selected and if E0 A2 A1 and A0 are all low then it shows that none of the inputs selected E0 and GS cannot be in the same state provided that E1 is enabled
                                                                                                                                                                                                                • Circuit Diagram
                                                                                                                                                                                                                  • ACTIVITY
                                                                                                                                                                                                                    • 14-ldst-exp09
                                                                                                                                                                                                                      • OBJECT
                                                                                                                                                                                                                      • 1 Following ICs and their Datasheets
                                                                                                                                                                                                                      • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                        • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                                        • Connecting wires Switches
                                                                                                                                                                                                                          • THEORY
                                                                                                                                                                                                                            • Parity Generator
                                                                                                                                                                                                                              • Let x y and z be the three bits that constitute the message and are the input to the Odd Parity Generator Circuit Since it is an odd parity system the bit P is generated so as to make the total number of 1s odd (including P) The function P can be expressed as follows
                                                                                                                                                                                                                              • Figure 91 Circuit Diagram for a 3-bit Parity Generator
                                                                                                                                                                                                                                • C = x Ο y Ο z Ο P
                                                                                                                                                                                                                                  • Implementation and Observations
                                                                                                                                                                                                                                    • ACTIVITY
                                                                                                                                                                                                                                        • 15-ldst-exp10
                                                                                                                                                                                                                                          • Driving a seven segment display using 7447 7448 driver IC
                                                                                                                                                                                                                                          • COMPONENTS AND APPARATUS REQUIRED
                                                                                                                                                                                                                                          • 1 Following ICs and their Datasheets
                                                                                                                                                                                                                                          • 7447 7448 BCD to Seven Segment Driver
                                                                                                                                                                                                                                          • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                                            • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches
                                                                                                                                                                                                                                              • THEORY
                                                                                                                                                                                                                                              • Seven Segment Displays
                                                                                                                                                                                                                                              • CIRCUIT DIAGRAM
                                                                                                                                                                                                                                              • Figure 102 Circuit diagram for 7447driving a common-anode display
                                                                                                                                                                                                                                                  • IMPLEMENTATION AND OBSERVATIONS
                                                                                                                                                                                                                                                    • Decimal Digit
                                                                                                                                                                                                                                                    • BCD Inputs
                                                                                                                                                                                                                                                    • Seven Segment Outputs
                                                                                                                                                                                                                                                    • D
                                                                                                                                                                                                                                                    • C
                                                                                                                                                                                                                                                    • B
                                                                                                                                                                                                                                                    • A
                                                                                                                                                                                                                                                    • a
                                                                                                                                                                                                                                                    • b
                                                                                                                                                                                                                                                    • c
                                                                                                                                                                                                                                                    • d
                                                                                                                                                                                                                                                    • e
                                                                                                                                                                                                                                                    • f
                                                                                                                                                                                                                                                    • g
                                                                                                                                                                                                                                                    • 0
                                                                                                                                                                                                                                                    • 0
                                                                                                                                                                                                                                                    • 0
                                                                                                                                                                                                                                                    • 0
                                                                                                                                                                                                                                                    • 0
                                                                                                                                                                                                                                                    • 1
                                                                                                                                                                                                                                                    • 0
                                                                                                                                                                                                                                                    • 0
                                                                                                                                                                                                                                                    • 0
                                                                                                                                                                                                                                                    • 1
                                                                                                                                                                                                                                                    • 2
                                                                                                                                                                                                                                                    • 0
                                                                                                                                                                                                                                                    • 0
                                                                                                                                                                                                                                                    • 1
                                                                                                                                                                                                                                                    • 0
                                                                                                                                                                                                                                                    • 3
                                                                                                                                                                                                                                                    • 0
                                                                                                                                                                                                                                                    • 0
                                                                                                                                                                                                                                                    • 1
                                                                                                                                                                                                                                                    • 1
                                                                                                                                                                                                                                                    • 4
                                                                                                                                                                                                                                                    • 0
                                                                                                                                                                                                                                                    • 1
                                                                                                                                                                                                                                                    • 0
                                                                                                                                                                                                                                                    • 0
                                                                                                                                                                                                                                                    • 5
                                                                                                                                                                                                                                                    • 0
                                                                                                                                                                                                                                                    • 1
                                                                                                                                                                                                                                                    • 0
                                                                                                                                                                                                                                                    • 1
                                                                                                                                                                                                                                                    • 6
                                                                                                                                                                                                                                                    • 0
                                                                                                                                                                                                                                                    • 1
                                                                                                                                                                                                                                                    • 1
                                                                                                                                                                                                                                                    • 0
                                                                                                                                                                                                                                                    • 7
                                                                                                                                                                                                                                                    • 0
                                                                                                                                                                                                                                                    • 1
                                                                                                                                                                                                                                                    • 1
                                                                                                                                                                                                                                                    • 1
                                                                                                                                                                                                                                                    • 8
                                                                                                                                                                                                                                                    • 1
                                                                                                                                                                                                                                                    • 0
                                                                                                                                                                                                                                                    • 0
                                                                                                                                                                                                                                                    • 0
                                                                                                                                                                                                                                                    • 9
                                                                                                                                                                                                                                                    • 1
                                                                                                                                                                                                                                                    • 0
                                                                                                                                                                                                                                                    • 0
                                                                                                                                                                                                                                                    • 1
                                                                                                                                                                                                                                                      • ACTIVITY
                                                                                                                                                                                                                                                        • 16-ldst-exp11
                                                                                                                                                                                                                                                          • Lab Session 11
                                                                                                                                                                                                                                                            • OBJECT
                                                                                                                                                                                                                                                            • COMPONENTS AND APPARATUS REQUIRED
                                                                                                                                                                                                                                                              • 1 Following ICs and their Datasheets
                                                                                                                                                                                                                                                              • 7473 7476 JK Flip-Flop
                                                                                                                                                                                                                                                              • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                                                                • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                                                                                • Connecting wires Switches
                                                                                                                                                                                                                                                                  • THEORY
                                                                                                                                                                                                                                                                      • Flip-Flop
                                                                                                                                                                                                                                                                      • JK Flip-Flop
                                                                                                                                                                                                                                                                        • Circuit Diagram
                                                                                                                                                                                                                                                                          • Observations
                                                                                                                                                                                                                                                                            • ACTIVITY
                                                                                                                                                                                                                                                                                • 17-ldst-exp12
                                                                                                                                                                                                                                                                                  • Lab Session 12
                                                                                                                                                                                                                                                                                    • OBJECT
                                                                                                                                                                                                                                                                                    • GIVEN STATE DIAGRAM
                                                                                                                                                                                                                                                                                    • Figure 121 State Diagram
                                                                                                                                                                                                                                                                                    • COMPONENTS AND APPARATUS REQUIRED
                                                                                                                                                                                                                                                                                      • 1 Following ICs and their Datasheets
                                                                                                                                                                                                                                                                                      • 7474 D Flip-Flop
                                                                                                                                                                                                                                                                                      • ICs of basic gates (AND OR NOT XOR etc) as required
                                                                                                                                                                                                                                                                                      • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                                                                                        • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                                                                                                        • Connecting wires Switches
                                                                                                                                                                                                                                                                                          • THEORY
                                                                                                                                                                                                                                                                                              • Sequential Circuits
                                                                                                                                                                                                                                                                                                • 18-ldst-exp13
                                                                                                                                                                                                                                                                                                  • Lab Session 13
                                                                                                                                                                                                                                                                                                    • Designing a modulo-5 asynchronous up-counter using JK-FF
                                                                                                                                                                                                                                                                                                      • 1 Following ICs and their Datasheets
                                                                                                                                                                                                                                                                                                      • 7400 Quad 2-input or 7410 Triple 3-input NAND Gates
                                                                                                                                                                                                                                                                                                      • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                                                                                                        • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                                                                                                                        • Connecting wires Switches
                                                                                                                                                                                                                                                                                                          • THEORY
                                                                                                                                                                                                                                                                                                              • Figure 131 A Mod-5 Asynchronous Up Counter
                                                                                                                                                                                                                                                                                                              • Implementation and Observations
                                                                                                                                                                                                                                                                                                                • ACTIVITY
                                                                                                                                                                                                                                                                                                                    • 19-ldst-exp14
                                                                                                                                                                                                                                                                                                                      • Experimenting with 74194 4-bit bidirectional universal shift register
                                                                                                                                                                                                                                                                                                                      • 1 Following ICs and their Datasheets
                                                                                                                                                                                                                                                                                                                      • 74194 4-bit bidirectional universal shift register
                                                                                                                                                                                                                                                                                                                      • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                                                                                                                        • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                                                                                                                                        • Connecting wires Switches
                                                                                                                                                                                                                                                                                                                          • THEORY
                                                                                                                                                                                                                                                                                                                            • Shift Registers
                                                                                                                                                                                                                                                                                                                            • Bidirectional Shift Registers
                                                                                                                                                                                                                                                                                                                            • Universal Shift Registers
                                                                                                                                                                                                                                                                                                                              • S1
                                                                                                                                                                                                                                                                                                                                • Circuit Diagram
                                                                                                                                                                                                                                                                                                                                • ACTIVITY
                                                                                                                                                                                                                                                                                                                                    • 20-ldst-exp15
                                                                                                                                                                                                                                                                                                                                      • COMPONENTS AND APPARATUS REQUIRED
                                                                                                                                                                                                                                                                                                                                      • 1 Parallel Port Connectors (DB-25) with Cable
                                                                                                                                                                                                                                                                                                                                      • 2 Personal Computer with Windows 98 and TurboC Compiler Installed
                                                                                                                                                                                                                                                                                                                                      • 3 Following ICs and their Datasheets
                                                                                                                                                                                                                                                                                                                                      • 74245 Octal Bus Transceivers with 3-State Outputs
                                                                                                                                                                                                                                                                                                                                      • 4 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                                                                                                                                        • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                                                                                                                                                          • Connecting wires Switches
                                                                                                                                                                                                                                                                                                                                            • THEORY
                                                                                                                                                                                                                                                                                                                                            • 3-State Logic
                                                                                                                                                                                                                                                                                                                                              • Serial and Parallel Port Connectors
                                                                                                                                                                                                                                                                                                                                              • Parallel Port Connector ndash DB-25
                                                                                                                                                                                                                                                                                                                                                • Accessing parallel port through C Language Programming
                                                                                                                                                                                                                                                                                                                                                    • 21-ldst-appendixA
                                                                                                                                                                                                                                                                                                                                                    • 22-ldst-appendixB
                                                                                                                                                                                                                                                                                                                                                      • DEBOUNCING CIRCUITRY FOR MECHANICAL SWITCHES

                                                                              Logic Design amp Switching Theory 1 Lab Session 08 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                              41

                                                                              CTIVITY

                                                                              Cascade the following two 74148 8 x 3 Priority Encoders to form 16 x 4 Priority

                                                                              A 1

                                                                              Encoder

                                                                              Logic Design amp Switching Theory 1 Lab Session 09 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering `

                                                                              Lab Session 09 OBJECT

                                                                              Designing an Odd Parity Generator and Checker for a 3-bit Data COMPONENTS AND APPARATUS REQUIRED

                                                                              1 Following ICs and their Datasheets

                                                                              bull 7486 Quad 2-input Exclusive-OR Gates bull 7404 Hex Inverter

                                                                              2 Digital Trainer DT-01 or the following components Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches

                                                                              THEORY

                                                                              Parity Generator When binary data is transmitted and processed it is ndash as are all electrical signals ndash susceptible to noise that can either alter or distort its contents 1s may be effectively changed to 0s and 0s to 1s To overcome this problem one or more bits are often added to the data as an aid in detecting errors caused by noise The most common of these is a Parity bit that signifies whether the total number of 1s in a code group is odd or even In an Odd Parity system the parity bit is made 0 or 1 as necessary to make the total number 1s odd (counting the parity bit itself) In an Even Parity system the parity bit is chosen to make the total number of 1s even Table 91 shows how parity bits would be added to BCD code group in both systems

                                                                              Decimal BCD Value Parity Bit ABCD Odd Parity Even Parity

                                                                              0 0000 1 0 1 0001 0 1 2 0010 0 1 3 0011 1 0 4 0100 0 1 5 0101 1 0 6 0110 1 0 7 0111 0 1 8 1000 0 1 9 1001 1 0

                                                                              Table 91 Odd and Even Parity in BCD

                                                                              When digital data is received a parity checking circuit generates an error signal if the total number of 1s is odd in an even parity system or if it is even in an odd parity system Parity check always detects a single error (one bit change from 0 to 1 or 1 to 0) but may not detect

                                                                              42

                                                                              Logic Design amp Switching Theory 1 Lab Session 09 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering ` two or more errors Odd parity is used more often than even parity because even parity does not detect a situation where all 0s are created due to short circuit or other fault condition DESIGN OF A 3-BIT ODD PARITY GENERATOR AND CHECKER Let x y and z be the three bits that constitute the message and are the input to the Odd Parity Generator Circuit Since it is an odd parity system the bit P is generated so as to make the total number of 1s odd (including P) The function P can be expressed as follows P = x oplus y Ο z or P = x Ο y oplus z Since the IC available is 7486 which is quad 2input XOR IC therefore we will convert XNOR also to XOR

                                                                              P = x oplus y Ο z

                                                                              P = ( x oplus y ) Ο z Since for even number of variables ______

                                                                              XOR = XNOR Therefore ___________ _________

                                                                              P = ( x oplus y ) oplus z = x oplus y oplus z This logical expression can be implemented with two XOR gates and an inverter (see figure 91)

                                                                              Figure 91 Circuit Diagram for a 3-bit Parity Generator

                                                                              The 3-bit message and the parity bit are transmitted to their destination where they are applied to a Parity Checker Circuit An error occurs during transmission if the parity of the four bits received is even since the binary information transmitted was originally odd The output C of the parity checker should be a 1 when an error occurs ie when the number of 1s in the four inputs is even Therefore the function C can be expressed as

                                                                              C = x Ο y Ο z Ο P

                                                                              Using the same logic applied for the conversion of the equation of P

                                                                              PzyxC oplusoplusoplus= This logical expression can be implemented with three XOR gates and an inverter (see figure 92)

                                                                              43

                                                                              Logic Design amp Switching Theory 1 Lab Session 09 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering `

                                                                              44

                                                                              Figure 92 Circuit Diagram for a 3-bit Parity Checker Implementation and Observations Implement the 3-bit Parity Generator and Checker circuits (figure 91 and 92) on a bread board (prepare the pin diagram (use appendix A) and refer to laboratory session 01 for implementation procedure) and record the observations in the following table

                                                                              x y z P x y z P C x y z P C 0 0 0 0 0 0 0 1 0 0 0 0 0 1 0 0 0 1 1 0 0 1 0 1 0 0 0 1 0 1 0 1 0 0 1 1 0 0 1 1 1 0 1 1 1 0 0 0 1 0 0 1 1 0 0 1 0 1 0 1 0 1 1 1 0 1 1 1 0 0 1 1 0 1 1 1 0 1 1 1 0 1 1 1 1 1 1 1

                                                                              Odd Parity Generation Odd Parity Check ACTIVITY 1 Try using the parity checker of figure 92 as 3-bit parity generator Write the details here

                                                                              _____________________________________________________________________________________________________________________________________________________________________________________________________________________ ______________________________________________________________________________________________________________________________________________ _______________________________________________________________________ ______________________________________________________________________________________________________________________________________________

                                                                              Logic Design amp Switching Theory 1 Lab Session 10 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                              Lab Session 10 OBJECT

                                                                              Driving a seven segment display using 7447 7448 driver IC COMPONENTS AND APPARATUS REQUIRED

                                                                              1 Following ICs and their Datasheets

                                                                              bull Seven Segment Displays (Common Anode Common Cathode) bull 7447 7448 BCD to Seven Segment Driver

                                                                              2 Digital Trainer DT-01 or the following components Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches

                                                                              THEORY Seven Segment Displays A Seven Segment Display consists of seven light-emitting segments The segments are designated by letters a through g (see figure 101) By illuminating various combinations of segments the numerals 0 through 9 can be displayed Seven Segment Displays are commonly constructed with light-emitting diodes (LEDs) and with liquid-crystal displays (LCDs) LEDs generally provide greater illumination levels but require much greater power than LCDs An LED display can be a common-anode type or common cathode type In common anode type a high voltage is applied at the common terminal of the display and low voltage is applied at a segmentrsquos terminal for illumination In the common-cathode type a low voltage is applied at the common terminal of the display and high voltage is applied at a segmentrsquos terminal for illumination

                                                                              Figure 101 Seven Segment Display

                                                                              a f b g

                                                                              e c d

                                                                              7447 7448 BCD to Seven Segment Driver 7447 7448 IC is particularly used to drive Seven Segment Its input is a BCD number and output drives a seven segment display 7447 is used to drive common-anode displays whereas 7448 is used to drive common cathode displays 7447 7448 is a 16 pin IC Function of various pins of these ICs is described below

                                                                              bull A B C D Inputs representing BCD digits (D being the MSB)

                                                                              45

                                                                              Logic Design amp Switching Theory 1 Lab Session 10 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering bull OA through OG Outputs to drive segments a through g of the display (Active low

                                                                              in 7447 and active high in 7448) bull RBI Ripple Blanking Input Turns off all the segments if kept low provided that LT

                                                                              is kept high and all other inputs (A B C D BI) are kept low Should be kept high otherwise

                                                                              bull BI RBO Wire-AND logic serving as a Blanking Input and or Ripple Blanking Output

                                                                              o BI Turns off all the segments if low o RBO Goes to a low level (response condition) along with other outputs when

                                                                              RBI and inputs A B C and D are low with LT input at high level bull LT Lamp Test input Tests whether all segments are working or not Illuminates all

                                                                              segments if kept low provided that BI is kept high Should be kept high otherwise bull VCC and GND Supply connections lines CIRCUIT DIAGRAM

                                                                              Figure 102 Circuit diagram for 7447driving a common-anode display

                                                                              IMPLEMENTATION AND OBSERVATIONS

                                                                              bull Make connections as shown in the circuit diagram (refer to laboratory session 01 for implementation procedure)

                                                                              bull Apply different combinations of 1s and 0s at data inputs bull Observe the output and record your observations in the following table

                                                                              46

                                                                              Logic Design amp Switching Theory 1 Lab Session 10 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                              47

                                                                              Decimal Digit

                                                                              BCD Inputs Seven Segment Outputs D C B A a b c d e f g

                                                                              0 0 0 0 0 1 0 0 0 1 2 0 0 1 0 3 0 0 1 1 4 0 1 0 0 5 0 1 0 1 6 0 1 1 0 7 0 1 1 1 8 1 0 0 0 9 1 0 0 1

                                                                              ACTIVITY 1 Perform the Lamp Test for the designed circuit and write your observations

                                                                              ____________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________

                                                                              2 How can you use 7447 IC to drive a common-cathode display

                                                                              ____________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________

                                                                              3 What symbols appear in the seven segment display if inputs DCBA are

                                                                              DCBA Symbol

                                                                              1010

                                                                              1011

                                                                              1100

                                                                              1101

                                                                              1110

                                                                              1111

                                                                              Logic Design amp Switching Theory 1 Lab Session 11 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                              48

                                                                              Lab Session 11 OBJECT

                                                                              Testing different modes of JK-FF COMPONENTS AND APPARATUS REQUIRED 1 Following ICs and their Datasheets

                                                                              bull 7473 7476 JK Flip-Flop 2 Digital Trainer DT-01 or the following components

                                                                              Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches

                                                                              THEORY

                                                                              Flip-Flop A flip-flop circuit can maintain a binary state indefinitely (as long as the power is delivered to the circuit) until directed by an input signal to switch states The major differences among various types of flip-flops are in the number of inputs they possess and in the manner in which the inputs affect the binary state

                                                                              JK Flip-Flop JK flip flop is an edge triggered device A typical JK flip flop has three inputs J K and a clock input The flip-flop can be either positive or negative edge triggered The output Q is available in complemented form as well Beside the usual inputs and output most of the flip-flop IC also possess two asynchronous inputs namely Preset and Clear These inputs are usually active low If used Preset and Clear inputs keep the flip-flop in set and reset state respectively irrespective of the other inputs Both of these inputs cannot be used simultaneously otherwise they will bring the flip-flop in unstable state

                                                                              Figure 111 Symbol for JK flip-flop

                                                                              (a) positive-edge triggering (b) active low Preset (PR) and Clear (CLR) with positive-edge triggering

                                                                              (c) active low Preset (PR) and Clear (CLR) with negative-edge triggering

                                                                              Logic Design amp Switching Theory 1 Lab Session 11 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                              49

                                                                              TESTING OF 7473 7476 DUAL JK FLIP-FLOP

                                                                              Both the ICs 7473 and 7476 are similar in functionality except for one difference The flip-flops in 7473 have only one type of active low asynchronous input which is the Clear input whereas the flip-flops in 7476 have both Preset and Clear inputs Both these ICs have negative edge triggered flip-flops

                                                                              Circuit Diagram

                                                                              Figure 112 Pin connections of 7476

                                                                              Testing Procedure

                                                                              bull Make connections as shown in the circuit diagram (figure 112) bull Apply different combinations of 1s and 0s at J and K inputs bull Observe the output and record your observations in the following table

                                                                              Observations

                                                                              J

                                                                              K Q

                                                                              0 0 0 1 1 0 1 1

                                                                              ACTIVITY

                                                                              1 Observe the output Q of JK flip-flop if the clock input is connected to VCC or GND instead of a clock source Write your observations here __________________________________________________________________________________________________________________________________________ _______________________________________________________________________________________________________________________________________________________________________________________________________________

                                                                              Logic Design amp Switching Theory 1 Lab Session 12 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                              50

                                                                              Lab Session 12 OBJECT

                                                                              Designing sequential circuit for the given state diagram using D flip-flop GIVEN STATE DIAGRAM

                                                                              00

                                                                              11

                                                                              Figure 121 State Diagram COMPONENTS AND APPARATUS REQUIRED 1 Following ICs and their Datasheets

                                                                              bull 7474 D Flip-Flop bull ICs of basic gates (AND OR NOT XOR etc) as required

                                                                              2 Digital Trainer DT-01 or the following components Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches

                                                                              THEORY

                                                                              Sequential Circuits In Sequential Circuits the output not only depends on the present inputs but also on previous states of the circuit These circuits use memory elements (latches flip-flops) and the binary information stored in the memory elements at any given time defines the state of the sequential circuit Analysis of a Sequential Circuit The behavior of a sequential circuit is determined from the inputs the outputs and the states of its flip-flops Both the outputs and next state are a function of the inputs and the

                                                                              10

                                                                              01

                                                                              00 11 10

                                                                              00

                                                                              00 11 10 00

                                                                              Logic Design amp Switching Theory 1 Lab Session 12 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                              51

                                                                              present state The analysis of a sequential circuit form a state diagram comprises of the following bull Selecting a particular flip-flop to design the circuit bull Obtaining state table from the state diagram bull Finding input equations for the selected flip-flop bull Finding state equations (not required for the construction of circuit) bull Implementing the circuit using selected flip-flops and their input equations ANALYZING THE GIVEN STATE DIAGRAM D Flip-Flop D flip-flop is also called transparent flip-flop as it simply transfers the input data to the output For our design we require the graphical symbol and excitation table of D flip-flop (see figure 122)

                                                                              Qt Qt+1 T 0 0 0 0 1 1 1 0 0 1 1 1

                                                                              (b) Excitation table of D Flip-Flop

                                                                              (a) Graphical Symbol

                                                                              Figure 122 Characteristic equation of D flip-flop is Q(t+1) = D State Table The given state diagram has four states so we will need two D flip-flops (FF-0 FF-1) Form state table form the given state diagram and record the results in the following table

                                                                              Present State Input Next State Output Input to FF-0 D0

                                                                              Input to FF-1 D1 Q1t Q0t x Q1(t+1) Q0(t+1) z

                                                                              Logic Design amp Switching Theory 1 Lab Session 12 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                              52

                                                                              Input Equations Using Karnaugh map the input equations D0 and D1 for the two flip-flops can be found

                                                                              D0 D1 Q0x

                                                                              Q1

                                                                              _ _ Q0x

                                                                              _ Q0x

                                                                              Q0x

                                                                              _ Q0x

                                                                              Q0x

                                                                              Q1

                                                                              _ _ Q0x

                                                                              _ Q0x

                                                                              Q0x

                                                                              _ Q0x

                                                                              _ Q1

                                                                              _ Q1

                                                                              Q1

                                                                              Q1

                                                                              D0 = _________________ D1 = _________________

                                                                              State Equations Using the characteristic equation of D flip-flop we can find the state equations Q0(t+1) and Q1(t+1) for the to flip flops Q0(t+1) = _______________________ Q1(t+1) = _______________________ _______________________ _______________________ _______________________ _______________________ Circuit Diagram

                                                                              Logic Design amp Switching Theory 1 Lab Session 12 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                              53

                                                                              Implementation Procedure and Observations

                                                                              1 Implement the circuit using digital ICs on a bread board (prepare the pin diagram (use appendix A) and refer to laboratory session 01 for procedure)

                                                                              2 Make the clear inputs of the flip-flops low (to clear the flip-flops) The flip-flops will remain in clear state as long as the clear inputs are connected to low level

                                                                              3 Connect output Q0 and the clock pulse to an oscilloscope 4 Apply 0 to the input x 5 Now make the clear inputs to high 6 Observe the waveform for the first 5 clock pulses and record it 7 Repeat steps 2 to 6 keeping x=1 in step 4 this time 8 Repeat steps 2 to 7 this time connecting Q1 instead of Q0 to the oscilloscope in step

                                                                              3 Record your observations (Keep frequency of the clock pulse low (eg1Hz) so that the output waveforms can be observed easily)

                                                                              1 2 3 4 5 Clock Pulse

                                                                              Output Waveform for Q0 when x=0

                                                                              Output Waveform for Q0 when x=1

                                                                              Output Waveform for Q1 when x=0

                                                                              Output Waveform for Q1 when x=1

                                                                              Logic Design amp Switching Theory 1 Lab Session 13 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                              Lab Session 13 OBJECT

                                                                              Designing a modulo-5 asynchronous up-counter using JK-FF COMPONENTS AND APPARATUS REQUIRED

                                                                              1 Following ICs and their Datasheets

                                                                              bull 7400 Quad 2-input or 7410 Triple 3-input NAND Gates bull 7476 7473 JK Flip-Flop

                                                                              2 Digital Trainer DT-01 or the following components Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches

                                                                              THEORY

                                                                              Digital Counters A digital counter is a set of flip-flops whose states change in response to pulses applied at the input to the counter The flip-flops are interconnected so that their combined state at any time is the binary equivalent of the total number of pulses that have occurred up to that time Every counter resets after a certain number of clock pulses Thus as it name implies a counter is used to count pulses An n stage counter can count up to a maximum of 2n states n is equal to the number of flip-flops required for the construction of counter

                                                                              Modulus Counters The number of input pulses that causes a counter to reset to its initial count is called the modulus of the counter Thus the modulus equals to total number of distinct states (counts) including zero that a counter can store A binary counter with n stages is a modulo-2n (or mod-2n) counter The largest count a mod-N counter can achieve is N-1 ie a mod-N counter never reaches the binary number equal to its modulus N is always equal to or less than 2n Counters can be classified as bull Synchronous Counters which are clock driven All the flip-flops are driven by a

                                                                              single clock bull Asynchronous Counters which are event driven Clock input is given to the first

                                                                              flip-flop only Rest of the flip-flops are driven by their preceding flip-flops

                                                                              DESIGN OF A MOD-5 ASYNCHRONOUS UP COUNTER The number of flip-flops required to construct a mod-5 counter is 3 because 5 should be less than or equal to 2n This counter will count from 0 to 4 a total of 5 distinct states Since a 3-stage counter can count up to 8 states at maximum a NAND gate is used to reset it after 5 clock pulses Figure 131 shows the logic diagram

                                                                              54

                                                                              Logic Design amp Switching Theory 1 Lab Session 13 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                              55

                                                                              Figure 131 A Mod-5 Asynchronous Up Counter

                                                                              Implementation and Observations

                                                                              Implement the mod-5 counter circuit (figure 131) on a bread board (prepare the pin diagram (use appendix A) and refer to laboratory session 01 for implementation procedure) and record the observations in the following table

                                                                              Clock Pulse Q2 Q1 Q0

                                                                              0 1 2 3 4 5 6 7

                                                                              ACTIVITY

                                                                              Draw the timing diagram for mod-5 counter designed in this laboratory session

                                                                              Logic Design amp Switching Theory 1 Lab Session 14 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                              Lab Session 14 OBJECT

                                                                              Experimenting with 74194 4-bit bidirectional universal shift register COMPONENTS AND APPARATUS REQUIRED

                                                                              1 Following ICs and their Datasheets

                                                                              bull 74194 4-bit bidirectional universal shift register 2 Digital Trainer DT-01 or the following components

                                                                              Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches

                                                                              THEORY

                                                                              Shift Registers

                                                                              A Register is a set of flip-flops used to store binary data A register which is capable of shifting its binary information either to the right or left is called a shift register The logical configuration of a register consists of a chain of flip-flops connected in cascade with the output of one flip-flop connected to the input of next flip-flop All flip-flops receive a common clock pulse which causes the shift from one stage to the next

                                                                              Bidirectional Shift Registers A bi-directional shift register is one whose bits can be shifted from left to right or from right to left

                                                                              Universal Shift Registers A universal shift register is a bi-directional register whose input can be in either serial or parallel form and whose output can be in either serial or parallel form

                                                                              74194 4-BIT BIDIRECTIONAL UNIVERSAL SHIFT REGISTER

                                                                              The 74194 register provides parallel as well as serial loading in both directions Function of various pins of this IC is described below

                                                                              bull A B C and D Active high inputs for parallel loading bull QA QB QC and QD Active high outputs bull S0 and S1 Active high mode control inputs The following table shows combinations

                                                                              of S1 and S0 to enable various modes

                                                                              S1 S0 Clock Action 0 0 x No change 0 1 uarr Shift right 1 0 uarr Shift left 1 1 uarr Parallel load

                                                                              uarr shows the rising edge of the clock pulse

                                                                              56

                                                                              Logic Design amp Switching Theory 1 Lab Session 14 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering bull SR Active high serial input for right shifting bull SL Active high serial input for left shifting bull CLR Active low input Clears all the flip-flops of the register if set to 0 should be

                                                                              kept high otherwise bull CLK Clock input bull VCC and GND Supply connections lines Thus A B C and D are inputs for parallel loading whereas SR and SL are inputs for serial loading with right or left shifting respectively S1 and S0 are used to select the loading mode Circuit Diagram

                                                                              Figure 141 Pin connections of 74194 Testing Procedure

                                                                              bull Make connections as shown in the circuit diagram bull Observe the output for the input combinations given in the following table

                                                                              57

                                                                              Logic Design amp Switching Theory 1 Lab Session 14 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                              58

                                                                              Observations

                                                                              S1 S0 SL SR A B C D QA QB QC QD 0 0 0 1 0 0 0 0 0 1 1 0 0 0 0 1 1 0 0 0 0 0 1 0 1 1 0 0 0 0 1 1 0 0 1 1 0 1 0 0 0 1 1 1 0 1 0 1 1 0 1 0 0 1 1 0 1 1 1 0 0 1 1 1 1 1 0 0 1 1 1 1

                                                                              ACTIVITY 1 Show connections of 74194 to convert it into a ring counter with right shifting

                                                                              Logic Design amp Switching Theory 1 Lab Session 15 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                              Lab Session 15

                                                                              OBJECT

                                                                              Experimenting with 74245 octal bus transceivers using parallel port PC interfacing COMPONENTS AND APPARATUS REQUIRED 1 Parallel Port Connectors (DB-25) with Cable 2 Personal Computer with Windows 98 and TurboC Compiler Installed 3 Following ICs and their Datasheets

                                                                              bull 74245 Octal Bus Transceivers with 3-State Outputs 4 Digital Trainer DT-01 or the following components

                                                                              Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches

                                                                              THEORY

                                                                              3-State Logic Sometimes it is necessary to isolate one part of circuit from the other part For this purpose some TTL ICs are designed with 3-state logic Such devices have three possible output states high low and high impedance The device can be put into high impedance state by a control signal applied to an appropriate pin When such a device is in high impedance state there is very high impedance at its output effectively isolating the device from whatever circuitry the output normally drives 74245 Octal Bus Transceivers A bus is any conducting path or set of paths having electrical connections to one or more devices 74245 octal bus transceivers are mainly used to control connectivity between two devices or circuits It also provides direction control for signal flow Function of various pin of this IC is given below

                                                                              bull A1 through A8 Bus A bull B1 through B8 Bus B bull G΄ Active low enable input When high sets all the bus pins to high impedance state bull DIR Direction control for signal flow When set to high logic level transfers bus A

                                                                              data to B bus When set to low logic level transfers bus B data to A bus bull VCC and GND Supply connections lines Serial and Parallel Port Connectors A Parallel Port can consist of only 25 pin port adapter called a DB-25 and a serial port can consist of either a 25 pin port adapter called a DB-25 or 9 pin adapter called a DB-9 port adapter Whether the port is a 9 pin or 25 pin it can accomplish all of the same tasks that serial port communications have been designed for

                                                                              59

                                                                              Logic Design amp Switching Theory 1 Lab Session 15 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                              60

                                                                              Each adapter can be a male type connector with pins or a female type adapter with tiny holes Generally a PRINTER port (called LPT1) on the back of a computer is female type adapter and we need to use MALE DB-25 pin cable on it for PRINTER connection or for parallel LAPLINK cable And a COM port on the back of a computer is male for the serial ports but it may not necessarily be Parallel Port Connector ndash DB-25 The DB-25 connector (named for its B-size D-shaped shell and 25 pins) is practically ubiquitous in the electronics industry The DB-25 connector is used for a variety of purposes Two common applications are RS-232EIA-232 (serial) connections and the parallel printer interface on the IBM PC The DB-25 connector is also used for SCSI connections Normally the parallel port is used for output to a printer or other device It sends data 8-bits or one byte at a time in parallel The other lines available on the DB-25 connector are a combination of status lines control lines and ground lines The status and control lines are used for handshaking commands and feedback when we are talking to a printer

                                                                              Figure 152 DB-25 Female Figure 151 DB-25 Male

                                                                              Figure 153 Pin Layout for DB-25 As can be seen form figure 153 there are four types of pins in this connector

                                                                              bull Data pins (8 pins - D0 to D7) Active high bidirectional lines

                                                                              Logic Design amp Switching Theory 1 Lab Session 15 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering bull Control pins (4 pins - C0 to C3) C0 C1 and C3 are active low whereas C2 is active

                                                                              high These lines also are bidirectional bull Status pins (5 pins ndash S3 to S7) Only S7 is active low rest are active high input lines bull Ground pins (8 pins) Used as a reference signal for the low (below 05 volts) charge

                                                                              Parallel Port Addresses A DB-25 connector at a parallel port has three address one for each kind of pins register data status and control The first or base address generally refers to data register Second address is for status register and the third one is for control register In Windows 98 the base address is usually found to be 278H 378H or 3BCH Now if 378H is the base address then it refers to the data register whereas addresses for status and control register are respectively 379H and 37AH For Windows 98 the base address can be found as follows 1 On your Desktop right-click on My Computer and select Properties 2 Click on the Device Manager tab and find LPT1 under Plug and Play BIOS 3 After selecting LPT1 click the Properties button 4 Next select the Resources tab and the address should then appear next to InputOutput

                                                                              Range Accessing parallel port through C Language Programming There are multiple functions in C Language for accessing external ports The most commonly used are listed below

                                                                              bull unsigned char inportb(int portid) inportb reads a byte from a hardware port

                                                                              bull int inport(int portid) reads a word from a hardware port

                                                                              bull void outportb(int portid unsigned char value) outputs a byte to a hardware port

                                                                              bull void outport(int portid int value) outputs a word to a hardware port

                                                                              portid refers to the port address whereas value refers to the data to be sent TESTING 74245 USING PARALLEL PORT PC INTERFACING At one end the parallel port connector will be connected to the PC via parallel port cable and another connector (to be plugged into the PC parallel port slot) At the other end it will be connected to the buffer IC 74245 Data lines of the connector will be used to transfer 8-bit data between the PC and the buffer Out of the 8-bits of 74245 4-bits will be used to enter data which will be displayed at the monitor through a C language

                                                                              61

                                                                              Logic Design amp Switching Theory 1 Lab Session 15 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering program The remaining 4-bits will receive data from PC as entered by the user via keyboard

                                                                              Circuit Diagram

                                                                              Figure 154 Interface of 74245 to PC via Parallel Port

                                                                              Procedure

                                                                              1 Connect the DB-25 connector to the PC at one end and solder it to the circuit board at the other end

                                                                              2 Connect various pins of the connector and 74245 according to the circuit diagram shown in figure 152

                                                                              3 Using the functions listed in the previous section write a program in C language to operate various pins of the buffer The user interface of the program should provide option to the user whether to send or receive data from the port

                                                                              4 Set DIR switch to 1 5 Try sending some data bits to the port The result should be displayed at the LEDs 6 Set DIR switch to 0 7 Set some binary 4-bit value through the switches Try reading it via parallel port

                                                                              C Language Program

                                                                              A program to access parallel port for data transfers

                                                                              use header file include ltstdiohgt main program void main() define variable

                                                                              62

                                                                              Logic Design amp Switching Theory 1 Lab Session 15 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering unsigned int data=0 char choice while(1) printing option menu clrscr() printf(This program will send or receive a BCD digit from the parallel portn) printf(nPress your choice numbern) printf(n1 Send Data) printf(n2 Receive Data) printf(n3 Exitn) choice = getch() sending entered digit to the port if(choice == 1) input BCD digit printf(nEnter BCD digit to be sent to the port) data = getche() masking the first four bits data = data amp 0x0f sending to the port outportb(0x378data) printf(nThe BCD digit c has been sent to the port data) printing on screen the data received from the port else if(choice == 2) receiving data from the port data = inportb(0x378) masking the last four bits data = data amp 0xf0 shifting first four bits to make them the last four bits datagtgt=4 printf(nThe BCD digit set at the port is c data) exit else if(choice == 3) break key pressed is not in the menu else printf(nEnter valid choice number) printf(nnPress any key to continue) getch()

                                                                              63

                                                                              Logic Design amp Switching Theory 1 Lab Session 15 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                              ACTIVITY 1 In the above circuit DIR and G΄ inputs are hardwired Connect them to status or

                                                                              control pins of the parallel port connector and control their function through your software program Circuit Diagram Program Code ______________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________

                                                                              ___________________________________________________________________________________________________________________________________________________

                                                                              64

                                                                              Logic Design amp Switching Theory 1 Lab Session 15 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                              65

                                                                              _____________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ _____________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ _______________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ _________________________________________________ _________________________________________________

                                                                              Logic Design amp Switching Theory 1 Appendix A NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                              Appendix A

                                                                              PIN DIAGRAMS OF THE ICS REQUIRED FOR THE LABORATORY SESSIONS Consult the TTLIC data book for internal diagrams and electrical characteristics of these ICs 7400 Quad 2-Input NAND 7402 Quad 2-Input NOR

                                                                              7404 Hex Inverter 7408 Quad 2-Input AND

                                                                              7410 Triple 3-Input NAND 7411 Triple 3-Input AND

                                                                              7421 Dual 4-Input AND 7432 Quad 2-Input OR

                                                                              66

                                                                              Logic Design amp Switching Theory 1 Appendix A NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                              BCD-to-Seven Segm 7448 BCD-to-Seven Segment 7447 ent

                                                                              Decoder (15V OC) Decoder (2kΩ pull-up output)

                                                                              7473 Dual JK Flip-Flop 7474 Dual D-Type Flip-Flop

                                                                              7476 Dual JK Flop-Flop -Bit Binary Full Adder 7483 4 with Fast Carry

                                                                              86 Quad 2-Inpu 74138 3-to-8 Line 74 t Exclusive OR Decoder Demultiplexer

                                                                              67

                                                                              Logic Design amp Switching Theory 1 Appendix A NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                              68

                                                                              74148 8-to-3 Line 16-to-1 Line Data

                                                                              Priority Encoder 74150 Selector Multiplexer

                                                                              74245 Oct nsceivers Universal Shift Register (PIPO) (3-State)

                                                                              74194 4-Bit Bidirectional al Bus Tra

                                                                              Logic Design amp Switching Theory 1 Appendix B NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                              Appendix B

                                                                              DEBOUNCING CIRCUITRY FOR MECHANICAL SWITCHES Mechanical switches form the interface between human beings and computers or other digital systems For example a keyboard is a matrix of switches used to supply alphanumeric data to a computer Whatever the switch design it is a potential source of problems due to contact bounce The contact bounce creates a sense of narrow pulses when a switch is opened or closed An example of device whose operation would be adversely affected by contact bounce is a digital counter used to count the number of times a switch is depressed Eliminating the effects of contact bounce is called debouncing When data is entered into a computer via a keyboard a software debounce is often used This type of debouncing is a program that causes the computer to sample the switch terminal (ie to input data from it) many times in succession during the interval of time that contact bounce occurs If the data is sensed to be 1s (or 0s) for a specific number of consecutive samples then it is assumed that contact bounce has ended and the last value sensed is valid Hardware debouncing is the use of electronic circuitry to eliminate the effects of contact bounce There are numerous versions of such circuitry including those that use monostable multivibrators (one-shots) but the most straightforward is simply an RS latch Figure B1 shows the circuit When the switch is in position 1 R = 0 and S = 1 so the latch is set and the output (Q) is 1 When the switch is in position 0 R = 1and S = 0 so the latch is reset and the output is 0 When the switch is moved form one position to the other the latch changes state and bouncing occurs at either the R or the S input The bouncing does not affect the latch after it has change state An RS latch will remain set for example when its R input is 0 and its S input is alternately changed form 1 to 0

                                                                              Figure B1 Use of RS latch to debounce a mechanical switch

                                                                              69

                                                                              • 01-ldst-Outer title
                                                                                • Practical Workbook
                                                                                • Logic Design amp Switching Theory I
                                                                                  • Dept of Computer amp Information Systems Engineering
                                                                                    • NED University of Engineering amp Technology
                                                                                    • Karachi ndash 75270 Pakistan
                                                                                      • 02-ldst-inner Title
                                                                                        • Practical Workbook
                                                                                        • Logic Design amp Switching Theory I
                                                                                          • Dept of Computer amp Information Systems Engineering
                                                                                            • NED University of Engineering amp Technology
                                                                                            • Karachi ndash 75270 Pakistan
                                                                                              • 03-ldst-general info
                                                                                              • 04-ldst-introduction
                                                                                              • 05-Table of Contents
                                                                                                • CONTENTS
                                                                                                  • Lab Session No Object Page No
                                                                                                  • 1
                                                                                                  • Also implementing and testing the given circuit on a bread board
                                                                                                    • Working with Electronics Workbench
                                                                                                      • Driving a seven segment display using 7447 7448 driver IC
                                                                                                        • Designing a modulus-5 asynchronous up-counter using JK-FF
                                                                                                          • Experimenting with 74194 4-bit bidirectional universal shift register
                                                                                                              • 13
                                                                                                                  • 06-ldst-Exp01
                                                                                                                    • Lab Session 01
                                                                                                                    • OBJECT
                                                                                                                      • 1 Bread board
                                                                                                                      • 2 5 V - power supply
                                                                                                                      • 3 Multimeter
                                                                                                                      • 4 Logic probe
                                                                                                                      • 5 LEDs with resistors
                                                                                                                      • 6 Connecting wires
                                                                                                                      • 8 Following ICs and their datasheets
                                                                                                                        • THEORY
                                                                                                                          • Logic Gates
                                                                                                                          • 1 The AND Gate ndash An AND gatersquos output is 1 if and only if all its inputs are 1 If A and B are two inputs to an AND gate then output F of the gate is given as F = AB
                                                                                                                          • 2 The OR Gate - An OR gatersquos output is 1 if at least one of its input is 1 If A and B are two inputs to an OR gate then output F of the gate is given as F = A+B
                                                                                                                          • 3 The NOT Gate (Inverter) ndash Its output is 1 when its input is 0 and its output is 0 when the input is 1 ie it complements a digital variable If A is the input to a NOT gate then output F of the gate is given as
                                                                                                                          • 4 The NAND Gate ndash Its output is 1 if at least one of its input is 0 This gate performs the same logic as an AND gate followed by an inverter If A and B are two inputs to a NAND gate then output F of the gate is given as
                                                                                                                            • 5 The NOR Gate - The output of a NOR gate is 1 if and only if all its inputs are 0 This gate performs the same logic function as an OR gate followed by an inverter If A and B are two inputs to a NAND gate then output F of the gate is given as
                                                                                                                                • DATA SHEETS
                                                                                                                                  • Logic expression for the given logic diagram __________________________________
                                                                                                                                      • 07-ldst-exp02
                                                                                                                                        • Working with Electronics Workbench
                                                                                                                                          • 08-ldst-exp03
                                                                                                                                            • Designing Half and Full Adder Circuits
                                                                                                                                              • COMPONENTS AND APPARATUS REQUIRED
                                                                                                                                                • 1 Following ICs and their Datasheets
                                                                                                                                                • 7408 Quad 2-input AND Gate
                                                                                                                                                • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                  • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                  • Connecting wires Switches
                                                                                                                                                    • THEORY
                                                                                                                                                        • IMPLEMENTATION AND OBSERVATIONS
                                                                                                                                                          • 09-ldst-Exp04
                                                                                                                                                            • Lab Session 04
                                                                                                                                                            • 1 Digital ICs and their Datasheets
                                                                                                                                                            • 7408 Quad 2-input AND Gate
                                                                                                                                                            • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                              • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                              • Connecting wires Switches
                                                                                                                                                              • PROCEDURE
                                                                                                                                                              • REDUCTION OF LOGIC EXPRESSION USING KARNAUGH MAP
                                                                                                                                                              • OBSERVATIONS
                                                                                                                                                              • RESULT
                                                                                                                                                                  • 10-ldst-Exp05
                                                                                                                                                                    • Lab Session 05
                                                                                                                                                                    • 1 Following ICs and their Datasheets
                                                                                                                                                                    • 7408 Quad 2-input AND Gate
                                                                                                                                                                    • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                      • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                      • (100 Ω) Connecting wires Switches
                                                                                                                                                                      • THEORY
                                                                                                                                                                        • IMPLEMENTATION AND OBSERVATIONS
                                                                                                                                                                          • 11-ldst-Exp06
                                                                                                                                                                            • OBJECT
                                                                                                                                                                            • 1 Following ICs and their Datasheets
                                                                                                                                                                            • 7408 Quad 2-input AND Gates or 7411 Triple 3-input AND Gates
                                                                                                                                                                            • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                              • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                              • Connecting wires Switches
                                                                                                                                                                                • Figure 62 Circuit Diagram for 4 x 1 Multiplexer
                                                                                                                                                                                • Implementation and Observations
                                                                                                                                                                                  • Circuit Diagram
                                                                                                                                                                                    • ACTIVITY
                                                                                                                                                                                      • 12-ldst-exp07
                                                                                                                                                                                        • 1 Following ICs and their Datasheets
                                                                                                                                                                                        • 7408 Quad 2-input or 7411 Triple 3-input AND Gates
                                                                                                                                                                                        • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                          • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                          • Connecting wires Switches
                                                                                                                                                                                            • THEORY
                                                                                                                                                                                                • Figure 72 Circuit Diagram for 2 x 4 Decoder 1 x 4 Demultiplexer
                                                                                                                                                                                                • Implementation and Observations
                                                                                                                                                                                                  • Circuit Diagram
                                                                                                                                                                                                    • ACTIVITY
                                                                                                                                                                                                      • 13-ldst-Exp08
                                                                                                                                                                                                        • OBJECT
                                                                                                                                                                                                        • 1 Following ICs and their Datasheets
                                                                                                                                                                                                        • 7408 Quad 2-input or 7421 Dual 4-input AND Gates
                                                                                                                                                                                                        • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                          • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                          • Connecting wires Switches
                                                                                                                                                                                                            • THEORY
                                                                                                                                                                                                                • Figure 81 Circuit Diagram for 4 x 2 Priority Encoder
                                                                                                                                                                                                                • Implementation and Observations
                                                                                                                                                                                                                  • Therefore if GS A2 A1 and A0 are all low then it shows that line 0 is selected and if E0 A2 A1 and A0 are all low then it shows that none of the inputs selected E0 and GS cannot be in the same state provided that E1 is enabled
                                                                                                                                                                                                                  • Circuit Diagram
                                                                                                                                                                                                                    • ACTIVITY
                                                                                                                                                                                                                      • 14-ldst-exp09
                                                                                                                                                                                                                        • OBJECT
                                                                                                                                                                                                                        • 1 Following ICs and their Datasheets
                                                                                                                                                                                                                        • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                          • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                                          • Connecting wires Switches
                                                                                                                                                                                                                            • THEORY
                                                                                                                                                                                                                              • Parity Generator
                                                                                                                                                                                                                                • Let x y and z be the three bits that constitute the message and are the input to the Odd Parity Generator Circuit Since it is an odd parity system the bit P is generated so as to make the total number of 1s odd (including P) The function P can be expressed as follows
                                                                                                                                                                                                                                • Figure 91 Circuit Diagram for a 3-bit Parity Generator
                                                                                                                                                                                                                                  • C = x Ο y Ο z Ο P
                                                                                                                                                                                                                                    • Implementation and Observations
                                                                                                                                                                                                                                      • ACTIVITY
                                                                                                                                                                                                                                          • 15-ldst-exp10
                                                                                                                                                                                                                                            • Driving a seven segment display using 7447 7448 driver IC
                                                                                                                                                                                                                                            • COMPONENTS AND APPARATUS REQUIRED
                                                                                                                                                                                                                                            • 1 Following ICs and their Datasheets
                                                                                                                                                                                                                                            • 7447 7448 BCD to Seven Segment Driver
                                                                                                                                                                                                                                            • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                                              • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches
                                                                                                                                                                                                                                                • THEORY
                                                                                                                                                                                                                                                • Seven Segment Displays
                                                                                                                                                                                                                                                • CIRCUIT DIAGRAM
                                                                                                                                                                                                                                                • Figure 102 Circuit diagram for 7447driving a common-anode display
                                                                                                                                                                                                                                                    • IMPLEMENTATION AND OBSERVATIONS
                                                                                                                                                                                                                                                      • Decimal Digit
                                                                                                                                                                                                                                                      • BCD Inputs
                                                                                                                                                                                                                                                      • Seven Segment Outputs
                                                                                                                                                                                                                                                      • D
                                                                                                                                                                                                                                                      • C
                                                                                                                                                                                                                                                      • B
                                                                                                                                                                                                                                                      • A
                                                                                                                                                                                                                                                      • a
                                                                                                                                                                                                                                                      • b
                                                                                                                                                                                                                                                      • c
                                                                                                                                                                                                                                                      • d
                                                                                                                                                                                                                                                      • e
                                                                                                                                                                                                                                                      • f
                                                                                                                                                                                                                                                      • g
                                                                                                                                                                                                                                                      • 0
                                                                                                                                                                                                                                                      • 0
                                                                                                                                                                                                                                                      • 0
                                                                                                                                                                                                                                                      • 0
                                                                                                                                                                                                                                                      • 0
                                                                                                                                                                                                                                                      • 1
                                                                                                                                                                                                                                                      • 0
                                                                                                                                                                                                                                                      • 0
                                                                                                                                                                                                                                                      • 0
                                                                                                                                                                                                                                                      • 1
                                                                                                                                                                                                                                                      • 2
                                                                                                                                                                                                                                                      • 0
                                                                                                                                                                                                                                                      • 0
                                                                                                                                                                                                                                                      • 1
                                                                                                                                                                                                                                                      • 0
                                                                                                                                                                                                                                                      • 3
                                                                                                                                                                                                                                                      • 0
                                                                                                                                                                                                                                                      • 0
                                                                                                                                                                                                                                                      • 1
                                                                                                                                                                                                                                                      • 1
                                                                                                                                                                                                                                                      • 4
                                                                                                                                                                                                                                                      • 0
                                                                                                                                                                                                                                                      • 1
                                                                                                                                                                                                                                                      • 0
                                                                                                                                                                                                                                                      • 0
                                                                                                                                                                                                                                                      • 5
                                                                                                                                                                                                                                                      • 0
                                                                                                                                                                                                                                                      • 1
                                                                                                                                                                                                                                                      • 0
                                                                                                                                                                                                                                                      • 1
                                                                                                                                                                                                                                                      • 6
                                                                                                                                                                                                                                                      • 0
                                                                                                                                                                                                                                                      • 1
                                                                                                                                                                                                                                                      • 1
                                                                                                                                                                                                                                                      • 0
                                                                                                                                                                                                                                                      • 7
                                                                                                                                                                                                                                                      • 0
                                                                                                                                                                                                                                                      • 1
                                                                                                                                                                                                                                                      • 1
                                                                                                                                                                                                                                                      • 1
                                                                                                                                                                                                                                                      • 8
                                                                                                                                                                                                                                                      • 1
                                                                                                                                                                                                                                                      • 0
                                                                                                                                                                                                                                                      • 0
                                                                                                                                                                                                                                                      • 0
                                                                                                                                                                                                                                                      • 9
                                                                                                                                                                                                                                                      • 1
                                                                                                                                                                                                                                                      • 0
                                                                                                                                                                                                                                                      • 0
                                                                                                                                                                                                                                                      • 1
                                                                                                                                                                                                                                                        • ACTIVITY
                                                                                                                                                                                                                                                          • 16-ldst-exp11
                                                                                                                                                                                                                                                            • Lab Session 11
                                                                                                                                                                                                                                                              • OBJECT
                                                                                                                                                                                                                                                              • COMPONENTS AND APPARATUS REQUIRED
                                                                                                                                                                                                                                                                • 1 Following ICs and their Datasheets
                                                                                                                                                                                                                                                                • 7473 7476 JK Flip-Flop
                                                                                                                                                                                                                                                                • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                                                                  • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                                                                                  • Connecting wires Switches
                                                                                                                                                                                                                                                                    • THEORY
                                                                                                                                                                                                                                                                        • Flip-Flop
                                                                                                                                                                                                                                                                        • JK Flip-Flop
                                                                                                                                                                                                                                                                          • Circuit Diagram
                                                                                                                                                                                                                                                                            • Observations
                                                                                                                                                                                                                                                                              • ACTIVITY
                                                                                                                                                                                                                                                                                  • 17-ldst-exp12
                                                                                                                                                                                                                                                                                    • Lab Session 12
                                                                                                                                                                                                                                                                                      • OBJECT
                                                                                                                                                                                                                                                                                      • GIVEN STATE DIAGRAM
                                                                                                                                                                                                                                                                                      • Figure 121 State Diagram
                                                                                                                                                                                                                                                                                      • COMPONENTS AND APPARATUS REQUIRED
                                                                                                                                                                                                                                                                                        • 1 Following ICs and their Datasheets
                                                                                                                                                                                                                                                                                        • 7474 D Flip-Flop
                                                                                                                                                                                                                                                                                        • ICs of basic gates (AND OR NOT XOR etc) as required
                                                                                                                                                                                                                                                                                        • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                                                                                          • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                                                                                                          • Connecting wires Switches
                                                                                                                                                                                                                                                                                            • THEORY
                                                                                                                                                                                                                                                                                                • Sequential Circuits
                                                                                                                                                                                                                                                                                                  • 18-ldst-exp13
                                                                                                                                                                                                                                                                                                    • Lab Session 13
                                                                                                                                                                                                                                                                                                      • Designing a modulo-5 asynchronous up-counter using JK-FF
                                                                                                                                                                                                                                                                                                        • 1 Following ICs and their Datasheets
                                                                                                                                                                                                                                                                                                        • 7400 Quad 2-input or 7410 Triple 3-input NAND Gates
                                                                                                                                                                                                                                                                                                        • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                                                                                                          • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                                                                                                                          • Connecting wires Switches
                                                                                                                                                                                                                                                                                                            • THEORY
                                                                                                                                                                                                                                                                                                                • Figure 131 A Mod-5 Asynchronous Up Counter
                                                                                                                                                                                                                                                                                                                • Implementation and Observations
                                                                                                                                                                                                                                                                                                                  • ACTIVITY
                                                                                                                                                                                                                                                                                                                      • 19-ldst-exp14
                                                                                                                                                                                                                                                                                                                        • Experimenting with 74194 4-bit bidirectional universal shift register
                                                                                                                                                                                                                                                                                                                        • 1 Following ICs and their Datasheets
                                                                                                                                                                                                                                                                                                                        • 74194 4-bit bidirectional universal shift register
                                                                                                                                                                                                                                                                                                                        • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                                                                                                                          • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                                                                                                                                          • Connecting wires Switches
                                                                                                                                                                                                                                                                                                                            • THEORY
                                                                                                                                                                                                                                                                                                                              • Shift Registers
                                                                                                                                                                                                                                                                                                                              • Bidirectional Shift Registers
                                                                                                                                                                                                                                                                                                                              • Universal Shift Registers
                                                                                                                                                                                                                                                                                                                                • S1
                                                                                                                                                                                                                                                                                                                                  • Circuit Diagram
                                                                                                                                                                                                                                                                                                                                  • ACTIVITY
                                                                                                                                                                                                                                                                                                                                      • 20-ldst-exp15
                                                                                                                                                                                                                                                                                                                                        • COMPONENTS AND APPARATUS REQUIRED
                                                                                                                                                                                                                                                                                                                                        • 1 Parallel Port Connectors (DB-25) with Cable
                                                                                                                                                                                                                                                                                                                                        • 2 Personal Computer with Windows 98 and TurboC Compiler Installed
                                                                                                                                                                                                                                                                                                                                        • 3 Following ICs and their Datasheets
                                                                                                                                                                                                                                                                                                                                        • 74245 Octal Bus Transceivers with 3-State Outputs
                                                                                                                                                                                                                                                                                                                                        • 4 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                                                                                                                                          • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                                                                                                                                                            • Connecting wires Switches
                                                                                                                                                                                                                                                                                                                                              • THEORY
                                                                                                                                                                                                                                                                                                                                              • 3-State Logic
                                                                                                                                                                                                                                                                                                                                                • Serial and Parallel Port Connectors
                                                                                                                                                                                                                                                                                                                                                • Parallel Port Connector ndash DB-25
                                                                                                                                                                                                                                                                                                                                                  • Accessing parallel port through C Language Programming
                                                                                                                                                                                                                                                                                                                                                      • 21-ldst-appendixA
                                                                                                                                                                                                                                                                                                                                                      • 22-ldst-appendixB
                                                                                                                                                                                                                                                                                                                                                        • DEBOUNCING CIRCUITRY FOR MECHANICAL SWITCHES

                                                                                Logic Design amp Switching Theory 1 Lab Session 09 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering `

                                                                                Lab Session 09 OBJECT

                                                                                Designing an Odd Parity Generator and Checker for a 3-bit Data COMPONENTS AND APPARATUS REQUIRED

                                                                                1 Following ICs and their Datasheets

                                                                                bull 7486 Quad 2-input Exclusive-OR Gates bull 7404 Hex Inverter

                                                                                2 Digital Trainer DT-01 or the following components Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches

                                                                                THEORY

                                                                                Parity Generator When binary data is transmitted and processed it is ndash as are all electrical signals ndash susceptible to noise that can either alter or distort its contents 1s may be effectively changed to 0s and 0s to 1s To overcome this problem one or more bits are often added to the data as an aid in detecting errors caused by noise The most common of these is a Parity bit that signifies whether the total number of 1s in a code group is odd or even In an Odd Parity system the parity bit is made 0 or 1 as necessary to make the total number 1s odd (counting the parity bit itself) In an Even Parity system the parity bit is chosen to make the total number of 1s even Table 91 shows how parity bits would be added to BCD code group in both systems

                                                                                Decimal BCD Value Parity Bit ABCD Odd Parity Even Parity

                                                                                0 0000 1 0 1 0001 0 1 2 0010 0 1 3 0011 1 0 4 0100 0 1 5 0101 1 0 6 0110 1 0 7 0111 0 1 8 1000 0 1 9 1001 1 0

                                                                                Table 91 Odd and Even Parity in BCD

                                                                                When digital data is received a parity checking circuit generates an error signal if the total number of 1s is odd in an even parity system or if it is even in an odd parity system Parity check always detects a single error (one bit change from 0 to 1 or 1 to 0) but may not detect

                                                                                42

                                                                                Logic Design amp Switching Theory 1 Lab Session 09 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering ` two or more errors Odd parity is used more often than even parity because even parity does not detect a situation where all 0s are created due to short circuit or other fault condition DESIGN OF A 3-BIT ODD PARITY GENERATOR AND CHECKER Let x y and z be the three bits that constitute the message and are the input to the Odd Parity Generator Circuit Since it is an odd parity system the bit P is generated so as to make the total number of 1s odd (including P) The function P can be expressed as follows P = x oplus y Ο z or P = x Ο y oplus z Since the IC available is 7486 which is quad 2input XOR IC therefore we will convert XNOR also to XOR

                                                                                P = x oplus y Ο z

                                                                                P = ( x oplus y ) Ο z Since for even number of variables ______

                                                                                XOR = XNOR Therefore ___________ _________

                                                                                P = ( x oplus y ) oplus z = x oplus y oplus z This logical expression can be implemented with two XOR gates and an inverter (see figure 91)

                                                                                Figure 91 Circuit Diagram for a 3-bit Parity Generator

                                                                                The 3-bit message and the parity bit are transmitted to their destination where they are applied to a Parity Checker Circuit An error occurs during transmission if the parity of the four bits received is even since the binary information transmitted was originally odd The output C of the parity checker should be a 1 when an error occurs ie when the number of 1s in the four inputs is even Therefore the function C can be expressed as

                                                                                C = x Ο y Ο z Ο P

                                                                                Using the same logic applied for the conversion of the equation of P

                                                                                PzyxC oplusoplusoplus= This logical expression can be implemented with three XOR gates and an inverter (see figure 92)

                                                                                43

                                                                                Logic Design amp Switching Theory 1 Lab Session 09 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering `

                                                                                44

                                                                                Figure 92 Circuit Diagram for a 3-bit Parity Checker Implementation and Observations Implement the 3-bit Parity Generator and Checker circuits (figure 91 and 92) on a bread board (prepare the pin diagram (use appendix A) and refer to laboratory session 01 for implementation procedure) and record the observations in the following table

                                                                                x y z P x y z P C x y z P C 0 0 0 0 0 0 0 1 0 0 0 0 0 1 0 0 0 1 1 0 0 1 0 1 0 0 0 1 0 1 0 1 0 0 1 1 0 0 1 1 1 0 1 1 1 0 0 0 1 0 0 1 1 0 0 1 0 1 0 1 0 1 1 1 0 1 1 1 0 0 1 1 0 1 1 1 0 1 1 1 0 1 1 1 1 1 1 1

                                                                                Odd Parity Generation Odd Parity Check ACTIVITY 1 Try using the parity checker of figure 92 as 3-bit parity generator Write the details here

                                                                                _____________________________________________________________________________________________________________________________________________________________________________________________________________________ ______________________________________________________________________________________________________________________________________________ _______________________________________________________________________ ______________________________________________________________________________________________________________________________________________

                                                                                Logic Design amp Switching Theory 1 Lab Session 10 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                                Lab Session 10 OBJECT

                                                                                Driving a seven segment display using 7447 7448 driver IC COMPONENTS AND APPARATUS REQUIRED

                                                                                1 Following ICs and their Datasheets

                                                                                bull Seven Segment Displays (Common Anode Common Cathode) bull 7447 7448 BCD to Seven Segment Driver

                                                                                2 Digital Trainer DT-01 or the following components Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches

                                                                                THEORY Seven Segment Displays A Seven Segment Display consists of seven light-emitting segments The segments are designated by letters a through g (see figure 101) By illuminating various combinations of segments the numerals 0 through 9 can be displayed Seven Segment Displays are commonly constructed with light-emitting diodes (LEDs) and with liquid-crystal displays (LCDs) LEDs generally provide greater illumination levels but require much greater power than LCDs An LED display can be a common-anode type or common cathode type In common anode type a high voltage is applied at the common terminal of the display and low voltage is applied at a segmentrsquos terminal for illumination In the common-cathode type a low voltage is applied at the common terminal of the display and high voltage is applied at a segmentrsquos terminal for illumination

                                                                                Figure 101 Seven Segment Display

                                                                                a f b g

                                                                                e c d

                                                                                7447 7448 BCD to Seven Segment Driver 7447 7448 IC is particularly used to drive Seven Segment Its input is a BCD number and output drives a seven segment display 7447 is used to drive common-anode displays whereas 7448 is used to drive common cathode displays 7447 7448 is a 16 pin IC Function of various pins of these ICs is described below

                                                                                bull A B C D Inputs representing BCD digits (D being the MSB)

                                                                                45

                                                                                Logic Design amp Switching Theory 1 Lab Session 10 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering bull OA through OG Outputs to drive segments a through g of the display (Active low

                                                                                in 7447 and active high in 7448) bull RBI Ripple Blanking Input Turns off all the segments if kept low provided that LT

                                                                                is kept high and all other inputs (A B C D BI) are kept low Should be kept high otherwise

                                                                                bull BI RBO Wire-AND logic serving as a Blanking Input and or Ripple Blanking Output

                                                                                o BI Turns off all the segments if low o RBO Goes to a low level (response condition) along with other outputs when

                                                                                RBI and inputs A B C and D are low with LT input at high level bull LT Lamp Test input Tests whether all segments are working or not Illuminates all

                                                                                segments if kept low provided that BI is kept high Should be kept high otherwise bull VCC and GND Supply connections lines CIRCUIT DIAGRAM

                                                                                Figure 102 Circuit diagram for 7447driving a common-anode display

                                                                                IMPLEMENTATION AND OBSERVATIONS

                                                                                bull Make connections as shown in the circuit diagram (refer to laboratory session 01 for implementation procedure)

                                                                                bull Apply different combinations of 1s and 0s at data inputs bull Observe the output and record your observations in the following table

                                                                                46

                                                                                Logic Design amp Switching Theory 1 Lab Session 10 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                                47

                                                                                Decimal Digit

                                                                                BCD Inputs Seven Segment Outputs D C B A a b c d e f g

                                                                                0 0 0 0 0 1 0 0 0 1 2 0 0 1 0 3 0 0 1 1 4 0 1 0 0 5 0 1 0 1 6 0 1 1 0 7 0 1 1 1 8 1 0 0 0 9 1 0 0 1

                                                                                ACTIVITY 1 Perform the Lamp Test for the designed circuit and write your observations

                                                                                ____________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________

                                                                                2 How can you use 7447 IC to drive a common-cathode display

                                                                                ____________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________

                                                                                3 What symbols appear in the seven segment display if inputs DCBA are

                                                                                DCBA Symbol

                                                                                1010

                                                                                1011

                                                                                1100

                                                                                1101

                                                                                1110

                                                                                1111

                                                                                Logic Design amp Switching Theory 1 Lab Session 11 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                                48

                                                                                Lab Session 11 OBJECT

                                                                                Testing different modes of JK-FF COMPONENTS AND APPARATUS REQUIRED 1 Following ICs and their Datasheets

                                                                                bull 7473 7476 JK Flip-Flop 2 Digital Trainer DT-01 or the following components

                                                                                Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches

                                                                                THEORY

                                                                                Flip-Flop A flip-flop circuit can maintain a binary state indefinitely (as long as the power is delivered to the circuit) until directed by an input signal to switch states The major differences among various types of flip-flops are in the number of inputs they possess and in the manner in which the inputs affect the binary state

                                                                                JK Flip-Flop JK flip flop is an edge triggered device A typical JK flip flop has three inputs J K and a clock input The flip-flop can be either positive or negative edge triggered The output Q is available in complemented form as well Beside the usual inputs and output most of the flip-flop IC also possess two asynchronous inputs namely Preset and Clear These inputs are usually active low If used Preset and Clear inputs keep the flip-flop in set and reset state respectively irrespective of the other inputs Both of these inputs cannot be used simultaneously otherwise they will bring the flip-flop in unstable state

                                                                                Figure 111 Symbol for JK flip-flop

                                                                                (a) positive-edge triggering (b) active low Preset (PR) and Clear (CLR) with positive-edge triggering

                                                                                (c) active low Preset (PR) and Clear (CLR) with negative-edge triggering

                                                                                Logic Design amp Switching Theory 1 Lab Session 11 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                                49

                                                                                TESTING OF 7473 7476 DUAL JK FLIP-FLOP

                                                                                Both the ICs 7473 and 7476 are similar in functionality except for one difference The flip-flops in 7473 have only one type of active low asynchronous input which is the Clear input whereas the flip-flops in 7476 have both Preset and Clear inputs Both these ICs have negative edge triggered flip-flops

                                                                                Circuit Diagram

                                                                                Figure 112 Pin connections of 7476

                                                                                Testing Procedure

                                                                                bull Make connections as shown in the circuit diagram (figure 112) bull Apply different combinations of 1s and 0s at J and K inputs bull Observe the output and record your observations in the following table

                                                                                Observations

                                                                                J

                                                                                K Q

                                                                                0 0 0 1 1 0 1 1

                                                                                ACTIVITY

                                                                                1 Observe the output Q of JK flip-flop if the clock input is connected to VCC or GND instead of a clock source Write your observations here __________________________________________________________________________________________________________________________________________ _______________________________________________________________________________________________________________________________________________________________________________________________________________

                                                                                Logic Design amp Switching Theory 1 Lab Session 12 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                                50

                                                                                Lab Session 12 OBJECT

                                                                                Designing sequential circuit for the given state diagram using D flip-flop GIVEN STATE DIAGRAM

                                                                                00

                                                                                11

                                                                                Figure 121 State Diagram COMPONENTS AND APPARATUS REQUIRED 1 Following ICs and their Datasheets

                                                                                bull 7474 D Flip-Flop bull ICs of basic gates (AND OR NOT XOR etc) as required

                                                                                2 Digital Trainer DT-01 or the following components Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches

                                                                                THEORY

                                                                                Sequential Circuits In Sequential Circuits the output not only depends on the present inputs but also on previous states of the circuit These circuits use memory elements (latches flip-flops) and the binary information stored in the memory elements at any given time defines the state of the sequential circuit Analysis of a Sequential Circuit The behavior of a sequential circuit is determined from the inputs the outputs and the states of its flip-flops Both the outputs and next state are a function of the inputs and the

                                                                                10

                                                                                01

                                                                                00 11 10

                                                                                00

                                                                                00 11 10 00

                                                                                Logic Design amp Switching Theory 1 Lab Session 12 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                                51

                                                                                present state The analysis of a sequential circuit form a state diagram comprises of the following bull Selecting a particular flip-flop to design the circuit bull Obtaining state table from the state diagram bull Finding input equations for the selected flip-flop bull Finding state equations (not required for the construction of circuit) bull Implementing the circuit using selected flip-flops and their input equations ANALYZING THE GIVEN STATE DIAGRAM D Flip-Flop D flip-flop is also called transparent flip-flop as it simply transfers the input data to the output For our design we require the graphical symbol and excitation table of D flip-flop (see figure 122)

                                                                                Qt Qt+1 T 0 0 0 0 1 1 1 0 0 1 1 1

                                                                                (b) Excitation table of D Flip-Flop

                                                                                (a) Graphical Symbol

                                                                                Figure 122 Characteristic equation of D flip-flop is Q(t+1) = D State Table The given state diagram has four states so we will need two D flip-flops (FF-0 FF-1) Form state table form the given state diagram and record the results in the following table

                                                                                Present State Input Next State Output Input to FF-0 D0

                                                                                Input to FF-1 D1 Q1t Q0t x Q1(t+1) Q0(t+1) z

                                                                                Logic Design amp Switching Theory 1 Lab Session 12 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                                52

                                                                                Input Equations Using Karnaugh map the input equations D0 and D1 for the two flip-flops can be found

                                                                                D0 D1 Q0x

                                                                                Q1

                                                                                _ _ Q0x

                                                                                _ Q0x

                                                                                Q0x

                                                                                _ Q0x

                                                                                Q0x

                                                                                Q1

                                                                                _ _ Q0x

                                                                                _ Q0x

                                                                                Q0x

                                                                                _ Q0x

                                                                                _ Q1

                                                                                _ Q1

                                                                                Q1

                                                                                Q1

                                                                                D0 = _________________ D1 = _________________

                                                                                State Equations Using the characteristic equation of D flip-flop we can find the state equations Q0(t+1) and Q1(t+1) for the to flip flops Q0(t+1) = _______________________ Q1(t+1) = _______________________ _______________________ _______________________ _______________________ _______________________ Circuit Diagram

                                                                                Logic Design amp Switching Theory 1 Lab Session 12 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                                53

                                                                                Implementation Procedure and Observations

                                                                                1 Implement the circuit using digital ICs on a bread board (prepare the pin diagram (use appendix A) and refer to laboratory session 01 for procedure)

                                                                                2 Make the clear inputs of the flip-flops low (to clear the flip-flops) The flip-flops will remain in clear state as long as the clear inputs are connected to low level

                                                                                3 Connect output Q0 and the clock pulse to an oscilloscope 4 Apply 0 to the input x 5 Now make the clear inputs to high 6 Observe the waveform for the first 5 clock pulses and record it 7 Repeat steps 2 to 6 keeping x=1 in step 4 this time 8 Repeat steps 2 to 7 this time connecting Q1 instead of Q0 to the oscilloscope in step

                                                                                3 Record your observations (Keep frequency of the clock pulse low (eg1Hz) so that the output waveforms can be observed easily)

                                                                                1 2 3 4 5 Clock Pulse

                                                                                Output Waveform for Q0 when x=0

                                                                                Output Waveform for Q0 when x=1

                                                                                Output Waveform for Q1 when x=0

                                                                                Output Waveform for Q1 when x=1

                                                                                Logic Design amp Switching Theory 1 Lab Session 13 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                                Lab Session 13 OBJECT

                                                                                Designing a modulo-5 asynchronous up-counter using JK-FF COMPONENTS AND APPARATUS REQUIRED

                                                                                1 Following ICs and their Datasheets

                                                                                bull 7400 Quad 2-input or 7410 Triple 3-input NAND Gates bull 7476 7473 JK Flip-Flop

                                                                                2 Digital Trainer DT-01 or the following components Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches

                                                                                THEORY

                                                                                Digital Counters A digital counter is a set of flip-flops whose states change in response to pulses applied at the input to the counter The flip-flops are interconnected so that their combined state at any time is the binary equivalent of the total number of pulses that have occurred up to that time Every counter resets after a certain number of clock pulses Thus as it name implies a counter is used to count pulses An n stage counter can count up to a maximum of 2n states n is equal to the number of flip-flops required for the construction of counter

                                                                                Modulus Counters The number of input pulses that causes a counter to reset to its initial count is called the modulus of the counter Thus the modulus equals to total number of distinct states (counts) including zero that a counter can store A binary counter with n stages is a modulo-2n (or mod-2n) counter The largest count a mod-N counter can achieve is N-1 ie a mod-N counter never reaches the binary number equal to its modulus N is always equal to or less than 2n Counters can be classified as bull Synchronous Counters which are clock driven All the flip-flops are driven by a

                                                                                single clock bull Asynchronous Counters which are event driven Clock input is given to the first

                                                                                flip-flop only Rest of the flip-flops are driven by their preceding flip-flops

                                                                                DESIGN OF A MOD-5 ASYNCHRONOUS UP COUNTER The number of flip-flops required to construct a mod-5 counter is 3 because 5 should be less than or equal to 2n This counter will count from 0 to 4 a total of 5 distinct states Since a 3-stage counter can count up to 8 states at maximum a NAND gate is used to reset it after 5 clock pulses Figure 131 shows the logic diagram

                                                                                54

                                                                                Logic Design amp Switching Theory 1 Lab Session 13 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                                55

                                                                                Figure 131 A Mod-5 Asynchronous Up Counter

                                                                                Implementation and Observations

                                                                                Implement the mod-5 counter circuit (figure 131) on a bread board (prepare the pin diagram (use appendix A) and refer to laboratory session 01 for implementation procedure) and record the observations in the following table

                                                                                Clock Pulse Q2 Q1 Q0

                                                                                0 1 2 3 4 5 6 7

                                                                                ACTIVITY

                                                                                Draw the timing diagram for mod-5 counter designed in this laboratory session

                                                                                Logic Design amp Switching Theory 1 Lab Session 14 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                                Lab Session 14 OBJECT

                                                                                Experimenting with 74194 4-bit bidirectional universal shift register COMPONENTS AND APPARATUS REQUIRED

                                                                                1 Following ICs and their Datasheets

                                                                                bull 74194 4-bit bidirectional universal shift register 2 Digital Trainer DT-01 or the following components

                                                                                Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches

                                                                                THEORY

                                                                                Shift Registers

                                                                                A Register is a set of flip-flops used to store binary data A register which is capable of shifting its binary information either to the right or left is called a shift register The logical configuration of a register consists of a chain of flip-flops connected in cascade with the output of one flip-flop connected to the input of next flip-flop All flip-flops receive a common clock pulse which causes the shift from one stage to the next

                                                                                Bidirectional Shift Registers A bi-directional shift register is one whose bits can be shifted from left to right or from right to left

                                                                                Universal Shift Registers A universal shift register is a bi-directional register whose input can be in either serial or parallel form and whose output can be in either serial or parallel form

                                                                                74194 4-BIT BIDIRECTIONAL UNIVERSAL SHIFT REGISTER

                                                                                The 74194 register provides parallel as well as serial loading in both directions Function of various pins of this IC is described below

                                                                                bull A B C and D Active high inputs for parallel loading bull QA QB QC and QD Active high outputs bull S0 and S1 Active high mode control inputs The following table shows combinations

                                                                                of S1 and S0 to enable various modes

                                                                                S1 S0 Clock Action 0 0 x No change 0 1 uarr Shift right 1 0 uarr Shift left 1 1 uarr Parallel load

                                                                                uarr shows the rising edge of the clock pulse

                                                                                56

                                                                                Logic Design amp Switching Theory 1 Lab Session 14 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering bull SR Active high serial input for right shifting bull SL Active high serial input for left shifting bull CLR Active low input Clears all the flip-flops of the register if set to 0 should be

                                                                                kept high otherwise bull CLK Clock input bull VCC and GND Supply connections lines Thus A B C and D are inputs for parallel loading whereas SR and SL are inputs for serial loading with right or left shifting respectively S1 and S0 are used to select the loading mode Circuit Diagram

                                                                                Figure 141 Pin connections of 74194 Testing Procedure

                                                                                bull Make connections as shown in the circuit diagram bull Observe the output for the input combinations given in the following table

                                                                                57

                                                                                Logic Design amp Switching Theory 1 Lab Session 14 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                                58

                                                                                Observations

                                                                                S1 S0 SL SR A B C D QA QB QC QD 0 0 0 1 0 0 0 0 0 1 1 0 0 0 0 1 1 0 0 0 0 0 1 0 1 1 0 0 0 0 1 1 0 0 1 1 0 1 0 0 0 1 1 1 0 1 0 1 1 0 1 0 0 1 1 0 1 1 1 0 0 1 1 1 1 1 0 0 1 1 1 1

                                                                                ACTIVITY 1 Show connections of 74194 to convert it into a ring counter with right shifting

                                                                                Logic Design amp Switching Theory 1 Lab Session 15 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                                Lab Session 15

                                                                                OBJECT

                                                                                Experimenting with 74245 octal bus transceivers using parallel port PC interfacing COMPONENTS AND APPARATUS REQUIRED 1 Parallel Port Connectors (DB-25) with Cable 2 Personal Computer with Windows 98 and TurboC Compiler Installed 3 Following ICs and their Datasheets

                                                                                bull 74245 Octal Bus Transceivers with 3-State Outputs 4 Digital Trainer DT-01 or the following components

                                                                                Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches

                                                                                THEORY

                                                                                3-State Logic Sometimes it is necessary to isolate one part of circuit from the other part For this purpose some TTL ICs are designed with 3-state logic Such devices have three possible output states high low and high impedance The device can be put into high impedance state by a control signal applied to an appropriate pin When such a device is in high impedance state there is very high impedance at its output effectively isolating the device from whatever circuitry the output normally drives 74245 Octal Bus Transceivers A bus is any conducting path or set of paths having electrical connections to one or more devices 74245 octal bus transceivers are mainly used to control connectivity between two devices or circuits It also provides direction control for signal flow Function of various pin of this IC is given below

                                                                                bull A1 through A8 Bus A bull B1 through B8 Bus B bull G΄ Active low enable input When high sets all the bus pins to high impedance state bull DIR Direction control for signal flow When set to high logic level transfers bus A

                                                                                data to B bus When set to low logic level transfers bus B data to A bus bull VCC and GND Supply connections lines Serial and Parallel Port Connectors A Parallel Port can consist of only 25 pin port adapter called a DB-25 and a serial port can consist of either a 25 pin port adapter called a DB-25 or 9 pin adapter called a DB-9 port adapter Whether the port is a 9 pin or 25 pin it can accomplish all of the same tasks that serial port communications have been designed for

                                                                                59

                                                                                Logic Design amp Switching Theory 1 Lab Session 15 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                                60

                                                                                Each adapter can be a male type connector with pins or a female type adapter with tiny holes Generally a PRINTER port (called LPT1) on the back of a computer is female type adapter and we need to use MALE DB-25 pin cable on it for PRINTER connection or for parallel LAPLINK cable And a COM port on the back of a computer is male for the serial ports but it may not necessarily be Parallel Port Connector ndash DB-25 The DB-25 connector (named for its B-size D-shaped shell and 25 pins) is practically ubiquitous in the electronics industry The DB-25 connector is used for a variety of purposes Two common applications are RS-232EIA-232 (serial) connections and the parallel printer interface on the IBM PC The DB-25 connector is also used for SCSI connections Normally the parallel port is used for output to a printer or other device It sends data 8-bits or one byte at a time in parallel The other lines available on the DB-25 connector are a combination of status lines control lines and ground lines The status and control lines are used for handshaking commands and feedback when we are talking to a printer

                                                                                Figure 152 DB-25 Female Figure 151 DB-25 Male

                                                                                Figure 153 Pin Layout for DB-25 As can be seen form figure 153 there are four types of pins in this connector

                                                                                bull Data pins (8 pins - D0 to D7) Active high bidirectional lines

                                                                                Logic Design amp Switching Theory 1 Lab Session 15 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering bull Control pins (4 pins - C0 to C3) C0 C1 and C3 are active low whereas C2 is active

                                                                                high These lines also are bidirectional bull Status pins (5 pins ndash S3 to S7) Only S7 is active low rest are active high input lines bull Ground pins (8 pins) Used as a reference signal for the low (below 05 volts) charge

                                                                                Parallel Port Addresses A DB-25 connector at a parallel port has three address one for each kind of pins register data status and control The first or base address generally refers to data register Second address is for status register and the third one is for control register In Windows 98 the base address is usually found to be 278H 378H or 3BCH Now if 378H is the base address then it refers to the data register whereas addresses for status and control register are respectively 379H and 37AH For Windows 98 the base address can be found as follows 1 On your Desktop right-click on My Computer and select Properties 2 Click on the Device Manager tab and find LPT1 under Plug and Play BIOS 3 After selecting LPT1 click the Properties button 4 Next select the Resources tab and the address should then appear next to InputOutput

                                                                                Range Accessing parallel port through C Language Programming There are multiple functions in C Language for accessing external ports The most commonly used are listed below

                                                                                bull unsigned char inportb(int portid) inportb reads a byte from a hardware port

                                                                                bull int inport(int portid) reads a word from a hardware port

                                                                                bull void outportb(int portid unsigned char value) outputs a byte to a hardware port

                                                                                bull void outport(int portid int value) outputs a word to a hardware port

                                                                                portid refers to the port address whereas value refers to the data to be sent TESTING 74245 USING PARALLEL PORT PC INTERFACING At one end the parallel port connector will be connected to the PC via parallel port cable and another connector (to be plugged into the PC parallel port slot) At the other end it will be connected to the buffer IC 74245 Data lines of the connector will be used to transfer 8-bit data between the PC and the buffer Out of the 8-bits of 74245 4-bits will be used to enter data which will be displayed at the monitor through a C language

                                                                                61

                                                                                Logic Design amp Switching Theory 1 Lab Session 15 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering program The remaining 4-bits will receive data from PC as entered by the user via keyboard

                                                                                Circuit Diagram

                                                                                Figure 154 Interface of 74245 to PC via Parallel Port

                                                                                Procedure

                                                                                1 Connect the DB-25 connector to the PC at one end and solder it to the circuit board at the other end

                                                                                2 Connect various pins of the connector and 74245 according to the circuit diagram shown in figure 152

                                                                                3 Using the functions listed in the previous section write a program in C language to operate various pins of the buffer The user interface of the program should provide option to the user whether to send or receive data from the port

                                                                                4 Set DIR switch to 1 5 Try sending some data bits to the port The result should be displayed at the LEDs 6 Set DIR switch to 0 7 Set some binary 4-bit value through the switches Try reading it via parallel port

                                                                                C Language Program

                                                                                A program to access parallel port for data transfers

                                                                                use header file include ltstdiohgt main program void main() define variable

                                                                                62

                                                                                Logic Design amp Switching Theory 1 Lab Session 15 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering unsigned int data=0 char choice while(1) printing option menu clrscr() printf(This program will send or receive a BCD digit from the parallel portn) printf(nPress your choice numbern) printf(n1 Send Data) printf(n2 Receive Data) printf(n3 Exitn) choice = getch() sending entered digit to the port if(choice == 1) input BCD digit printf(nEnter BCD digit to be sent to the port) data = getche() masking the first four bits data = data amp 0x0f sending to the port outportb(0x378data) printf(nThe BCD digit c has been sent to the port data) printing on screen the data received from the port else if(choice == 2) receiving data from the port data = inportb(0x378) masking the last four bits data = data amp 0xf0 shifting first four bits to make them the last four bits datagtgt=4 printf(nThe BCD digit set at the port is c data) exit else if(choice == 3) break key pressed is not in the menu else printf(nEnter valid choice number) printf(nnPress any key to continue) getch()

                                                                                63

                                                                                Logic Design amp Switching Theory 1 Lab Session 15 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                                ACTIVITY 1 In the above circuit DIR and G΄ inputs are hardwired Connect them to status or

                                                                                control pins of the parallel port connector and control their function through your software program Circuit Diagram Program Code ______________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________

                                                                                ___________________________________________________________________________________________________________________________________________________

                                                                                64

                                                                                Logic Design amp Switching Theory 1 Lab Session 15 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                                65

                                                                                _____________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ _____________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ _______________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ _________________________________________________ _________________________________________________

                                                                                Logic Design amp Switching Theory 1 Appendix A NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                                Appendix A

                                                                                PIN DIAGRAMS OF THE ICS REQUIRED FOR THE LABORATORY SESSIONS Consult the TTLIC data book for internal diagrams and electrical characteristics of these ICs 7400 Quad 2-Input NAND 7402 Quad 2-Input NOR

                                                                                7404 Hex Inverter 7408 Quad 2-Input AND

                                                                                7410 Triple 3-Input NAND 7411 Triple 3-Input AND

                                                                                7421 Dual 4-Input AND 7432 Quad 2-Input OR

                                                                                66

                                                                                Logic Design amp Switching Theory 1 Appendix A NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                                BCD-to-Seven Segm 7448 BCD-to-Seven Segment 7447 ent

                                                                                Decoder (15V OC) Decoder (2kΩ pull-up output)

                                                                                7473 Dual JK Flip-Flop 7474 Dual D-Type Flip-Flop

                                                                                7476 Dual JK Flop-Flop -Bit Binary Full Adder 7483 4 with Fast Carry

                                                                                86 Quad 2-Inpu 74138 3-to-8 Line 74 t Exclusive OR Decoder Demultiplexer

                                                                                67

                                                                                Logic Design amp Switching Theory 1 Appendix A NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                                68

                                                                                74148 8-to-3 Line 16-to-1 Line Data

                                                                                Priority Encoder 74150 Selector Multiplexer

                                                                                74245 Oct nsceivers Universal Shift Register (PIPO) (3-State)

                                                                                74194 4-Bit Bidirectional al Bus Tra

                                                                                Logic Design amp Switching Theory 1 Appendix B NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                                Appendix B

                                                                                DEBOUNCING CIRCUITRY FOR MECHANICAL SWITCHES Mechanical switches form the interface between human beings and computers or other digital systems For example a keyboard is a matrix of switches used to supply alphanumeric data to a computer Whatever the switch design it is a potential source of problems due to contact bounce The contact bounce creates a sense of narrow pulses when a switch is opened or closed An example of device whose operation would be adversely affected by contact bounce is a digital counter used to count the number of times a switch is depressed Eliminating the effects of contact bounce is called debouncing When data is entered into a computer via a keyboard a software debounce is often used This type of debouncing is a program that causes the computer to sample the switch terminal (ie to input data from it) many times in succession during the interval of time that contact bounce occurs If the data is sensed to be 1s (or 0s) for a specific number of consecutive samples then it is assumed that contact bounce has ended and the last value sensed is valid Hardware debouncing is the use of electronic circuitry to eliminate the effects of contact bounce There are numerous versions of such circuitry including those that use monostable multivibrators (one-shots) but the most straightforward is simply an RS latch Figure B1 shows the circuit When the switch is in position 1 R = 0 and S = 1 so the latch is set and the output (Q) is 1 When the switch is in position 0 R = 1and S = 0 so the latch is reset and the output is 0 When the switch is moved form one position to the other the latch changes state and bouncing occurs at either the R or the S input The bouncing does not affect the latch after it has change state An RS latch will remain set for example when its R input is 0 and its S input is alternately changed form 1 to 0

                                                                                Figure B1 Use of RS latch to debounce a mechanical switch

                                                                                69

                                                                                • 01-ldst-Outer title
                                                                                  • Practical Workbook
                                                                                  • Logic Design amp Switching Theory I
                                                                                    • Dept of Computer amp Information Systems Engineering
                                                                                      • NED University of Engineering amp Technology
                                                                                      • Karachi ndash 75270 Pakistan
                                                                                        • 02-ldst-inner Title
                                                                                          • Practical Workbook
                                                                                          • Logic Design amp Switching Theory I
                                                                                            • Dept of Computer amp Information Systems Engineering
                                                                                              • NED University of Engineering amp Technology
                                                                                              • Karachi ndash 75270 Pakistan
                                                                                                • 03-ldst-general info
                                                                                                • 04-ldst-introduction
                                                                                                • 05-Table of Contents
                                                                                                  • CONTENTS
                                                                                                    • Lab Session No Object Page No
                                                                                                    • 1
                                                                                                    • Also implementing and testing the given circuit on a bread board
                                                                                                      • Working with Electronics Workbench
                                                                                                        • Driving a seven segment display using 7447 7448 driver IC
                                                                                                          • Designing a modulus-5 asynchronous up-counter using JK-FF
                                                                                                            • Experimenting with 74194 4-bit bidirectional universal shift register
                                                                                                                • 13
                                                                                                                    • 06-ldst-Exp01
                                                                                                                      • Lab Session 01
                                                                                                                      • OBJECT
                                                                                                                        • 1 Bread board
                                                                                                                        • 2 5 V - power supply
                                                                                                                        • 3 Multimeter
                                                                                                                        • 4 Logic probe
                                                                                                                        • 5 LEDs with resistors
                                                                                                                        • 6 Connecting wires
                                                                                                                        • 8 Following ICs and their datasheets
                                                                                                                          • THEORY
                                                                                                                            • Logic Gates
                                                                                                                            • 1 The AND Gate ndash An AND gatersquos output is 1 if and only if all its inputs are 1 If A and B are two inputs to an AND gate then output F of the gate is given as F = AB
                                                                                                                            • 2 The OR Gate - An OR gatersquos output is 1 if at least one of its input is 1 If A and B are two inputs to an OR gate then output F of the gate is given as F = A+B
                                                                                                                            • 3 The NOT Gate (Inverter) ndash Its output is 1 when its input is 0 and its output is 0 when the input is 1 ie it complements a digital variable If A is the input to a NOT gate then output F of the gate is given as
                                                                                                                            • 4 The NAND Gate ndash Its output is 1 if at least one of its input is 0 This gate performs the same logic as an AND gate followed by an inverter If A and B are two inputs to a NAND gate then output F of the gate is given as
                                                                                                                              • 5 The NOR Gate - The output of a NOR gate is 1 if and only if all its inputs are 0 This gate performs the same logic function as an OR gate followed by an inverter If A and B are two inputs to a NAND gate then output F of the gate is given as
                                                                                                                                  • DATA SHEETS
                                                                                                                                    • Logic expression for the given logic diagram __________________________________
                                                                                                                                        • 07-ldst-exp02
                                                                                                                                          • Working with Electronics Workbench
                                                                                                                                            • 08-ldst-exp03
                                                                                                                                              • Designing Half and Full Adder Circuits
                                                                                                                                                • COMPONENTS AND APPARATUS REQUIRED
                                                                                                                                                  • 1 Following ICs and their Datasheets
                                                                                                                                                  • 7408 Quad 2-input AND Gate
                                                                                                                                                  • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                    • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                    • Connecting wires Switches
                                                                                                                                                      • THEORY
                                                                                                                                                          • IMPLEMENTATION AND OBSERVATIONS
                                                                                                                                                            • 09-ldst-Exp04
                                                                                                                                                              • Lab Session 04
                                                                                                                                                              • 1 Digital ICs and their Datasheets
                                                                                                                                                              • 7408 Quad 2-input AND Gate
                                                                                                                                                              • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                • Connecting wires Switches
                                                                                                                                                                • PROCEDURE
                                                                                                                                                                • REDUCTION OF LOGIC EXPRESSION USING KARNAUGH MAP
                                                                                                                                                                • OBSERVATIONS
                                                                                                                                                                • RESULT
                                                                                                                                                                    • 10-ldst-Exp05
                                                                                                                                                                      • Lab Session 05
                                                                                                                                                                      • 1 Following ICs and their Datasheets
                                                                                                                                                                      • 7408 Quad 2-input AND Gate
                                                                                                                                                                      • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                        • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                        • (100 Ω) Connecting wires Switches
                                                                                                                                                                        • THEORY
                                                                                                                                                                          • IMPLEMENTATION AND OBSERVATIONS
                                                                                                                                                                            • 11-ldst-Exp06
                                                                                                                                                                              • OBJECT
                                                                                                                                                                              • 1 Following ICs and their Datasheets
                                                                                                                                                                              • 7408 Quad 2-input AND Gates or 7411 Triple 3-input AND Gates
                                                                                                                                                                              • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                • Connecting wires Switches
                                                                                                                                                                                  • Figure 62 Circuit Diagram for 4 x 1 Multiplexer
                                                                                                                                                                                  • Implementation and Observations
                                                                                                                                                                                    • Circuit Diagram
                                                                                                                                                                                      • ACTIVITY
                                                                                                                                                                                        • 12-ldst-exp07
                                                                                                                                                                                          • 1 Following ICs and their Datasheets
                                                                                                                                                                                          • 7408 Quad 2-input or 7411 Triple 3-input AND Gates
                                                                                                                                                                                          • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                            • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                            • Connecting wires Switches
                                                                                                                                                                                              • THEORY
                                                                                                                                                                                                  • Figure 72 Circuit Diagram for 2 x 4 Decoder 1 x 4 Demultiplexer
                                                                                                                                                                                                  • Implementation and Observations
                                                                                                                                                                                                    • Circuit Diagram
                                                                                                                                                                                                      • ACTIVITY
                                                                                                                                                                                                        • 13-ldst-Exp08
                                                                                                                                                                                                          • OBJECT
                                                                                                                                                                                                          • 1 Following ICs and their Datasheets
                                                                                                                                                                                                          • 7408 Quad 2-input or 7421 Dual 4-input AND Gates
                                                                                                                                                                                                          • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                            • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                            • Connecting wires Switches
                                                                                                                                                                                                              • THEORY
                                                                                                                                                                                                                  • Figure 81 Circuit Diagram for 4 x 2 Priority Encoder
                                                                                                                                                                                                                  • Implementation and Observations
                                                                                                                                                                                                                    • Therefore if GS A2 A1 and A0 are all low then it shows that line 0 is selected and if E0 A2 A1 and A0 are all low then it shows that none of the inputs selected E0 and GS cannot be in the same state provided that E1 is enabled
                                                                                                                                                                                                                    • Circuit Diagram
                                                                                                                                                                                                                      • ACTIVITY
                                                                                                                                                                                                                        • 14-ldst-exp09
                                                                                                                                                                                                                          • OBJECT
                                                                                                                                                                                                                          • 1 Following ICs and their Datasheets
                                                                                                                                                                                                                          • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                            • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                                            • Connecting wires Switches
                                                                                                                                                                                                                              • THEORY
                                                                                                                                                                                                                                • Parity Generator
                                                                                                                                                                                                                                  • Let x y and z be the three bits that constitute the message and are the input to the Odd Parity Generator Circuit Since it is an odd parity system the bit P is generated so as to make the total number of 1s odd (including P) The function P can be expressed as follows
                                                                                                                                                                                                                                  • Figure 91 Circuit Diagram for a 3-bit Parity Generator
                                                                                                                                                                                                                                    • C = x Ο y Ο z Ο P
                                                                                                                                                                                                                                      • Implementation and Observations
                                                                                                                                                                                                                                        • ACTIVITY
                                                                                                                                                                                                                                            • 15-ldst-exp10
                                                                                                                                                                                                                                              • Driving a seven segment display using 7447 7448 driver IC
                                                                                                                                                                                                                                              • COMPONENTS AND APPARATUS REQUIRED
                                                                                                                                                                                                                                              • 1 Following ICs and their Datasheets
                                                                                                                                                                                                                                              • 7447 7448 BCD to Seven Segment Driver
                                                                                                                                                                                                                                              • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                                                • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches
                                                                                                                                                                                                                                                  • THEORY
                                                                                                                                                                                                                                                  • Seven Segment Displays
                                                                                                                                                                                                                                                  • CIRCUIT DIAGRAM
                                                                                                                                                                                                                                                  • Figure 102 Circuit diagram for 7447driving a common-anode display
                                                                                                                                                                                                                                                      • IMPLEMENTATION AND OBSERVATIONS
                                                                                                                                                                                                                                                        • Decimal Digit
                                                                                                                                                                                                                                                        • BCD Inputs
                                                                                                                                                                                                                                                        • Seven Segment Outputs
                                                                                                                                                                                                                                                        • D
                                                                                                                                                                                                                                                        • C
                                                                                                                                                                                                                                                        • B
                                                                                                                                                                                                                                                        • A
                                                                                                                                                                                                                                                        • a
                                                                                                                                                                                                                                                        • b
                                                                                                                                                                                                                                                        • c
                                                                                                                                                                                                                                                        • d
                                                                                                                                                                                                                                                        • e
                                                                                                                                                                                                                                                        • f
                                                                                                                                                                                                                                                        • g
                                                                                                                                                                                                                                                        • 0
                                                                                                                                                                                                                                                        • 0
                                                                                                                                                                                                                                                        • 0
                                                                                                                                                                                                                                                        • 0
                                                                                                                                                                                                                                                        • 0
                                                                                                                                                                                                                                                        • 1
                                                                                                                                                                                                                                                        • 0
                                                                                                                                                                                                                                                        • 0
                                                                                                                                                                                                                                                        • 0
                                                                                                                                                                                                                                                        • 1
                                                                                                                                                                                                                                                        • 2
                                                                                                                                                                                                                                                        • 0
                                                                                                                                                                                                                                                        • 0
                                                                                                                                                                                                                                                        • 1
                                                                                                                                                                                                                                                        • 0
                                                                                                                                                                                                                                                        • 3
                                                                                                                                                                                                                                                        • 0
                                                                                                                                                                                                                                                        • 0
                                                                                                                                                                                                                                                        • 1
                                                                                                                                                                                                                                                        • 1
                                                                                                                                                                                                                                                        • 4
                                                                                                                                                                                                                                                        • 0
                                                                                                                                                                                                                                                        • 1
                                                                                                                                                                                                                                                        • 0
                                                                                                                                                                                                                                                        • 0
                                                                                                                                                                                                                                                        • 5
                                                                                                                                                                                                                                                        • 0
                                                                                                                                                                                                                                                        • 1
                                                                                                                                                                                                                                                        • 0
                                                                                                                                                                                                                                                        • 1
                                                                                                                                                                                                                                                        • 6
                                                                                                                                                                                                                                                        • 0
                                                                                                                                                                                                                                                        • 1
                                                                                                                                                                                                                                                        • 1
                                                                                                                                                                                                                                                        • 0
                                                                                                                                                                                                                                                        • 7
                                                                                                                                                                                                                                                        • 0
                                                                                                                                                                                                                                                        • 1
                                                                                                                                                                                                                                                        • 1
                                                                                                                                                                                                                                                        • 1
                                                                                                                                                                                                                                                        • 8
                                                                                                                                                                                                                                                        • 1
                                                                                                                                                                                                                                                        • 0
                                                                                                                                                                                                                                                        • 0
                                                                                                                                                                                                                                                        • 0
                                                                                                                                                                                                                                                        • 9
                                                                                                                                                                                                                                                        • 1
                                                                                                                                                                                                                                                        • 0
                                                                                                                                                                                                                                                        • 0
                                                                                                                                                                                                                                                        • 1
                                                                                                                                                                                                                                                          • ACTIVITY
                                                                                                                                                                                                                                                            • 16-ldst-exp11
                                                                                                                                                                                                                                                              • Lab Session 11
                                                                                                                                                                                                                                                                • OBJECT
                                                                                                                                                                                                                                                                • COMPONENTS AND APPARATUS REQUIRED
                                                                                                                                                                                                                                                                  • 1 Following ICs and their Datasheets
                                                                                                                                                                                                                                                                  • 7473 7476 JK Flip-Flop
                                                                                                                                                                                                                                                                  • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                                                                    • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                                                                                    • Connecting wires Switches
                                                                                                                                                                                                                                                                      • THEORY
                                                                                                                                                                                                                                                                          • Flip-Flop
                                                                                                                                                                                                                                                                          • JK Flip-Flop
                                                                                                                                                                                                                                                                            • Circuit Diagram
                                                                                                                                                                                                                                                                              • Observations
                                                                                                                                                                                                                                                                                • ACTIVITY
                                                                                                                                                                                                                                                                                    • 17-ldst-exp12
                                                                                                                                                                                                                                                                                      • Lab Session 12
                                                                                                                                                                                                                                                                                        • OBJECT
                                                                                                                                                                                                                                                                                        • GIVEN STATE DIAGRAM
                                                                                                                                                                                                                                                                                        • Figure 121 State Diagram
                                                                                                                                                                                                                                                                                        • COMPONENTS AND APPARATUS REQUIRED
                                                                                                                                                                                                                                                                                          • 1 Following ICs and their Datasheets
                                                                                                                                                                                                                                                                                          • 7474 D Flip-Flop
                                                                                                                                                                                                                                                                                          • ICs of basic gates (AND OR NOT XOR etc) as required
                                                                                                                                                                                                                                                                                          • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                                                                                            • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                                                                                                            • Connecting wires Switches
                                                                                                                                                                                                                                                                                              • THEORY
                                                                                                                                                                                                                                                                                                  • Sequential Circuits
                                                                                                                                                                                                                                                                                                    • 18-ldst-exp13
                                                                                                                                                                                                                                                                                                      • Lab Session 13
                                                                                                                                                                                                                                                                                                        • Designing a modulo-5 asynchronous up-counter using JK-FF
                                                                                                                                                                                                                                                                                                          • 1 Following ICs and their Datasheets
                                                                                                                                                                                                                                                                                                          • 7400 Quad 2-input or 7410 Triple 3-input NAND Gates
                                                                                                                                                                                                                                                                                                          • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                                                                                                            • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                                                                                                                            • Connecting wires Switches
                                                                                                                                                                                                                                                                                                              • THEORY
                                                                                                                                                                                                                                                                                                                  • Figure 131 A Mod-5 Asynchronous Up Counter
                                                                                                                                                                                                                                                                                                                  • Implementation and Observations
                                                                                                                                                                                                                                                                                                                    • ACTIVITY
                                                                                                                                                                                                                                                                                                                        • 19-ldst-exp14
                                                                                                                                                                                                                                                                                                                          • Experimenting with 74194 4-bit bidirectional universal shift register
                                                                                                                                                                                                                                                                                                                          • 1 Following ICs and their Datasheets
                                                                                                                                                                                                                                                                                                                          • 74194 4-bit bidirectional universal shift register
                                                                                                                                                                                                                                                                                                                          • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                                                                                                                            • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                                                                                                                                            • Connecting wires Switches
                                                                                                                                                                                                                                                                                                                              • THEORY
                                                                                                                                                                                                                                                                                                                                • Shift Registers
                                                                                                                                                                                                                                                                                                                                • Bidirectional Shift Registers
                                                                                                                                                                                                                                                                                                                                • Universal Shift Registers
                                                                                                                                                                                                                                                                                                                                  • S1
                                                                                                                                                                                                                                                                                                                                    • Circuit Diagram
                                                                                                                                                                                                                                                                                                                                    • ACTIVITY
                                                                                                                                                                                                                                                                                                                                        • 20-ldst-exp15
                                                                                                                                                                                                                                                                                                                                          • COMPONENTS AND APPARATUS REQUIRED
                                                                                                                                                                                                                                                                                                                                          • 1 Parallel Port Connectors (DB-25) with Cable
                                                                                                                                                                                                                                                                                                                                          • 2 Personal Computer with Windows 98 and TurboC Compiler Installed
                                                                                                                                                                                                                                                                                                                                          • 3 Following ICs and their Datasheets
                                                                                                                                                                                                                                                                                                                                          • 74245 Octal Bus Transceivers with 3-State Outputs
                                                                                                                                                                                                                                                                                                                                          • 4 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                                                                                                                                            • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                                                                                                                                                              • Connecting wires Switches
                                                                                                                                                                                                                                                                                                                                                • THEORY
                                                                                                                                                                                                                                                                                                                                                • 3-State Logic
                                                                                                                                                                                                                                                                                                                                                  • Serial and Parallel Port Connectors
                                                                                                                                                                                                                                                                                                                                                  • Parallel Port Connector ndash DB-25
                                                                                                                                                                                                                                                                                                                                                    • Accessing parallel port through C Language Programming
                                                                                                                                                                                                                                                                                                                                                        • 21-ldst-appendixA
                                                                                                                                                                                                                                                                                                                                                        • 22-ldst-appendixB
                                                                                                                                                                                                                                                                                                                                                          • DEBOUNCING CIRCUITRY FOR MECHANICAL SWITCHES

                                                                                  Logic Design amp Switching Theory 1 Lab Session 09 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering ` two or more errors Odd parity is used more often than even parity because even parity does not detect a situation where all 0s are created due to short circuit or other fault condition DESIGN OF A 3-BIT ODD PARITY GENERATOR AND CHECKER Let x y and z be the three bits that constitute the message and are the input to the Odd Parity Generator Circuit Since it is an odd parity system the bit P is generated so as to make the total number of 1s odd (including P) The function P can be expressed as follows P = x oplus y Ο z or P = x Ο y oplus z Since the IC available is 7486 which is quad 2input XOR IC therefore we will convert XNOR also to XOR

                                                                                  P = x oplus y Ο z

                                                                                  P = ( x oplus y ) Ο z Since for even number of variables ______

                                                                                  XOR = XNOR Therefore ___________ _________

                                                                                  P = ( x oplus y ) oplus z = x oplus y oplus z This logical expression can be implemented with two XOR gates and an inverter (see figure 91)

                                                                                  Figure 91 Circuit Diagram for a 3-bit Parity Generator

                                                                                  The 3-bit message and the parity bit are transmitted to their destination where they are applied to a Parity Checker Circuit An error occurs during transmission if the parity of the four bits received is even since the binary information transmitted was originally odd The output C of the parity checker should be a 1 when an error occurs ie when the number of 1s in the four inputs is even Therefore the function C can be expressed as

                                                                                  C = x Ο y Ο z Ο P

                                                                                  Using the same logic applied for the conversion of the equation of P

                                                                                  PzyxC oplusoplusoplus= This logical expression can be implemented with three XOR gates and an inverter (see figure 92)

                                                                                  43

                                                                                  Logic Design amp Switching Theory 1 Lab Session 09 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering `

                                                                                  44

                                                                                  Figure 92 Circuit Diagram for a 3-bit Parity Checker Implementation and Observations Implement the 3-bit Parity Generator and Checker circuits (figure 91 and 92) on a bread board (prepare the pin diagram (use appendix A) and refer to laboratory session 01 for implementation procedure) and record the observations in the following table

                                                                                  x y z P x y z P C x y z P C 0 0 0 0 0 0 0 1 0 0 0 0 0 1 0 0 0 1 1 0 0 1 0 1 0 0 0 1 0 1 0 1 0 0 1 1 0 0 1 1 1 0 1 1 1 0 0 0 1 0 0 1 1 0 0 1 0 1 0 1 0 1 1 1 0 1 1 1 0 0 1 1 0 1 1 1 0 1 1 1 0 1 1 1 1 1 1 1

                                                                                  Odd Parity Generation Odd Parity Check ACTIVITY 1 Try using the parity checker of figure 92 as 3-bit parity generator Write the details here

                                                                                  _____________________________________________________________________________________________________________________________________________________________________________________________________________________ ______________________________________________________________________________________________________________________________________________ _______________________________________________________________________ ______________________________________________________________________________________________________________________________________________

                                                                                  Logic Design amp Switching Theory 1 Lab Session 10 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                                  Lab Session 10 OBJECT

                                                                                  Driving a seven segment display using 7447 7448 driver IC COMPONENTS AND APPARATUS REQUIRED

                                                                                  1 Following ICs and their Datasheets

                                                                                  bull Seven Segment Displays (Common Anode Common Cathode) bull 7447 7448 BCD to Seven Segment Driver

                                                                                  2 Digital Trainer DT-01 or the following components Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches

                                                                                  THEORY Seven Segment Displays A Seven Segment Display consists of seven light-emitting segments The segments are designated by letters a through g (see figure 101) By illuminating various combinations of segments the numerals 0 through 9 can be displayed Seven Segment Displays are commonly constructed with light-emitting diodes (LEDs) and with liquid-crystal displays (LCDs) LEDs generally provide greater illumination levels but require much greater power than LCDs An LED display can be a common-anode type or common cathode type In common anode type a high voltage is applied at the common terminal of the display and low voltage is applied at a segmentrsquos terminal for illumination In the common-cathode type a low voltage is applied at the common terminal of the display and high voltage is applied at a segmentrsquos terminal for illumination

                                                                                  Figure 101 Seven Segment Display

                                                                                  a f b g

                                                                                  e c d

                                                                                  7447 7448 BCD to Seven Segment Driver 7447 7448 IC is particularly used to drive Seven Segment Its input is a BCD number and output drives a seven segment display 7447 is used to drive common-anode displays whereas 7448 is used to drive common cathode displays 7447 7448 is a 16 pin IC Function of various pins of these ICs is described below

                                                                                  bull A B C D Inputs representing BCD digits (D being the MSB)

                                                                                  45

                                                                                  Logic Design amp Switching Theory 1 Lab Session 10 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering bull OA through OG Outputs to drive segments a through g of the display (Active low

                                                                                  in 7447 and active high in 7448) bull RBI Ripple Blanking Input Turns off all the segments if kept low provided that LT

                                                                                  is kept high and all other inputs (A B C D BI) are kept low Should be kept high otherwise

                                                                                  bull BI RBO Wire-AND logic serving as a Blanking Input and or Ripple Blanking Output

                                                                                  o BI Turns off all the segments if low o RBO Goes to a low level (response condition) along with other outputs when

                                                                                  RBI and inputs A B C and D are low with LT input at high level bull LT Lamp Test input Tests whether all segments are working or not Illuminates all

                                                                                  segments if kept low provided that BI is kept high Should be kept high otherwise bull VCC and GND Supply connections lines CIRCUIT DIAGRAM

                                                                                  Figure 102 Circuit diagram for 7447driving a common-anode display

                                                                                  IMPLEMENTATION AND OBSERVATIONS

                                                                                  bull Make connections as shown in the circuit diagram (refer to laboratory session 01 for implementation procedure)

                                                                                  bull Apply different combinations of 1s and 0s at data inputs bull Observe the output and record your observations in the following table

                                                                                  46

                                                                                  Logic Design amp Switching Theory 1 Lab Session 10 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                                  47

                                                                                  Decimal Digit

                                                                                  BCD Inputs Seven Segment Outputs D C B A a b c d e f g

                                                                                  0 0 0 0 0 1 0 0 0 1 2 0 0 1 0 3 0 0 1 1 4 0 1 0 0 5 0 1 0 1 6 0 1 1 0 7 0 1 1 1 8 1 0 0 0 9 1 0 0 1

                                                                                  ACTIVITY 1 Perform the Lamp Test for the designed circuit and write your observations

                                                                                  ____________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________

                                                                                  2 How can you use 7447 IC to drive a common-cathode display

                                                                                  ____________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________

                                                                                  3 What symbols appear in the seven segment display if inputs DCBA are

                                                                                  DCBA Symbol

                                                                                  1010

                                                                                  1011

                                                                                  1100

                                                                                  1101

                                                                                  1110

                                                                                  1111

                                                                                  Logic Design amp Switching Theory 1 Lab Session 11 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                                  48

                                                                                  Lab Session 11 OBJECT

                                                                                  Testing different modes of JK-FF COMPONENTS AND APPARATUS REQUIRED 1 Following ICs and their Datasheets

                                                                                  bull 7473 7476 JK Flip-Flop 2 Digital Trainer DT-01 or the following components

                                                                                  Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches

                                                                                  THEORY

                                                                                  Flip-Flop A flip-flop circuit can maintain a binary state indefinitely (as long as the power is delivered to the circuit) until directed by an input signal to switch states The major differences among various types of flip-flops are in the number of inputs they possess and in the manner in which the inputs affect the binary state

                                                                                  JK Flip-Flop JK flip flop is an edge triggered device A typical JK flip flop has three inputs J K and a clock input The flip-flop can be either positive or negative edge triggered The output Q is available in complemented form as well Beside the usual inputs and output most of the flip-flop IC also possess two asynchronous inputs namely Preset and Clear These inputs are usually active low If used Preset and Clear inputs keep the flip-flop in set and reset state respectively irrespective of the other inputs Both of these inputs cannot be used simultaneously otherwise they will bring the flip-flop in unstable state

                                                                                  Figure 111 Symbol for JK flip-flop

                                                                                  (a) positive-edge triggering (b) active low Preset (PR) and Clear (CLR) with positive-edge triggering

                                                                                  (c) active low Preset (PR) and Clear (CLR) with negative-edge triggering

                                                                                  Logic Design amp Switching Theory 1 Lab Session 11 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                                  49

                                                                                  TESTING OF 7473 7476 DUAL JK FLIP-FLOP

                                                                                  Both the ICs 7473 and 7476 are similar in functionality except for one difference The flip-flops in 7473 have only one type of active low asynchronous input which is the Clear input whereas the flip-flops in 7476 have both Preset and Clear inputs Both these ICs have negative edge triggered flip-flops

                                                                                  Circuit Diagram

                                                                                  Figure 112 Pin connections of 7476

                                                                                  Testing Procedure

                                                                                  bull Make connections as shown in the circuit diagram (figure 112) bull Apply different combinations of 1s and 0s at J and K inputs bull Observe the output and record your observations in the following table

                                                                                  Observations

                                                                                  J

                                                                                  K Q

                                                                                  0 0 0 1 1 0 1 1

                                                                                  ACTIVITY

                                                                                  1 Observe the output Q of JK flip-flop if the clock input is connected to VCC or GND instead of a clock source Write your observations here __________________________________________________________________________________________________________________________________________ _______________________________________________________________________________________________________________________________________________________________________________________________________________

                                                                                  Logic Design amp Switching Theory 1 Lab Session 12 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                                  50

                                                                                  Lab Session 12 OBJECT

                                                                                  Designing sequential circuit for the given state diagram using D flip-flop GIVEN STATE DIAGRAM

                                                                                  00

                                                                                  11

                                                                                  Figure 121 State Diagram COMPONENTS AND APPARATUS REQUIRED 1 Following ICs and their Datasheets

                                                                                  bull 7474 D Flip-Flop bull ICs of basic gates (AND OR NOT XOR etc) as required

                                                                                  2 Digital Trainer DT-01 or the following components Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches

                                                                                  THEORY

                                                                                  Sequential Circuits In Sequential Circuits the output not only depends on the present inputs but also on previous states of the circuit These circuits use memory elements (latches flip-flops) and the binary information stored in the memory elements at any given time defines the state of the sequential circuit Analysis of a Sequential Circuit The behavior of a sequential circuit is determined from the inputs the outputs and the states of its flip-flops Both the outputs and next state are a function of the inputs and the

                                                                                  10

                                                                                  01

                                                                                  00 11 10

                                                                                  00

                                                                                  00 11 10 00

                                                                                  Logic Design amp Switching Theory 1 Lab Session 12 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                                  51

                                                                                  present state The analysis of a sequential circuit form a state diagram comprises of the following bull Selecting a particular flip-flop to design the circuit bull Obtaining state table from the state diagram bull Finding input equations for the selected flip-flop bull Finding state equations (not required for the construction of circuit) bull Implementing the circuit using selected flip-flops and their input equations ANALYZING THE GIVEN STATE DIAGRAM D Flip-Flop D flip-flop is also called transparent flip-flop as it simply transfers the input data to the output For our design we require the graphical symbol and excitation table of D flip-flop (see figure 122)

                                                                                  Qt Qt+1 T 0 0 0 0 1 1 1 0 0 1 1 1

                                                                                  (b) Excitation table of D Flip-Flop

                                                                                  (a) Graphical Symbol

                                                                                  Figure 122 Characteristic equation of D flip-flop is Q(t+1) = D State Table The given state diagram has four states so we will need two D flip-flops (FF-0 FF-1) Form state table form the given state diagram and record the results in the following table

                                                                                  Present State Input Next State Output Input to FF-0 D0

                                                                                  Input to FF-1 D1 Q1t Q0t x Q1(t+1) Q0(t+1) z

                                                                                  Logic Design amp Switching Theory 1 Lab Session 12 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                                  52

                                                                                  Input Equations Using Karnaugh map the input equations D0 and D1 for the two flip-flops can be found

                                                                                  D0 D1 Q0x

                                                                                  Q1

                                                                                  _ _ Q0x

                                                                                  _ Q0x

                                                                                  Q0x

                                                                                  _ Q0x

                                                                                  Q0x

                                                                                  Q1

                                                                                  _ _ Q0x

                                                                                  _ Q0x

                                                                                  Q0x

                                                                                  _ Q0x

                                                                                  _ Q1

                                                                                  _ Q1

                                                                                  Q1

                                                                                  Q1

                                                                                  D0 = _________________ D1 = _________________

                                                                                  State Equations Using the characteristic equation of D flip-flop we can find the state equations Q0(t+1) and Q1(t+1) for the to flip flops Q0(t+1) = _______________________ Q1(t+1) = _______________________ _______________________ _______________________ _______________________ _______________________ Circuit Diagram

                                                                                  Logic Design amp Switching Theory 1 Lab Session 12 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                                  53

                                                                                  Implementation Procedure and Observations

                                                                                  1 Implement the circuit using digital ICs on a bread board (prepare the pin diagram (use appendix A) and refer to laboratory session 01 for procedure)

                                                                                  2 Make the clear inputs of the flip-flops low (to clear the flip-flops) The flip-flops will remain in clear state as long as the clear inputs are connected to low level

                                                                                  3 Connect output Q0 and the clock pulse to an oscilloscope 4 Apply 0 to the input x 5 Now make the clear inputs to high 6 Observe the waveform for the first 5 clock pulses and record it 7 Repeat steps 2 to 6 keeping x=1 in step 4 this time 8 Repeat steps 2 to 7 this time connecting Q1 instead of Q0 to the oscilloscope in step

                                                                                  3 Record your observations (Keep frequency of the clock pulse low (eg1Hz) so that the output waveforms can be observed easily)

                                                                                  1 2 3 4 5 Clock Pulse

                                                                                  Output Waveform for Q0 when x=0

                                                                                  Output Waveform for Q0 when x=1

                                                                                  Output Waveform for Q1 when x=0

                                                                                  Output Waveform for Q1 when x=1

                                                                                  Logic Design amp Switching Theory 1 Lab Session 13 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                                  Lab Session 13 OBJECT

                                                                                  Designing a modulo-5 asynchronous up-counter using JK-FF COMPONENTS AND APPARATUS REQUIRED

                                                                                  1 Following ICs and their Datasheets

                                                                                  bull 7400 Quad 2-input or 7410 Triple 3-input NAND Gates bull 7476 7473 JK Flip-Flop

                                                                                  2 Digital Trainer DT-01 or the following components Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches

                                                                                  THEORY

                                                                                  Digital Counters A digital counter is a set of flip-flops whose states change in response to pulses applied at the input to the counter The flip-flops are interconnected so that their combined state at any time is the binary equivalent of the total number of pulses that have occurred up to that time Every counter resets after a certain number of clock pulses Thus as it name implies a counter is used to count pulses An n stage counter can count up to a maximum of 2n states n is equal to the number of flip-flops required for the construction of counter

                                                                                  Modulus Counters The number of input pulses that causes a counter to reset to its initial count is called the modulus of the counter Thus the modulus equals to total number of distinct states (counts) including zero that a counter can store A binary counter with n stages is a modulo-2n (or mod-2n) counter The largest count a mod-N counter can achieve is N-1 ie a mod-N counter never reaches the binary number equal to its modulus N is always equal to or less than 2n Counters can be classified as bull Synchronous Counters which are clock driven All the flip-flops are driven by a

                                                                                  single clock bull Asynchronous Counters which are event driven Clock input is given to the first

                                                                                  flip-flop only Rest of the flip-flops are driven by their preceding flip-flops

                                                                                  DESIGN OF A MOD-5 ASYNCHRONOUS UP COUNTER The number of flip-flops required to construct a mod-5 counter is 3 because 5 should be less than or equal to 2n This counter will count from 0 to 4 a total of 5 distinct states Since a 3-stage counter can count up to 8 states at maximum a NAND gate is used to reset it after 5 clock pulses Figure 131 shows the logic diagram

                                                                                  54

                                                                                  Logic Design amp Switching Theory 1 Lab Session 13 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                                  55

                                                                                  Figure 131 A Mod-5 Asynchronous Up Counter

                                                                                  Implementation and Observations

                                                                                  Implement the mod-5 counter circuit (figure 131) on a bread board (prepare the pin diagram (use appendix A) and refer to laboratory session 01 for implementation procedure) and record the observations in the following table

                                                                                  Clock Pulse Q2 Q1 Q0

                                                                                  0 1 2 3 4 5 6 7

                                                                                  ACTIVITY

                                                                                  Draw the timing diagram for mod-5 counter designed in this laboratory session

                                                                                  Logic Design amp Switching Theory 1 Lab Session 14 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                                  Lab Session 14 OBJECT

                                                                                  Experimenting with 74194 4-bit bidirectional universal shift register COMPONENTS AND APPARATUS REQUIRED

                                                                                  1 Following ICs and their Datasheets

                                                                                  bull 74194 4-bit bidirectional universal shift register 2 Digital Trainer DT-01 or the following components

                                                                                  Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches

                                                                                  THEORY

                                                                                  Shift Registers

                                                                                  A Register is a set of flip-flops used to store binary data A register which is capable of shifting its binary information either to the right or left is called a shift register The logical configuration of a register consists of a chain of flip-flops connected in cascade with the output of one flip-flop connected to the input of next flip-flop All flip-flops receive a common clock pulse which causes the shift from one stage to the next

                                                                                  Bidirectional Shift Registers A bi-directional shift register is one whose bits can be shifted from left to right or from right to left

                                                                                  Universal Shift Registers A universal shift register is a bi-directional register whose input can be in either serial or parallel form and whose output can be in either serial or parallel form

                                                                                  74194 4-BIT BIDIRECTIONAL UNIVERSAL SHIFT REGISTER

                                                                                  The 74194 register provides parallel as well as serial loading in both directions Function of various pins of this IC is described below

                                                                                  bull A B C and D Active high inputs for parallel loading bull QA QB QC and QD Active high outputs bull S0 and S1 Active high mode control inputs The following table shows combinations

                                                                                  of S1 and S0 to enable various modes

                                                                                  S1 S0 Clock Action 0 0 x No change 0 1 uarr Shift right 1 0 uarr Shift left 1 1 uarr Parallel load

                                                                                  uarr shows the rising edge of the clock pulse

                                                                                  56

                                                                                  Logic Design amp Switching Theory 1 Lab Session 14 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering bull SR Active high serial input for right shifting bull SL Active high serial input for left shifting bull CLR Active low input Clears all the flip-flops of the register if set to 0 should be

                                                                                  kept high otherwise bull CLK Clock input bull VCC and GND Supply connections lines Thus A B C and D are inputs for parallel loading whereas SR and SL are inputs for serial loading with right or left shifting respectively S1 and S0 are used to select the loading mode Circuit Diagram

                                                                                  Figure 141 Pin connections of 74194 Testing Procedure

                                                                                  bull Make connections as shown in the circuit diagram bull Observe the output for the input combinations given in the following table

                                                                                  57

                                                                                  Logic Design amp Switching Theory 1 Lab Session 14 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                                  58

                                                                                  Observations

                                                                                  S1 S0 SL SR A B C D QA QB QC QD 0 0 0 1 0 0 0 0 0 1 1 0 0 0 0 1 1 0 0 0 0 0 1 0 1 1 0 0 0 0 1 1 0 0 1 1 0 1 0 0 0 1 1 1 0 1 0 1 1 0 1 0 0 1 1 0 1 1 1 0 0 1 1 1 1 1 0 0 1 1 1 1

                                                                                  ACTIVITY 1 Show connections of 74194 to convert it into a ring counter with right shifting

                                                                                  Logic Design amp Switching Theory 1 Lab Session 15 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                                  Lab Session 15

                                                                                  OBJECT

                                                                                  Experimenting with 74245 octal bus transceivers using parallel port PC interfacing COMPONENTS AND APPARATUS REQUIRED 1 Parallel Port Connectors (DB-25) with Cable 2 Personal Computer with Windows 98 and TurboC Compiler Installed 3 Following ICs and their Datasheets

                                                                                  bull 74245 Octal Bus Transceivers with 3-State Outputs 4 Digital Trainer DT-01 or the following components

                                                                                  Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches

                                                                                  THEORY

                                                                                  3-State Logic Sometimes it is necessary to isolate one part of circuit from the other part For this purpose some TTL ICs are designed with 3-state logic Such devices have three possible output states high low and high impedance The device can be put into high impedance state by a control signal applied to an appropriate pin When such a device is in high impedance state there is very high impedance at its output effectively isolating the device from whatever circuitry the output normally drives 74245 Octal Bus Transceivers A bus is any conducting path or set of paths having electrical connections to one or more devices 74245 octal bus transceivers are mainly used to control connectivity between two devices or circuits It also provides direction control for signal flow Function of various pin of this IC is given below

                                                                                  bull A1 through A8 Bus A bull B1 through B8 Bus B bull G΄ Active low enable input When high sets all the bus pins to high impedance state bull DIR Direction control for signal flow When set to high logic level transfers bus A

                                                                                  data to B bus When set to low logic level transfers bus B data to A bus bull VCC and GND Supply connections lines Serial and Parallel Port Connectors A Parallel Port can consist of only 25 pin port adapter called a DB-25 and a serial port can consist of either a 25 pin port adapter called a DB-25 or 9 pin adapter called a DB-9 port adapter Whether the port is a 9 pin or 25 pin it can accomplish all of the same tasks that serial port communications have been designed for

                                                                                  59

                                                                                  Logic Design amp Switching Theory 1 Lab Session 15 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                                  60

                                                                                  Each adapter can be a male type connector with pins or a female type adapter with tiny holes Generally a PRINTER port (called LPT1) on the back of a computer is female type adapter and we need to use MALE DB-25 pin cable on it for PRINTER connection or for parallel LAPLINK cable And a COM port on the back of a computer is male for the serial ports but it may not necessarily be Parallel Port Connector ndash DB-25 The DB-25 connector (named for its B-size D-shaped shell and 25 pins) is practically ubiquitous in the electronics industry The DB-25 connector is used for a variety of purposes Two common applications are RS-232EIA-232 (serial) connections and the parallel printer interface on the IBM PC The DB-25 connector is also used for SCSI connections Normally the parallel port is used for output to a printer or other device It sends data 8-bits or one byte at a time in parallel The other lines available on the DB-25 connector are a combination of status lines control lines and ground lines The status and control lines are used for handshaking commands and feedback when we are talking to a printer

                                                                                  Figure 152 DB-25 Female Figure 151 DB-25 Male

                                                                                  Figure 153 Pin Layout for DB-25 As can be seen form figure 153 there are four types of pins in this connector

                                                                                  bull Data pins (8 pins - D0 to D7) Active high bidirectional lines

                                                                                  Logic Design amp Switching Theory 1 Lab Session 15 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering bull Control pins (4 pins - C0 to C3) C0 C1 and C3 are active low whereas C2 is active

                                                                                  high These lines also are bidirectional bull Status pins (5 pins ndash S3 to S7) Only S7 is active low rest are active high input lines bull Ground pins (8 pins) Used as a reference signal for the low (below 05 volts) charge

                                                                                  Parallel Port Addresses A DB-25 connector at a parallel port has three address one for each kind of pins register data status and control The first or base address generally refers to data register Second address is for status register and the third one is for control register In Windows 98 the base address is usually found to be 278H 378H or 3BCH Now if 378H is the base address then it refers to the data register whereas addresses for status and control register are respectively 379H and 37AH For Windows 98 the base address can be found as follows 1 On your Desktop right-click on My Computer and select Properties 2 Click on the Device Manager tab and find LPT1 under Plug and Play BIOS 3 After selecting LPT1 click the Properties button 4 Next select the Resources tab and the address should then appear next to InputOutput

                                                                                  Range Accessing parallel port through C Language Programming There are multiple functions in C Language for accessing external ports The most commonly used are listed below

                                                                                  bull unsigned char inportb(int portid) inportb reads a byte from a hardware port

                                                                                  bull int inport(int portid) reads a word from a hardware port

                                                                                  bull void outportb(int portid unsigned char value) outputs a byte to a hardware port

                                                                                  bull void outport(int portid int value) outputs a word to a hardware port

                                                                                  portid refers to the port address whereas value refers to the data to be sent TESTING 74245 USING PARALLEL PORT PC INTERFACING At one end the parallel port connector will be connected to the PC via parallel port cable and another connector (to be plugged into the PC parallel port slot) At the other end it will be connected to the buffer IC 74245 Data lines of the connector will be used to transfer 8-bit data between the PC and the buffer Out of the 8-bits of 74245 4-bits will be used to enter data which will be displayed at the monitor through a C language

                                                                                  61

                                                                                  Logic Design amp Switching Theory 1 Lab Session 15 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering program The remaining 4-bits will receive data from PC as entered by the user via keyboard

                                                                                  Circuit Diagram

                                                                                  Figure 154 Interface of 74245 to PC via Parallel Port

                                                                                  Procedure

                                                                                  1 Connect the DB-25 connector to the PC at one end and solder it to the circuit board at the other end

                                                                                  2 Connect various pins of the connector and 74245 according to the circuit diagram shown in figure 152

                                                                                  3 Using the functions listed in the previous section write a program in C language to operate various pins of the buffer The user interface of the program should provide option to the user whether to send or receive data from the port

                                                                                  4 Set DIR switch to 1 5 Try sending some data bits to the port The result should be displayed at the LEDs 6 Set DIR switch to 0 7 Set some binary 4-bit value through the switches Try reading it via parallel port

                                                                                  C Language Program

                                                                                  A program to access parallel port for data transfers

                                                                                  use header file include ltstdiohgt main program void main() define variable

                                                                                  62

                                                                                  Logic Design amp Switching Theory 1 Lab Session 15 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering unsigned int data=0 char choice while(1) printing option menu clrscr() printf(This program will send or receive a BCD digit from the parallel portn) printf(nPress your choice numbern) printf(n1 Send Data) printf(n2 Receive Data) printf(n3 Exitn) choice = getch() sending entered digit to the port if(choice == 1) input BCD digit printf(nEnter BCD digit to be sent to the port) data = getche() masking the first four bits data = data amp 0x0f sending to the port outportb(0x378data) printf(nThe BCD digit c has been sent to the port data) printing on screen the data received from the port else if(choice == 2) receiving data from the port data = inportb(0x378) masking the last four bits data = data amp 0xf0 shifting first four bits to make them the last four bits datagtgt=4 printf(nThe BCD digit set at the port is c data) exit else if(choice == 3) break key pressed is not in the menu else printf(nEnter valid choice number) printf(nnPress any key to continue) getch()

                                                                                  63

                                                                                  Logic Design amp Switching Theory 1 Lab Session 15 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                                  ACTIVITY 1 In the above circuit DIR and G΄ inputs are hardwired Connect them to status or

                                                                                  control pins of the parallel port connector and control their function through your software program Circuit Diagram Program Code ______________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________

                                                                                  ___________________________________________________________________________________________________________________________________________________

                                                                                  64

                                                                                  Logic Design amp Switching Theory 1 Lab Session 15 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                                  65

                                                                                  _____________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ _____________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ _______________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ _________________________________________________ _________________________________________________

                                                                                  Logic Design amp Switching Theory 1 Appendix A NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                                  Appendix A

                                                                                  PIN DIAGRAMS OF THE ICS REQUIRED FOR THE LABORATORY SESSIONS Consult the TTLIC data book for internal diagrams and electrical characteristics of these ICs 7400 Quad 2-Input NAND 7402 Quad 2-Input NOR

                                                                                  7404 Hex Inverter 7408 Quad 2-Input AND

                                                                                  7410 Triple 3-Input NAND 7411 Triple 3-Input AND

                                                                                  7421 Dual 4-Input AND 7432 Quad 2-Input OR

                                                                                  66

                                                                                  Logic Design amp Switching Theory 1 Appendix A NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                                  BCD-to-Seven Segm 7448 BCD-to-Seven Segment 7447 ent

                                                                                  Decoder (15V OC) Decoder (2kΩ pull-up output)

                                                                                  7473 Dual JK Flip-Flop 7474 Dual D-Type Flip-Flop

                                                                                  7476 Dual JK Flop-Flop -Bit Binary Full Adder 7483 4 with Fast Carry

                                                                                  86 Quad 2-Inpu 74138 3-to-8 Line 74 t Exclusive OR Decoder Demultiplexer

                                                                                  67

                                                                                  Logic Design amp Switching Theory 1 Appendix A NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                                  68

                                                                                  74148 8-to-3 Line 16-to-1 Line Data

                                                                                  Priority Encoder 74150 Selector Multiplexer

                                                                                  74245 Oct nsceivers Universal Shift Register (PIPO) (3-State)

                                                                                  74194 4-Bit Bidirectional al Bus Tra

                                                                                  Logic Design amp Switching Theory 1 Appendix B NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                                  Appendix B

                                                                                  DEBOUNCING CIRCUITRY FOR MECHANICAL SWITCHES Mechanical switches form the interface between human beings and computers or other digital systems For example a keyboard is a matrix of switches used to supply alphanumeric data to a computer Whatever the switch design it is a potential source of problems due to contact bounce The contact bounce creates a sense of narrow pulses when a switch is opened or closed An example of device whose operation would be adversely affected by contact bounce is a digital counter used to count the number of times a switch is depressed Eliminating the effects of contact bounce is called debouncing When data is entered into a computer via a keyboard a software debounce is often used This type of debouncing is a program that causes the computer to sample the switch terminal (ie to input data from it) many times in succession during the interval of time that contact bounce occurs If the data is sensed to be 1s (or 0s) for a specific number of consecutive samples then it is assumed that contact bounce has ended and the last value sensed is valid Hardware debouncing is the use of electronic circuitry to eliminate the effects of contact bounce There are numerous versions of such circuitry including those that use monostable multivibrators (one-shots) but the most straightforward is simply an RS latch Figure B1 shows the circuit When the switch is in position 1 R = 0 and S = 1 so the latch is set and the output (Q) is 1 When the switch is in position 0 R = 1and S = 0 so the latch is reset and the output is 0 When the switch is moved form one position to the other the latch changes state and bouncing occurs at either the R or the S input The bouncing does not affect the latch after it has change state An RS latch will remain set for example when its R input is 0 and its S input is alternately changed form 1 to 0

                                                                                  Figure B1 Use of RS latch to debounce a mechanical switch

                                                                                  69

                                                                                  • 01-ldst-Outer title
                                                                                    • Practical Workbook
                                                                                    • Logic Design amp Switching Theory I
                                                                                      • Dept of Computer amp Information Systems Engineering
                                                                                        • NED University of Engineering amp Technology
                                                                                        • Karachi ndash 75270 Pakistan
                                                                                          • 02-ldst-inner Title
                                                                                            • Practical Workbook
                                                                                            • Logic Design amp Switching Theory I
                                                                                              • Dept of Computer amp Information Systems Engineering
                                                                                                • NED University of Engineering amp Technology
                                                                                                • Karachi ndash 75270 Pakistan
                                                                                                  • 03-ldst-general info
                                                                                                  • 04-ldst-introduction
                                                                                                  • 05-Table of Contents
                                                                                                    • CONTENTS
                                                                                                      • Lab Session No Object Page No
                                                                                                      • 1
                                                                                                      • Also implementing and testing the given circuit on a bread board
                                                                                                        • Working with Electronics Workbench
                                                                                                          • Driving a seven segment display using 7447 7448 driver IC
                                                                                                            • Designing a modulus-5 asynchronous up-counter using JK-FF
                                                                                                              • Experimenting with 74194 4-bit bidirectional universal shift register
                                                                                                                  • 13
                                                                                                                      • 06-ldst-Exp01
                                                                                                                        • Lab Session 01
                                                                                                                        • OBJECT
                                                                                                                          • 1 Bread board
                                                                                                                          • 2 5 V - power supply
                                                                                                                          • 3 Multimeter
                                                                                                                          • 4 Logic probe
                                                                                                                          • 5 LEDs with resistors
                                                                                                                          • 6 Connecting wires
                                                                                                                          • 8 Following ICs and their datasheets
                                                                                                                            • THEORY
                                                                                                                              • Logic Gates
                                                                                                                              • 1 The AND Gate ndash An AND gatersquos output is 1 if and only if all its inputs are 1 If A and B are two inputs to an AND gate then output F of the gate is given as F = AB
                                                                                                                              • 2 The OR Gate - An OR gatersquos output is 1 if at least one of its input is 1 If A and B are two inputs to an OR gate then output F of the gate is given as F = A+B
                                                                                                                              • 3 The NOT Gate (Inverter) ndash Its output is 1 when its input is 0 and its output is 0 when the input is 1 ie it complements a digital variable If A is the input to a NOT gate then output F of the gate is given as
                                                                                                                              • 4 The NAND Gate ndash Its output is 1 if at least one of its input is 0 This gate performs the same logic as an AND gate followed by an inverter If A and B are two inputs to a NAND gate then output F of the gate is given as
                                                                                                                                • 5 The NOR Gate - The output of a NOR gate is 1 if and only if all its inputs are 0 This gate performs the same logic function as an OR gate followed by an inverter If A and B are two inputs to a NAND gate then output F of the gate is given as
                                                                                                                                    • DATA SHEETS
                                                                                                                                      • Logic expression for the given logic diagram __________________________________
                                                                                                                                          • 07-ldst-exp02
                                                                                                                                            • Working with Electronics Workbench
                                                                                                                                              • 08-ldst-exp03
                                                                                                                                                • Designing Half and Full Adder Circuits
                                                                                                                                                  • COMPONENTS AND APPARATUS REQUIRED
                                                                                                                                                    • 1 Following ICs and their Datasheets
                                                                                                                                                    • 7408 Quad 2-input AND Gate
                                                                                                                                                    • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                      • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                      • Connecting wires Switches
                                                                                                                                                        • THEORY
                                                                                                                                                            • IMPLEMENTATION AND OBSERVATIONS
                                                                                                                                                              • 09-ldst-Exp04
                                                                                                                                                                • Lab Session 04
                                                                                                                                                                • 1 Digital ICs and their Datasheets
                                                                                                                                                                • 7408 Quad 2-input AND Gate
                                                                                                                                                                • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                  • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                  • Connecting wires Switches
                                                                                                                                                                  • PROCEDURE
                                                                                                                                                                  • REDUCTION OF LOGIC EXPRESSION USING KARNAUGH MAP
                                                                                                                                                                  • OBSERVATIONS
                                                                                                                                                                  • RESULT
                                                                                                                                                                      • 10-ldst-Exp05
                                                                                                                                                                        • Lab Session 05
                                                                                                                                                                        • 1 Following ICs and their Datasheets
                                                                                                                                                                        • 7408 Quad 2-input AND Gate
                                                                                                                                                                        • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                          • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                          • (100 Ω) Connecting wires Switches
                                                                                                                                                                          • THEORY
                                                                                                                                                                            • IMPLEMENTATION AND OBSERVATIONS
                                                                                                                                                                              • 11-ldst-Exp06
                                                                                                                                                                                • OBJECT
                                                                                                                                                                                • 1 Following ICs and their Datasheets
                                                                                                                                                                                • 7408 Quad 2-input AND Gates or 7411 Triple 3-input AND Gates
                                                                                                                                                                                • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                  • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                  • Connecting wires Switches
                                                                                                                                                                                    • Figure 62 Circuit Diagram for 4 x 1 Multiplexer
                                                                                                                                                                                    • Implementation and Observations
                                                                                                                                                                                      • Circuit Diagram
                                                                                                                                                                                        • ACTIVITY
                                                                                                                                                                                          • 12-ldst-exp07
                                                                                                                                                                                            • 1 Following ICs and their Datasheets
                                                                                                                                                                                            • 7408 Quad 2-input or 7411 Triple 3-input AND Gates
                                                                                                                                                                                            • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                              • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                              • Connecting wires Switches
                                                                                                                                                                                                • THEORY
                                                                                                                                                                                                    • Figure 72 Circuit Diagram for 2 x 4 Decoder 1 x 4 Demultiplexer
                                                                                                                                                                                                    • Implementation and Observations
                                                                                                                                                                                                      • Circuit Diagram
                                                                                                                                                                                                        • ACTIVITY
                                                                                                                                                                                                          • 13-ldst-Exp08
                                                                                                                                                                                                            • OBJECT
                                                                                                                                                                                                            • 1 Following ICs and their Datasheets
                                                                                                                                                                                                            • 7408 Quad 2-input or 7421 Dual 4-input AND Gates
                                                                                                                                                                                                            • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                              • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                              • Connecting wires Switches
                                                                                                                                                                                                                • THEORY
                                                                                                                                                                                                                    • Figure 81 Circuit Diagram for 4 x 2 Priority Encoder
                                                                                                                                                                                                                    • Implementation and Observations
                                                                                                                                                                                                                      • Therefore if GS A2 A1 and A0 are all low then it shows that line 0 is selected and if E0 A2 A1 and A0 are all low then it shows that none of the inputs selected E0 and GS cannot be in the same state provided that E1 is enabled
                                                                                                                                                                                                                      • Circuit Diagram
                                                                                                                                                                                                                        • ACTIVITY
                                                                                                                                                                                                                          • 14-ldst-exp09
                                                                                                                                                                                                                            • OBJECT
                                                                                                                                                                                                                            • 1 Following ICs and their Datasheets
                                                                                                                                                                                                                            • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                              • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                                              • Connecting wires Switches
                                                                                                                                                                                                                                • THEORY
                                                                                                                                                                                                                                  • Parity Generator
                                                                                                                                                                                                                                    • Let x y and z be the three bits that constitute the message and are the input to the Odd Parity Generator Circuit Since it is an odd parity system the bit P is generated so as to make the total number of 1s odd (including P) The function P can be expressed as follows
                                                                                                                                                                                                                                    • Figure 91 Circuit Diagram for a 3-bit Parity Generator
                                                                                                                                                                                                                                      • C = x Ο y Ο z Ο P
                                                                                                                                                                                                                                        • Implementation and Observations
                                                                                                                                                                                                                                          • ACTIVITY
                                                                                                                                                                                                                                              • 15-ldst-exp10
                                                                                                                                                                                                                                                • Driving a seven segment display using 7447 7448 driver IC
                                                                                                                                                                                                                                                • COMPONENTS AND APPARATUS REQUIRED
                                                                                                                                                                                                                                                • 1 Following ICs and their Datasheets
                                                                                                                                                                                                                                                • 7447 7448 BCD to Seven Segment Driver
                                                                                                                                                                                                                                                • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                                                  • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches
                                                                                                                                                                                                                                                    • THEORY
                                                                                                                                                                                                                                                    • Seven Segment Displays
                                                                                                                                                                                                                                                    • CIRCUIT DIAGRAM
                                                                                                                                                                                                                                                    • Figure 102 Circuit diagram for 7447driving a common-anode display
                                                                                                                                                                                                                                                        • IMPLEMENTATION AND OBSERVATIONS
                                                                                                                                                                                                                                                          • Decimal Digit
                                                                                                                                                                                                                                                          • BCD Inputs
                                                                                                                                                                                                                                                          • Seven Segment Outputs
                                                                                                                                                                                                                                                          • D
                                                                                                                                                                                                                                                          • C
                                                                                                                                                                                                                                                          • B
                                                                                                                                                                                                                                                          • A
                                                                                                                                                                                                                                                          • a
                                                                                                                                                                                                                                                          • b
                                                                                                                                                                                                                                                          • c
                                                                                                                                                                                                                                                          • d
                                                                                                                                                                                                                                                          • e
                                                                                                                                                                                                                                                          • f
                                                                                                                                                                                                                                                          • g
                                                                                                                                                                                                                                                          • 0
                                                                                                                                                                                                                                                          • 0
                                                                                                                                                                                                                                                          • 0
                                                                                                                                                                                                                                                          • 0
                                                                                                                                                                                                                                                          • 0
                                                                                                                                                                                                                                                          • 1
                                                                                                                                                                                                                                                          • 0
                                                                                                                                                                                                                                                          • 0
                                                                                                                                                                                                                                                          • 0
                                                                                                                                                                                                                                                          • 1
                                                                                                                                                                                                                                                          • 2
                                                                                                                                                                                                                                                          • 0
                                                                                                                                                                                                                                                          • 0
                                                                                                                                                                                                                                                          • 1
                                                                                                                                                                                                                                                          • 0
                                                                                                                                                                                                                                                          • 3
                                                                                                                                                                                                                                                          • 0
                                                                                                                                                                                                                                                          • 0
                                                                                                                                                                                                                                                          • 1
                                                                                                                                                                                                                                                          • 1
                                                                                                                                                                                                                                                          • 4
                                                                                                                                                                                                                                                          • 0
                                                                                                                                                                                                                                                          • 1
                                                                                                                                                                                                                                                          • 0
                                                                                                                                                                                                                                                          • 0
                                                                                                                                                                                                                                                          • 5
                                                                                                                                                                                                                                                          • 0
                                                                                                                                                                                                                                                          • 1
                                                                                                                                                                                                                                                          • 0
                                                                                                                                                                                                                                                          • 1
                                                                                                                                                                                                                                                          • 6
                                                                                                                                                                                                                                                          • 0
                                                                                                                                                                                                                                                          • 1
                                                                                                                                                                                                                                                          • 1
                                                                                                                                                                                                                                                          • 0
                                                                                                                                                                                                                                                          • 7
                                                                                                                                                                                                                                                          • 0
                                                                                                                                                                                                                                                          • 1
                                                                                                                                                                                                                                                          • 1
                                                                                                                                                                                                                                                          • 1
                                                                                                                                                                                                                                                          • 8
                                                                                                                                                                                                                                                          • 1
                                                                                                                                                                                                                                                          • 0
                                                                                                                                                                                                                                                          • 0
                                                                                                                                                                                                                                                          • 0
                                                                                                                                                                                                                                                          • 9
                                                                                                                                                                                                                                                          • 1
                                                                                                                                                                                                                                                          • 0
                                                                                                                                                                                                                                                          • 0
                                                                                                                                                                                                                                                          • 1
                                                                                                                                                                                                                                                            • ACTIVITY
                                                                                                                                                                                                                                                              • 16-ldst-exp11
                                                                                                                                                                                                                                                                • Lab Session 11
                                                                                                                                                                                                                                                                  • OBJECT
                                                                                                                                                                                                                                                                  • COMPONENTS AND APPARATUS REQUIRED
                                                                                                                                                                                                                                                                    • 1 Following ICs and their Datasheets
                                                                                                                                                                                                                                                                    • 7473 7476 JK Flip-Flop
                                                                                                                                                                                                                                                                    • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                                                                      • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                                                                                      • Connecting wires Switches
                                                                                                                                                                                                                                                                        • THEORY
                                                                                                                                                                                                                                                                            • Flip-Flop
                                                                                                                                                                                                                                                                            • JK Flip-Flop
                                                                                                                                                                                                                                                                              • Circuit Diagram
                                                                                                                                                                                                                                                                                • Observations
                                                                                                                                                                                                                                                                                  • ACTIVITY
                                                                                                                                                                                                                                                                                      • 17-ldst-exp12
                                                                                                                                                                                                                                                                                        • Lab Session 12
                                                                                                                                                                                                                                                                                          • OBJECT
                                                                                                                                                                                                                                                                                          • GIVEN STATE DIAGRAM
                                                                                                                                                                                                                                                                                          • Figure 121 State Diagram
                                                                                                                                                                                                                                                                                          • COMPONENTS AND APPARATUS REQUIRED
                                                                                                                                                                                                                                                                                            • 1 Following ICs and their Datasheets
                                                                                                                                                                                                                                                                                            • 7474 D Flip-Flop
                                                                                                                                                                                                                                                                                            • ICs of basic gates (AND OR NOT XOR etc) as required
                                                                                                                                                                                                                                                                                            • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                                                                                              • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                                                                                                              • Connecting wires Switches
                                                                                                                                                                                                                                                                                                • THEORY
                                                                                                                                                                                                                                                                                                    • Sequential Circuits
                                                                                                                                                                                                                                                                                                      • 18-ldst-exp13
                                                                                                                                                                                                                                                                                                        • Lab Session 13
                                                                                                                                                                                                                                                                                                          • Designing a modulo-5 asynchronous up-counter using JK-FF
                                                                                                                                                                                                                                                                                                            • 1 Following ICs and their Datasheets
                                                                                                                                                                                                                                                                                                            • 7400 Quad 2-input or 7410 Triple 3-input NAND Gates
                                                                                                                                                                                                                                                                                                            • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                                                                                                              • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                                                                                                                              • Connecting wires Switches
                                                                                                                                                                                                                                                                                                                • THEORY
                                                                                                                                                                                                                                                                                                                    • Figure 131 A Mod-5 Asynchronous Up Counter
                                                                                                                                                                                                                                                                                                                    • Implementation and Observations
                                                                                                                                                                                                                                                                                                                      • ACTIVITY
                                                                                                                                                                                                                                                                                                                          • 19-ldst-exp14
                                                                                                                                                                                                                                                                                                                            • Experimenting with 74194 4-bit bidirectional universal shift register
                                                                                                                                                                                                                                                                                                                            • 1 Following ICs and their Datasheets
                                                                                                                                                                                                                                                                                                                            • 74194 4-bit bidirectional universal shift register
                                                                                                                                                                                                                                                                                                                            • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                                                                                                                              • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                                                                                                                                              • Connecting wires Switches
                                                                                                                                                                                                                                                                                                                                • THEORY
                                                                                                                                                                                                                                                                                                                                  • Shift Registers
                                                                                                                                                                                                                                                                                                                                  • Bidirectional Shift Registers
                                                                                                                                                                                                                                                                                                                                  • Universal Shift Registers
                                                                                                                                                                                                                                                                                                                                    • S1
                                                                                                                                                                                                                                                                                                                                      • Circuit Diagram
                                                                                                                                                                                                                                                                                                                                      • ACTIVITY
                                                                                                                                                                                                                                                                                                                                          • 20-ldst-exp15
                                                                                                                                                                                                                                                                                                                                            • COMPONENTS AND APPARATUS REQUIRED
                                                                                                                                                                                                                                                                                                                                            • 1 Parallel Port Connectors (DB-25) with Cable
                                                                                                                                                                                                                                                                                                                                            • 2 Personal Computer with Windows 98 and TurboC Compiler Installed
                                                                                                                                                                                                                                                                                                                                            • 3 Following ICs and their Datasheets
                                                                                                                                                                                                                                                                                                                                            • 74245 Octal Bus Transceivers with 3-State Outputs
                                                                                                                                                                                                                                                                                                                                            • 4 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                                                                                                                                              • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                                                                                                                                                                • Connecting wires Switches
                                                                                                                                                                                                                                                                                                                                                  • THEORY
                                                                                                                                                                                                                                                                                                                                                  • 3-State Logic
                                                                                                                                                                                                                                                                                                                                                    • Serial and Parallel Port Connectors
                                                                                                                                                                                                                                                                                                                                                    • Parallel Port Connector ndash DB-25
                                                                                                                                                                                                                                                                                                                                                      • Accessing parallel port through C Language Programming
                                                                                                                                                                                                                                                                                                                                                          • 21-ldst-appendixA
                                                                                                                                                                                                                                                                                                                                                          • 22-ldst-appendixB
                                                                                                                                                                                                                                                                                                                                                            • DEBOUNCING CIRCUITRY FOR MECHANICAL SWITCHES

                                                                                    Logic Design amp Switching Theory 1 Lab Session 09 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering `

                                                                                    44

                                                                                    Figure 92 Circuit Diagram for a 3-bit Parity Checker Implementation and Observations Implement the 3-bit Parity Generator and Checker circuits (figure 91 and 92) on a bread board (prepare the pin diagram (use appendix A) and refer to laboratory session 01 for implementation procedure) and record the observations in the following table

                                                                                    x y z P x y z P C x y z P C 0 0 0 0 0 0 0 1 0 0 0 0 0 1 0 0 0 1 1 0 0 1 0 1 0 0 0 1 0 1 0 1 0 0 1 1 0 0 1 1 1 0 1 1 1 0 0 0 1 0 0 1 1 0 0 1 0 1 0 1 0 1 1 1 0 1 1 1 0 0 1 1 0 1 1 1 0 1 1 1 0 1 1 1 1 1 1 1

                                                                                    Odd Parity Generation Odd Parity Check ACTIVITY 1 Try using the parity checker of figure 92 as 3-bit parity generator Write the details here

                                                                                    _____________________________________________________________________________________________________________________________________________________________________________________________________________________ ______________________________________________________________________________________________________________________________________________ _______________________________________________________________________ ______________________________________________________________________________________________________________________________________________

                                                                                    Logic Design amp Switching Theory 1 Lab Session 10 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                                    Lab Session 10 OBJECT

                                                                                    Driving a seven segment display using 7447 7448 driver IC COMPONENTS AND APPARATUS REQUIRED

                                                                                    1 Following ICs and their Datasheets

                                                                                    bull Seven Segment Displays (Common Anode Common Cathode) bull 7447 7448 BCD to Seven Segment Driver

                                                                                    2 Digital Trainer DT-01 or the following components Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches

                                                                                    THEORY Seven Segment Displays A Seven Segment Display consists of seven light-emitting segments The segments are designated by letters a through g (see figure 101) By illuminating various combinations of segments the numerals 0 through 9 can be displayed Seven Segment Displays are commonly constructed with light-emitting diodes (LEDs) and with liquid-crystal displays (LCDs) LEDs generally provide greater illumination levels but require much greater power than LCDs An LED display can be a common-anode type or common cathode type In common anode type a high voltage is applied at the common terminal of the display and low voltage is applied at a segmentrsquos terminal for illumination In the common-cathode type a low voltage is applied at the common terminal of the display and high voltage is applied at a segmentrsquos terminal for illumination

                                                                                    Figure 101 Seven Segment Display

                                                                                    a f b g

                                                                                    e c d

                                                                                    7447 7448 BCD to Seven Segment Driver 7447 7448 IC is particularly used to drive Seven Segment Its input is a BCD number and output drives a seven segment display 7447 is used to drive common-anode displays whereas 7448 is used to drive common cathode displays 7447 7448 is a 16 pin IC Function of various pins of these ICs is described below

                                                                                    bull A B C D Inputs representing BCD digits (D being the MSB)

                                                                                    45

                                                                                    Logic Design amp Switching Theory 1 Lab Session 10 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering bull OA through OG Outputs to drive segments a through g of the display (Active low

                                                                                    in 7447 and active high in 7448) bull RBI Ripple Blanking Input Turns off all the segments if kept low provided that LT

                                                                                    is kept high and all other inputs (A B C D BI) are kept low Should be kept high otherwise

                                                                                    bull BI RBO Wire-AND logic serving as a Blanking Input and or Ripple Blanking Output

                                                                                    o BI Turns off all the segments if low o RBO Goes to a low level (response condition) along with other outputs when

                                                                                    RBI and inputs A B C and D are low with LT input at high level bull LT Lamp Test input Tests whether all segments are working or not Illuminates all

                                                                                    segments if kept low provided that BI is kept high Should be kept high otherwise bull VCC and GND Supply connections lines CIRCUIT DIAGRAM

                                                                                    Figure 102 Circuit diagram for 7447driving a common-anode display

                                                                                    IMPLEMENTATION AND OBSERVATIONS

                                                                                    bull Make connections as shown in the circuit diagram (refer to laboratory session 01 for implementation procedure)

                                                                                    bull Apply different combinations of 1s and 0s at data inputs bull Observe the output and record your observations in the following table

                                                                                    46

                                                                                    Logic Design amp Switching Theory 1 Lab Session 10 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                                    47

                                                                                    Decimal Digit

                                                                                    BCD Inputs Seven Segment Outputs D C B A a b c d e f g

                                                                                    0 0 0 0 0 1 0 0 0 1 2 0 0 1 0 3 0 0 1 1 4 0 1 0 0 5 0 1 0 1 6 0 1 1 0 7 0 1 1 1 8 1 0 0 0 9 1 0 0 1

                                                                                    ACTIVITY 1 Perform the Lamp Test for the designed circuit and write your observations

                                                                                    ____________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________

                                                                                    2 How can you use 7447 IC to drive a common-cathode display

                                                                                    ____________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________

                                                                                    3 What symbols appear in the seven segment display if inputs DCBA are

                                                                                    DCBA Symbol

                                                                                    1010

                                                                                    1011

                                                                                    1100

                                                                                    1101

                                                                                    1110

                                                                                    1111

                                                                                    Logic Design amp Switching Theory 1 Lab Session 11 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                                    48

                                                                                    Lab Session 11 OBJECT

                                                                                    Testing different modes of JK-FF COMPONENTS AND APPARATUS REQUIRED 1 Following ICs and their Datasheets

                                                                                    bull 7473 7476 JK Flip-Flop 2 Digital Trainer DT-01 or the following components

                                                                                    Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches

                                                                                    THEORY

                                                                                    Flip-Flop A flip-flop circuit can maintain a binary state indefinitely (as long as the power is delivered to the circuit) until directed by an input signal to switch states The major differences among various types of flip-flops are in the number of inputs they possess and in the manner in which the inputs affect the binary state

                                                                                    JK Flip-Flop JK flip flop is an edge triggered device A typical JK flip flop has three inputs J K and a clock input The flip-flop can be either positive or negative edge triggered The output Q is available in complemented form as well Beside the usual inputs and output most of the flip-flop IC also possess two asynchronous inputs namely Preset and Clear These inputs are usually active low If used Preset and Clear inputs keep the flip-flop in set and reset state respectively irrespective of the other inputs Both of these inputs cannot be used simultaneously otherwise they will bring the flip-flop in unstable state

                                                                                    Figure 111 Symbol for JK flip-flop

                                                                                    (a) positive-edge triggering (b) active low Preset (PR) and Clear (CLR) with positive-edge triggering

                                                                                    (c) active low Preset (PR) and Clear (CLR) with negative-edge triggering

                                                                                    Logic Design amp Switching Theory 1 Lab Session 11 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                                    49

                                                                                    TESTING OF 7473 7476 DUAL JK FLIP-FLOP

                                                                                    Both the ICs 7473 and 7476 are similar in functionality except for one difference The flip-flops in 7473 have only one type of active low asynchronous input which is the Clear input whereas the flip-flops in 7476 have both Preset and Clear inputs Both these ICs have negative edge triggered flip-flops

                                                                                    Circuit Diagram

                                                                                    Figure 112 Pin connections of 7476

                                                                                    Testing Procedure

                                                                                    bull Make connections as shown in the circuit diagram (figure 112) bull Apply different combinations of 1s and 0s at J and K inputs bull Observe the output and record your observations in the following table

                                                                                    Observations

                                                                                    J

                                                                                    K Q

                                                                                    0 0 0 1 1 0 1 1

                                                                                    ACTIVITY

                                                                                    1 Observe the output Q of JK flip-flop if the clock input is connected to VCC or GND instead of a clock source Write your observations here __________________________________________________________________________________________________________________________________________ _______________________________________________________________________________________________________________________________________________________________________________________________________________

                                                                                    Logic Design amp Switching Theory 1 Lab Session 12 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                                    50

                                                                                    Lab Session 12 OBJECT

                                                                                    Designing sequential circuit for the given state diagram using D flip-flop GIVEN STATE DIAGRAM

                                                                                    00

                                                                                    11

                                                                                    Figure 121 State Diagram COMPONENTS AND APPARATUS REQUIRED 1 Following ICs and their Datasheets

                                                                                    bull 7474 D Flip-Flop bull ICs of basic gates (AND OR NOT XOR etc) as required

                                                                                    2 Digital Trainer DT-01 or the following components Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches

                                                                                    THEORY

                                                                                    Sequential Circuits In Sequential Circuits the output not only depends on the present inputs but also on previous states of the circuit These circuits use memory elements (latches flip-flops) and the binary information stored in the memory elements at any given time defines the state of the sequential circuit Analysis of a Sequential Circuit The behavior of a sequential circuit is determined from the inputs the outputs and the states of its flip-flops Both the outputs and next state are a function of the inputs and the

                                                                                    10

                                                                                    01

                                                                                    00 11 10

                                                                                    00

                                                                                    00 11 10 00

                                                                                    Logic Design amp Switching Theory 1 Lab Session 12 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                                    51

                                                                                    present state The analysis of a sequential circuit form a state diagram comprises of the following bull Selecting a particular flip-flop to design the circuit bull Obtaining state table from the state diagram bull Finding input equations for the selected flip-flop bull Finding state equations (not required for the construction of circuit) bull Implementing the circuit using selected flip-flops and their input equations ANALYZING THE GIVEN STATE DIAGRAM D Flip-Flop D flip-flop is also called transparent flip-flop as it simply transfers the input data to the output For our design we require the graphical symbol and excitation table of D flip-flop (see figure 122)

                                                                                    Qt Qt+1 T 0 0 0 0 1 1 1 0 0 1 1 1

                                                                                    (b) Excitation table of D Flip-Flop

                                                                                    (a) Graphical Symbol

                                                                                    Figure 122 Characteristic equation of D flip-flop is Q(t+1) = D State Table The given state diagram has four states so we will need two D flip-flops (FF-0 FF-1) Form state table form the given state diagram and record the results in the following table

                                                                                    Present State Input Next State Output Input to FF-0 D0

                                                                                    Input to FF-1 D1 Q1t Q0t x Q1(t+1) Q0(t+1) z

                                                                                    Logic Design amp Switching Theory 1 Lab Session 12 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                                    52

                                                                                    Input Equations Using Karnaugh map the input equations D0 and D1 for the two flip-flops can be found

                                                                                    D0 D1 Q0x

                                                                                    Q1

                                                                                    _ _ Q0x

                                                                                    _ Q0x

                                                                                    Q0x

                                                                                    _ Q0x

                                                                                    Q0x

                                                                                    Q1

                                                                                    _ _ Q0x

                                                                                    _ Q0x

                                                                                    Q0x

                                                                                    _ Q0x

                                                                                    _ Q1

                                                                                    _ Q1

                                                                                    Q1

                                                                                    Q1

                                                                                    D0 = _________________ D1 = _________________

                                                                                    State Equations Using the characteristic equation of D flip-flop we can find the state equations Q0(t+1) and Q1(t+1) for the to flip flops Q0(t+1) = _______________________ Q1(t+1) = _______________________ _______________________ _______________________ _______________________ _______________________ Circuit Diagram

                                                                                    Logic Design amp Switching Theory 1 Lab Session 12 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                                    53

                                                                                    Implementation Procedure and Observations

                                                                                    1 Implement the circuit using digital ICs on a bread board (prepare the pin diagram (use appendix A) and refer to laboratory session 01 for procedure)

                                                                                    2 Make the clear inputs of the flip-flops low (to clear the flip-flops) The flip-flops will remain in clear state as long as the clear inputs are connected to low level

                                                                                    3 Connect output Q0 and the clock pulse to an oscilloscope 4 Apply 0 to the input x 5 Now make the clear inputs to high 6 Observe the waveform for the first 5 clock pulses and record it 7 Repeat steps 2 to 6 keeping x=1 in step 4 this time 8 Repeat steps 2 to 7 this time connecting Q1 instead of Q0 to the oscilloscope in step

                                                                                    3 Record your observations (Keep frequency of the clock pulse low (eg1Hz) so that the output waveforms can be observed easily)

                                                                                    1 2 3 4 5 Clock Pulse

                                                                                    Output Waveform for Q0 when x=0

                                                                                    Output Waveform for Q0 when x=1

                                                                                    Output Waveform for Q1 when x=0

                                                                                    Output Waveform for Q1 when x=1

                                                                                    Logic Design amp Switching Theory 1 Lab Session 13 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                                    Lab Session 13 OBJECT

                                                                                    Designing a modulo-5 asynchronous up-counter using JK-FF COMPONENTS AND APPARATUS REQUIRED

                                                                                    1 Following ICs and their Datasheets

                                                                                    bull 7400 Quad 2-input or 7410 Triple 3-input NAND Gates bull 7476 7473 JK Flip-Flop

                                                                                    2 Digital Trainer DT-01 or the following components Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches

                                                                                    THEORY

                                                                                    Digital Counters A digital counter is a set of flip-flops whose states change in response to pulses applied at the input to the counter The flip-flops are interconnected so that their combined state at any time is the binary equivalent of the total number of pulses that have occurred up to that time Every counter resets after a certain number of clock pulses Thus as it name implies a counter is used to count pulses An n stage counter can count up to a maximum of 2n states n is equal to the number of flip-flops required for the construction of counter

                                                                                    Modulus Counters The number of input pulses that causes a counter to reset to its initial count is called the modulus of the counter Thus the modulus equals to total number of distinct states (counts) including zero that a counter can store A binary counter with n stages is a modulo-2n (or mod-2n) counter The largest count a mod-N counter can achieve is N-1 ie a mod-N counter never reaches the binary number equal to its modulus N is always equal to or less than 2n Counters can be classified as bull Synchronous Counters which are clock driven All the flip-flops are driven by a

                                                                                    single clock bull Asynchronous Counters which are event driven Clock input is given to the first

                                                                                    flip-flop only Rest of the flip-flops are driven by their preceding flip-flops

                                                                                    DESIGN OF A MOD-5 ASYNCHRONOUS UP COUNTER The number of flip-flops required to construct a mod-5 counter is 3 because 5 should be less than or equal to 2n This counter will count from 0 to 4 a total of 5 distinct states Since a 3-stage counter can count up to 8 states at maximum a NAND gate is used to reset it after 5 clock pulses Figure 131 shows the logic diagram

                                                                                    54

                                                                                    Logic Design amp Switching Theory 1 Lab Session 13 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                                    55

                                                                                    Figure 131 A Mod-5 Asynchronous Up Counter

                                                                                    Implementation and Observations

                                                                                    Implement the mod-5 counter circuit (figure 131) on a bread board (prepare the pin diagram (use appendix A) and refer to laboratory session 01 for implementation procedure) and record the observations in the following table

                                                                                    Clock Pulse Q2 Q1 Q0

                                                                                    0 1 2 3 4 5 6 7

                                                                                    ACTIVITY

                                                                                    Draw the timing diagram for mod-5 counter designed in this laboratory session

                                                                                    Logic Design amp Switching Theory 1 Lab Session 14 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                                    Lab Session 14 OBJECT

                                                                                    Experimenting with 74194 4-bit bidirectional universal shift register COMPONENTS AND APPARATUS REQUIRED

                                                                                    1 Following ICs and their Datasheets

                                                                                    bull 74194 4-bit bidirectional universal shift register 2 Digital Trainer DT-01 or the following components

                                                                                    Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches

                                                                                    THEORY

                                                                                    Shift Registers

                                                                                    A Register is a set of flip-flops used to store binary data A register which is capable of shifting its binary information either to the right or left is called a shift register The logical configuration of a register consists of a chain of flip-flops connected in cascade with the output of one flip-flop connected to the input of next flip-flop All flip-flops receive a common clock pulse which causes the shift from one stage to the next

                                                                                    Bidirectional Shift Registers A bi-directional shift register is one whose bits can be shifted from left to right or from right to left

                                                                                    Universal Shift Registers A universal shift register is a bi-directional register whose input can be in either serial or parallel form and whose output can be in either serial or parallel form

                                                                                    74194 4-BIT BIDIRECTIONAL UNIVERSAL SHIFT REGISTER

                                                                                    The 74194 register provides parallel as well as serial loading in both directions Function of various pins of this IC is described below

                                                                                    bull A B C and D Active high inputs for parallel loading bull QA QB QC and QD Active high outputs bull S0 and S1 Active high mode control inputs The following table shows combinations

                                                                                    of S1 and S0 to enable various modes

                                                                                    S1 S0 Clock Action 0 0 x No change 0 1 uarr Shift right 1 0 uarr Shift left 1 1 uarr Parallel load

                                                                                    uarr shows the rising edge of the clock pulse

                                                                                    56

                                                                                    Logic Design amp Switching Theory 1 Lab Session 14 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering bull SR Active high serial input for right shifting bull SL Active high serial input for left shifting bull CLR Active low input Clears all the flip-flops of the register if set to 0 should be

                                                                                    kept high otherwise bull CLK Clock input bull VCC and GND Supply connections lines Thus A B C and D are inputs for parallel loading whereas SR and SL are inputs for serial loading with right or left shifting respectively S1 and S0 are used to select the loading mode Circuit Diagram

                                                                                    Figure 141 Pin connections of 74194 Testing Procedure

                                                                                    bull Make connections as shown in the circuit diagram bull Observe the output for the input combinations given in the following table

                                                                                    57

                                                                                    Logic Design amp Switching Theory 1 Lab Session 14 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                                    58

                                                                                    Observations

                                                                                    S1 S0 SL SR A B C D QA QB QC QD 0 0 0 1 0 0 0 0 0 1 1 0 0 0 0 1 1 0 0 0 0 0 1 0 1 1 0 0 0 0 1 1 0 0 1 1 0 1 0 0 0 1 1 1 0 1 0 1 1 0 1 0 0 1 1 0 1 1 1 0 0 1 1 1 1 1 0 0 1 1 1 1

                                                                                    ACTIVITY 1 Show connections of 74194 to convert it into a ring counter with right shifting

                                                                                    Logic Design amp Switching Theory 1 Lab Session 15 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                                    Lab Session 15

                                                                                    OBJECT

                                                                                    Experimenting with 74245 octal bus transceivers using parallel port PC interfacing COMPONENTS AND APPARATUS REQUIRED 1 Parallel Port Connectors (DB-25) with Cable 2 Personal Computer with Windows 98 and TurboC Compiler Installed 3 Following ICs and their Datasheets

                                                                                    bull 74245 Octal Bus Transceivers with 3-State Outputs 4 Digital Trainer DT-01 or the following components

                                                                                    Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches

                                                                                    THEORY

                                                                                    3-State Logic Sometimes it is necessary to isolate one part of circuit from the other part For this purpose some TTL ICs are designed with 3-state logic Such devices have three possible output states high low and high impedance The device can be put into high impedance state by a control signal applied to an appropriate pin When such a device is in high impedance state there is very high impedance at its output effectively isolating the device from whatever circuitry the output normally drives 74245 Octal Bus Transceivers A bus is any conducting path or set of paths having electrical connections to one or more devices 74245 octal bus transceivers are mainly used to control connectivity between two devices or circuits It also provides direction control for signal flow Function of various pin of this IC is given below

                                                                                    bull A1 through A8 Bus A bull B1 through B8 Bus B bull G΄ Active low enable input When high sets all the bus pins to high impedance state bull DIR Direction control for signal flow When set to high logic level transfers bus A

                                                                                    data to B bus When set to low logic level transfers bus B data to A bus bull VCC and GND Supply connections lines Serial and Parallel Port Connectors A Parallel Port can consist of only 25 pin port adapter called a DB-25 and a serial port can consist of either a 25 pin port adapter called a DB-25 or 9 pin adapter called a DB-9 port adapter Whether the port is a 9 pin or 25 pin it can accomplish all of the same tasks that serial port communications have been designed for

                                                                                    59

                                                                                    Logic Design amp Switching Theory 1 Lab Session 15 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                                    60

                                                                                    Each adapter can be a male type connector with pins or a female type adapter with tiny holes Generally a PRINTER port (called LPT1) on the back of a computer is female type adapter and we need to use MALE DB-25 pin cable on it for PRINTER connection or for parallel LAPLINK cable And a COM port on the back of a computer is male for the serial ports but it may not necessarily be Parallel Port Connector ndash DB-25 The DB-25 connector (named for its B-size D-shaped shell and 25 pins) is practically ubiquitous in the electronics industry The DB-25 connector is used for a variety of purposes Two common applications are RS-232EIA-232 (serial) connections and the parallel printer interface on the IBM PC The DB-25 connector is also used for SCSI connections Normally the parallel port is used for output to a printer or other device It sends data 8-bits or one byte at a time in parallel The other lines available on the DB-25 connector are a combination of status lines control lines and ground lines The status and control lines are used for handshaking commands and feedback when we are talking to a printer

                                                                                    Figure 152 DB-25 Female Figure 151 DB-25 Male

                                                                                    Figure 153 Pin Layout for DB-25 As can be seen form figure 153 there are four types of pins in this connector

                                                                                    bull Data pins (8 pins - D0 to D7) Active high bidirectional lines

                                                                                    Logic Design amp Switching Theory 1 Lab Session 15 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering bull Control pins (4 pins - C0 to C3) C0 C1 and C3 are active low whereas C2 is active

                                                                                    high These lines also are bidirectional bull Status pins (5 pins ndash S3 to S7) Only S7 is active low rest are active high input lines bull Ground pins (8 pins) Used as a reference signal for the low (below 05 volts) charge

                                                                                    Parallel Port Addresses A DB-25 connector at a parallel port has three address one for each kind of pins register data status and control The first or base address generally refers to data register Second address is for status register and the third one is for control register In Windows 98 the base address is usually found to be 278H 378H or 3BCH Now if 378H is the base address then it refers to the data register whereas addresses for status and control register are respectively 379H and 37AH For Windows 98 the base address can be found as follows 1 On your Desktop right-click on My Computer and select Properties 2 Click on the Device Manager tab and find LPT1 under Plug and Play BIOS 3 After selecting LPT1 click the Properties button 4 Next select the Resources tab and the address should then appear next to InputOutput

                                                                                    Range Accessing parallel port through C Language Programming There are multiple functions in C Language for accessing external ports The most commonly used are listed below

                                                                                    bull unsigned char inportb(int portid) inportb reads a byte from a hardware port

                                                                                    bull int inport(int portid) reads a word from a hardware port

                                                                                    bull void outportb(int portid unsigned char value) outputs a byte to a hardware port

                                                                                    bull void outport(int portid int value) outputs a word to a hardware port

                                                                                    portid refers to the port address whereas value refers to the data to be sent TESTING 74245 USING PARALLEL PORT PC INTERFACING At one end the parallel port connector will be connected to the PC via parallel port cable and another connector (to be plugged into the PC parallel port slot) At the other end it will be connected to the buffer IC 74245 Data lines of the connector will be used to transfer 8-bit data between the PC and the buffer Out of the 8-bits of 74245 4-bits will be used to enter data which will be displayed at the monitor through a C language

                                                                                    61

                                                                                    Logic Design amp Switching Theory 1 Lab Session 15 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering program The remaining 4-bits will receive data from PC as entered by the user via keyboard

                                                                                    Circuit Diagram

                                                                                    Figure 154 Interface of 74245 to PC via Parallel Port

                                                                                    Procedure

                                                                                    1 Connect the DB-25 connector to the PC at one end and solder it to the circuit board at the other end

                                                                                    2 Connect various pins of the connector and 74245 according to the circuit diagram shown in figure 152

                                                                                    3 Using the functions listed in the previous section write a program in C language to operate various pins of the buffer The user interface of the program should provide option to the user whether to send or receive data from the port

                                                                                    4 Set DIR switch to 1 5 Try sending some data bits to the port The result should be displayed at the LEDs 6 Set DIR switch to 0 7 Set some binary 4-bit value through the switches Try reading it via parallel port

                                                                                    C Language Program

                                                                                    A program to access parallel port for data transfers

                                                                                    use header file include ltstdiohgt main program void main() define variable

                                                                                    62

                                                                                    Logic Design amp Switching Theory 1 Lab Session 15 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering unsigned int data=0 char choice while(1) printing option menu clrscr() printf(This program will send or receive a BCD digit from the parallel portn) printf(nPress your choice numbern) printf(n1 Send Data) printf(n2 Receive Data) printf(n3 Exitn) choice = getch() sending entered digit to the port if(choice == 1) input BCD digit printf(nEnter BCD digit to be sent to the port) data = getche() masking the first four bits data = data amp 0x0f sending to the port outportb(0x378data) printf(nThe BCD digit c has been sent to the port data) printing on screen the data received from the port else if(choice == 2) receiving data from the port data = inportb(0x378) masking the last four bits data = data amp 0xf0 shifting first four bits to make them the last four bits datagtgt=4 printf(nThe BCD digit set at the port is c data) exit else if(choice == 3) break key pressed is not in the menu else printf(nEnter valid choice number) printf(nnPress any key to continue) getch()

                                                                                    63

                                                                                    Logic Design amp Switching Theory 1 Lab Session 15 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                                    ACTIVITY 1 In the above circuit DIR and G΄ inputs are hardwired Connect them to status or

                                                                                    control pins of the parallel port connector and control their function through your software program Circuit Diagram Program Code ______________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________

                                                                                    ___________________________________________________________________________________________________________________________________________________

                                                                                    64

                                                                                    Logic Design amp Switching Theory 1 Lab Session 15 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                                    65

                                                                                    _____________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ _____________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ _______________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ _________________________________________________ _________________________________________________

                                                                                    Logic Design amp Switching Theory 1 Appendix A NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                                    Appendix A

                                                                                    PIN DIAGRAMS OF THE ICS REQUIRED FOR THE LABORATORY SESSIONS Consult the TTLIC data book for internal diagrams and electrical characteristics of these ICs 7400 Quad 2-Input NAND 7402 Quad 2-Input NOR

                                                                                    7404 Hex Inverter 7408 Quad 2-Input AND

                                                                                    7410 Triple 3-Input NAND 7411 Triple 3-Input AND

                                                                                    7421 Dual 4-Input AND 7432 Quad 2-Input OR

                                                                                    66

                                                                                    Logic Design amp Switching Theory 1 Appendix A NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                                    BCD-to-Seven Segm 7448 BCD-to-Seven Segment 7447 ent

                                                                                    Decoder (15V OC) Decoder (2kΩ pull-up output)

                                                                                    7473 Dual JK Flip-Flop 7474 Dual D-Type Flip-Flop

                                                                                    7476 Dual JK Flop-Flop -Bit Binary Full Adder 7483 4 with Fast Carry

                                                                                    86 Quad 2-Inpu 74138 3-to-8 Line 74 t Exclusive OR Decoder Demultiplexer

                                                                                    67

                                                                                    Logic Design amp Switching Theory 1 Appendix A NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                                    68

                                                                                    74148 8-to-3 Line 16-to-1 Line Data

                                                                                    Priority Encoder 74150 Selector Multiplexer

                                                                                    74245 Oct nsceivers Universal Shift Register (PIPO) (3-State)

                                                                                    74194 4-Bit Bidirectional al Bus Tra

                                                                                    Logic Design amp Switching Theory 1 Appendix B NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                                    Appendix B

                                                                                    DEBOUNCING CIRCUITRY FOR MECHANICAL SWITCHES Mechanical switches form the interface between human beings and computers or other digital systems For example a keyboard is a matrix of switches used to supply alphanumeric data to a computer Whatever the switch design it is a potential source of problems due to contact bounce The contact bounce creates a sense of narrow pulses when a switch is opened or closed An example of device whose operation would be adversely affected by contact bounce is a digital counter used to count the number of times a switch is depressed Eliminating the effects of contact bounce is called debouncing When data is entered into a computer via a keyboard a software debounce is often used This type of debouncing is a program that causes the computer to sample the switch terminal (ie to input data from it) many times in succession during the interval of time that contact bounce occurs If the data is sensed to be 1s (or 0s) for a specific number of consecutive samples then it is assumed that contact bounce has ended and the last value sensed is valid Hardware debouncing is the use of electronic circuitry to eliminate the effects of contact bounce There are numerous versions of such circuitry including those that use monostable multivibrators (one-shots) but the most straightforward is simply an RS latch Figure B1 shows the circuit When the switch is in position 1 R = 0 and S = 1 so the latch is set and the output (Q) is 1 When the switch is in position 0 R = 1and S = 0 so the latch is reset and the output is 0 When the switch is moved form one position to the other the latch changes state and bouncing occurs at either the R or the S input The bouncing does not affect the latch after it has change state An RS latch will remain set for example when its R input is 0 and its S input is alternately changed form 1 to 0

                                                                                    Figure B1 Use of RS latch to debounce a mechanical switch

                                                                                    69

                                                                                    • 01-ldst-Outer title
                                                                                      • Practical Workbook
                                                                                      • Logic Design amp Switching Theory I
                                                                                        • Dept of Computer amp Information Systems Engineering
                                                                                          • NED University of Engineering amp Technology
                                                                                          • Karachi ndash 75270 Pakistan
                                                                                            • 02-ldst-inner Title
                                                                                              • Practical Workbook
                                                                                              • Logic Design amp Switching Theory I
                                                                                                • Dept of Computer amp Information Systems Engineering
                                                                                                  • NED University of Engineering amp Technology
                                                                                                  • Karachi ndash 75270 Pakistan
                                                                                                    • 03-ldst-general info
                                                                                                    • 04-ldst-introduction
                                                                                                    • 05-Table of Contents
                                                                                                      • CONTENTS
                                                                                                        • Lab Session No Object Page No
                                                                                                        • 1
                                                                                                        • Also implementing and testing the given circuit on a bread board
                                                                                                          • Working with Electronics Workbench
                                                                                                            • Driving a seven segment display using 7447 7448 driver IC
                                                                                                              • Designing a modulus-5 asynchronous up-counter using JK-FF
                                                                                                                • Experimenting with 74194 4-bit bidirectional universal shift register
                                                                                                                    • 13
                                                                                                                        • 06-ldst-Exp01
                                                                                                                          • Lab Session 01
                                                                                                                          • OBJECT
                                                                                                                            • 1 Bread board
                                                                                                                            • 2 5 V - power supply
                                                                                                                            • 3 Multimeter
                                                                                                                            • 4 Logic probe
                                                                                                                            • 5 LEDs with resistors
                                                                                                                            • 6 Connecting wires
                                                                                                                            • 8 Following ICs and their datasheets
                                                                                                                              • THEORY
                                                                                                                                • Logic Gates
                                                                                                                                • 1 The AND Gate ndash An AND gatersquos output is 1 if and only if all its inputs are 1 If A and B are two inputs to an AND gate then output F of the gate is given as F = AB
                                                                                                                                • 2 The OR Gate - An OR gatersquos output is 1 if at least one of its input is 1 If A and B are two inputs to an OR gate then output F of the gate is given as F = A+B
                                                                                                                                • 3 The NOT Gate (Inverter) ndash Its output is 1 when its input is 0 and its output is 0 when the input is 1 ie it complements a digital variable If A is the input to a NOT gate then output F of the gate is given as
                                                                                                                                • 4 The NAND Gate ndash Its output is 1 if at least one of its input is 0 This gate performs the same logic as an AND gate followed by an inverter If A and B are two inputs to a NAND gate then output F of the gate is given as
                                                                                                                                  • 5 The NOR Gate - The output of a NOR gate is 1 if and only if all its inputs are 0 This gate performs the same logic function as an OR gate followed by an inverter If A and B are two inputs to a NAND gate then output F of the gate is given as
                                                                                                                                      • DATA SHEETS
                                                                                                                                        • Logic expression for the given logic diagram __________________________________
                                                                                                                                            • 07-ldst-exp02
                                                                                                                                              • Working with Electronics Workbench
                                                                                                                                                • 08-ldst-exp03
                                                                                                                                                  • Designing Half and Full Adder Circuits
                                                                                                                                                    • COMPONENTS AND APPARATUS REQUIRED
                                                                                                                                                      • 1 Following ICs and their Datasheets
                                                                                                                                                      • 7408 Quad 2-input AND Gate
                                                                                                                                                      • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                        • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                        • Connecting wires Switches
                                                                                                                                                          • THEORY
                                                                                                                                                              • IMPLEMENTATION AND OBSERVATIONS
                                                                                                                                                                • 09-ldst-Exp04
                                                                                                                                                                  • Lab Session 04
                                                                                                                                                                  • 1 Digital ICs and their Datasheets
                                                                                                                                                                  • 7408 Quad 2-input AND Gate
                                                                                                                                                                  • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                    • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                    • Connecting wires Switches
                                                                                                                                                                    • PROCEDURE
                                                                                                                                                                    • REDUCTION OF LOGIC EXPRESSION USING KARNAUGH MAP
                                                                                                                                                                    • OBSERVATIONS
                                                                                                                                                                    • RESULT
                                                                                                                                                                        • 10-ldst-Exp05
                                                                                                                                                                          • Lab Session 05
                                                                                                                                                                          • 1 Following ICs and their Datasheets
                                                                                                                                                                          • 7408 Quad 2-input AND Gate
                                                                                                                                                                          • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                            • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                            • (100 Ω) Connecting wires Switches
                                                                                                                                                                            • THEORY
                                                                                                                                                                              • IMPLEMENTATION AND OBSERVATIONS
                                                                                                                                                                                • 11-ldst-Exp06
                                                                                                                                                                                  • OBJECT
                                                                                                                                                                                  • 1 Following ICs and their Datasheets
                                                                                                                                                                                  • 7408 Quad 2-input AND Gates or 7411 Triple 3-input AND Gates
                                                                                                                                                                                  • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                    • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                    • Connecting wires Switches
                                                                                                                                                                                      • Figure 62 Circuit Diagram for 4 x 1 Multiplexer
                                                                                                                                                                                      • Implementation and Observations
                                                                                                                                                                                        • Circuit Diagram
                                                                                                                                                                                          • ACTIVITY
                                                                                                                                                                                            • 12-ldst-exp07
                                                                                                                                                                                              • 1 Following ICs and their Datasheets
                                                                                                                                                                                              • 7408 Quad 2-input or 7411 Triple 3-input AND Gates
                                                                                                                                                                                              • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                • Connecting wires Switches
                                                                                                                                                                                                  • THEORY
                                                                                                                                                                                                      • Figure 72 Circuit Diagram for 2 x 4 Decoder 1 x 4 Demultiplexer
                                                                                                                                                                                                      • Implementation and Observations
                                                                                                                                                                                                        • Circuit Diagram
                                                                                                                                                                                                          • ACTIVITY
                                                                                                                                                                                                            • 13-ldst-Exp08
                                                                                                                                                                                                              • OBJECT
                                                                                                                                                                                                              • 1 Following ICs and their Datasheets
                                                                                                                                                                                                              • 7408 Quad 2-input or 7421 Dual 4-input AND Gates
                                                                                                                                                                                                              • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                                • Connecting wires Switches
                                                                                                                                                                                                                  • THEORY
                                                                                                                                                                                                                      • Figure 81 Circuit Diagram for 4 x 2 Priority Encoder
                                                                                                                                                                                                                      • Implementation and Observations
                                                                                                                                                                                                                        • Therefore if GS A2 A1 and A0 are all low then it shows that line 0 is selected and if E0 A2 A1 and A0 are all low then it shows that none of the inputs selected E0 and GS cannot be in the same state provided that E1 is enabled
                                                                                                                                                                                                                        • Circuit Diagram
                                                                                                                                                                                                                          • ACTIVITY
                                                                                                                                                                                                                            • 14-ldst-exp09
                                                                                                                                                                                                                              • OBJECT
                                                                                                                                                                                                                              • 1 Following ICs and their Datasheets
                                                                                                                                                                                                                              • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                                • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                                                • Connecting wires Switches
                                                                                                                                                                                                                                  • THEORY
                                                                                                                                                                                                                                    • Parity Generator
                                                                                                                                                                                                                                      • Let x y and z be the three bits that constitute the message and are the input to the Odd Parity Generator Circuit Since it is an odd parity system the bit P is generated so as to make the total number of 1s odd (including P) The function P can be expressed as follows
                                                                                                                                                                                                                                      • Figure 91 Circuit Diagram for a 3-bit Parity Generator
                                                                                                                                                                                                                                        • C = x Ο y Ο z Ο P
                                                                                                                                                                                                                                          • Implementation and Observations
                                                                                                                                                                                                                                            • ACTIVITY
                                                                                                                                                                                                                                                • 15-ldst-exp10
                                                                                                                                                                                                                                                  • Driving a seven segment display using 7447 7448 driver IC
                                                                                                                                                                                                                                                  • COMPONENTS AND APPARATUS REQUIRED
                                                                                                                                                                                                                                                  • 1 Following ICs and their Datasheets
                                                                                                                                                                                                                                                  • 7447 7448 BCD to Seven Segment Driver
                                                                                                                                                                                                                                                  • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                                                    • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches
                                                                                                                                                                                                                                                      • THEORY
                                                                                                                                                                                                                                                      • Seven Segment Displays
                                                                                                                                                                                                                                                      • CIRCUIT DIAGRAM
                                                                                                                                                                                                                                                      • Figure 102 Circuit diagram for 7447driving a common-anode display
                                                                                                                                                                                                                                                          • IMPLEMENTATION AND OBSERVATIONS
                                                                                                                                                                                                                                                            • Decimal Digit
                                                                                                                                                                                                                                                            • BCD Inputs
                                                                                                                                                                                                                                                            • Seven Segment Outputs
                                                                                                                                                                                                                                                            • D
                                                                                                                                                                                                                                                            • C
                                                                                                                                                                                                                                                            • B
                                                                                                                                                                                                                                                            • A
                                                                                                                                                                                                                                                            • a
                                                                                                                                                                                                                                                            • b
                                                                                                                                                                                                                                                            • c
                                                                                                                                                                                                                                                            • d
                                                                                                                                                                                                                                                            • e
                                                                                                                                                                                                                                                            • f
                                                                                                                                                                                                                                                            • g
                                                                                                                                                                                                                                                            • 0
                                                                                                                                                                                                                                                            • 0
                                                                                                                                                                                                                                                            • 0
                                                                                                                                                                                                                                                            • 0
                                                                                                                                                                                                                                                            • 0
                                                                                                                                                                                                                                                            • 1
                                                                                                                                                                                                                                                            • 0
                                                                                                                                                                                                                                                            • 0
                                                                                                                                                                                                                                                            • 0
                                                                                                                                                                                                                                                            • 1
                                                                                                                                                                                                                                                            • 2
                                                                                                                                                                                                                                                            • 0
                                                                                                                                                                                                                                                            • 0
                                                                                                                                                                                                                                                            • 1
                                                                                                                                                                                                                                                            • 0
                                                                                                                                                                                                                                                            • 3
                                                                                                                                                                                                                                                            • 0
                                                                                                                                                                                                                                                            • 0
                                                                                                                                                                                                                                                            • 1
                                                                                                                                                                                                                                                            • 1
                                                                                                                                                                                                                                                            • 4
                                                                                                                                                                                                                                                            • 0
                                                                                                                                                                                                                                                            • 1
                                                                                                                                                                                                                                                            • 0
                                                                                                                                                                                                                                                            • 0
                                                                                                                                                                                                                                                            • 5
                                                                                                                                                                                                                                                            • 0
                                                                                                                                                                                                                                                            • 1
                                                                                                                                                                                                                                                            • 0
                                                                                                                                                                                                                                                            • 1
                                                                                                                                                                                                                                                            • 6
                                                                                                                                                                                                                                                            • 0
                                                                                                                                                                                                                                                            • 1
                                                                                                                                                                                                                                                            • 1
                                                                                                                                                                                                                                                            • 0
                                                                                                                                                                                                                                                            • 7
                                                                                                                                                                                                                                                            • 0
                                                                                                                                                                                                                                                            • 1
                                                                                                                                                                                                                                                            • 1
                                                                                                                                                                                                                                                            • 1
                                                                                                                                                                                                                                                            • 8
                                                                                                                                                                                                                                                            • 1
                                                                                                                                                                                                                                                            • 0
                                                                                                                                                                                                                                                            • 0
                                                                                                                                                                                                                                                            • 0
                                                                                                                                                                                                                                                            • 9
                                                                                                                                                                                                                                                            • 1
                                                                                                                                                                                                                                                            • 0
                                                                                                                                                                                                                                                            • 0
                                                                                                                                                                                                                                                            • 1
                                                                                                                                                                                                                                                              • ACTIVITY
                                                                                                                                                                                                                                                                • 16-ldst-exp11
                                                                                                                                                                                                                                                                  • Lab Session 11
                                                                                                                                                                                                                                                                    • OBJECT
                                                                                                                                                                                                                                                                    • COMPONENTS AND APPARATUS REQUIRED
                                                                                                                                                                                                                                                                      • 1 Following ICs and their Datasheets
                                                                                                                                                                                                                                                                      • 7473 7476 JK Flip-Flop
                                                                                                                                                                                                                                                                      • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                                                                        • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                                                                                        • Connecting wires Switches
                                                                                                                                                                                                                                                                          • THEORY
                                                                                                                                                                                                                                                                              • Flip-Flop
                                                                                                                                                                                                                                                                              • JK Flip-Flop
                                                                                                                                                                                                                                                                                • Circuit Diagram
                                                                                                                                                                                                                                                                                  • Observations
                                                                                                                                                                                                                                                                                    • ACTIVITY
                                                                                                                                                                                                                                                                                        • 17-ldst-exp12
                                                                                                                                                                                                                                                                                          • Lab Session 12
                                                                                                                                                                                                                                                                                            • OBJECT
                                                                                                                                                                                                                                                                                            • GIVEN STATE DIAGRAM
                                                                                                                                                                                                                                                                                            • Figure 121 State Diagram
                                                                                                                                                                                                                                                                                            • COMPONENTS AND APPARATUS REQUIRED
                                                                                                                                                                                                                                                                                              • 1 Following ICs and their Datasheets
                                                                                                                                                                                                                                                                                              • 7474 D Flip-Flop
                                                                                                                                                                                                                                                                                              • ICs of basic gates (AND OR NOT XOR etc) as required
                                                                                                                                                                                                                                                                                              • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                                                                                                • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                                                                                                                • Connecting wires Switches
                                                                                                                                                                                                                                                                                                  • THEORY
                                                                                                                                                                                                                                                                                                      • Sequential Circuits
                                                                                                                                                                                                                                                                                                        • 18-ldst-exp13
                                                                                                                                                                                                                                                                                                          • Lab Session 13
                                                                                                                                                                                                                                                                                                            • Designing a modulo-5 asynchronous up-counter using JK-FF
                                                                                                                                                                                                                                                                                                              • 1 Following ICs and their Datasheets
                                                                                                                                                                                                                                                                                                              • 7400 Quad 2-input or 7410 Triple 3-input NAND Gates
                                                                                                                                                                                                                                                                                                              • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                                                                                                                • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                                                                                                                                • Connecting wires Switches
                                                                                                                                                                                                                                                                                                                  • THEORY
                                                                                                                                                                                                                                                                                                                      • Figure 131 A Mod-5 Asynchronous Up Counter
                                                                                                                                                                                                                                                                                                                      • Implementation and Observations
                                                                                                                                                                                                                                                                                                                        • ACTIVITY
                                                                                                                                                                                                                                                                                                                            • 19-ldst-exp14
                                                                                                                                                                                                                                                                                                                              • Experimenting with 74194 4-bit bidirectional universal shift register
                                                                                                                                                                                                                                                                                                                              • 1 Following ICs and their Datasheets
                                                                                                                                                                                                                                                                                                                              • 74194 4-bit bidirectional universal shift register
                                                                                                                                                                                                                                                                                                                              • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                                                                                                                                • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                                                                                                                                                • Connecting wires Switches
                                                                                                                                                                                                                                                                                                                                  • THEORY
                                                                                                                                                                                                                                                                                                                                    • Shift Registers
                                                                                                                                                                                                                                                                                                                                    • Bidirectional Shift Registers
                                                                                                                                                                                                                                                                                                                                    • Universal Shift Registers
                                                                                                                                                                                                                                                                                                                                      • S1
                                                                                                                                                                                                                                                                                                                                        • Circuit Diagram
                                                                                                                                                                                                                                                                                                                                        • ACTIVITY
                                                                                                                                                                                                                                                                                                                                            • 20-ldst-exp15
                                                                                                                                                                                                                                                                                                                                              • COMPONENTS AND APPARATUS REQUIRED
                                                                                                                                                                                                                                                                                                                                              • 1 Parallel Port Connectors (DB-25) with Cable
                                                                                                                                                                                                                                                                                                                                              • 2 Personal Computer with Windows 98 and TurboC Compiler Installed
                                                                                                                                                                                                                                                                                                                                              • 3 Following ICs and their Datasheets
                                                                                                                                                                                                                                                                                                                                              • 74245 Octal Bus Transceivers with 3-State Outputs
                                                                                                                                                                                                                                                                                                                                              • 4 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                                                                                                                                                • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                                                                                                                                                                  • Connecting wires Switches
                                                                                                                                                                                                                                                                                                                                                    • THEORY
                                                                                                                                                                                                                                                                                                                                                    • 3-State Logic
                                                                                                                                                                                                                                                                                                                                                      • Serial and Parallel Port Connectors
                                                                                                                                                                                                                                                                                                                                                      • Parallel Port Connector ndash DB-25
                                                                                                                                                                                                                                                                                                                                                        • Accessing parallel port through C Language Programming
                                                                                                                                                                                                                                                                                                                                                            • 21-ldst-appendixA
                                                                                                                                                                                                                                                                                                                                                            • 22-ldst-appendixB
                                                                                                                                                                                                                                                                                                                                                              • DEBOUNCING CIRCUITRY FOR MECHANICAL SWITCHES

                                                                                      Logic Design amp Switching Theory 1 Lab Session 10 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                                      Lab Session 10 OBJECT

                                                                                      Driving a seven segment display using 7447 7448 driver IC COMPONENTS AND APPARATUS REQUIRED

                                                                                      1 Following ICs and their Datasheets

                                                                                      bull Seven Segment Displays (Common Anode Common Cathode) bull 7447 7448 BCD to Seven Segment Driver

                                                                                      2 Digital Trainer DT-01 or the following components Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches

                                                                                      THEORY Seven Segment Displays A Seven Segment Display consists of seven light-emitting segments The segments are designated by letters a through g (see figure 101) By illuminating various combinations of segments the numerals 0 through 9 can be displayed Seven Segment Displays are commonly constructed with light-emitting diodes (LEDs) and with liquid-crystal displays (LCDs) LEDs generally provide greater illumination levels but require much greater power than LCDs An LED display can be a common-anode type or common cathode type In common anode type a high voltage is applied at the common terminal of the display and low voltage is applied at a segmentrsquos terminal for illumination In the common-cathode type a low voltage is applied at the common terminal of the display and high voltage is applied at a segmentrsquos terminal for illumination

                                                                                      Figure 101 Seven Segment Display

                                                                                      a f b g

                                                                                      e c d

                                                                                      7447 7448 BCD to Seven Segment Driver 7447 7448 IC is particularly used to drive Seven Segment Its input is a BCD number and output drives a seven segment display 7447 is used to drive common-anode displays whereas 7448 is used to drive common cathode displays 7447 7448 is a 16 pin IC Function of various pins of these ICs is described below

                                                                                      bull A B C D Inputs representing BCD digits (D being the MSB)

                                                                                      45

                                                                                      Logic Design amp Switching Theory 1 Lab Session 10 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering bull OA through OG Outputs to drive segments a through g of the display (Active low

                                                                                      in 7447 and active high in 7448) bull RBI Ripple Blanking Input Turns off all the segments if kept low provided that LT

                                                                                      is kept high and all other inputs (A B C D BI) are kept low Should be kept high otherwise

                                                                                      bull BI RBO Wire-AND logic serving as a Blanking Input and or Ripple Blanking Output

                                                                                      o BI Turns off all the segments if low o RBO Goes to a low level (response condition) along with other outputs when

                                                                                      RBI and inputs A B C and D are low with LT input at high level bull LT Lamp Test input Tests whether all segments are working or not Illuminates all

                                                                                      segments if kept low provided that BI is kept high Should be kept high otherwise bull VCC and GND Supply connections lines CIRCUIT DIAGRAM

                                                                                      Figure 102 Circuit diagram for 7447driving a common-anode display

                                                                                      IMPLEMENTATION AND OBSERVATIONS

                                                                                      bull Make connections as shown in the circuit diagram (refer to laboratory session 01 for implementation procedure)

                                                                                      bull Apply different combinations of 1s and 0s at data inputs bull Observe the output and record your observations in the following table

                                                                                      46

                                                                                      Logic Design amp Switching Theory 1 Lab Session 10 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                                      47

                                                                                      Decimal Digit

                                                                                      BCD Inputs Seven Segment Outputs D C B A a b c d e f g

                                                                                      0 0 0 0 0 1 0 0 0 1 2 0 0 1 0 3 0 0 1 1 4 0 1 0 0 5 0 1 0 1 6 0 1 1 0 7 0 1 1 1 8 1 0 0 0 9 1 0 0 1

                                                                                      ACTIVITY 1 Perform the Lamp Test for the designed circuit and write your observations

                                                                                      ____________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________

                                                                                      2 How can you use 7447 IC to drive a common-cathode display

                                                                                      ____________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________

                                                                                      3 What symbols appear in the seven segment display if inputs DCBA are

                                                                                      DCBA Symbol

                                                                                      1010

                                                                                      1011

                                                                                      1100

                                                                                      1101

                                                                                      1110

                                                                                      1111

                                                                                      Logic Design amp Switching Theory 1 Lab Session 11 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                                      48

                                                                                      Lab Session 11 OBJECT

                                                                                      Testing different modes of JK-FF COMPONENTS AND APPARATUS REQUIRED 1 Following ICs and their Datasheets

                                                                                      bull 7473 7476 JK Flip-Flop 2 Digital Trainer DT-01 or the following components

                                                                                      Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches

                                                                                      THEORY

                                                                                      Flip-Flop A flip-flop circuit can maintain a binary state indefinitely (as long as the power is delivered to the circuit) until directed by an input signal to switch states The major differences among various types of flip-flops are in the number of inputs they possess and in the manner in which the inputs affect the binary state

                                                                                      JK Flip-Flop JK flip flop is an edge triggered device A typical JK flip flop has three inputs J K and a clock input The flip-flop can be either positive or negative edge triggered The output Q is available in complemented form as well Beside the usual inputs and output most of the flip-flop IC also possess two asynchronous inputs namely Preset and Clear These inputs are usually active low If used Preset and Clear inputs keep the flip-flop in set and reset state respectively irrespective of the other inputs Both of these inputs cannot be used simultaneously otherwise they will bring the flip-flop in unstable state

                                                                                      Figure 111 Symbol for JK flip-flop

                                                                                      (a) positive-edge triggering (b) active low Preset (PR) and Clear (CLR) with positive-edge triggering

                                                                                      (c) active low Preset (PR) and Clear (CLR) with negative-edge triggering

                                                                                      Logic Design amp Switching Theory 1 Lab Session 11 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                                      49

                                                                                      TESTING OF 7473 7476 DUAL JK FLIP-FLOP

                                                                                      Both the ICs 7473 and 7476 are similar in functionality except for one difference The flip-flops in 7473 have only one type of active low asynchronous input which is the Clear input whereas the flip-flops in 7476 have both Preset and Clear inputs Both these ICs have negative edge triggered flip-flops

                                                                                      Circuit Diagram

                                                                                      Figure 112 Pin connections of 7476

                                                                                      Testing Procedure

                                                                                      bull Make connections as shown in the circuit diagram (figure 112) bull Apply different combinations of 1s and 0s at J and K inputs bull Observe the output and record your observations in the following table

                                                                                      Observations

                                                                                      J

                                                                                      K Q

                                                                                      0 0 0 1 1 0 1 1

                                                                                      ACTIVITY

                                                                                      1 Observe the output Q of JK flip-flop if the clock input is connected to VCC or GND instead of a clock source Write your observations here __________________________________________________________________________________________________________________________________________ _______________________________________________________________________________________________________________________________________________________________________________________________________________

                                                                                      Logic Design amp Switching Theory 1 Lab Session 12 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                                      50

                                                                                      Lab Session 12 OBJECT

                                                                                      Designing sequential circuit for the given state diagram using D flip-flop GIVEN STATE DIAGRAM

                                                                                      00

                                                                                      11

                                                                                      Figure 121 State Diagram COMPONENTS AND APPARATUS REQUIRED 1 Following ICs and their Datasheets

                                                                                      bull 7474 D Flip-Flop bull ICs of basic gates (AND OR NOT XOR etc) as required

                                                                                      2 Digital Trainer DT-01 or the following components Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches

                                                                                      THEORY

                                                                                      Sequential Circuits In Sequential Circuits the output not only depends on the present inputs but also on previous states of the circuit These circuits use memory elements (latches flip-flops) and the binary information stored in the memory elements at any given time defines the state of the sequential circuit Analysis of a Sequential Circuit The behavior of a sequential circuit is determined from the inputs the outputs and the states of its flip-flops Both the outputs and next state are a function of the inputs and the

                                                                                      10

                                                                                      01

                                                                                      00 11 10

                                                                                      00

                                                                                      00 11 10 00

                                                                                      Logic Design amp Switching Theory 1 Lab Session 12 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                                      51

                                                                                      present state The analysis of a sequential circuit form a state diagram comprises of the following bull Selecting a particular flip-flop to design the circuit bull Obtaining state table from the state diagram bull Finding input equations for the selected flip-flop bull Finding state equations (not required for the construction of circuit) bull Implementing the circuit using selected flip-flops and their input equations ANALYZING THE GIVEN STATE DIAGRAM D Flip-Flop D flip-flop is also called transparent flip-flop as it simply transfers the input data to the output For our design we require the graphical symbol and excitation table of D flip-flop (see figure 122)

                                                                                      Qt Qt+1 T 0 0 0 0 1 1 1 0 0 1 1 1

                                                                                      (b) Excitation table of D Flip-Flop

                                                                                      (a) Graphical Symbol

                                                                                      Figure 122 Characteristic equation of D flip-flop is Q(t+1) = D State Table The given state diagram has four states so we will need two D flip-flops (FF-0 FF-1) Form state table form the given state diagram and record the results in the following table

                                                                                      Present State Input Next State Output Input to FF-0 D0

                                                                                      Input to FF-1 D1 Q1t Q0t x Q1(t+1) Q0(t+1) z

                                                                                      Logic Design amp Switching Theory 1 Lab Session 12 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                                      52

                                                                                      Input Equations Using Karnaugh map the input equations D0 and D1 for the two flip-flops can be found

                                                                                      D0 D1 Q0x

                                                                                      Q1

                                                                                      _ _ Q0x

                                                                                      _ Q0x

                                                                                      Q0x

                                                                                      _ Q0x

                                                                                      Q0x

                                                                                      Q1

                                                                                      _ _ Q0x

                                                                                      _ Q0x

                                                                                      Q0x

                                                                                      _ Q0x

                                                                                      _ Q1

                                                                                      _ Q1

                                                                                      Q1

                                                                                      Q1

                                                                                      D0 = _________________ D1 = _________________

                                                                                      State Equations Using the characteristic equation of D flip-flop we can find the state equations Q0(t+1) and Q1(t+1) for the to flip flops Q0(t+1) = _______________________ Q1(t+1) = _______________________ _______________________ _______________________ _______________________ _______________________ Circuit Diagram

                                                                                      Logic Design amp Switching Theory 1 Lab Session 12 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                                      53

                                                                                      Implementation Procedure and Observations

                                                                                      1 Implement the circuit using digital ICs on a bread board (prepare the pin diagram (use appendix A) and refer to laboratory session 01 for procedure)

                                                                                      2 Make the clear inputs of the flip-flops low (to clear the flip-flops) The flip-flops will remain in clear state as long as the clear inputs are connected to low level

                                                                                      3 Connect output Q0 and the clock pulse to an oscilloscope 4 Apply 0 to the input x 5 Now make the clear inputs to high 6 Observe the waveform for the first 5 clock pulses and record it 7 Repeat steps 2 to 6 keeping x=1 in step 4 this time 8 Repeat steps 2 to 7 this time connecting Q1 instead of Q0 to the oscilloscope in step

                                                                                      3 Record your observations (Keep frequency of the clock pulse low (eg1Hz) so that the output waveforms can be observed easily)

                                                                                      1 2 3 4 5 Clock Pulse

                                                                                      Output Waveform for Q0 when x=0

                                                                                      Output Waveform for Q0 when x=1

                                                                                      Output Waveform for Q1 when x=0

                                                                                      Output Waveform for Q1 when x=1

                                                                                      Logic Design amp Switching Theory 1 Lab Session 13 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                                      Lab Session 13 OBJECT

                                                                                      Designing a modulo-5 asynchronous up-counter using JK-FF COMPONENTS AND APPARATUS REQUIRED

                                                                                      1 Following ICs and their Datasheets

                                                                                      bull 7400 Quad 2-input or 7410 Triple 3-input NAND Gates bull 7476 7473 JK Flip-Flop

                                                                                      2 Digital Trainer DT-01 or the following components Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches

                                                                                      THEORY

                                                                                      Digital Counters A digital counter is a set of flip-flops whose states change in response to pulses applied at the input to the counter The flip-flops are interconnected so that their combined state at any time is the binary equivalent of the total number of pulses that have occurred up to that time Every counter resets after a certain number of clock pulses Thus as it name implies a counter is used to count pulses An n stage counter can count up to a maximum of 2n states n is equal to the number of flip-flops required for the construction of counter

                                                                                      Modulus Counters The number of input pulses that causes a counter to reset to its initial count is called the modulus of the counter Thus the modulus equals to total number of distinct states (counts) including zero that a counter can store A binary counter with n stages is a modulo-2n (or mod-2n) counter The largest count a mod-N counter can achieve is N-1 ie a mod-N counter never reaches the binary number equal to its modulus N is always equal to or less than 2n Counters can be classified as bull Synchronous Counters which are clock driven All the flip-flops are driven by a

                                                                                      single clock bull Asynchronous Counters which are event driven Clock input is given to the first

                                                                                      flip-flop only Rest of the flip-flops are driven by their preceding flip-flops

                                                                                      DESIGN OF A MOD-5 ASYNCHRONOUS UP COUNTER The number of flip-flops required to construct a mod-5 counter is 3 because 5 should be less than or equal to 2n This counter will count from 0 to 4 a total of 5 distinct states Since a 3-stage counter can count up to 8 states at maximum a NAND gate is used to reset it after 5 clock pulses Figure 131 shows the logic diagram

                                                                                      54

                                                                                      Logic Design amp Switching Theory 1 Lab Session 13 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                                      55

                                                                                      Figure 131 A Mod-5 Asynchronous Up Counter

                                                                                      Implementation and Observations

                                                                                      Implement the mod-5 counter circuit (figure 131) on a bread board (prepare the pin diagram (use appendix A) and refer to laboratory session 01 for implementation procedure) and record the observations in the following table

                                                                                      Clock Pulse Q2 Q1 Q0

                                                                                      0 1 2 3 4 5 6 7

                                                                                      ACTIVITY

                                                                                      Draw the timing diagram for mod-5 counter designed in this laboratory session

                                                                                      Logic Design amp Switching Theory 1 Lab Session 14 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                                      Lab Session 14 OBJECT

                                                                                      Experimenting with 74194 4-bit bidirectional universal shift register COMPONENTS AND APPARATUS REQUIRED

                                                                                      1 Following ICs and their Datasheets

                                                                                      bull 74194 4-bit bidirectional universal shift register 2 Digital Trainer DT-01 or the following components

                                                                                      Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches

                                                                                      THEORY

                                                                                      Shift Registers

                                                                                      A Register is a set of flip-flops used to store binary data A register which is capable of shifting its binary information either to the right or left is called a shift register The logical configuration of a register consists of a chain of flip-flops connected in cascade with the output of one flip-flop connected to the input of next flip-flop All flip-flops receive a common clock pulse which causes the shift from one stage to the next

                                                                                      Bidirectional Shift Registers A bi-directional shift register is one whose bits can be shifted from left to right or from right to left

                                                                                      Universal Shift Registers A universal shift register is a bi-directional register whose input can be in either serial or parallel form and whose output can be in either serial or parallel form

                                                                                      74194 4-BIT BIDIRECTIONAL UNIVERSAL SHIFT REGISTER

                                                                                      The 74194 register provides parallel as well as serial loading in both directions Function of various pins of this IC is described below

                                                                                      bull A B C and D Active high inputs for parallel loading bull QA QB QC and QD Active high outputs bull S0 and S1 Active high mode control inputs The following table shows combinations

                                                                                      of S1 and S0 to enable various modes

                                                                                      S1 S0 Clock Action 0 0 x No change 0 1 uarr Shift right 1 0 uarr Shift left 1 1 uarr Parallel load

                                                                                      uarr shows the rising edge of the clock pulse

                                                                                      56

                                                                                      Logic Design amp Switching Theory 1 Lab Session 14 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering bull SR Active high serial input for right shifting bull SL Active high serial input for left shifting bull CLR Active low input Clears all the flip-flops of the register if set to 0 should be

                                                                                      kept high otherwise bull CLK Clock input bull VCC and GND Supply connections lines Thus A B C and D are inputs for parallel loading whereas SR and SL are inputs for serial loading with right or left shifting respectively S1 and S0 are used to select the loading mode Circuit Diagram

                                                                                      Figure 141 Pin connections of 74194 Testing Procedure

                                                                                      bull Make connections as shown in the circuit diagram bull Observe the output for the input combinations given in the following table

                                                                                      57

                                                                                      Logic Design amp Switching Theory 1 Lab Session 14 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                                      58

                                                                                      Observations

                                                                                      S1 S0 SL SR A B C D QA QB QC QD 0 0 0 1 0 0 0 0 0 1 1 0 0 0 0 1 1 0 0 0 0 0 1 0 1 1 0 0 0 0 1 1 0 0 1 1 0 1 0 0 0 1 1 1 0 1 0 1 1 0 1 0 0 1 1 0 1 1 1 0 0 1 1 1 1 1 0 0 1 1 1 1

                                                                                      ACTIVITY 1 Show connections of 74194 to convert it into a ring counter with right shifting

                                                                                      Logic Design amp Switching Theory 1 Lab Session 15 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                                      Lab Session 15

                                                                                      OBJECT

                                                                                      Experimenting with 74245 octal bus transceivers using parallel port PC interfacing COMPONENTS AND APPARATUS REQUIRED 1 Parallel Port Connectors (DB-25) with Cable 2 Personal Computer with Windows 98 and TurboC Compiler Installed 3 Following ICs and their Datasheets

                                                                                      bull 74245 Octal Bus Transceivers with 3-State Outputs 4 Digital Trainer DT-01 or the following components

                                                                                      Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches

                                                                                      THEORY

                                                                                      3-State Logic Sometimes it is necessary to isolate one part of circuit from the other part For this purpose some TTL ICs are designed with 3-state logic Such devices have three possible output states high low and high impedance The device can be put into high impedance state by a control signal applied to an appropriate pin When such a device is in high impedance state there is very high impedance at its output effectively isolating the device from whatever circuitry the output normally drives 74245 Octal Bus Transceivers A bus is any conducting path or set of paths having electrical connections to one or more devices 74245 octal bus transceivers are mainly used to control connectivity between two devices or circuits It also provides direction control for signal flow Function of various pin of this IC is given below

                                                                                      bull A1 through A8 Bus A bull B1 through B8 Bus B bull G΄ Active low enable input When high sets all the bus pins to high impedance state bull DIR Direction control for signal flow When set to high logic level transfers bus A

                                                                                      data to B bus When set to low logic level transfers bus B data to A bus bull VCC and GND Supply connections lines Serial and Parallel Port Connectors A Parallel Port can consist of only 25 pin port adapter called a DB-25 and a serial port can consist of either a 25 pin port adapter called a DB-25 or 9 pin adapter called a DB-9 port adapter Whether the port is a 9 pin or 25 pin it can accomplish all of the same tasks that serial port communications have been designed for

                                                                                      59

                                                                                      Logic Design amp Switching Theory 1 Lab Session 15 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                                      60

                                                                                      Each adapter can be a male type connector with pins or a female type adapter with tiny holes Generally a PRINTER port (called LPT1) on the back of a computer is female type adapter and we need to use MALE DB-25 pin cable on it for PRINTER connection or for parallel LAPLINK cable And a COM port on the back of a computer is male for the serial ports but it may not necessarily be Parallel Port Connector ndash DB-25 The DB-25 connector (named for its B-size D-shaped shell and 25 pins) is practically ubiquitous in the electronics industry The DB-25 connector is used for a variety of purposes Two common applications are RS-232EIA-232 (serial) connections and the parallel printer interface on the IBM PC The DB-25 connector is also used for SCSI connections Normally the parallel port is used for output to a printer or other device It sends data 8-bits or one byte at a time in parallel The other lines available on the DB-25 connector are a combination of status lines control lines and ground lines The status and control lines are used for handshaking commands and feedback when we are talking to a printer

                                                                                      Figure 152 DB-25 Female Figure 151 DB-25 Male

                                                                                      Figure 153 Pin Layout for DB-25 As can be seen form figure 153 there are four types of pins in this connector

                                                                                      bull Data pins (8 pins - D0 to D7) Active high bidirectional lines

                                                                                      Logic Design amp Switching Theory 1 Lab Session 15 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering bull Control pins (4 pins - C0 to C3) C0 C1 and C3 are active low whereas C2 is active

                                                                                      high These lines also are bidirectional bull Status pins (5 pins ndash S3 to S7) Only S7 is active low rest are active high input lines bull Ground pins (8 pins) Used as a reference signal for the low (below 05 volts) charge

                                                                                      Parallel Port Addresses A DB-25 connector at a parallel port has three address one for each kind of pins register data status and control The first or base address generally refers to data register Second address is for status register and the third one is for control register In Windows 98 the base address is usually found to be 278H 378H or 3BCH Now if 378H is the base address then it refers to the data register whereas addresses for status and control register are respectively 379H and 37AH For Windows 98 the base address can be found as follows 1 On your Desktop right-click on My Computer and select Properties 2 Click on the Device Manager tab and find LPT1 under Plug and Play BIOS 3 After selecting LPT1 click the Properties button 4 Next select the Resources tab and the address should then appear next to InputOutput

                                                                                      Range Accessing parallel port through C Language Programming There are multiple functions in C Language for accessing external ports The most commonly used are listed below

                                                                                      bull unsigned char inportb(int portid) inportb reads a byte from a hardware port

                                                                                      bull int inport(int portid) reads a word from a hardware port

                                                                                      bull void outportb(int portid unsigned char value) outputs a byte to a hardware port

                                                                                      bull void outport(int portid int value) outputs a word to a hardware port

                                                                                      portid refers to the port address whereas value refers to the data to be sent TESTING 74245 USING PARALLEL PORT PC INTERFACING At one end the parallel port connector will be connected to the PC via parallel port cable and another connector (to be plugged into the PC parallel port slot) At the other end it will be connected to the buffer IC 74245 Data lines of the connector will be used to transfer 8-bit data between the PC and the buffer Out of the 8-bits of 74245 4-bits will be used to enter data which will be displayed at the monitor through a C language

                                                                                      61

                                                                                      Logic Design amp Switching Theory 1 Lab Session 15 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering program The remaining 4-bits will receive data from PC as entered by the user via keyboard

                                                                                      Circuit Diagram

                                                                                      Figure 154 Interface of 74245 to PC via Parallel Port

                                                                                      Procedure

                                                                                      1 Connect the DB-25 connector to the PC at one end and solder it to the circuit board at the other end

                                                                                      2 Connect various pins of the connector and 74245 according to the circuit diagram shown in figure 152

                                                                                      3 Using the functions listed in the previous section write a program in C language to operate various pins of the buffer The user interface of the program should provide option to the user whether to send or receive data from the port

                                                                                      4 Set DIR switch to 1 5 Try sending some data bits to the port The result should be displayed at the LEDs 6 Set DIR switch to 0 7 Set some binary 4-bit value through the switches Try reading it via parallel port

                                                                                      C Language Program

                                                                                      A program to access parallel port for data transfers

                                                                                      use header file include ltstdiohgt main program void main() define variable

                                                                                      62

                                                                                      Logic Design amp Switching Theory 1 Lab Session 15 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering unsigned int data=0 char choice while(1) printing option menu clrscr() printf(This program will send or receive a BCD digit from the parallel portn) printf(nPress your choice numbern) printf(n1 Send Data) printf(n2 Receive Data) printf(n3 Exitn) choice = getch() sending entered digit to the port if(choice == 1) input BCD digit printf(nEnter BCD digit to be sent to the port) data = getche() masking the first four bits data = data amp 0x0f sending to the port outportb(0x378data) printf(nThe BCD digit c has been sent to the port data) printing on screen the data received from the port else if(choice == 2) receiving data from the port data = inportb(0x378) masking the last four bits data = data amp 0xf0 shifting first four bits to make them the last four bits datagtgt=4 printf(nThe BCD digit set at the port is c data) exit else if(choice == 3) break key pressed is not in the menu else printf(nEnter valid choice number) printf(nnPress any key to continue) getch()

                                                                                      63

                                                                                      Logic Design amp Switching Theory 1 Lab Session 15 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                                      ACTIVITY 1 In the above circuit DIR and G΄ inputs are hardwired Connect them to status or

                                                                                      control pins of the parallel port connector and control their function through your software program Circuit Diagram Program Code ______________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________

                                                                                      ___________________________________________________________________________________________________________________________________________________

                                                                                      64

                                                                                      Logic Design amp Switching Theory 1 Lab Session 15 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                                      65

                                                                                      _____________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ _____________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ _______________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ _________________________________________________ _________________________________________________

                                                                                      Logic Design amp Switching Theory 1 Appendix A NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                                      Appendix A

                                                                                      PIN DIAGRAMS OF THE ICS REQUIRED FOR THE LABORATORY SESSIONS Consult the TTLIC data book for internal diagrams and electrical characteristics of these ICs 7400 Quad 2-Input NAND 7402 Quad 2-Input NOR

                                                                                      7404 Hex Inverter 7408 Quad 2-Input AND

                                                                                      7410 Triple 3-Input NAND 7411 Triple 3-Input AND

                                                                                      7421 Dual 4-Input AND 7432 Quad 2-Input OR

                                                                                      66

                                                                                      Logic Design amp Switching Theory 1 Appendix A NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                                      BCD-to-Seven Segm 7448 BCD-to-Seven Segment 7447 ent

                                                                                      Decoder (15V OC) Decoder (2kΩ pull-up output)

                                                                                      7473 Dual JK Flip-Flop 7474 Dual D-Type Flip-Flop

                                                                                      7476 Dual JK Flop-Flop -Bit Binary Full Adder 7483 4 with Fast Carry

                                                                                      86 Quad 2-Inpu 74138 3-to-8 Line 74 t Exclusive OR Decoder Demultiplexer

                                                                                      67

                                                                                      Logic Design amp Switching Theory 1 Appendix A NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                                      68

                                                                                      74148 8-to-3 Line 16-to-1 Line Data

                                                                                      Priority Encoder 74150 Selector Multiplexer

                                                                                      74245 Oct nsceivers Universal Shift Register (PIPO) (3-State)

                                                                                      74194 4-Bit Bidirectional al Bus Tra

                                                                                      Logic Design amp Switching Theory 1 Appendix B NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                                      Appendix B

                                                                                      DEBOUNCING CIRCUITRY FOR MECHANICAL SWITCHES Mechanical switches form the interface between human beings and computers or other digital systems For example a keyboard is a matrix of switches used to supply alphanumeric data to a computer Whatever the switch design it is a potential source of problems due to contact bounce The contact bounce creates a sense of narrow pulses when a switch is opened or closed An example of device whose operation would be adversely affected by contact bounce is a digital counter used to count the number of times a switch is depressed Eliminating the effects of contact bounce is called debouncing When data is entered into a computer via a keyboard a software debounce is often used This type of debouncing is a program that causes the computer to sample the switch terminal (ie to input data from it) many times in succession during the interval of time that contact bounce occurs If the data is sensed to be 1s (or 0s) for a specific number of consecutive samples then it is assumed that contact bounce has ended and the last value sensed is valid Hardware debouncing is the use of electronic circuitry to eliminate the effects of contact bounce There are numerous versions of such circuitry including those that use monostable multivibrators (one-shots) but the most straightforward is simply an RS latch Figure B1 shows the circuit When the switch is in position 1 R = 0 and S = 1 so the latch is set and the output (Q) is 1 When the switch is in position 0 R = 1and S = 0 so the latch is reset and the output is 0 When the switch is moved form one position to the other the latch changes state and bouncing occurs at either the R or the S input The bouncing does not affect the latch after it has change state An RS latch will remain set for example when its R input is 0 and its S input is alternately changed form 1 to 0

                                                                                      Figure B1 Use of RS latch to debounce a mechanical switch

                                                                                      69

                                                                                      • 01-ldst-Outer title
                                                                                        • Practical Workbook
                                                                                        • Logic Design amp Switching Theory I
                                                                                          • Dept of Computer amp Information Systems Engineering
                                                                                            • NED University of Engineering amp Technology
                                                                                            • Karachi ndash 75270 Pakistan
                                                                                              • 02-ldst-inner Title
                                                                                                • Practical Workbook
                                                                                                • Logic Design amp Switching Theory I
                                                                                                  • Dept of Computer amp Information Systems Engineering
                                                                                                    • NED University of Engineering amp Technology
                                                                                                    • Karachi ndash 75270 Pakistan
                                                                                                      • 03-ldst-general info
                                                                                                      • 04-ldst-introduction
                                                                                                      • 05-Table of Contents
                                                                                                        • CONTENTS
                                                                                                          • Lab Session No Object Page No
                                                                                                          • 1
                                                                                                          • Also implementing and testing the given circuit on a bread board
                                                                                                            • Working with Electronics Workbench
                                                                                                              • Driving a seven segment display using 7447 7448 driver IC
                                                                                                                • Designing a modulus-5 asynchronous up-counter using JK-FF
                                                                                                                  • Experimenting with 74194 4-bit bidirectional universal shift register
                                                                                                                      • 13
                                                                                                                          • 06-ldst-Exp01
                                                                                                                            • Lab Session 01
                                                                                                                            • OBJECT
                                                                                                                              • 1 Bread board
                                                                                                                              • 2 5 V - power supply
                                                                                                                              • 3 Multimeter
                                                                                                                              • 4 Logic probe
                                                                                                                              • 5 LEDs with resistors
                                                                                                                              • 6 Connecting wires
                                                                                                                              • 8 Following ICs and their datasheets
                                                                                                                                • THEORY
                                                                                                                                  • Logic Gates
                                                                                                                                  • 1 The AND Gate ndash An AND gatersquos output is 1 if and only if all its inputs are 1 If A and B are two inputs to an AND gate then output F of the gate is given as F = AB
                                                                                                                                  • 2 The OR Gate - An OR gatersquos output is 1 if at least one of its input is 1 If A and B are two inputs to an OR gate then output F of the gate is given as F = A+B
                                                                                                                                  • 3 The NOT Gate (Inverter) ndash Its output is 1 when its input is 0 and its output is 0 when the input is 1 ie it complements a digital variable If A is the input to a NOT gate then output F of the gate is given as
                                                                                                                                  • 4 The NAND Gate ndash Its output is 1 if at least one of its input is 0 This gate performs the same logic as an AND gate followed by an inverter If A and B are two inputs to a NAND gate then output F of the gate is given as
                                                                                                                                    • 5 The NOR Gate - The output of a NOR gate is 1 if and only if all its inputs are 0 This gate performs the same logic function as an OR gate followed by an inverter If A and B are two inputs to a NAND gate then output F of the gate is given as
                                                                                                                                        • DATA SHEETS
                                                                                                                                          • Logic expression for the given logic diagram __________________________________
                                                                                                                                              • 07-ldst-exp02
                                                                                                                                                • Working with Electronics Workbench
                                                                                                                                                  • 08-ldst-exp03
                                                                                                                                                    • Designing Half and Full Adder Circuits
                                                                                                                                                      • COMPONENTS AND APPARATUS REQUIRED
                                                                                                                                                        • 1 Following ICs and their Datasheets
                                                                                                                                                        • 7408 Quad 2-input AND Gate
                                                                                                                                                        • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                          • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                          • Connecting wires Switches
                                                                                                                                                            • THEORY
                                                                                                                                                                • IMPLEMENTATION AND OBSERVATIONS
                                                                                                                                                                  • 09-ldst-Exp04
                                                                                                                                                                    • Lab Session 04
                                                                                                                                                                    • 1 Digital ICs and their Datasheets
                                                                                                                                                                    • 7408 Quad 2-input AND Gate
                                                                                                                                                                    • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                      • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                      • Connecting wires Switches
                                                                                                                                                                      • PROCEDURE
                                                                                                                                                                      • REDUCTION OF LOGIC EXPRESSION USING KARNAUGH MAP
                                                                                                                                                                      • OBSERVATIONS
                                                                                                                                                                      • RESULT
                                                                                                                                                                          • 10-ldst-Exp05
                                                                                                                                                                            • Lab Session 05
                                                                                                                                                                            • 1 Following ICs and their Datasheets
                                                                                                                                                                            • 7408 Quad 2-input AND Gate
                                                                                                                                                                            • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                              • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                              • (100 Ω) Connecting wires Switches
                                                                                                                                                                              • THEORY
                                                                                                                                                                                • IMPLEMENTATION AND OBSERVATIONS
                                                                                                                                                                                  • 11-ldst-Exp06
                                                                                                                                                                                    • OBJECT
                                                                                                                                                                                    • 1 Following ICs and their Datasheets
                                                                                                                                                                                    • 7408 Quad 2-input AND Gates or 7411 Triple 3-input AND Gates
                                                                                                                                                                                    • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                      • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                      • Connecting wires Switches
                                                                                                                                                                                        • Figure 62 Circuit Diagram for 4 x 1 Multiplexer
                                                                                                                                                                                        • Implementation and Observations
                                                                                                                                                                                          • Circuit Diagram
                                                                                                                                                                                            • ACTIVITY
                                                                                                                                                                                              • 12-ldst-exp07
                                                                                                                                                                                                • 1 Following ICs and their Datasheets
                                                                                                                                                                                                • 7408 Quad 2-input or 7411 Triple 3-input AND Gates
                                                                                                                                                                                                • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                  • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                  • Connecting wires Switches
                                                                                                                                                                                                    • THEORY
                                                                                                                                                                                                        • Figure 72 Circuit Diagram for 2 x 4 Decoder 1 x 4 Demultiplexer
                                                                                                                                                                                                        • Implementation and Observations
                                                                                                                                                                                                          • Circuit Diagram
                                                                                                                                                                                                            • ACTIVITY
                                                                                                                                                                                                              • 13-ldst-Exp08
                                                                                                                                                                                                                • OBJECT
                                                                                                                                                                                                                • 1 Following ICs and their Datasheets
                                                                                                                                                                                                                • 7408 Quad 2-input or 7421 Dual 4-input AND Gates
                                                                                                                                                                                                                • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                  • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                                  • Connecting wires Switches
                                                                                                                                                                                                                    • THEORY
                                                                                                                                                                                                                        • Figure 81 Circuit Diagram for 4 x 2 Priority Encoder
                                                                                                                                                                                                                        • Implementation and Observations
                                                                                                                                                                                                                          • Therefore if GS A2 A1 and A0 are all low then it shows that line 0 is selected and if E0 A2 A1 and A0 are all low then it shows that none of the inputs selected E0 and GS cannot be in the same state provided that E1 is enabled
                                                                                                                                                                                                                          • Circuit Diagram
                                                                                                                                                                                                                            • ACTIVITY
                                                                                                                                                                                                                              • 14-ldst-exp09
                                                                                                                                                                                                                                • OBJECT
                                                                                                                                                                                                                                • 1 Following ICs and their Datasheets
                                                                                                                                                                                                                                • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                                  • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                                                  • Connecting wires Switches
                                                                                                                                                                                                                                    • THEORY
                                                                                                                                                                                                                                      • Parity Generator
                                                                                                                                                                                                                                        • Let x y and z be the three bits that constitute the message and are the input to the Odd Parity Generator Circuit Since it is an odd parity system the bit P is generated so as to make the total number of 1s odd (including P) The function P can be expressed as follows
                                                                                                                                                                                                                                        • Figure 91 Circuit Diagram for a 3-bit Parity Generator
                                                                                                                                                                                                                                          • C = x Ο y Ο z Ο P
                                                                                                                                                                                                                                            • Implementation and Observations
                                                                                                                                                                                                                                              • ACTIVITY
                                                                                                                                                                                                                                                  • 15-ldst-exp10
                                                                                                                                                                                                                                                    • Driving a seven segment display using 7447 7448 driver IC
                                                                                                                                                                                                                                                    • COMPONENTS AND APPARATUS REQUIRED
                                                                                                                                                                                                                                                    • 1 Following ICs and their Datasheets
                                                                                                                                                                                                                                                    • 7447 7448 BCD to Seven Segment Driver
                                                                                                                                                                                                                                                    • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                                                      • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches
                                                                                                                                                                                                                                                        • THEORY
                                                                                                                                                                                                                                                        • Seven Segment Displays
                                                                                                                                                                                                                                                        • CIRCUIT DIAGRAM
                                                                                                                                                                                                                                                        • Figure 102 Circuit diagram for 7447driving a common-anode display
                                                                                                                                                                                                                                                            • IMPLEMENTATION AND OBSERVATIONS
                                                                                                                                                                                                                                                              • Decimal Digit
                                                                                                                                                                                                                                                              • BCD Inputs
                                                                                                                                                                                                                                                              • Seven Segment Outputs
                                                                                                                                                                                                                                                              • D
                                                                                                                                                                                                                                                              • C
                                                                                                                                                                                                                                                              • B
                                                                                                                                                                                                                                                              • A
                                                                                                                                                                                                                                                              • a
                                                                                                                                                                                                                                                              • b
                                                                                                                                                                                                                                                              • c
                                                                                                                                                                                                                                                              • d
                                                                                                                                                                                                                                                              • e
                                                                                                                                                                                                                                                              • f
                                                                                                                                                                                                                                                              • g
                                                                                                                                                                                                                                                              • 0
                                                                                                                                                                                                                                                              • 0
                                                                                                                                                                                                                                                              • 0
                                                                                                                                                                                                                                                              • 0
                                                                                                                                                                                                                                                              • 0
                                                                                                                                                                                                                                                              • 1
                                                                                                                                                                                                                                                              • 0
                                                                                                                                                                                                                                                              • 0
                                                                                                                                                                                                                                                              • 0
                                                                                                                                                                                                                                                              • 1
                                                                                                                                                                                                                                                              • 2
                                                                                                                                                                                                                                                              • 0
                                                                                                                                                                                                                                                              • 0
                                                                                                                                                                                                                                                              • 1
                                                                                                                                                                                                                                                              • 0
                                                                                                                                                                                                                                                              • 3
                                                                                                                                                                                                                                                              • 0
                                                                                                                                                                                                                                                              • 0
                                                                                                                                                                                                                                                              • 1
                                                                                                                                                                                                                                                              • 1
                                                                                                                                                                                                                                                              • 4
                                                                                                                                                                                                                                                              • 0
                                                                                                                                                                                                                                                              • 1
                                                                                                                                                                                                                                                              • 0
                                                                                                                                                                                                                                                              • 0
                                                                                                                                                                                                                                                              • 5
                                                                                                                                                                                                                                                              • 0
                                                                                                                                                                                                                                                              • 1
                                                                                                                                                                                                                                                              • 0
                                                                                                                                                                                                                                                              • 1
                                                                                                                                                                                                                                                              • 6
                                                                                                                                                                                                                                                              • 0
                                                                                                                                                                                                                                                              • 1
                                                                                                                                                                                                                                                              • 1
                                                                                                                                                                                                                                                              • 0
                                                                                                                                                                                                                                                              • 7
                                                                                                                                                                                                                                                              • 0
                                                                                                                                                                                                                                                              • 1
                                                                                                                                                                                                                                                              • 1
                                                                                                                                                                                                                                                              • 1
                                                                                                                                                                                                                                                              • 8
                                                                                                                                                                                                                                                              • 1
                                                                                                                                                                                                                                                              • 0
                                                                                                                                                                                                                                                              • 0
                                                                                                                                                                                                                                                              • 0
                                                                                                                                                                                                                                                              • 9
                                                                                                                                                                                                                                                              • 1
                                                                                                                                                                                                                                                              • 0
                                                                                                                                                                                                                                                              • 0
                                                                                                                                                                                                                                                              • 1
                                                                                                                                                                                                                                                                • ACTIVITY
                                                                                                                                                                                                                                                                  • 16-ldst-exp11
                                                                                                                                                                                                                                                                    • Lab Session 11
                                                                                                                                                                                                                                                                      • OBJECT
                                                                                                                                                                                                                                                                      • COMPONENTS AND APPARATUS REQUIRED
                                                                                                                                                                                                                                                                        • 1 Following ICs and their Datasheets
                                                                                                                                                                                                                                                                        • 7473 7476 JK Flip-Flop
                                                                                                                                                                                                                                                                        • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                                                                          • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                                                                                          • Connecting wires Switches
                                                                                                                                                                                                                                                                            • THEORY
                                                                                                                                                                                                                                                                                • Flip-Flop
                                                                                                                                                                                                                                                                                • JK Flip-Flop
                                                                                                                                                                                                                                                                                  • Circuit Diagram
                                                                                                                                                                                                                                                                                    • Observations
                                                                                                                                                                                                                                                                                      • ACTIVITY
                                                                                                                                                                                                                                                                                          • 17-ldst-exp12
                                                                                                                                                                                                                                                                                            • Lab Session 12
                                                                                                                                                                                                                                                                                              • OBJECT
                                                                                                                                                                                                                                                                                              • GIVEN STATE DIAGRAM
                                                                                                                                                                                                                                                                                              • Figure 121 State Diagram
                                                                                                                                                                                                                                                                                              • COMPONENTS AND APPARATUS REQUIRED
                                                                                                                                                                                                                                                                                                • 1 Following ICs and their Datasheets
                                                                                                                                                                                                                                                                                                • 7474 D Flip-Flop
                                                                                                                                                                                                                                                                                                • ICs of basic gates (AND OR NOT XOR etc) as required
                                                                                                                                                                                                                                                                                                • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                                                                                                  • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                                                                                                                  • Connecting wires Switches
                                                                                                                                                                                                                                                                                                    • THEORY
                                                                                                                                                                                                                                                                                                        • Sequential Circuits
                                                                                                                                                                                                                                                                                                          • 18-ldst-exp13
                                                                                                                                                                                                                                                                                                            • Lab Session 13
                                                                                                                                                                                                                                                                                                              • Designing a modulo-5 asynchronous up-counter using JK-FF
                                                                                                                                                                                                                                                                                                                • 1 Following ICs and their Datasheets
                                                                                                                                                                                                                                                                                                                • 7400 Quad 2-input or 7410 Triple 3-input NAND Gates
                                                                                                                                                                                                                                                                                                                • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                                                                                                                  • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                                                                                                                                  • Connecting wires Switches
                                                                                                                                                                                                                                                                                                                    • THEORY
                                                                                                                                                                                                                                                                                                                        • Figure 131 A Mod-5 Asynchronous Up Counter
                                                                                                                                                                                                                                                                                                                        • Implementation and Observations
                                                                                                                                                                                                                                                                                                                          • ACTIVITY
                                                                                                                                                                                                                                                                                                                              • 19-ldst-exp14
                                                                                                                                                                                                                                                                                                                                • Experimenting with 74194 4-bit bidirectional universal shift register
                                                                                                                                                                                                                                                                                                                                • 1 Following ICs and their Datasheets
                                                                                                                                                                                                                                                                                                                                • 74194 4-bit bidirectional universal shift register
                                                                                                                                                                                                                                                                                                                                • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                                                                                                                                  • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                                                                                                                                                  • Connecting wires Switches
                                                                                                                                                                                                                                                                                                                                    • THEORY
                                                                                                                                                                                                                                                                                                                                      • Shift Registers
                                                                                                                                                                                                                                                                                                                                      • Bidirectional Shift Registers
                                                                                                                                                                                                                                                                                                                                      • Universal Shift Registers
                                                                                                                                                                                                                                                                                                                                        • S1
                                                                                                                                                                                                                                                                                                                                          • Circuit Diagram
                                                                                                                                                                                                                                                                                                                                          • ACTIVITY
                                                                                                                                                                                                                                                                                                                                              • 20-ldst-exp15
                                                                                                                                                                                                                                                                                                                                                • COMPONENTS AND APPARATUS REQUIRED
                                                                                                                                                                                                                                                                                                                                                • 1 Parallel Port Connectors (DB-25) with Cable
                                                                                                                                                                                                                                                                                                                                                • 2 Personal Computer with Windows 98 and TurboC Compiler Installed
                                                                                                                                                                                                                                                                                                                                                • 3 Following ICs and their Datasheets
                                                                                                                                                                                                                                                                                                                                                • 74245 Octal Bus Transceivers with 3-State Outputs
                                                                                                                                                                                                                                                                                                                                                • 4 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                                                                                                                                                  • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                                                                                                                                                                    • Connecting wires Switches
                                                                                                                                                                                                                                                                                                                                                      • THEORY
                                                                                                                                                                                                                                                                                                                                                      • 3-State Logic
                                                                                                                                                                                                                                                                                                                                                        • Serial and Parallel Port Connectors
                                                                                                                                                                                                                                                                                                                                                        • Parallel Port Connector ndash DB-25
                                                                                                                                                                                                                                                                                                                                                          • Accessing parallel port through C Language Programming
                                                                                                                                                                                                                                                                                                                                                              • 21-ldst-appendixA
                                                                                                                                                                                                                                                                                                                                                              • 22-ldst-appendixB
                                                                                                                                                                                                                                                                                                                                                                • DEBOUNCING CIRCUITRY FOR MECHANICAL SWITCHES

                                                                                        Logic Design amp Switching Theory 1 Lab Session 10 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering bull OA through OG Outputs to drive segments a through g of the display (Active low

                                                                                        in 7447 and active high in 7448) bull RBI Ripple Blanking Input Turns off all the segments if kept low provided that LT

                                                                                        is kept high and all other inputs (A B C D BI) are kept low Should be kept high otherwise

                                                                                        bull BI RBO Wire-AND logic serving as a Blanking Input and or Ripple Blanking Output

                                                                                        o BI Turns off all the segments if low o RBO Goes to a low level (response condition) along with other outputs when

                                                                                        RBI and inputs A B C and D are low with LT input at high level bull LT Lamp Test input Tests whether all segments are working or not Illuminates all

                                                                                        segments if kept low provided that BI is kept high Should be kept high otherwise bull VCC and GND Supply connections lines CIRCUIT DIAGRAM

                                                                                        Figure 102 Circuit diagram for 7447driving a common-anode display

                                                                                        IMPLEMENTATION AND OBSERVATIONS

                                                                                        bull Make connections as shown in the circuit diagram (refer to laboratory session 01 for implementation procedure)

                                                                                        bull Apply different combinations of 1s and 0s at data inputs bull Observe the output and record your observations in the following table

                                                                                        46

                                                                                        Logic Design amp Switching Theory 1 Lab Session 10 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                                        47

                                                                                        Decimal Digit

                                                                                        BCD Inputs Seven Segment Outputs D C B A a b c d e f g

                                                                                        0 0 0 0 0 1 0 0 0 1 2 0 0 1 0 3 0 0 1 1 4 0 1 0 0 5 0 1 0 1 6 0 1 1 0 7 0 1 1 1 8 1 0 0 0 9 1 0 0 1

                                                                                        ACTIVITY 1 Perform the Lamp Test for the designed circuit and write your observations

                                                                                        ____________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________

                                                                                        2 How can you use 7447 IC to drive a common-cathode display

                                                                                        ____________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________

                                                                                        3 What symbols appear in the seven segment display if inputs DCBA are

                                                                                        DCBA Symbol

                                                                                        1010

                                                                                        1011

                                                                                        1100

                                                                                        1101

                                                                                        1110

                                                                                        1111

                                                                                        Logic Design amp Switching Theory 1 Lab Session 11 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                                        48

                                                                                        Lab Session 11 OBJECT

                                                                                        Testing different modes of JK-FF COMPONENTS AND APPARATUS REQUIRED 1 Following ICs and their Datasheets

                                                                                        bull 7473 7476 JK Flip-Flop 2 Digital Trainer DT-01 or the following components

                                                                                        Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches

                                                                                        THEORY

                                                                                        Flip-Flop A flip-flop circuit can maintain a binary state indefinitely (as long as the power is delivered to the circuit) until directed by an input signal to switch states The major differences among various types of flip-flops are in the number of inputs they possess and in the manner in which the inputs affect the binary state

                                                                                        JK Flip-Flop JK flip flop is an edge triggered device A typical JK flip flop has three inputs J K and a clock input The flip-flop can be either positive or negative edge triggered The output Q is available in complemented form as well Beside the usual inputs and output most of the flip-flop IC also possess two asynchronous inputs namely Preset and Clear These inputs are usually active low If used Preset and Clear inputs keep the flip-flop in set and reset state respectively irrespective of the other inputs Both of these inputs cannot be used simultaneously otherwise they will bring the flip-flop in unstable state

                                                                                        Figure 111 Symbol for JK flip-flop

                                                                                        (a) positive-edge triggering (b) active low Preset (PR) and Clear (CLR) with positive-edge triggering

                                                                                        (c) active low Preset (PR) and Clear (CLR) with negative-edge triggering

                                                                                        Logic Design amp Switching Theory 1 Lab Session 11 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                                        49

                                                                                        TESTING OF 7473 7476 DUAL JK FLIP-FLOP

                                                                                        Both the ICs 7473 and 7476 are similar in functionality except for one difference The flip-flops in 7473 have only one type of active low asynchronous input which is the Clear input whereas the flip-flops in 7476 have both Preset and Clear inputs Both these ICs have negative edge triggered flip-flops

                                                                                        Circuit Diagram

                                                                                        Figure 112 Pin connections of 7476

                                                                                        Testing Procedure

                                                                                        bull Make connections as shown in the circuit diagram (figure 112) bull Apply different combinations of 1s and 0s at J and K inputs bull Observe the output and record your observations in the following table

                                                                                        Observations

                                                                                        J

                                                                                        K Q

                                                                                        0 0 0 1 1 0 1 1

                                                                                        ACTIVITY

                                                                                        1 Observe the output Q of JK flip-flop if the clock input is connected to VCC or GND instead of a clock source Write your observations here __________________________________________________________________________________________________________________________________________ _______________________________________________________________________________________________________________________________________________________________________________________________________________

                                                                                        Logic Design amp Switching Theory 1 Lab Session 12 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                                        50

                                                                                        Lab Session 12 OBJECT

                                                                                        Designing sequential circuit for the given state diagram using D flip-flop GIVEN STATE DIAGRAM

                                                                                        00

                                                                                        11

                                                                                        Figure 121 State Diagram COMPONENTS AND APPARATUS REQUIRED 1 Following ICs and their Datasheets

                                                                                        bull 7474 D Flip-Flop bull ICs of basic gates (AND OR NOT XOR etc) as required

                                                                                        2 Digital Trainer DT-01 or the following components Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches

                                                                                        THEORY

                                                                                        Sequential Circuits In Sequential Circuits the output not only depends on the present inputs but also on previous states of the circuit These circuits use memory elements (latches flip-flops) and the binary information stored in the memory elements at any given time defines the state of the sequential circuit Analysis of a Sequential Circuit The behavior of a sequential circuit is determined from the inputs the outputs and the states of its flip-flops Both the outputs and next state are a function of the inputs and the

                                                                                        10

                                                                                        01

                                                                                        00 11 10

                                                                                        00

                                                                                        00 11 10 00

                                                                                        Logic Design amp Switching Theory 1 Lab Session 12 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                                        51

                                                                                        present state The analysis of a sequential circuit form a state diagram comprises of the following bull Selecting a particular flip-flop to design the circuit bull Obtaining state table from the state diagram bull Finding input equations for the selected flip-flop bull Finding state equations (not required for the construction of circuit) bull Implementing the circuit using selected flip-flops and their input equations ANALYZING THE GIVEN STATE DIAGRAM D Flip-Flop D flip-flop is also called transparent flip-flop as it simply transfers the input data to the output For our design we require the graphical symbol and excitation table of D flip-flop (see figure 122)

                                                                                        Qt Qt+1 T 0 0 0 0 1 1 1 0 0 1 1 1

                                                                                        (b) Excitation table of D Flip-Flop

                                                                                        (a) Graphical Symbol

                                                                                        Figure 122 Characteristic equation of D flip-flop is Q(t+1) = D State Table The given state diagram has four states so we will need two D flip-flops (FF-0 FF-1) Form state table form the given state diagram and record the results in the following table

                                                                                        Present State Input Next State Output Input to FF-0 D0

                                                                                        Input to FF-1 D1 Q1t Q0t x Q1(t+1) Q0(t+1) z

                                                                                        Logic Design amp Switching Theory 1 Lab Session 12 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                                        52

                                                                                        Input Equations Using Karnaugh map the input equations D0 and D1 for the two flip-flops can be found

                                                                                        D0 D1 Q0x

                                                                                        Q1

                                                                                        _ _ Q0x

                                                                                        _ Q0x

                                                                                        Q0x

                                                                                        _ Q0x

                                                                                        Q0x

                                                                                        Q1

                                                                                        _ _ Q0x

                                                                                        _ Q0x

                                                                                        Q0x

                                                                                        _ Q0x

                                                                                        _ Q1

                                                                                        _ Q1

                                                                                        Q1

                                                                                        Q1

                                                                                        D0 = _________________ D1 = _________________

                                                                                        State Equations Using the characteristic equation of D flip-flop we can find the state equations Q0(t+1) and Q1(t+1) for the to flip flops Q0(t+1) = _______________________ Q1(t+1) = _______________________ _______________________ _______________________ _______________________ _______________________ Circuit Diagram

                                                                                        Logic Design amp Switching Theory 1 Lab Session 12 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                                        53

                                                                                        Implementation Procedure and Observations

                                                                                        1 Implement the circuit using digital ICs on a bread board (prepare the pin diagram (use appendix A) and refer to laboratory session 01 for procedure)

                                                                                        2 Make the clear inputs of the flip-flops low (to clear the flip-flops) The flip-flops will remain in clear state as long as the clear inputs are connected to low level

                                                                                        3 Connect output Q0 and the clock pulse to an oscilloscope 4 Apply 0 to the input x 5 Now make the clear inputs to high 6 Observe the waveform for the first 5 clock pulses and record it 7 Repeat steps 2 to 6 keeping x=1 in step 4 this time 8 Repeat steps 2 to 7 this time connecting Q1 instead of Q0 to the oscilloscope in step

                                                                                        3 Record your observations (Keep frequency of the clock pulse low (eg1Hz) so that the output waveforms can be observed easily)

                                                                                        1 2 3 4 5 Clock Pulse

                                                                                        Output Waveform for Q0 when x=0

                                                                                        Output Waveform for Q0 when x=1

                                                                                        Output Waveform for Q1 when x=0

                                                                                        Output Waveform for Q1 when x=1

                                                                                        Logic Design amp Switching Theory 1 Lab Session 13 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                                        Lab Session 13 OBJECT

                                                                                        Designing a modulo-5 asynchronous up-counter using JK-FF COMPONENTS AND APPARATUS REQUIRED

                                                                                        1 Following ICs and their Datasheets

                                                                                        bull 7400 Quad 2-input or 7410 Triple 3-input NAND Gates bull 7476 7473 JK Flip-Flop

                                                                                        2 Digital Trainer DT-01 or the following components Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches

                                                                                        THEORY

                                                                                        Digital Counters A digital counter is a set of flip-flops whose states change in response to pulses applied at the input to the counter The flip-flops are interconnected so that their combined state at any time is the binary equivalent of the total number of pulses that have occurred up to that time Every counter resets after a certain number of clock pulses Thus as it name implies a counter is used to count pulses An n stage counter can count up to a maximum of 2n states n is equal to the number of flip-flops required for the construction of counter

                                                                                        Modulus Counters The number of input pulses that causes a counter to reset to its initial count is called the modulus of the counter Thus the modulus equals to total number of distinct states (counts) including zero that a counter can store A binary counter with n stages is a modulo-2n (or mod-2n) counter The largest count a mod-N counter can achieve is N-1 ie a mod-N counter never reaches the binary number equal to its modulus N is always equal to or less than 2n Counters can be classified as bull Synchronous Counters which are clock driven All the flip-flops are driven by a

                                                                                        single clock bull Asynchronous Counters which are event driven Clock input is given to the first

                                                                                        flip-flop only Rest of the flip-flops are driven by their preceding flip-flops

                                                                                        DESIGN OF A MOD-5 ASYNCHRONOUS UP COUNTER The number of flip-flops required to construct a mod-5 counter is 3 because 5 should be less than or equal to 2n This counter will count from 0 to 4 a total of 5 distinct states Since a 3-stage counter can count up to 8 states at maximum a NAND gate is used to reset it after 5 clock pulses Figure 131 shows the logic diagram

                                                                                        54

                                                                                        Logic Design amp Switching Theory 1 Lab Session 13 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                                        55

                                                                                        Figure 131 A Mod-5 Asynchronous Up Counter

                                                                                        Implementation and Observations

                                                                                        Implement the mod-5 counter circuit (figure 131) on a bread board (prepare the pin diagram (use appendix A) and refer to laboratory session 01 for implementation procedure) and record the observations in the following table

                                                                                        Clock Pulse Q2 Q1 Q0

                                                                                        0 1 2 3 4 5 6 7

                                                                                        ACTIVITY

                                                                                        Draw the timing diagram for mod-5 counter designed in this laboratory session

                                                                                        Logic Design amp Switching Theory 1 Lab Session 14 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                                        Lab Session 14 OBJECT

                                                                                        Experimenting with 74194 4-bit bidirectional universal shift register COMPONENTS AND APPARATUS REQUIRED

                                                                                        1 Following ICs and their Datasheets

                                                                                        bull 74194 4-bit bidirectional universal shift register 2 Digital Trainer DT-01 or the following components

                                                                                        Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches

                                                                                        THEORY

                                                                                        Shift Registers

                                                                                        A Register is a set of flip-flops used to store binary data A register which is capable of shifting its binary information either to the right or left is called a shift register The logical configuration of a register consists of a chain of flip-flops connected in cascade with the output of one flip-flop connected to the input of next flip-flop All flip-flops receive a common clock pulse which causes the shift from one stage to the next

                                                                                        Bidirectional Shift Registers A bi-directional shift register is one whose bits can be shifted from left to right or from right to left

                                                                                        Universal Shift Registers A universal shift register is a bi-directional register whose input can be in either serial or parallel form and whose output can be in either serial or parallel form

                                                                                        74194 4-BIT BIDIRECTIONAL UNIVERSAL SHIFT REGISTER

                                                                                        The 74194 register provides parallel as well as serial loading in both directions Function of various pins of this IC is described below

                                                                                        bull A B C and D Active high inputs for parallel loading bull QA QB QC and QD Active high outputs bull S0 and S1 Active high mode control inputs The following table shows combinations

                                                                                        of S1 and S0 to enable various modes

                                                                                        S1 S0 Clock Action 0 0 x No change 0 1 uarr Shift right 1 0 uarr Shift left 1 1 uarr Parallel load

                                                                                        uarr shows the rising edge of the clock pulse

                                                                                        56

                                                                                        Logic Design amp Switching Theory 1 Lab Session 14 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering bull SR Active high serial input for right shifting bull SL Active high serial input for left shifting bull CLR Active low input Clears all the flip-flops of the register if set to 0 should be

                                                                                        kept high otherwise bull CLK Clock input bull VCC and GND Supply connections lines Thus A B C and D are inputs for parallel loading whereas SR and SL are inputs for serial loading with right or left shifting respectively S1 and S0 are used to select the loading mode Circuit Diagram

                                                                                        Figure 141 Pin connections of 74194 Testing Procedure

                                                                                        bull Make connections as shown in the circuit diagram bull Observe the output for the input combinations given in the following table

                                                                                        57

                                                                                        Logic Design amp Switching Theory 1 Lab Session 14 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                                        58

                                                                                        Observations

                                                                                        S1 S0 SL SR A B C D QA QB QC QD 0 0 0 1 0 0 0 0 0 1 1 0 0 0 0 1 1 0 0 0 0 0 1 0 1 1 0 0 0 0 1 1 0 0 1 1 0 1 0 0 0 1 1 1 0 1 0 1 1 0 1 0 0 1 1 0 1 1 1 0 0 1 1 1 1 1 0 0 1 1 1 1

                                                                                        ACTIVITY 1 Show connections of 74194 to convert it into a ring counter with right shifting

                                                                                        Logic Design amp Switching Theory 1 Lab Session 15 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                                        Lab Session 15

                                                                                        OBJECT

                                                                                        Experimenting with 74245 octal bus transceivers using parallel port PC interfacing COMPONENTS AND APPARATUS REQUIRED 1 Parallel Port Connectors (DB-25) with Cable 2 Personal Computer with Windows 98 and TurboC Compiler Installed 3 Following ICs and their Datasheets

                                                                                        bull 74245 Octal Bus Transceivers with 3-State Outputs 4 Digital Trainer DT-01 or the following components

                                                                                        Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches

                                                                                        THEORY

                                                                                        3-State Logic Sometimes it is necessary to isolate one part of circuit from the other part For this purpose some TTL ICs are designed with 3-state logic Such devices have three possible output states high low and high impedance The device can be put into high impedance state by a control signal applied to an appropriate pin When such a device is in high impedance state there is very high impedance at its output effectively isolating the device from whatever circuitry the output normally drives 74245 Octal Bus Transceivers A bus is any conducting path or set of paths having electrical connections to one or more devices 74245 octal bus transceivers are mainly used to control connectivity between two devices or circuits It also provides direction control for signal flow Function of various pin of this IC is given below

                                                                                        bull A1 through A8 Bus A bull B1 through B8 Bus B bull G΄ Active low enable input When high sets all the bus pins to high impedance state bull DIR Direction control for signal flow When set to high logic level transfers bus A

                                                                                        data to B bus When set to low logic level transfers bus B data to A bus bull VCC and GND Supply connections lines Serial and Parallel Port Connectors A Parallel Port can consist of only 25 pin port adapter called a DB-25 and a serial port can consist of either a 25 pin port adapter called a DB-25 or 9 pin adapter called a DB-9 port adapter Whether the port is a 9 pin or 25 pin it can accomplish all of the same tasks that serial port communications have been designed for

                                                                                        59

                                                                                        Logic Design amp Switching Theory 1 Lab Session 15 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                                        60

                                                                                        Each adapter can be a male type connector with pins or a female type adapter with tiny holes Generally a PRINTER port (called LPT1) on the back of a computer is female type adapter and we need to use MALE DB-25 pin cable on it for PRINTER connection or for parallel LAPLINK cable And a COM port on the back of a computer is male for the serial ports but it may not necessarily be Parallel Port Connector ndash DB-25 The DB-25 connector (named for its B-size D-shaped shell and 25 pins) is practically ubiquitous in the electronics industry The DB-25 connector is used for a variety of purposes Two common applications are RS-232EIA-232 (serial) connections and the parallel printer interface on the IBM PC The DB-25 connector is also used for SCSI connections Normally the parallel port is used for output to a printer or other device It sends data 8-bits or one byte at a time in parallel The other lines available on the DB-25 connector are a combination of status lines control lines and ground lines The status and control lines are used for handshaking commands and feedback when we are talking to a printer

                                                                                        Figure 152 DB-25 Female Figure 151 DB-25 Male

                                                                                        Figure 153 Pin Layout for DB-25 As can be seen form figure 153 there are four types of pins in this connector

                                                                                        bull Data pins (8 pins - D0 to D7) Active high bidirectional lines

                                                                                        Logic Design amp Switching Theory 1 Lab Session 15 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering bull Control pins (4 pins - C0 to C3) C0 C1 and C3 are active low whereas C2 is active

                                                                                        high These lines also are bidirectional bull Status pins (5 pins ndash S3 to S7) Only S7 is active low rest are active high input lines bull Ground pins (8 pins) Used as a reference signal for the low (below 05 volts) charge

                                                                                        Parallel Port Addresses A DB-25 connector at a parallel port has three address one for each kind of pins register data status and control The first or base address generally refers to data register Second address is for status register and the third one is for control register In Windows 98 the base address is usually found to be 278H 378H or 3BCH Now if 378H is the base address then it refers to the data register whereas addresses for status and control register are respectively 379H and 37AH For Windows 98 the base address can be found as follows 1 On your Desktop right-click on My Computer and select Properties 2 Click on the Device Manager tab and find LPT1 under Plug and Play BIOS 3 After selecting LPT1 click the Properties button 4 Next select the Resources tab and the address should then appear next to InputOutput

                                                                                        Range Accessing parallel port through C Language Programming There are multiple functions in C Language for accessing external ports The most commonly used are listed below

                                                                                        bull unsigned char inportb(int portid) inportb reads a byte from a hardware port

                                                                                        bull int inport(int portid) reads a word from a hardware port

                                                                                        bull void outportb(int portid unsigned char value) outputs a byte to a hardware port

                                                                                        bull void outport(int portid int value) outputs a word to a hardware port

                                                                                        portid refers to the port address whereas value refers to the data to be sent TESTING 74245 USING PARALLEL PORT PC INTERFACING At one end the parallel port connector will be connected to the PC via parallel port cable and another connector (to be plugged into the PC parallel port slot) At the other end it will be connected to the buffer IC 74245 Data lines of the connector will be used to transfer 8-bit data between the PC and the buffer Out of the 8-bits of 74245 4-bits will be used to enter data which will be displayed at the monitor through a C language

                                                                                        61

                                                                                        Logic Design amp Switching Theory 1 Lab Session 15 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering program The remaining 4-bits will receive data from PC as entered by the user via keyboard

                                                                                        Circuit Diagram

                                                                                        Figure 154 Interface of 74245 to PC via Parallel Port

                                                                                        Procedure

                                                                                        1 Connect the DB-25 connector to the PC at one end and solder it to the circuit board at the other end

                                                                                        2 Connect various pins of the connector and 74245 according to the circuit diagram shown in figure 152

                                                                                        3 Using the functions listed in the previous section write a program in C language to operate various pins of the buffer The user interface of the program should provide option to the user whether to send or receive data from the port

                                                                                        4 Set DIR switch to 1 5 Try sending some data bits to the port The result should be displayed at the LEDs 6 Set DIR switch to 0 7 Set some binary 4-bit value through the switches Try reading it via parallel port

                                                                                        C Language Program

                                                                                        A program to access parallel port for data transfers

                                                                                        use header file include ltstdiohgt main program void main() define variable

                                                                                        62

                                                                                        Logic Design amp Switching Theory 1 Lab Session 15 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering unsigned int data=0 char choice while(1) printing option menu clrscr() printf(This program will send or receive a BCD digit from the parallel portn) printf(nPress your choice numbern) printf(n1 Send Data) printf(n2 Receive Data) printf(n3 Exitn) choice = getch() sending entered digit to the port if(choice == 1) input BCD digit printf(nEnter BCD digit to be sent to the port) data = getche() masking the first four bits data = data amp 0x0f sending to the port outportb(0x378data) printf(nThe BCD digit c has been sent to the port data) printing on screen the data received from the port else if(choice == 2) receiving data from the port data = inportb(0x378) masking the last four bits data = data amp 0xf0 shifting first four bits to make them the last four bits datagtgt=4 printf(nThe BCD digit set at the port is c data) exit else if(choice == 3) break key pressed is not in the menu else printf(nEnter valid choice number) printf(nnPress any key to continue) getch()

                                                                                        63

                                                                                        Logic Design amp Switching Theory 1 Lab Session 15 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                                        ACTIVITY 1 In the above circuit DIR and G΄ inputs are hardwired Connect them to status or

                                                                                        control pins of the parallel port connector and control their function through your software program Circuit Diagram Program Code ______________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________

                                                                                        ___________________________________________________________________________________________________________________________________________________

                                                                                        64

                                                                                        Logic Design amp Switching Theory 1 Lab Session 15 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                                        65

                                                                                        _____________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ _____________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ _______________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ _________________________________________________ _________________________________________________

                                                                                        Logic Design amp Switching Theory 1 Appendix A NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                                        Appendix A

                                                                                        PIN DIAGRAMS OF THE ICS REQUIRED FOR THE LABORATORY SESSIONS Consult the TTLIC data book for internal diagrams and electrical characteristics of these ICs 7400 Quad 2-Input NAND 7402 Quad 2-Input NOR

                                                                                        7404 Hex Inverter 7408 Quad 2-Input AND

                                                                                        7410 Triple 3-Input NAND 7411 Triple 3-Input AND

                                                                                        7421 Dual 4-Input AND 7432 Quad 2-Input OR

                                                                                        66

                                                                                        Logic Design amp Switching Theory 1 Appendix A NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                                        BCD-to-Seven Segm 7448 BCD-to-Seven Segment 7447 ent

                                                                                        Decoder (15V OC) Decoder (2kΩ pull-up output)

                                                                                        7473 Dual JK Flip-Flop 7474 Dual D-Type Flip-Flop

                                                                                        7476 Dual JK Flop-Flop -Bit Binary Full Adder 7483 4 with Fast Carry

                                                                                        86 Quad 2-Inpu 74138 3-to-8 Line 74 t Exclusive OR Decoder Demultiplexer

                                                                                        67

                                                                                        Logic Design amp Switching Theory 1 Appendix A NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                                        68

                                                                                        74148 8-to-3 Line 16-to-1 Line Data

                                                                                        Priority Encoder 74150 Selector Multiplexer

                                                                                        74245 Oct nsceivers Universal Shift Register (PIPO) (3-State)

                                                                                        74194 4-Bit Bidirectional al Bus Tra

                                                                                        Logic Design amp Switching Theory 1 Appendix B NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                                        Appendix B

                                                                                        DEBOUNCING CIRCUITRY FOR MECHANICAL SWITCHES Mechanical switches form the interface between human beings and computers or other digital systems For example a keyboard is a matrix of switches used to supply alphanumeric data to a computer Whatever the switch design it is a potential source of problems due to contact bounce The contact bounce creates a sense of narrow pulses when a switch is opened or closed An example of device whose operation would be adversely affected by contact bounce is a digital counter used to count the number of times a switch is depressed Eliminating the effects of contact bounce is called debouncing When data is entered into a computer via a keyboard a software debounce is often used This type of debouncing is a program that causes the computer to sample the switch terminal (ie to input data from it) many times in succession during the interval of time that contact bounce occurs If the data is sensed to be 1s (or 0s) for a specific number of consecutive samples then it is assumed that contact bounce has ended and the last value sensed is valid Hardware debouncing is the use of electronic circuitry to eliminate the effects of contact bounce There are numerous versions of such circuitry including those that use monostable multivibrators (one-shots) but the most straightforward is simply an RS latch Figure B1 shows the circuit When the switch is in position 1 R = 0 and S = 1 so the latch is set and the output (Q) is 1 When the switch is in position 0 R = 1and S = 0 so the latch is reset and the output is 0 When the switch is moved form one position to the other the latch changes state and bouncing occurs at either the R or the S input The bouncing does not affect the latch after it has change state An RS latch will remain set for example when its R input is 0 and its S input is alternately changed form 1 to 0

                                                                                        Figure B1 Use of RS latch to debounce a mechanical switch

                                                                                        69

                                                                                        • 01-ldst-Outer title
                                                                                          • Practical Workbook
                                                                                          • Logic Design amp Switching Theory I
                                                                                            • Dept of Computer amp Information Systems Engineering
                                                                                              • NED University of Engineering amp Technology
                                                                                              • Karachi ndash 75270 Pakistan
                                                                                                • 02-ldst-inner Title
                                                                                                  • Practical Workbook
                                                                                                  • Logic Design amp Switching Theory I
                                                                                                    • Dept of Computer amp Information Systems Engineering
                                                                                                      • NED University of Engineering amp Technology
                                                                                                      • Karachi ndash 75270 Pakistan
                                                                                                        • 03-ldst-general info
                                                                                                        • 04-ldst-introduction
                                                                                                        • 05-Table of Contents
                                                                                                          • CONTENTS
                                                                                                            • Lab Session No Object Page No
                                                                                                            • 1
                                                                                                            • Also implementing and testing the given circuit on a bread board
                                                                                                              • Working with Electronics Workbench
                                                                                                                • Driving a seven segment display using 7447 7448 driver IC
                                                                                                                  • Designing a modulus-5 asynchronous up-counter using JK-FF
                                                                                                                    • Experimenting with 74194 4-bit bidirectional universal shift register
                                                                                                                        • 13
                                                                                                                            • 06-ldst-Exp01
                                                                                                                              • Lab Session 01
                                                                                                                              • OBJECT
                                                                                                                                • 1 Bread board
                                                                                                                                • 2 5 V - power supply
                                                                                                                                • 3 Multimeter
                                                                                                                                • 4 Logic probe
                                                                                                                                • 5 LEDs with resistors
                                                                                                                                • 6 Connecting wires
                                                                                                                                • 8 Following ICs and their datasheets
                                                                                                                                  • THEORY
                                                                                                                                    • Logic Gates
                                                                                                                                    • 1 The AND Gate ndash An AND gatersquos output is 1 if and only if all its inputs are 1 If A and B are two inputs to an AND gate then output F of the gate is given as F = AB
                                                                                                                                    • 2 The OR Gate - An OR gatersquos output is 1 if at least one of its input is 1 If A and B are two inputs to an OR gate then output F of the gate is given as F = A+B
                                                                                                                                    • 3 The NOT Gate (Inverter) ndash Its output is 1 when its input is 0 and its output is 0 when the input is 1 ie it complements a digital variable If A is the input to a NOT gate then output F of the gate is given as
                                                                                                                                    • 4 The NAND Gate ndash Its output is 1 if at least one of its input is 0 This gate performs the same logic as an AND gate followed by an inverter If A and B are two inputs to a NAND gate then output F of the gate is given as
                                                                                                                                      • 5 The NOR Gate - The output of a NOR gate is 1 if and only if all its inputs are 0 This gate performs the same logic function as an OR gate followed by an inverter If A and B are two inputs to a NAND gate then output F of the gate is given as
                                                                                                                                          • DATA SHEETS
                                                                                                                                            • Logic expression for the given logic diagram __________________________________
                                                                                                                                                • 07-ldst-exp02
                                                                                                                                                  • Working with Electronics Workbench
                                                                                                                                                    • 08-ldst-exp03
                                                                                                                                                      • Designing Half and Full Adder Circuits
                                                                                                                                                        • COMPONENTS AND APPARATUS REQUIRED
                                                                                                                                                          • 1 Following ICs and their Datasheets
                                                                                                                                                          • 7408 Quad 2-input AND Gate
                                                                                                                                                          • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                            • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                            • Connecting wires Switches
                                                                                                                                                              • THEORY
                                                                                                                                                                  • IMPLEMENTATION AND OBSERVATIONS
                                                                                                                                                                    • 09-ldst-Exp04
                                                                                                                                                                      • Lab Session 04
                                                                                                                                                                      • 1 Digital ICs and their Datasheets
                                                                                                                                                                      • 7408 Quad 2-input AND Gate
                                                                                                                                                                      • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                        • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                        • Connecting wires Switches
                                                                                                                                                                        • PROCEDURE
                                                                                                                                                                        • REDUCTION OF LOGIC EXPRESSION USING KARNAUGH MAP
                                                                                                                                                                        • OBSERVATIONS
                                                                                                                                                                        • RESULT
                                                                                                                                                                            • 10-ldst-Exp05
                                                                                                                                                                              • Lab Session 05
                                                                                                                                                                              • 1 Following ICs and their Datasheets
                                                                                                                                                                              • 7408 Quad 2-input AND Gate
                                                                                                                                                                              • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                • (100 Ω) Connecting wires Switches
                                                                                                                                                                                • THEORY
                                                                                                                                                                                  • IMPLEMENTATION AND OBSERVATIONS
                                                                                                                                                                                    • 11-ldst-Exp06
                                                                                                                                                                                      • OBJECT
                                                                                                                                                                                      • 1 Following ICs and their Datasheets
                                                                                                                                                                                      • 7408 Quad 2-input AND Gates or 7411 Triple 3-input AND Gates
                                                                                                                                                                                      • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                        • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                        • Connecting wires Switches
                                                                                                                                                                                          • Figure 62 Circuit Diagram for 4 x 1 Multiplexer
                                                                                                                                                                                          • Implementation and Observations
                                                                                                                                                                                            • Circuit Diagram
                                                                                                                                                                                              • ACTIVITY
                                                                                                                                                                                                • 12-ldst-exp07
                                                                                                                                                                                                  • 1 Following ICs and their Datasheets
                                                                                                                                                                                                  • 7408 Quad 2-input or 7411 Triple 3-input AND Gates
                                                                                                                                                                                                  • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                    • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                    • Connecting wires Switches
                                                                                                                                                                                                      • THEORY
                                                                                                                                                                                                          • Figure 72 Circuit Diagram for 2 x 4 Decoder 1 x 4 Demultiplexer
                                                                                                                                                                                                          • Implementation and Observations
                                                                                                                                                                                                            • Circuit Diagram
                                                                                                                                                                                                              • ACTIVITY
                                                                                                                                                                                                                • 13-ldst-Exp08
                                                                                                                                                                                                                  • OBJECT
                                                                                                                                                                                                                  • 1 Following ICs and their Datasheets
                                                                                                                                                                                                                  • 7408 Quad 2-input or 7421 Dual 4-input AND Gates
                                                                                                                                                                                                                  • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                    • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                                    • Connecting wires Switches
                                                                                                                                                                                                                      • THEORY
                                                                                                                                                                                                                          • Figure 81 Circuit Diagram for 4 x 2 Priority Encoder
                                                                                                                                                                                                                          • Implementation and Observations
                                                                                                                                                                                                                            • Therefore if GS A2 A1 and A0 are all low then it shows that line 0 is selected and if E0 A2 A1 and A0 are all low then it shows that none of the inputs selected E0 and GS cannot be in the same state provided that E1 is enabled
                                                                                                                                                                                                                            • Circuit Diagram
                                                                                                                                                                                                                              • ACTIVITY
                                                                                                                                                                                                                                • 14-ldst-exp09
                                                                                                                                                                                                                                  • OBJECT
                                                                                                                                                                                                                                  • 1 Following ICs and their Datasheets
                                                                                                                                                                                                                                  • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                                    • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                                                    • Connecting wires Switches
                                                                                                                                                                                                                                      • THEORY
                                                                                                                                                                                                                                        • Parity Generator
                                                                                                                                                                                                                                          • Let x y and z be the three bits that constitute the message and are the input to the Odd Parity Generator Circuit Since it is an odd parity system the bit P is generated so as to make the total number of 1s odd (including P) The function P can be expressed as follows
                                                                                                                                                                                                                                          • Figure 91 Circuit Diagram for a 3-bit Parity Generator
                                                                                                                                                                                                                                            • C = x Ο y Ο z Ο P
                                                                                                                                                                                                                                              • Implementation and Observations
                                                                                                                                                                                                                                                • ACTIVITY
                                                                                                                                                                                                                                                    • 15-ldst-exp10
                                                                                                                                                                                                                                                      • Driving a seven segment display using 7447 7448 driver IC
                                                                                                                                                                                                                                                      • COMPONENTS AND APPARATUS REQUIRED
                                                                                                                                                                                                                                                      • 1 Following ICs and their Datasheets
                                                                                                                                                                                                                                                      • 7447 7448 BCD to Seven Segment Driver
                                                                                                                                                                                                                                                      • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                                                        • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches
                                                                                                                                                                                                                                                          • THEORY
                                                                                                                                                                                                                                                          • Seven Segment Displays
                                                                                                                                                                                                                                                          • CIRCUIT DIAGRAM
                                                                                                                                                                                                                                                          • Figure 102 Circuit diagram for 7447driving a common-anode display
                                                                                                                                                                                                                                                              • IMPLEMENTATION AND OBSERVATIONS
                                                                                                                                                                                                                                                                • Decimal Digit
                                                                                                                                                                                                                                                                • BCD Inputs
                                                                                                                                                                                                                                                                • Seven Segment Outputs
                                                                                                                                                                                                                                                                • D
                                                                                                                                                                                                                                                                • C
                                                                                                                                                                                                                                                                • B
                                                                                                                                                                                                                                                                • A
                                                                                                                                                                                                                                                                • a
                                                                                                                                                                                                                                                                • b
                                                                                                                                                                                                                                                                • c
                                                                                                                                                                                                                                                                • d
                                                                                                                                                                                                                                                                • e
                                                                                                                                                                                                                                                                • f
                                                                                                                                                                                                                                                                • g
                                                                                                                                                                                                                                                                • 0
                                                                                                                                                                                                                                                                • 0
                                                                                                                                                                                                                                                                • 0
                                                                                                                                                                                                                                                                • 0
                                                                                                                                                                                                                                                                • 0
                                                                                                                                                                                                                                                                • 1
                                                                                                                                                                                                                                                                • 0
                                                                                                                                                                                                                                                                • 0
                                                                                                                                                                                                                                                                • 0
                                                                                                                                                                                                                                                                • 1
                                                                                                                                                                                                                                                                • 2
                                                                                                                                                                                                                                                                • 0
                                                                                                                                                                                                                                                                • 0
                                                                                                                                                                                                                                                                • 1
                                                                                                                                                                                                                                                                • 0
                                                                                                                                                                                                                                                                • 3
                                                                                                                                                                                                                                                                • 0
                                                                                                                                                                                                                                                                • 0
                                                                                                                                                                                                                                                                • 1
                                                                                                                                                                                                                                                                • 1
                                                                                                                                                                                                                                                                • 4
                                                                                                                                                                                                                                                                • 0
                                                                                                                                                                                                                                                                • 1
                                                                                                                                                                                                                                                                • 0
                                                                                                                                                                                                                                                                • 0
                                                                                                                                                                                                                                                                • 5
                                                                                                                                                                                                                                                                • 0
                                                                                                                                                                                                                                                                • 1
                                                                                                                                                                                                                                                                • 0
                                                                                                                                                                                                                                                                • 1
                                                                                                                                                                                                                                                                • 6
                                                                                                                                                                                                                                                                • 0
                                                                                                                                                                                                                                                                • 1
                                                                                                                                                                                                                                                                • 1
                                                                                                                                                                                                                                                                • 0
                                                                                                                                                                                                                                                                • 7
                                                                                                                                                                                                                                                                • 0
                                                                                                                                                                                                                                                                • 1
                                                                                                                                                                                                                                                                • 1
                                                                                                                                                                                                                                                                • 1
                                                                                                                                                                                                                                                                • 8
                                                                                                                                                                                                                                                                • 1
                                                                                                                                                                                                                                                                • 0
                                                                                                                                                                                                                                                                • 0
                                                                                                                                                                                                                                                                • 0
                                                                                                                                                                                                                                                                • 9
                                                                                                                                                                                                                                                                • 1
                                                                                                                                                                                                                                                                • 0
                                                                                                                                                                                                                                                                • 0
                                                                                                                                                                                                                                                                • 1
                                                                                                                                                                                                                                                                  • ACTIVITY
                                                                                                                                                                                                                                                                    • 16-ldst-exp11
                                                                                                                                                                                                                                                                      • Lab Session 11
                                                                                                                                                                                                                                                                        • OBJECT
                                                                                                                                                                                                                                                                        • COMPONENTS AND APPARATUS REQUIRED
                                                                                                                                                                                                                                                                          • 1 Following ICs and their Datasheets
                                                                                                                                                                                                                                                                          • 7473 7476 JK Flip-Flop
                                                                                                                                                                                                                                                                          • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                                                                            • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                                                                                            • Connecting wires Switches
                                                                                                                                                                                                                                                                              • THEORY
                                                                                                                                                                                                                                                                                  • Flip-Flop
                                                                                                                                                                                                                                                                                  • JK Flip-Flop
                                                                                                                                                                                                                                                                                    • Circuit Diagram
                                                                                                                                                                                                                                                                                      • Observations
                                                                                                                                                                                                                                                                                        • ACTIVITY
                                                                                                                                                                                                                                                                                            • 17-ldst-exp12
                                                                                                                                                                                                                                                                                              • Lab Session 12
                                                                                                                                                                                                                                                                                                • OBJECT
                                                                                                                                                                                                                                                                                                • GIVEN STATE DIAGRAM
                                                                                                                                                                                                                                                                                                • Figure 121 State Diagram
                                                                                                                                                                                                                                                                                                • COMPONENTS AND APPARATUS REQUIRED
                                                                                                                                                                                                                                                                                                  • 1 Following ICs and their Datasheets
                                                                                                                                                                                                                                                                                                  • 7474 D Flip-Flop
                                                                                                                                                                                                                                                                                                  • ICs of basic gates (AND OR NOT XOR etc) as required
                                                                                                                                                                                                                                                                                                  • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                                                                                                    • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                                                                                                                    • Connecting wires Switches
                                                                                                                                                                                                                                                                                                      • THEORY
                                                                                                                                                                                                                                                                                                          • Sequential Circuits
                                                                                                                                                                                                                                                                                                            • 18-ldst-exp13
                                                                                                                                                                                                                                                                                                              • Lab Session 13
                                                                                                                                                                                                                                                                                                                • Designing a modulo-5 asynchronous up-counter using JK-FF
                                                                                                                                                                                                                                                                                                                  • 1 Following ICs and their Datasheets
                                                                                                                                                                                                                                                                                                                  • 7400 Quad 2-input or 7410 Triple 3-input NAND Gates
                                                                                                                                                                                                                                                                                                                  • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                                                                                                                    • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                                                                                                                                    • Connecting wires Switches
                                                                                                                                                                                                                                                                                                                      • THEORY
                                                                                                                                                                                                                                                                                                                          • Figure 131 A Mod-5 Asynchronous Up Counter
                                                                                                                                                                                                                                                                                                                          • Implementation and Observations
                                                                                                                                                                                                                                                                                                                            • ACTIVITY
                                                                                                                                                                                                                                                                                                                                • 19-ldst-exp14
                                                                                                                                                                                                                                                                                                                                  • Experimenting with 74194 4-bit bidirectional universal shift register
                                                                                                                                                                                                                                                                                                                                  • 1 Following ICs and their Datasheets
                                                                                                                                                                                                                                                                                                                                  • 74194 4-bit bidirectional universal shift register
                                                                                                                                                                                                                                                                                                                                  • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                                                                                                                                    • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                                                                                                                                                    • Connecting wires Switches
                                                                                                                                                                                                                                                                                                                                      • THEORY
                                                                                                                                                                                                                                                                                                                                        • Shift Registers
                                                                                                                                                                                                                                                                                                                                        • Bidirectional Shift Registers
                                                                                                                                                                                                                                                                                                                                        • Universal Shift Registers
                                                                                                                                                                                                                                                                                                                                          • S1
                                                                                                                                                                                                                                                                                                                                            • Circuit Diagram
                                                                                                                                                                                                                                                                                                                                            • ACTIVITY
                                                                                                                                                                                                                                                                                                                                                • 20-ldst-exp15
                                                                                                                                                                                                                                                                                                                                                  • COMPONENTS AND APPARATUS REQUIRED
                                                                                                                                                                                                                                                                                                                                                  • 1 Parallel Port Connectors (DB-25) with Cable
                                                                                                                                                                                                                                                                                                                                                  • 2 Personal Computer with Windows 98 and TurboC Compiler Installed
                                                                                                                                                                                                                                                                                                                                                  • 3 Following ICs and their Datasheets
                                                                                                                                                                                                                                                                                                                                                  • 74245 Octal Bus Transceivers with 3-State Outputs
                                                                                                                                                                                                                                                                                                                                                  • 4 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                                                                                                                                                    • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                                                                                                                                                                      • Connecting wires Switches
                                                                                                                                                                                                                                                                                                                                                        • THEORY
                                                                                                                                                                                                                                                                                                                                                        • 3-State Logic
                                                                                                                                                                                                                                                                                                                                                          • Serial and Parallel Port Connectors
                                                                                                                                                                                                                                                                                                                                                          • Parallel Port Connector ndash DB-25
                                                                                                                                                                                                                                                                                                                                                            • Accessing parallel port through C Language Programming
                                                                                                                                                                                                                                                                                                                                                                • 21-ldst-appendixA
                                                                                                                                                                                                                                                                                                                                                                • 22-ldst-appendixB
                                                                                                                                                                                                                                                                                                                                                                  • DEBOUNCING CIRCUITRY FOR MECHANICAL SWITCHES

                                                                                          Logic Design amp Switching Theory 1 Lab Session 10 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                                          47

                                                                                          Decimal Digit

                                                                                          BCD Inputs Seven Segment Outputs D C B A a b c d e f g

                                                                                          0 0 0 0 0 1 0 0 0 1 2 0 0 1 0 3 0 0 1 1 4 0 1 0 0 5 0 1 0 1 6 0 1 1 0 7 0 1 1 1 8 1 0 0 0 9 1 0 0 1

                                                                                          ACTIVITY 1 Perform the Lamp Test for the designed circuit and write your observations

                                                                                          ____________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________

                                                                                          2 How can you use 7447 IC to drive a common-cathode display

                                                                                          ____________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________

                                                                                          3 What symbols appear in the seven segment display if inputs DCBA are

                                                                                          DCBA Symbol

                                                                                          1010

                                                                                          1011

                                                                                          1100

                                                                                          1101

                                                                                          1110

                                                                                          1111

                                                                                          Logic Design amp Switching Theory 1 Lab Session 11 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                                          48

                                                                                          Lab Session 11 OBJECT

                                                                                          Testing different modes of JK-FF COMPONENTS AND APPARATUS REQUIRED 1 Following ICs and their Datasheets

                                                                                          bull 7473 7476 JK Flip-Flop 2 Digital Trainer DT-01 or the following components

                                                                                          Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches

                                                                                          THEORY

                                                                                          Flip-Flop A flip-flop circuit can maintain a binary state indefinitely (as long as the power is delivered to the circuit) until directed by an input signal to switch states The major differences among various types of flip-flops are in the number of inputs they possess and in the manner in which the inputs affect the binary state

                                                                                          JK Flip-Flop JK flip flop is an edge triggered device A typical JK flip flop has three inputs J K and a clock input The flip-flop can be either positive or negative edge triggered The output Q is available in complemented form as well Beside the usual inputs and output most of the flip-flop IC also possess two asynchronous inputs namely Preset and Clear These inputs are usually active low If used Preset and Clear inputs keep the flip-flop in set and reset state respectively irrespective of the other inputs Both of these inputs cannot be used simultaneously otherwise they will bring the flip-flop in unstable state

                                                                                          Figure 111 Symbol for JK flip-flop

                                                                                          (a) positive-edge triggering (b) active low Preset (PR) and Clear (CLR) with positive-edge triggering

                                                                                          (c) active low Preset (PR) and Clear (CLR) with negative-edge triggering

                                                                                          Logic Design amp Switching Theory 1 Lab Session 11 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                                          49

                                                                                          TESTING OF 7473 7476 DUAL JK FLIP-FLOP

                                                                                          Both the ICs 7473 and 7476 are similar in functionality except for one difference The flip-flops in 7473 have only one type of active low asynchronous input which is the Clear input whereas the flip-flops in 7476 have both Preset and Clear inputs Both these ICs have negative edge triggered flip-flops

                                                                                          Circuit Diagram

                                                                                          Figure 112 Pin connections of 7476

                                                                                          Testing Procedure

                                                                                          bull Make connections as shown in the circuit diagram (figure 112) bull Apply different combinations of 1s and 0s at J and K inputs bull Observe the output and record your observations in the following table

                                                                                          Observations

                                                                                          J

                                                                                          K Q

                                                                                          0 0 0 1 1 0 1 1

                                                                                          ACTIVITY

                                                                                          1 Observe the output Q of JK flip-flop if the clock input is connected to VCC or GND instead of a clock source Write your observations here __________________________________________________________________________________________________________________________________________ _______________________________________________________________________________________________________________________________________________________________________________________________________________

                                                                                          Logic Design amp Switching Theory 1 Lab Session 12 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                                          50

                                                                                          Lab Session 12 OBJECT

                                                                                          Designing sequential circuit for the given state diagram using D flip-flop GIVEN STATE DIAGRAM

                                                                                          00

                                                                                          11

                                                                                          Figure 121 State Diagram COMPONENTS AND APPARATUS REQUIRED 1 Following ICs and their Datasheets

                                                                                          bull 7474 D Flip-Flop bull ICs of basic gates (AND OR NOT XOR etc) as required

                                                                                          2 Digital Trainer DT-01 or the following components Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches

                                                                                          THEORY

                                                                                          Sequential Circuits In Sequential Circuits the output not only depends on the present inputs but also on previous states of the circuit These circuits use memory elements (latches flip-flops) and the binary information stored in the memory elements at any given time defines the state of the sequential circuit Analysis of a Sequential Circuit The behavior of a sequential circuit is determined from the inputs the outputs and the states of its flip-flops Both the outputs and next state are a function of the inputs and the

                                                                                          10

                                                                                          01

                                                                                          00 11 10

                                                                                          00

                                                                                          00 11 10 00

                                                                                          Logic Design amp Switching Theory 1 Lab Session 12 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                                          51

                                                                                          present state The analysis of a sequential circuit form a state diagram comprises of the following bull Selecting a particular flip-flop to design the circuit bull Obtaining state table from the state diagram bull Finding input equations for the selected flip-flop bull Finding state equations (not required for the construction of circuit) bull Implementing the circuit using selected flip-flops and their input equations ANALYZING THE GIVEN STATE DIAGRAM D Flip-Flop D flip-flop is also called transparent flip-flop as it simply transfers the input data to the output For our design we require the graphical symbol and excitation table of D flip-flop (see figure 122)

                                                                                          Qt Qt+1 T 0 0 0 0 1 1 1 0 0 1 1 1

                                                                                          (b) Excitation table of D Flip-Flop

                                                                                          (a) Graphical Symbol

                                                                                          Figure 122 Characteristic equation of D flip-flop is Q(t+1) = D State Table The given state diagram has four states so we will need two D flip-flops (FF-0 FF-1) Form state table form the given state diagram and record the results in the following table

                                                                                          Present State Input Next State Output Input to FF-0 D0

                                                                                          Input to FF-1 D1 Q1t Q0t x Q1(t+1) Q0(t+1) z

                                                                                          Logic Design amp Switching Theory 1 Lab Session 12 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                                          52

                                                                                          Input Equations Using Karnaugh map the input equations D0 and D1 for the two flip-flops can be found

                                                                                          D0 D1 Q0x

                                                                                          Q1

                                                                                          _ _ Q0x

                                                                                          _ Q0x

                                                                                          Q0x

                                                                                          _ Q0x

                                                                                          Q0x

                                                                                          Q1

                                                                                          _ _ Q0x

                                                                                          _ Q0x

                                                                                          Q0x

                                                                                          _ Q0x

                                                                                          _ Q1

                                                                                          _ Q1

                                                                                          Q1

                                                                                          Q1

                                                                                          D0 = _________________ D1 = _________________

                                                                                          State Equations Using the characteristic equation of D flip-flop we can find the state equations Q0(t+1) and Q1(t+1) for the to flip flops Q0(t+1) = _______________________ Q1(t+1) = _______________________ _______________________ _______________________ _______________________ _______________________ Circuit Diagram

                                                                                          Logic Design amp Switching Theory 1 Lab Session 12 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                                          53

                                                                                          Implementation Procedure and Observations

                                                                                          1 Implement the circuit using digital ICs on a bread board (prepare the pin diagram (use appendix A) and refer to laboratory session 01 for procedure)

                                                                                          2 Make the clear inputs of the flip-flops low (to clear the flip-flops) The flip-flops will remain in clear state as long as the clear inputs are connected to low level

                                                                                          3 Connect output Q0 and the clock pulse to an oscilloscope 4 Apply 0 to the input x 5 Now make the clear inputs to high 6 Observe the waveform for the first 5 clock pulses and record it 7 Repeat steps 2 to 6 keeping x=1 in step 4 this time 8 Repeat steps 2 to 7 this time connecting Q1 instead of Q0 to the oscilloscope in step

                                                                                          3 Record your observations (Keep frequency of the clock pulse low (eg1Hz) so that the output waveforms can be observed easily)

                                                                                          1 2 3 4 5 Clock Pulse

                                                                                          Output Waveform for Q0 when x=0

                                                                                          Output Waveform for Q0 when x=1

                                                                                          Output Waveform for Q1 when x=0

                                                                                          Output Waveform for Q1 when x=1

                                                                                          Logic Design amp Switching Theory 1 Lab Session 13 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                                          Lab Session 13 OBJECT

                                                                                          Designing a modulo-5 asynchronous up-counter using JK-FF COMPONENTS AND APPARATUS REQUIRED

                                                                                          1 Following ICs and their Datasheets

                                                                                          bull 7400 Quad 2-input or 7410 Triple 3-input NAND Gates bull 7476 7473 JK Flip-Flop

                                                                                          2 Digital Trainer DT-01 or the following components Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches

                                                                                          THEORY

                                                                                          Digital Counters A digital counter is a set of flip-flops whose states change in response to pulses applied at the input to the counter The flip-flops are interconnected so that their combined state at any time is the binary equivalent of the total number of pulses that have occurred up to that time Every counter resets after a certain number of clock pulses Thus as it name implies a counter is used to count pulses An n stage counter can count up to a maximum of 2n states n is equal to the number of flip-flops required for the construction of counter

                                                                                          Modulus Counters The number of input pulses that causes a counter to reset to its initial count is called the modulus of the counter Thus the modulus equals to total number of distinct states (counts) including zero that a counter can store A binary counter with n stages is a modulo-2n (or mod-2n) counter The largest count a mod-N counter can achieve is N-1 ie a mod-N counter never reaches the binary number equal to its modulus N is always equal to or less than 2n Counters can be classified as bull Synchronous Counters which are clock driven All the flip-flops are driven by a

                                                                                          single clock bull Asynchronous Counters which are event driven Clock input is given to the first

                                                                                          flip-flop only Rest of the flip-flops are driven by their preceding flip-flops

                                                                                          DESIGN OF A MOD-5 ASYNCHRONOUS UP COUNTER The number of flip-flops required to construct a mod-5 counter is 3 because 5 should be less than or equal to 2n This counter will count from 0 to 4 a total of 5 distinct states Since a 3-stage counter can count up to 8 states at maximum a NAND gate is used to reset it after 5 clock pulses Figure 131 shows the logic diagram

                                                                                          54

                                                                                          Logic Design amp Switching Theory 1 Lab Session 13 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                                          55

                                                                                          Figure 131 A Mod-5 Asynchronous Up Counter

                                                                                          Implementation and Observations

                                                                                          Implement the mod-5 counter circuit (figure 131) on a bread board (prepare the pin diagram (use appendix A) and refer to laboratory session 01 for implementation procedure) and record the observations in the following table

                                                                                          Clock Pulse Q2 Q1 Q0

                                                                                          0 1 2 3 4 5 6 7

                                                                                          ACTIVITY

                                                                                          Draw the timing diagram for mod-5 counter designed in this laboratory session

                                                                                          Logic Design amp Switching Theory 1 Lab Session 14 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                                          Lab Session 14 OBJECT

                                                                                          Experimenting with 74194 4-bit bidirectional universal shift register COMPONENTS AND APPARATUS REQUIRED

                                                                                          1 Following ICs and their Datasheets

                                                                                          bull 74194 4-bit bidirectional universal shift register 2 Digital Trainer DT-01 or the following components

                                                                                          Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches

                                                                                          THEORY

                                                                                          Shift Registers

                                                                                          A Register is a set of flip-flops used to store binary data A register which is capable of shifting its binary information either to the right or left is called a shift register The logical configuration of a register consists of a chain of flip-flops connected in cascade with the output of one flip-flop connected to the input of next flip-flop All flip-flops receive a common clock pulse which causes the shift from one stage to the next

                                                                                          Bidirectional Shift Registers A bi-directional shift register is one whose bits can be shifted from left to right or from right to left

                                                                                          Universal Shift Registers A universal shift register is a bi-directional register whose input can be in either serial or parallel form and whose output can be in either serial or parallel form

                                                                                          74194 4-BIT BIDIRECTIONAL UNIVERSAL SHIFT REGISTER

                                                                                          The 74194 register provides parallel as well as serial loading in both directions Function of various pins of this IC is described below

                                                                                          bull A B C and D Active high inputs for parallel loading bull QA QB QC and QD Active high outputs bull S0 and S1 Active high mode control inputs The following table shows combinations

                                                                                          of S1 and S0 to enable various modes

                                                                                          S1 S0 Clock Action 0 0 x No change 0 1 uarr Shift right 1 0 uarr Shift left 1 1 uarr Parallel load

                                                                                          uarr shows the rising edge of the clock pulse

                                                                                          56

                                                                                          Logic Design amp Switching Theory 1 Lab Session 14 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering bull SR Active high serial input for right shifting bull SL Active high serial input for left shifting bull CLR Active low input Clears all the flip-flops of the register if set to 0 should be

                                                                                          kept high otherwise bull CLK Clock input bull VCC and GND Supply connections lines Thus A B C and D are inputs for parallel loading whereas SR and SL are inputs for serial loading with right or left shifting respectively S1 and S0 are used to select the loading mode Circuit Diagram

                                                                                          Figure 141 Pin connections of 74194 Testing Procedure

                                                                                          bull Make connections as shown in the circuit diagram bull Observe the output for the input combinations given in the following table

                                                                                          57

                                                                                          Logic Design amp Switching Theory 1 Lab Session 14 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                                          58

                                                                                          Observations

                                                                                          S1 S0 SL SR A B C D QA QB QC QD 0 0 0 1 0 0 0 0 0 1 1 0 0 0 0 1 1 0 0 0 0 0 1 0 1 1 0 0 0 0 1 1 0 0 1 1 0 1 0 0 0 1 1 1 0 1 0 1 1 0 1 0 0 1 1 0 1 1 1 0 0 1 1 1 1 1 0 0 1 1 1 1

                                                                                          ACTIVITY 1 Show connections of 74194 to convert it into a ring counter with right shifting

                                                                                          Logic Design amp Switching Theory 1 Lab Session 15 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                                          Lab Session 15

                                                                                          OBJECT

                                                                                          Experimenting with 74245 octal bus transceivers using parallel port PC interfacing COMPONENTS AND APPARATUS REQUIRED 1 Parallel Port Connectors (DB-25) with Cable 2 Personal Computer with Windows 98 and TurboC Compiler Installed 3 Following ICs and their Datasheets

                                                                                          bull 74245 Octal Bus Transceivers with 3-State Outputs 4 Digital Trainer DT-01 or the following components

                                                                                          Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches

                                                                                          THEORY

                                                                                          3-State Logic Sometimes it is necessary to isolate one part of circuit from the other part For this purpose some TTL ICs are designed with 3-state logic Such devices have three possible output states high low and high impedance The device can be put into high impedance state by a control signal applied to an appropriate pin When such a device is in high impedance state there is very high impedance at its output effectively isolating the device from whatever circuitry the output normally drives 74245 Octal Bus Transceivers A bus is any conducting path or set of paths having electrical connections to one or more devices 74245 octal bus transceivers are mainly used to control connectivity between two devices or circuits It also provides direction control for signal flow Function of various pin of this IC is given below

                                                                                          bull A1 through A8 Bus A bull B1 through B8 Bus B bull G΄ Active low enable input When high sets all the bus pins to high impedance state bull DIR Direction control for signal flow When set to high logic level transfers bus A

                                                                                          data to B bus When set to low logic level transfers bus B data to A bus bull VCC and GND Supply connections lines Serial and Parallel Port Connectors A Parallel Port can consist of only 25 pin port adapter called a DB-25 and a serial port can consist of either a 25 pin port adapter called a DB-25 or 9 pin adapter called a DB-9 port adapter Whether the port is a 9 pin or 25 pin it can accomplish all of the same tasks that serial port communications have been designed for

                                                                                          59

                                                                                          Logic Design amp Switching Theory 1 Lab Session 15 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                                          60

                                                                                          Each adapter can be a male type connector with pins or a female type adapter with tiny holes Generally a PRINTER port (called LPT1) on the back of a computer is female type adapter and we need to use MALE DB-25 pin cable on it for PRINTER connection or for parallel LAPLINK cable And a COM port on the back of a computer is male for the serial ports but it may not necessarily be Parallel Port Connector ndash DB-25 The DB-25 connector (named for its B-size D-shaped shell and 25 pins) is practically ubiquitous in the electronics industry The DB-25 connector is used for a variety of purposes Two common applications are RS-232EIA-232 (serial) connections and the parallel printer interface on the IBM PC The DB-25 connector is also used for SCSI connections Normally the parallel port is used for output to a printer or other device It sends data 8-bits or one byte at a time in parallel The other lines available on the DB-25 connector are a combination of status lines control lines and ground lines The status and control lines are used for handshaking commands and feedback when we are talking to a printer

                                                                                          Figure 152 DB-25 Female Figure 151 DB-25 Male

                                                                                          Figure 153 Pin Layout for DB-25 As can be seen form figure 153 there are four types of pins in this connector

                                                                                          bull Data pins (8 pins - D0 to D7) Active high bidirectional lines

                                                                                          Logic Design amp Switching Theory 1 Lab Session 15 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering bull Control pins (4 pins - C0 to C3) C0 C1 and C3 are active low whereas C2 is active

                                                                                          high These lines also are bidirectional bull Status pins (5 pins ndash S3 to S7) Only S7 is active low rest are active high input lines bull Ground pins (8 pins) Used as a reference signal for the low (below 05 volts) charge

                                                                                          Parallel Port Addresses A DB-25 connector at a parallel port has three address one for each kind of pins register data status and control The first or base address generally refers to data register Second address is for status register and the third one is for control register In Windows 98 the base address is usually found to be 278H 378H or 3BCH Now if 378H is the base address then it refers to the data register whereas addresses for status and control register are respectively 379H and 37AH For Windows 98 the base address can be found as follows 1 On your Desktop right-click on My Computer and select Properties 2 Click on the Device Manager tab and find LPT1 under Plug and Play BIOS 3 After selecting LPT1 click the Properties button 4 Next select the Resources tab and the address should then appear next to InputOutput

                                                                                          Range Accessing parallel port through C Language Programming There are multiple functions in C Language for accessing external ports The most commonly used are listed below

                                                                                          bull unsigned char inportb(int portid) inportb reads a byte from a hardware port

                                                                                          bull int inport(int portid) reads a word from a hardware port

                                                                                          bull void outportb(int portid unsigned char value) outputs a byte to a hardware port

                                                                                          bull void outport(int portid int value) outputs a word to a hardware port

                                                                                          portid refers to the port address whereas value refers to the data to be sent TESTING 74245 USING PARALLEL PORT PC INTERFACING At one end the parallel port connector will be connected to the PC via parallel port cable and another connector (to be plugged into the PC parallel port slot) At the other end it will be connected to the buffer IC 74245 Data lines of the connector will be used to transfer 8-bit data between the PC and the buffer Out of the 8-bits of 74245 4-bits will be used to enter data which will be displayed at the monitor through a C language

                                                                                          61

                                                                                          Logic Design amp Switching Theory 1 Lab Session 15 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering program The remaining 4-bits will receive data from PC as entered by the user via keyboard

                                                                                          Circuit Diagram

                                                                                          Figure 154 Interface of 74245 to PC via Parallel Port

                                                                                          Procedure

                                                                                          1 Connect the DB-25 connector to the PC at one end and solder it to the circuit board at the other end

                                                                                          2 Connect various pins of the connector and 74245 according to the circuit diagram shown in figure 152

                                                                                          3 Using the functions listed in the previous section write a program in C language to operate various pins of the buffer The user interface of the program should provide option to the user whether to send or receive data from the port

                                                                                          4 Set DIR switch to 1 5 Try sending some data bits to the port The result should be displayed at the LEDs 6 Set DIR switch to 0 7 Set some binary 4-bit value through the switches Try reading it via parallel port

                                                                                          C Language Program

                                                                                          A program to access parallel port for data transfers

                                                                                          use header file include ltstdiohgt main program void main() define variable

                                                                                          62

                                                                                          Logic Design amp Switching Theory 1 Lab Session 15 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering unsigned int data=0 char choice while(1) printing option menu clrscr() printf(This program will send or receive a BCD digit from the parallel portn) printf(nPress your choice numbern) printf(n1 Send Data) printf(n2 Receive Data) printf(n3 Exitn) choice = getch() sending entered digit to the port if(choice == 1) input BCD digit printf(nEnter BCD digit to be sent to the port) data = getche() masking the first four bits data = data amp 0x0f sending to the port outportb(0x378data) printf(nThe BCD digit c has been sent to the port data) printing on screen the data received from the port else if(choice == 2) receiving data from the port data = inportb(0x378) masking the last four bits data = data amp 0xf0 shifting first four bits to make them the last four bits datagtgt=4 printf(nThe BCD digit set at the port is c data) exit else if(choice == 3) break key pressed is not in the menu else printf(nEnter valid choice number) printf(nnPress any key to continue) getch()

                                                                                          63

                                                                                          Logic Design amp Switching Theory 1 Lab Session 15 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                                          ACTIVITY 1 In the above circuit DIR and G΄ inputs are hardwired Connect them to status or

                                                                                          control pins of the parallel port connector and control their function through your software program Circuit Diagram Program Code ______________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________

                                                                                          ___________________________________________________________________________________________________________________________________________________

                                                                                          64

                                                                                          Logic Design amp Switching Theory 1 Lab Session 15 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                                          65

                                                                                          _____________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ _____________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ _______________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ _________________________________________________ _________________________________________________

                                                                                          Logic Design amp Switching Theory 1 Appendix A NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                                          Appendix A

                                                                                          PIN DIAGRAMS OF THE ICS REQUIRED FOR THE LABORATORY SESSIONS Consult the TTLIC data book for internal diagrams and electrical characteristics of these ICs 7400 Quad 2-Input NAND 7402 Quad 2-Input NOR

                                                                                          7404 Hex Inverter 7408 Quad 2-Input AND

                                                                                          7410 Triple 3-Input NAND 7411 Triple 3-Input AND

                                                                                          7421 Dual 4-Input AND 7432 Quad 2-Input OR

                                                                                          66

                                                                                          Logic Design amp Switching Theory 1 Appendix A NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                                          BCD-to-Seven Segm 7448 BCD-to-Seven Segment 7447 ent

                                                                                          Decoder (15V OC) Decoder (2kΩ pull-up output)

                                                                                          7473 Dual JK Flip-Flop 7474 Dual D-Type Flip-Flop

                                                                                          7476 Dual JK Flop-Flop -Bit Binary Full Adder 7483 4 with Fast Carry

                                                                                          86 Quad 2-Inpu 74138 3-to-8 Line 74 t Exclusive OR Decoder Demultiplexer

                                                                                          67

                                                                                          Logic Design amp Switching Theory 1 Appendix A NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                                          68

                                                                                          74148 8-to-3 Line 16-to-1 Line Data

                                                                                          Priority Encoder 74150 Selector Multiplexer

                                                                                          74245 Oct nsceivers Universal Shift Register (PIPO) (3-State)

                                                                                          74194 4-Bit Bidirectional al Bus Tra

                                                                                          Logic Design amp Switching Theory 1 Appendix B NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                                          Appendix B

                                                                                          DEBOUNCING CIRCUITRY FOR MECHANICAL SWITCHES Mechanical switches form the interface between human beings and computers or other digital systems For example a keyboard is a matrix of switches used to supply alphanumeric data to a computer Whatever the switch design it is a potential source of problems due to contact bounce The contact bounce creates a sense of narrow pulses when a switch is opened or closed An example of device whose operation would be adversely affected by contact bounce is a digital counter used to count the number of times a switch is depressed Eliminating the effects of contact bounce is called debouncing When data is entered into a computer via a keyboard a software debounce is often used This type of debouncing is a program that causes the computer to sample the switch terminal (ie to input data from it) many times in succession during the interval of time that contact bounce occurs If the data is sensed to be 1s (or 0s) for a specific number of consecutive samples then it is assumed that contact bounce has ended and the last value sensed is valid Hardware debouncing is the use of electronic circuitry to eliminate the effects of contact bounce There are numerous versions of such circuitry including those that use monostable multivibrators (one-shots) but the most straightforward is simply an RS latch Figure B1 shows the circuit When the switch is in position 1 R = 0 and S = 1 so the latch is set and the output (Q) is 1 When the switch is in position 0 R = 1and S = 0 so the latch is reset and the output is 0 When the switch is moved form one position to the other the latch changes state and bouncing occurs at either the R or the S input The bouncing does not affect the latch after it has change state An RS latch will remain set for example when its R input is 0 and its S input is alternately changed form 1 to 0

                                                                                          Figure B1 Use of RS latch to debounce a mechanical switch

                                                                                          69

                                                                                          • 01-ldst-Outer title
                                                                                            • Practical Workbook
                                                                                            • Logic Design amp Switching Theory I
                                                                                              • Dept of Computer amp Information Systems Engineering
                                                                                                • NED University of Engineering amp Technology
                                                                                                • Karachi ndash 75270 Pakistan
                                                                                                  • 02-ldst-inner Title
                                                                                                    • Practical Workbook
                                                                                                    • Logic Design amp Switching Theory I
                                                                                                      • Dept of Computer amp Information Systems Engineering
                                                                                                        • NED University of Engineering amp Technology
                                                                                                        • Karachi ndash 75270 Pakistan
                                                                                                          • 03-ldst-general info
                                                                                                          • 04-ldst-introduction
                                                                                                          • 05-Table of Contents
                                                                                                            • CONTENTS
                                                                                                              • Lab Session No Object Page No
                                                                                                              • 1
                                                                                                              • Also implementing and testing the given circuit on a bread board
                                                                                                                • Working with Electronics Workbench
                                                                                                                  • Driving a seven segment display using 7447 7448 driver IC
                                                                                                                    • Designing a modulus-5 asynchronous up-counter using JK-FF
                                                                                                                      • Experimenting with 74194 4-bit bidirectional universal shift register
                                                                                                                          • 13
                                                                                                                              • 06-ldst-Exp01
                                                                                                                                • Lab Session 01
                                                                                                                                • OBJECT
                                                                                                                                  • 1 Bread board
                                                                                                                                  • 2 5 V - power supply
                                                                                                                                  • 3 Multimeter
                                                                                                                                  • 4 Logic probe
                                                                                                                                  • 5 LEDs with resistors
                                                                                                                                  • 6 Connecting wires
                                                                                                                                  • 8 Following ICs and their datasheets
                                                                                                                                    • THEORY
                                                                                                                                      • Logic Gates
                                                                                                                                      • 1 The AND Gate ndash An AND gatersquos output is 1 if and only if all its inputs are 1 If A and B are two inputs to an AND gate then output F of the gate is given as F = AB
                                                                                                                                      • 2 The OR Gate - An OR gatersquos output is 1 if at least one of its input is 1 If A and B are two inputs to an OR gate then output F of the gate is given as F = A+B
                                                                                                                                      • 3 The NOT Gate (Inverter) ndash Its output is 1 when its input is 0 and its output is 0 when the input is 1 ie it complements a digital variable If A is the input to a NOT gate then output F of the gate is given as
                                                                                                                                      • 4 The NAND Gate ndash Its output is 1 if at least one of its input is 0 This gate performs the same logic as an AND gate followed by an inverter If A and B are two inputs to a NAND gate then output F of the gate is given as
                                                                                                                                        • 5 The NOR Gate - The output of a NOR gate is 1 if and only if all its inputs are 0 This gate performs the same logic function as an OR gate followed by an inverter If A and B are two inputs to a NAND gate then output F of the gate is given as
                                                                                                                                            • DATA SHEETS
                                                                                                                                              • Logic expression for the given logic diagram __________________________________
                                                                                                                                                  • 07-ldst-exp02
                                                                                                                                                    • Working with Electronics Workbench
                                                                                                                                                      • 08-ldst-exp03
                                                                                                                                                        • Designing Half and Full Adder Circuits
                                                                                                                                                          • COMPONENTS AND APPARATUS REQUIRED
                                                                                                                                                            • 1 Following ICs and their Datasheets
                                                                                                                                                            • 7408 Quad 2-input AND Gate
                                                                                                                                                            • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                              • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                              • Connecting wires Switches
                                                                                                                                                                • THEORY
                                                                                                                                                                    • IMPLEMENTATION AND OBSERVATIONS
                                                                                                                                                                      • 09-ldst-Exp04
                                                                                                                                                                        • Lab Session 04
                                                                                                                                                                        • 1 Digital ICs and their Datasheets
                                                                                                                                                                        • 7408 Quad 2-input AND Gate
                                                                                                                                                                        • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                          • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                          • Connecting wires Switches
                                                                                                                                                                          • PROCEDURE
                                                                                                                                                                          • REDUCTION OF LOGIC EXPRESSION USING KARNAUGH MAP
                                                                                                                                                                          • OBSERVATIONS
                                                                                                                                                                          • RESULT
                                                                                                                                                                              • 10-ldst-Exp05
                                                                                                                                                                                • Lab Session 05
                                                                                                                                                                                • 1 Following ICs and their Datasheets
                                                                                                                                                                                • 7408 Quad 2-input AND Gate
                                                                                                                                                                                • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                  • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                  • (100 Ω) Connecting wires Switches
                                                                                                                                                                                  • THEORY
                                                                                                                                                                                    • IMPLEMENTATION AND OBSERVATIONS
                                                                                                                                                                                      • 11-ldst-Exp06
                                                                                                                                                                                        • OBJECT
                                                                                                                                                                                        • 1 Following ICs and their Datasheets
                                                                                                                                                                                        • 7408 Quad 2-input AND Gates or 7411 Triple 3-input AND Gates
                                                                                                                                                                                        • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                          • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                          • Connecting wires Switches
                                                                                                                                                                                            • Figure 62 Circuit Diagram for 4 x 1 Multiplexer
                                                                                                                                                                                            • Implementation and Observations
                                                                                                                                                                                              • Circuit Diagram
                                                                                                                                                                                                • ACTIVITY
                                                                                                                                                                                                  • 12-ldst-exp07
                                                                                                                                                                                                    • 1 Following ICs and their Datasheets
                                                                                                                                                                                                    • 7408 Quad 2-input or 7411 Triple 3-input AND Gates
                                                                                                                                                                                                    • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                      • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                      • Connecting wires Switches
                                                                                                                                                                                                        • THEORY
                                                                                                                                                                                                            • Figure 72 Circuit Diagram for 2 x 4 Decoder 1 x 4 Demultiplexer
                                                                                                                                                                                                            • Implementation and Observations
                                                                                                                                                                                                              • Circuit Diagram
                                                                                                                                                                                                                • ACTIVITY
                                                                                                                                                                                                                  • 13-ldst-Exp08
                                                                                                                                                                                                                    • OBJECT
                                                                                                                                                                                                                    • 1 Following ICs and their Datasheets
                                                                                                                                                                                                                    • 7408 Quad 2-input or 7421 Dual 4-input AND Gates
                                                                                                                                                                                                                    • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                      • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                                      • Connecting wires Switches
                                                                                                                                                                                                                        • THEORY
                                                                                                                                                                                                                            • Figure 81 Circuit Diagram for 4 x 2 Priority Encoder
                                                                                                                                                                                                                            • Implementation and Observations
                                                                                                                                                                                                                              • Therefore if GS A2 A1 and A0 are all low then it shows that line 0 is selected and if E0 A2 A1 and A0 are all low then it shows that none of the inputs selected E0 and GS cannot be in the same state provided that E1 is enabled
                                                                                                                                                                                                                              • Circuit Diagram
                                                                                                                                                                                                                                • ACTIVITY
                                                                                                                                                                                                                                  • 14-ldst-exp09
                                                                                                                                                                                                                                    • OBJECT
                                                                                                                                                                                                                                    • 1 Following ICs and their Datasheets
                                                                                                                                                                                                                                    • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                                      • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                                                      • Connecting wires Switches
                                                                                                                                                                                                                                        • THEORY
                                                                                                                                                                                                                                          • Parity Generator
                                                                                                                                                                                                                                            • Let x y and z be the three bits that constitute the message and are the input to the Odd Parity Generator Circuit Since it is an odd parity system the bit P is generated so as to make the total number of 1s odd (including P) The function P can be expressed as follows
                                                                                                                                                                                                                                            • Figure 91 Circuit Diagram for a 3-bit Parity Generator
                                                                                                                                                                                                                                              • C = x Ο y Ο z Ο P
                                                                                                                                                                                                                                                • Implementation and Observations
                                                                                                                                                                                                                                                  • ACTIVITY
                                                                                                                                                                                                                                                      • 15-ldst-exp10
                                                                                                                                                                                                                                                        • Driving a seven segment display using 7447 7448 driver IC
                                                                                                                                                                                                                                                        • COMPONENTS AND APPARATUS REQUIRED
                                                                                                                                                                                                                                                        • 1 Following ICs and their Datasheets
                                                                                                                                                                                                                                                        • 7447 7448 BCD to Seven Segment Driver
                                                                                                                                                                                                                                                        • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                                                          • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches
                                                                                                                                                                                                                                                            • THEORY
                                                                                                                                                                                                                                                            • Seven Segment Displays
                                                                                                                                                                                                                                                            • CIRCUIT DIAGRAM
                                                                                                                                                                                                                                                            • Figure 102 Circuit diagram for 7447driving a common-anode display
                                                                                                                                                                                                                                                                • IMPLEMENTATION AND OBSERVATIONS
                                                                                                                                                                                                                                                                  • Decimal Digit
                                                                                                                                                                                                                                                                  • BCD Inputs
                                                                                                                                                                                                                                                                  • Seven Segment Outputs
                                                                                                                                                                                                                                                                  • D
                                                                                                                                                                                                                                                                  • C
                                                                                                                                                                                                                                                                  • B
                                                                                                                                                                                                                                                                  • A
                                                                                                                                                                                                                                                                  • a
                                                                                                                                                                                                                                                                  • b
                                                                                                                                                                                                                                                                  • c
                                                                                                                                                                                                                                                                  • d
                                                                                                                                                                                                                                                                  • e
                                                                                                                                                                                                                                                                  • f
                                                                                                                                                                                                                                                                  • g
                                                                                                                                                                                                                                                                  • 0
                                                                                                                                                                                                                                                                  • 0
                                                                                                                                                                                                                                                                  • 0
                                                                                                                                                                                                                                                                  • 0
                                                                                                                                                                                                                                                                  • 0
                                                                                                                                                                                                                                                                  • 1
                                                                                                                                                                                                                                                                  • 0
                                                                                                                                                                                                                                                                  • 0
                                                                                                                                                                                                                                                                  • 0
                                                                                                                                                                                                                                                                  • 1
                                                                                                                                                                                                                                                                  • 2
                                                                                                                                                                                                                                                                  • 0
                                                                                                                                                                                                                                                                  • 0
                                                                                                                                                                                                                                                                  • 1
                                                                                                                                                                                                                                                                  • 0
                                                                                                                                                                                                                                                                  • 3
                                                                                                                                                                                                                                                                  • 0
                                                                                                                                                                                                                                                                  • 0
                                                                                                                                                                                                                                                                  • 1
                                                                                                                                                                                                                                                                  • 1
                                                                                                                                                                                                                                                                  • 4
                                                                                                                                                                                                                                                                  • 0
                                                                                                                                                                                                                                                                  • 1
                                                                                                                                                                                                                                                                  • 0
                                                                                                                                                                                                                                                                  • 0
                                                                                                                                                                                                                                                                  • 5
                                                                                                                                                                                                                                                                  • 0
                                                                                                                                                                                                                                                                  • 1
                                                                                                                                                                                                                                                                  • 0
                                                                                                                                                                                                                                                                  • 1
                                                                                                                                                                                                                                                                  • 6
                                                                                                                                                                                                                                                                  • 0
                                                                                                                                                                                                                                                                  • 1
                                                                                                                                                                                                                                                                  • 1
                                                                                                                                                                                                                                                                  • 0
                                                                                                                                                                                                                                                                  • 7
                                                                                                                                                                                                                                                                  • 0
                                                                                                                                                                                                                                                                  • 1
                                                                                                                                                                                                                                                                  • 1
                                                                                                                                                                                                                                                                  • 1
                                                                                                                                                                                                                                                                  • 8
                                                                                                                                                                                                                                                                  • 1
                                                                                                                                                                                                                                                                  • 0
                                                                                                                                                                                                                                                                  • 0
                                                                                                                                                                                                                                                                  • 0
                                                                                                                                                                                                                                                                  • 9
                                                                                                                                                                                                                                                                  • 1
                                                                                                                                                                                                                                                                  • 0
                                                                                                                                                                                                                                                                  • 0
                                                                                                                                                                                                                                                                  • 1
                                                                                                                                                                                                                                                                    • ACTIVITY
                                                                                                                                                                                                                                                                      • 16-ldst-exp11
                                                                                                                                                                                                                                                                        • Lab Session 11
                                                                                                                                                                                                                                                                          • OBJECT
                                                                                                                                                                                                                                                                          • COMPONENTS AND APPARATUS REQUIRED
                                                                                                                                                                                                                                                                            • 1 Following ICs and their Datasheets
                                                                                                                                                                                                                                                                            • 7473 7476 JK Flip-Flop
                                                                                                                                                                                                                                                                            • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                                                                              • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                                                                                              • Connecting wires Switches
                                                                                                                                                                                                                                                                                • THEORY
                                                                                                                                                                                                                                                                                    • Flip-Flop
                                                                                                                                                                                                                                                                                    • JK Flip-Flop
                                                                                                                                                                                                                                                                                      • Circuit Diagram
                                                                                                                                                                                                                                                                                        • Observations
                                                                                                                                                                                                                                                                                          • ACTIVITY
                                                                                                                                                                                                                                                                                              • 17-ldst-exp12
                                                                                                                                                                                                                                                                                                • Lab Session 12
                                                                                                                                                                                                                                                                                                  • OBJECT
                                                                                                                                                                                                                                                                                                  • GIVEN STATE DIAGRAM
                                                                                                                                                                                                                                                                                                  • Figure 121 State Diagram
                                                                                                                                                                                                                                                                                                  • COMPONENTS AND APPARATUS REQUIRED
                                                                                                                                                                                                                                                                                                    • 1 Following ICs and their Datasheets
                                                                                                                                                                                                                                                                                                    • 7474 D Flip-Flop
                                                                                                                                                                                                                                                                                                    • ICs of basic gates (AND OR NOT XOR etc) as required
                                                                                                                                                                                                                                                                                                    • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                                                                                                      • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                                                                                                                      • Connecting wires Switches
                                                                                                                                                                                                                                                                                                        • THEORY
                                                                                                                                                                                                                                                                                                            • Sequential Circuits
                                                                                                                                                                                                                                                                                                              • 18-ldst-exp13
                                                                                                                                                                                                                                                                                                                • Lab Session 13
                                                                                                                                                                                                                                                                                                                  • Designing a modulo-5 asynchronous up-counter using JK-FF
                                                                                                                                                                                                                                                                                                                    • 1 Following ICs and their Datasheets
                                                                                                                                                                                                                                                                                                                    • 7400 Quad 2-input or 7410 Triple 3-input NAND Gates
                                                                                                                                                                                                                                                                                                                    • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                                                                                                                      • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                                                                                                                                      • Connecting wires Switches
                                                                                                                                                                                                                                                                                                                        • THEORY
                                                                                                                                                                                                                                                                                                                            • Figure 131 A Mod-5 Asynchronous Up Counter
                                                                                                                                                                                                                                                                                                                            • Implementation and Observations
                                                                                                                                                                                                                                                                                                                              • ACTIVITY
                                                                                                                                                                                                                                                                                                                                  • 19-ldst-exp14
                                                                                                                                                                                                                                                                                                                                    • Experimenting with 74194 4-bit bidirectional universal shift register
                                                                                                                                                                                                                                                                                                                                    • 1 Following ICs and their Datasheets
                                                                                                                                                                                                                                                                                                                                    • 74194 4-bit bidirectional universal shift register
                                                                                                                                                                                                                                                                                                                                    • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                                                                                                                                      • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                                                                                                                                                      • Connecting wires Switches
                                                                                                                                                                                                                                                                                                                                        • THEORY
                                                                                                                                                                                                                                                                                                                                          • Shift Registers
                                                                                                                                                                                                                                                                                                                                          • Bidirectional Shift Registers
                                                                                                                                                                                                                                                                                                                                          • Universal Shift Registers
                                                                                                                                                                                                                                                                                                                                            • S1
                                                                                                                                                                                                                                                                                                                                              • Circuit Diagram
                                                                                                                                                                                                                                                                                                                                              • ACTIVITY
                                                                                                                                                                                                                                                                                                                                                  • 20-ldst-exp15
                                                                                                                                                                                                                                                                                                                                                    • COMPONENTS AND APPARATUS REQUIRED
                                                                                                                                                                                                                                                                                                                                                    • 1 Parallel Port Connectors (DB-25) with Cable
                                                                                                                                                                                                                                                                                                                                                    • 2 Personal Computer with Windows 98 and TurboC Compiler Installed
                                                                                                                                                                                                                                                                                                                                                    • 3 Following ICs and their Datasheets
                                                                                                                                                                                                                                                                                                                                                    • 74245 Octal Bus Transceivers with 3-State Outputs
                                                                                                                                                                                                                                                                                                                                                    • 4 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                                                                                                                                                      • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                                                                                                                                                                        • Connecting wires Switches
                                                                                                                                                                                                                                                                                                                                                          • THEORY
                                                                                                                                                                                                                                                                                                                                                          • 3-State Logic
                                                                                                                                                                                                                                                                                                                                                            • Serial and Parallel Port Connectors
                                                                                                                                                                                                                                                                                                                                                            • Parallel Port Connector ndash DB-25
                                                                                                                                                                                                                                                                                                                                                              • Accessing parallel port through C Language Programming
                                                                                                                                                                                                                                                                                                                                                                  • 21-ldst-appendixA
                                                                                                                                                                                                                                                                                                                                                                  • 22-ldst-appendixB
                                                                                                                                                                                                                                                                                                                                                                    • DEBOUNCING CIRCUITRY FOR MECHANICAL SWITCHES

                                                                                            Logic Design amp Switching Theory 1 Lab Session 11 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                                            48

                                                                                            Lab Session 11 OBJECT

                                                                                            Testing different modes of JK-FF COMPONENTS AND APPARATUS REQUIRED 1 Following ICs and their Datasheets

                                                                                            bull 7473 7476 JK Flip-Flop 2 Digital Trainer DT-01 or the following components

                                                                                            Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches

                                                                                            THEORY

                                                                                            Flip-Flop A flip-flop circuit can maintain a binary state indefinitely (as long as the power is delivered to the circuit) until directed by an input signal to switch states The major differences among various types of flip-flops are in the number of inputs they possess and in the manner in which the inputs affect the binary state

                                                                                            JK Flip-Flop JK flip flop is an edge triggered device A typical JK flip flop has three inputs J K and a clock input The flip-flop can be either positive or negative edge triggered The output Q is available in complemented form as well Beside the usual inputs and output most of the flip-flop IC also possess two asynchronous inputs namely Preset and Clear These inputs are usually active low If used Preset and Clear inputs keep the flip-flop in set and reset state respectively irrespective of the other inputs Both of these inputs cannot be used simultaneously otherwise they will bring the flip-flop in unstable state

                                                                                            Figure 111 Symbol for JK flip-flop

                                                                                            (a) positive-edge triggering (b) active low Preset (PR) and Clear (CLR) with positive-edge triggering

                                                                                            (c) active low Preset (PR) and Clear (CLR) with negative-edge triggering

                                                                                            Logic Design amp Switching Theory 1 Lab Session 11 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                                            49

                                                                                            TESTING OF 7473 7476 DUAL JK FLIP-FLOP

                                                                                            Both the ICs 7473 and 7476 are similar in functionality except for one difference The flip-flops in 7473 have only one type of active low asynchronous input which is the Clear input whereas the flip-flops in 7476 have both Preset and Clear inputs Both these ICs have negative edge triggered flip-flops

                                                                                            Circuit Diagram

                                                                                            Figure 112 Pin connections of 7476

                                                                                            Testing Procedure

                                                                                            bull Make connections as shown in the circuit diagram (figure 112) bull Apply different combinations of 1s and 0s at J and K inputs bull Observe the output and record your observations in the following table

                                                                                            Observations

                                                                                            J

                                                                                            K Q

                                                                                            0 0 0 1 1 0 1 1

                                                                                            ACTIVITY

                                                                                            1 Observe the output Q of JK flip-flop if the clock input is connected to VCC or GND instead of a clock source Write your observations here __________________________________________________________________________________________________________________________________________ _______________________________________________________________________________________________________________________________________________________________________________________________________________

                                                                                            Logic Design amp Switching Theory 1 Lab Session 12 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                                            50

                                                                                            Lab Session 12 OBJECT

                                                                                            Designing sequential circuit for the given state diagram using D flip-flop GIVEN STATE DIAGRAM

                                                                                            00

                                                                                            11

                                                                                            Figure 121 State Diagram COMPONENTS AND APPARATUS REQUIRED 1 Following ICs and their Datasheets

                                                                                            bull 7474 D Flip-Flop bull ICs of basic gates (AND OR NOT XOR etc) as required

                                                                                            2 Digital Trainer DT-01 or the following components Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches

                                                                                            THEORY

                                                                                            Sequential Circuits In Sequential Circuits the output not only depends on the present inputs but also on previous states of the circuit These circuits use memory elements (latches flip-flops) and the binary information stored in the memory elements at any given time defines the state of the sequential circuit Analysis of a Sequential Circuit The behavior of a sequential circuit is determined from the inputs the outputs and the states of its flip-flops Both the outputs and next state are a function of the inputs and the

                                                                                            10

                                                                                            01

                                                                                            00 11 10

                                                                                            00

                                                                                            00 11 10 00

                                                                                            Logic Design amp Switching Theory 1 Lab Session 12 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                                            51

                                                                                            present state The analysis of a sequential circuit form a state diagram comprises of the following bull Selecting a particular flip-flop to design the circuit bull Obtaining state table from the state diagram bull Finding input equations for the selected flip-flop bull Finding state equations (not required for the construction of circuit) bull Implementing the circuit using selected flip-flops and their input equations ANALYZING THE GIVEN STATE DIAGRAM D Flip-Flop D flip-flop is also called transparent flip-flop as it simply transfers the input data to the output For our design we require the graphical symbol and excitation table of D flip-flop (see figure 122)

                                                                                            Qt Qt+1 T 0 0 0 0 1 1 1 0 0 1 1 1

                                                                                            (b) Excitation table of D Flip-Flop

                                                                                            (a) Graphical Symbol

                                                                                            Figure 122 Characteristic equation of D flip-flop is Q(t+1) = D State Table The given state diagram has four states so we will need two D flip-flops (FF-0 FF-1) Form state table form the given state diagram and record the results in the following table

                                                                                            Present State Input Next State Output Input to FF-0 D0

                                                                                            Input to FF-1 D1 Q1t Q0t x Q1(t+1) Q0(t+1) z

                                                                                            Logic Design amp Switching Theory 1 Lab Session 12 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                                            52

                                                                                            Input Equations Using Karnaugh map the input equations D0 and D1 for the two flip-flops can be found

                                                                                            D0 D1 Q0x

                                                                                            Q1

                                                                                            _ _ Q0x

                                                                                            _ Q0x

                                                                                            Q0x

                                                                                            _ Q0x

                                                                                            Q0x

                                                                                            Q1

                                                                                            _ _ Q0x

                                                                                            _ Q0x

                                                                                            Q0x

                                                                                            _ Q0x

                                                                                            _ Q1

                                                                                            _ Q1

                                                                                            Q1

                                                                                            Q1

                                                                                            D0 = _________________ D1 = _________________

                                                                                            State Equations Using the characteristic equation of D flip-flop we can find the state equations Q0(t+1) and Q1(t+1) for the to flip flops Q0(t+1) = _______________________ Q1(t+1) = _______________________ _______________________ _______________________ _______________________ _______________________ Circuit Diagram

                                                                                            Logic Design amp Switching Theory 1 Lab Session 12 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                                            53

                                                                                            Implementation Procedure and Observations

                                                                                            1 Implement the circuit using digital ICs on a bread board (prepare the pin diagram (use appendix A) and refer to laboratory session 01 for procedure)

                                                                                            2 Make the clear inputs of the flip-flops low (to clear the flip-flops) The flip-flops will remain in clear state as long as the clear inputs are connected to low level

                                                                                            3 Connect output Q0 and the clock pulse to an oscilloscope 4 Apply 0 to the input x 5 Now make the clear inputs to high 6 Observe the waveform for the first 5 clock pulses and record it 7 Repeat steps 2 to 6 keeping x=1 in step 4 this time 8 Repeat steps 2 to 7 this time connecting Q1 instead of Q0 to the oscilloscope in step

                                                                                            3 Record your observations (Keep frequency of the clock pulse low (eg1Hz) so that the output waveforms can be observed easily)

                                                                                            1 2 3 4 5 Clock Pulse

                                                                                            Output Waveform for Q0 when x=0

                                                                                            Output Waveform for Q0 when x=1

                                                                                            Output Waveform for Q1 when x=0

                                                                                            Output Waveform for Q1 when x=1

                                                                                            Logic Design amp Switching Theory 1 Lab Session 13 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                                            Lab Session 13 OBJECT

                                                                                            Designing a modulo-5 asynchronous up-counter using JK-FF COMPONENTS AND APPARATUS REQUIRED

                                                                                            1 Following ICs and their Datasheets

                                                                                            bull 7400 Quad 2-input or 7410 Triple 3-input NAND Gates bull 7476 7473 JK Flip-Flop

                                                                                            2 Digital Trainer DT-01 or the following components Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches

                                                                                            THEORY

                                                                                            Digital Counters A digital counter is a set of flip-flops whose states change in response to pulses applied at the input to the counter The flip-flops are interconnected so that their combined state at any time is the binary equivalent of the total number of pulses that have occurred up to that time Every counter resets after a certain number of clock pulses Thus as it name implies a counter is used to count pulses An n stage counter can count up to a maximum of 2n states n is equal to the number of flip-flops required for the construction of counter

                                                                                            Modulus Counters The number of input pulses that causes a counter to reset to its initial count is called the modulus of the counter Thus the modulus equals to total number of distinct states (counts) including zero that a counter can store A binary counter with n stages is a modulo-2n (or mod-2n) counter The largest count a mod-N counter can achieve is N-1 ie a mod-N counter never reaches the binary number equal to its modulus N is always equal to or less than 2n Counters can be classified as bull Synchronous Counters which are clock driven All the flip-flops are driven by a

                                                                                            single clock bull Asynchronous Counters which are event driven Clock input is given to the first

                                                                                            flip-flop only Rest of the flip-flops are driven by their preceding flip-flops

                                                                                            DESIGN OF A MOD-5 ASYNCHRONOUS UP COUNTER The number of flip-flops required to construct a mod-5 counter is 3 because 5 should be less than or equal to 2n This counter will count from 0 to 4 a total of 5 distinct states Since a 3-stage counter can count up to 8 states at maximum a NAND gate is used to reset it after 5 clock pulses Figure 131 shows the logic diagram

                                                                                            54

                                                                                            Logic Design amp Switching Theory 1 Lab Session 13 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                                            55

                                                                                            Figure 131 A Mod-5 Asynchronous Up Counter

                                                                                            Implementation and Observations

                                                                                            Implement the mod-5 counter circuit (figure 131) on a bread board (prepare the pin diagram (use appendix A) and refer to laboratory session 01 for implementation procedure) and record the observations in the following table

                                                                                            Clock Pulse Q2 Q1 Q0

                                                                                            0 1 2 3 4 5 6 7

                                                                                            ACTIVITY

                                                                                            Draw the timing diagram for mod-5 counter designed in this laboratory session

                                                                                            Logic Design amp Switching Theory 1 Lab Session 14 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                                            Lab Session 14 OBJECT

                                                                                            Experimenting with 74194 4-bit bidirectional universal shift register COMPONENTS AND APPARATUS REQUIRED

                                                                                            1 Following ICs and their Datasheets

                                                                                            bull 74194 4-bit bidirectional universal shift register 2 Digital Trainer DT-01 or the following components

                                                                                            Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches

                                                                                            THEORY

                                                                                            Shift Registers

                                                                                            A Register is a set of flip-flops used to store binary data A register which is capable of shifting its binary information either to the right or left is called a shift register The logical configuration of a register consists of a chain of flip-flops connected in cascade with the output of one flip-flop connected to the input of next flip-flop All flip-flops receive a common clock pulse which causes the shift from one stage to the next

                                                                                            Bidirectional Shift Registers A bi-directional shift register is one whose bits can be shifted from left to right or from right to left

                                                                                            Universal Shift Registers A universal shift register is a bi-directional register whose input can be in either serial or parallel form and whose output can be in either serial or parallel form

                                                                                            74194 4-BIT BIDIRECTIONAL UNIVERSAL SHIFT REGISTER

                                                                                            The 74194 register provides parallel as well as serial loading in both directions Function of various pins of this IC is described below

                                                                                            bull A B C and D Active high inputs for parallel loading bull QA QB QC and QD Active high outputs bull S0 and S1 Active high mode control inputs The following table shows combinations

                                                                                            of S1 and S0 to enable various modes

                                                                                            S1 S0 Clock Action 0 0 x No change 0 1 uarr Shift right 1 0 uarr Shift left 1 1 uarr Parallel load

                                                                                            uarr shows the rising edge of the clock pulse

                                                                                            56

                                                                                            Logic Design amp Switching Theory 1 Lab Session 14 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering bull SR Active high serial input for right shifting bull SL Active high serial input for left shifting bull CLR Active low input Clears all the flip-flops of the register if set to 0 should be

                                                                                            kept high otherwise bull CLK Clock input bull VCC and GND Supply connections lines Thus A B C and D are inputs for parallel loading whereas SR and SL are inputs for serial loading with right or left shifting respectively S1 and S0 are used to select the loading mode Circuit Diagram

                                                                                            Figure 141 Pin connections of 74194 Testing Procedure

                                                                                            bull Make connections as shown in the circuit diagram bull Observe the output for the input combinations given in the following table

                                                                                            57

                                                                                            Logic Design amp Switching Theory 1 Lab Session 14 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                                            58

                                                                                            Observations

                                                                                            S1 S0 SL SR A B C D QA QB QC QD 0 0 0 1 0 0 0 0 0 1 1 0 0 0 0 1 1 0 0 0 0 0 1 0 1 1 0 0 0 0 1 1 0 0 1 1 0 1 0 0 0 1 1 1 0 1 0 1 1 0 1 0 0 1 1 0 1 1 1 0 0 1 1 1 1 1 0 0 1 1 1 1

                                                                                            ACTIVITY 1 Show connections of 74194 to convert it into a ring counter with right shifting

                                                                                            Logic Design amp Switching Theory 1 Lab Session 15 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                                            Lab Session 15

                                                                                            OBJECT

                                                                                            Experimenting with 74245 octal bus transceivers using parallel port PC interfacing COMPONENTS AND APPARATUS REQUIRED 1 Parallel Port Connectors (DB-25) with Cable 2 Personal Computer with Windows 98 and TurboC Compiler Installed 3 Following ICs and their Datasheets

                                                                                            bull 74245 Octal Bus Transceivers with 3-State Outputs 4 Digital Trainer DT-01 or the following components

                                                                                            Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches

                                                                                            THEORY

                                                                                            3-State Logic Sometimes it is necessary to isolate one part of circuit from the other part For this purpose some TTL ICs are designed with 3-state logic Such devices have three possible output states high low and high impedance The device can be put into high impedance state by a control signal applied to an appropriate pin When such a device is in high impedance state there is very high impedance at its output effectively isolating the device from whatever circuitry the output normally drives 74245 Octal Bus Transceivers A bus is any conducting path or set of paths having electrical connections to one or more devices 74245 octal bus transceivers are mainly used to control connectivity between two devices or circuits It also provides direction control for signal flow Function of various pin of this IC is given below

                                                                                            bull A1 through A8 Bus A bull B1 through B8 Bus B bull G΄ Active low enable input When high sets all the bus pins to high impedance state bull DIR Direction control for signal flow When set to high logic level transfers bus A

                                                                                            data to B bus When set to low logic level transfers bus B data to A bus bull VCC and GND Supply connections lines Serial and Parallel Port Connectors A Parallel Port can consist of only 25 pin port adapter called a DB-25 and a serial port can consist of either a 25 pin port adapter called a DB-25 or 9 pin adapter called a DB-9 port adapter Whether the port is a 9 pin or 25 pin it can accomplish all of the same tasks that serial port communications have been designed for

                                                                                            59

                                                                                            Logic Design amp Switching Theory 1 Lab Session 15 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                                            60

                                                                                            Each adapter can be a male type connector with pins or a female type adapter with tiny holes Generally a PRINTER port (called LPT1) on the back of a computer is female type adapter and we need to use MALE DB-25 pin cable on it for PRINTER connection or for parallel LAPLINK cable And a COM port on the back of a computer is male for the serial ports but it may not necessarily be Parallel Port Connector ndash DB-25 The DB-25 connector (named for its B-size D-shaped shell and 25 pins) is practically ubiquitous in the electronics industry The DB-25 connector is used for a variety of purposes Two common applications are RS-232EIA-232 (serial) connections and the parallel printer interface on the IBM PC The DB-25 connector is also used for SCSI connections Normally the parallel port is used for output to a printer or other device It sends data 8-bits or one byte at a time in parallel The other lines available on the DB-25 connector are a combination of status lines control lines and ground lines The status and control lines are used for handshaking commands and feedback when we are talking to a printer

                                                                                            Figure 152 DB-25 Female Figure 151 DB-25 Male

                                                                                            Figure 153 Pin Layout for DB-25 As can be seen form figure 153 there are four types of pins in this connector

                                                                                            bull Data pins (8 pins - D0 to D7) Active high bidirectional lines

                                                                                            Logic Design amp Switching Theory 1 Lab Session 15 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering bull Control pins (4 pins - C0 to C3) C0 C1 and C3 are active low whereas C2 is active

                                                                                            high These lines also are bidirectional bull Status pins (5 pins ndash S3 to S7) Only S7 is active low rest are active high input lines bull Ground pins (8 pins) Used as a reference signal for the low (below 05 volts) charge

                                                                                            Parallel Port Addresses A DB-25 connector at a parallel port has three address one for each kind of pins register data status and control The first or base address generally refers to data register Second address is for status register and the third one is for control register In Windows 98 the base address is usually found to be 278H 378H or 3BCH Now if 378H is the base address then it refers to the data register whereas addresses for status and control register are respectively 379H and 37AH For Windows 98 the base address can be found as follows 1 On your Desktop right-click on My Computer and select Properties 2 Click on the Device Manager tab and find LPT1 under Plug and Play BIOS 3 After selecting LPT1 click the Properties button 4 Next select the Resources tab and the address should then appear next to InputOutput

                                                                                            Range Accessing parallel port through C Language Programming There are multiple functions in C Language for accessing external ports The most commonly used are listed below

                                                                                            bull unsigned char inportb(int portid) inportb reads a byte from a hardware port

                                                                                            bull int inport(int portid) reads a word from a hardware port

                                                                                            bull void outportb(int portid unsigned char value) outputs a byte to a hardware port

                                                                                            bull void outport(int portid int value) outputs a word to a hardware port

                                                                                            portid refers to the port address whereas value refers to the data to be sent TESTING 74245 USING PARALLEL PORT PC INTERFACING At one end the parallel port connector will be connected to the PC via parallel port cable and another connector (to be plugged into the PC parallel port slot) At the other end it will be connected to the buffer IC 74245 Data lines of the connector will be used to transfer 8-bit data between the PC and the buffer Out of the 8-bits of 74245 4-bits will be used to enter data which will be displayed at the monitor through a C language

                                                                                            61

                                                                                            Logic Design amp Switching Theory 1 Lab Session 15 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering program The remaining 4-bits will receive data from PC as entered by the user via keyboard

                                                                                            Circuit Diagram

                                                                                            Figure 154 Interface of 74245 to PC via Parallel Port

                                                                                            Procedure

                                                                                            1 Connect the DB-25 connector to the PC at one end and solder it to the circuit board at the other end

                                                                                            2 Connect various pins of the connector and 74245 according to the circuit diagram shown in figure 152

                                                                                            3 Using the functions listed in the previous section write a program in C language to operate various pins of the buffer The user interface of the program should provide option to the user whether to send or receive data from the port

                                                                                            4 Set DIR switch to 1 5 Try sending some data bits to the port The result should be displayed at the LEDs 6 Set DIR switch to 0 7 Set some binary 4-bit value through the switches Try reading it via parallel port

                                                                                            C Language Program

                                                                                            A program to access parallel port for data transfers

                                                                                            use header file include ltstdiohgt main program void main() define variable

                                                                                            62

                                                                                            Logic Design amp Switching Theory 1 Lab Session 15 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering unsigned int data=0 char choice while(1) printing option menu clrscr() printf(This program will send or receive a BCD digit from the parallel portn) printf(nPress your choice numbern) printf(n1 Send Data) printf(n2 Receive Data) printf(n3 Exitn) choice = getch() sending entered digit to the port if(choice == 1) input BCD digit printf(nEnter BCD digit to be sent to the port) data = getche() masking the first four bits data = data amp 0x0f sending to the port outportb(0x378data) printf(nThe BCD digit c has been sent to the port data) printing on screen the data received from the port else if(choice == 2) receiving data from the port data = inportb(0x378) masking the last four bits data = data amp 0xf0 shifting first four bits to make them the last four bits datagtgt=4 printf(nThe BCD digit set at the port is c data) exit else if(choice == 3) break key pressed is not in the menu else printf(nEnter valid choice number) printf(nnPress any key to continue) getch()

                                                                                            63

                                                                                            Logic Design amp Switching Theory 1 Lab Session 15 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                                            ACTIVITY 1 In the above circuit DIR and G΄ inputs are hardwired Connect them to status or

                                                                                            control pins of the parallel port connector and control their function through your software program Circuit Diagram Program Code ______________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________

                                                                                            ___________________________________________________________________________________________________________________________________________________

                                                                                            64

                                                                                            Logic Design amp Switching Theory 1 Lab Session 15 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                                            65

                                                                                            _____________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ _____________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ _______________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ _________________________________________________ _________________________________________________

                                                                                            Logic Design amp Switching Theory 1 Appendix A NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                                            Appendix A

                                                                                            PIN DIAGRAMS OF THE ICS REQUIRED FOR THE LABORATORY SESSIONS Consult the TTLIC data book for internal diagrams and electrical characteristics of these ICs 7400 Quad 2-Input NAND 7402 Quad 2-Input NOR

                                                                                            7404 Hex Inverter 7408 Quad 2-Input AND

                                                                                            7410 Triple 3-Input NAND 7411 Triple 3-Input AND

                                                                                            7421 Dual 4-Input AND 7432 Quad 2-Input OR

                                                                                            66

                                                                                            Logic Design amp Switching Theory 1 Appendix A NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                                            BCD-to-Seven Segm 7448 BCD-to-Seven Segment 7447 ent

                                                                                            Decoder (15V OC) Decoder (2kΩ pull-up output)

                                                                                            7473 Dual JK Flip-Flop 7474 Dual D-Type Flip-Flop

                                                                                            7476 Dual JK Flop-Flop -Bit Binary Full Adder 7483 4 with Fast Carry

                                                                                            86 Quad 2-Inpu 74138 3-to-8 Line 74 t Exclusive OR Decoder Demultiplexer

                                                                                            67

                                                                                            Logic Design amp Switching Theory 1 Appendix A NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                                            68

                                                                                            74148 8-to-3 Line 16-to-1 Line Data

                                                                                            Priority Encoder 74150 Selector Multiplexer

                                                                                            74245 Oct nsceivers Universal Shift Register (PIPO) (3-State)

                                                                                            74194 4-Bit Bidirectional al Bus Tra

                                                                                            Logic Design amp Switching Theory 1 Appendix B NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                                            Appendix B

                                                                                            DEBOUNCING CIRCUITRY FOR MECHANICAL SWITCHES Mechanical switches form the interface between human beings and computers or other digital systems For example a keyboard is a matrix of switches used to supply alphanumeric data to a computer Whatever the switch design it is a potential source of problems due to contact bounce The contact bounce creates a sense of narrow pulses when a switch is opened or closed An example of device whose operation would be adversely affected by contact bounce is a digital counter used to count the number of times a switch is depressed Eliminating the effects of contact bounce is called debouncing When data is entered into a computer via a keyboard a software debounce is often used This type of debouncing is a program that causes the computer to sample the switch terminal (ie to input data from it) many times in succession during the interval of time that contact bounce occurs If the data is sensed to be 1s (or 0s) for a specific number of consecutive samples then it is assumed that contact bounce has ended and the last value sensed is valid Hardware debouncing is the use of electronic circuitry to eliminate the effects of contact bounce There are numerous versions of such circuitry including those that use monostable multivibrators (one-shots) but the most straightforward is simply an RS latch Figure B1 shows the circuit When the switch is in position 1 R = 0 and S = 1 so the latch is set and the output (Q) is 1 When the switch is in position 0 R = 1and S = 0 so the latch is reset and the output is 0 When the switch is moved form one position to the other the latch changes state and bouncing occurs at either the R or the S input The bouncing does not affect the latch after it has change state An RS latch will remain set for example when its R input is 0 and its S input is alternately changed form 1 to 0

                                                                                            Figure B1 Use of RS latch to debounce a mechanical switch

                                                                                            69

                                                                                            • 01-ldst-Outer title
                                                                                              • Practical Workbook
                                                                                              • Logic Design amp Switching Theory I
                                                                                                • Dept of Computer amp Information Systems Engineering
                                                                                                  • NED University of Engineering amp Technology
                                                                                                  • Karachi ndash 75270 Pakistan
                                                                                                    • 02-ldst-inner Title
                                                                                                      • Practical Workbook
                                                                                                      • Logic Design amp Switching Theory I
                                                                                                        • Dept of Computer amp Information Systems Engineering
                                                                                                          • NED University of Engineering amp Technology
                                                                                                          • Karachi ndash 75270 Pakistan
                                                                                                            • 03-ldst-general info
                                                                                                            • 04-ldst-introduction
                                                                                                            • 05-Table of Contents
                                                                                                              • CONTENTS
                                                                                                                • Lab Session No Object Page No
                                                                                                                • 1
                                                                                                                • Also implementing and testing the given circuit on a bread board
                                                                                                                  • Working with Electronics Workbench
                                                                                                                    • Driving a seven segment display using 7447 7448 driver IC
                                                                                                                      • Designing a modulus-5 asynchronous up-counter using JK-FF
                                                                                                                        • Experimenting with 74194 4-bit bidirectional universal shift register
                                                                                                                            • 13
                                                                                                                                • 06-ldst-Exp01
                                                                                                                                  • Lab Session 01
                                                                                                                                  • OBJECT
                                                                                                                                    • 1 Bread board
                                                                                                                                    • 2 5 V - power supply
                                                                                                                                    • 3 Multimeter
                                                                                                                                    • 4 Logic probe
                                                                                                                                    • 5 LEDs with resistors
                                                                                                                                    • 6 Connecting wires
                                                                                                                                    • 8 Following ICs and their datasheets
                                                                                                                                      • THEORY
                                                                                                                                        • Logic Gates
                                                                                                                                        • 1 The AND Gate ndash An AND gatersquos output is 1 if and only if all its inputs are 1 If A and B are two inputs to an AND gate then output F of the gate is given as F = AB
                                                                                                                                        • 2 The OR Gate - An OR gatersquos output is 1 if at least one of its input is 1 If A and B are two inputs to an OR gate then output F of the gate is given as F = A+B
                                                                                                                                        • 3 The NOT Gate (Inverter) ndash Its output is 1 when its input is 0 and its output is 0 when the input is 1 ie it complements a digital variable If A is the input to a NOT gate then output F of the gate is given as
                                                                                                                                        • 4 The NAND Gate ndash Its output is 1 if at least one of its input is 0 This gate performs the same logic as an AND gate followed by an inverter If A and B are two inputs to a NAND gate then output F of the gate is given as
                                                                                                                                          • 5 The NOR Gate - The output of a NOR gate is 1 if and only if all its inputs are 0 This gate performs the same logic function as an OR gate followed by an inverter If A and B are two inputs to a NAND gate then output F of the gate is given as
                                                                                                                                              • DATA SHEETS
                                                                                                                                                • Logic expression for the given logic diagram __________________________________
                                                                                                                                                    • 07-ldst-exp02
                                                                                                                                                      • Working with Electronics Workbench
                                                                                                                                                        • 08-ldst-exp03
                                                                                                                                                          • Designing Half and Full Adder Circuits
                                                                                                                                                            • COMPONENTS AND APPARATUS REQUIRED
                                                                                                                                                              • 1 Following ICs and their Datasheets
                                                                                                                                                              • 7408 Quad 2-input AND Gate
                                                                                                                                                              • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                • Connecting wires Switches
                                                                                                                                                                  • THEORY
                                                                                                                                                                      • IMPLEMENTATION AND OBSERVATIONS
                                                                                                                                                                        • 09-ldst-Exp04
                                                                                                                                                                          • Lab Session 04
                                                                                                                                                                          • 1 Digital ICs and their Datasheets
                                                                                                                                                                          • 7408 Quad 2-input AND Gate
                                                                                                                                                                          • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                            • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                            • Connecting wires Switches
                                                                                                                                                                            • PROCEDURE
                                                                                                                                                                            • REDUCTION OF LOGIC EXPRESSION USING KARNAUGH MAP
                                                                                                                                                                            • OBSERVATIONS
                                                                                                                                                                            • RESULT
                                                                                                                                                                                • 10-ldst-Exp05
                                                                                                                                                                                  • Lab Session 05
                                                                                                                                                                                  • 1 Following ICs and their Datasheets
                                                                                                                                                                                  • 7408 Quad 2-input AND Gate
                                                                                                                                                                                  • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                    • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                    • (100 Ω) Connecting wires Switches
                                                                                                                                                                                    • THEORY
                                                                                                                                                                                      • IMPLEMENTATION AND OBSERVATIONS
                                                                                                                                                                                        • 11-ldst-Exp06
                                                                                                                                                                                          • OBJECT
                                                                                                                                                                                          • 1 Following ICs and their Datasheets
                                                                                                                                                                                          • 7408 Quad 2-input AND Gates or 7411 Triple 3-input AND Gates
                                                                                                                                                                                          • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                            • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                            • Connecting wires Switches
                                                                                                                                                                                              • Figure 62 Circuit Diagram for 4 x 1 Multiplexer
                                                                                                                                                                                              • Implementation and Observations
                                                                                                                                                                                                • Circuit Diagram
                                                                                                                                                                                                  • ACTIVITY
                                                                                                                                                                                                    • 12-ldst-exp07
                                                                                                                                                                                                      • 1 Following ICs and their Datasheets
                                                                                                                                                                                                      • 7408 Quad 2-input or 7411 Triple 3-input AND Gates
                                                                                                                                                                                                      • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                        • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                        • Connecting wires Switches
                                                                                                                                                                                                          • THEORY
                                                                                                                                                                                                              • Figure 72 Circuit Diagram for 2 x 4 Decoder 1 x 4 Demultiplexer
                                                                                                                                                                                                              • Implementation and Observations
                                                                                                                                                                                                                • Circuit Diagram
                                                                                                                                                                                                                  • ACTIVITY
                                                                                                                                                                                                                    • 13-ldst-Exp08
                                                                                                                                                                                                                      • OBJECT
                                                                                                                                                                                                                      • 1 Following ICs and their Datasheets
                                                                                                                                                                                                                      • 7408 Quad 2-input or 7421 Dual 4-input AND Gates
                                                                                                                                                                                                                      • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                        • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                                        • Connecting wires Switches
                                                                                                                                                                                                                          • THEORY
                                                                                                                                                                                                                              • Figure 81 Circuit Diagram for 4 x 2 Priority Encoder
                                                                                                                                                                                                                              • Implementation and Observations
                                                                                                                                                                                                                                • Therefore if GS A2 A1 and A0 are all low then it shows that line 0 is selected and if E0 A2 A1 and A0 are all low then it shows that none of the inputs selected E0 and GS cannot be in the same state provided that E1 is enabled
                                                                                                                                                                                                                                • Circuit Diagram
                                                                                                                                                                                                                                  • ACTIVITY
                                                                                                                                                                                                                                    • 14-ldst-exp09
                                                                                                                                                                                                                                      • OBJECT
                                                                                                                                                                                                                                      • 1 Following ICs and their Datasheets
                                                                                                                                                                                                                                      • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                                        • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                                                        • Connecting wires Switches
                                                                                                                                                                                                                                          • THEORY
                                                                                                                                                                                                                                            • Parity Generator
                                                                                                                                                                                                                                              • Let x y and z be the three bits that constitute the message and are the input to the Odd Parity Generator Circuit Since it is an odd parity system the bit P is generated so as to make the total number of 1s odd (including P) The function P can be expressed as follows
                                                                                                                                                                                                                                              • Figure 91 Circuit Diagram for a 3-bit Parity Generator
                                                                                                                                                                                                                                                • C = x Ο y Ο z Ο P
                                                                                                                                                                                                                                                  • Implementation and Observations
                                                                                                                                                                                                                                                    • ACTIVITY
                                                                                                                                                                                                                                                        • 15-ldst-exp10
                                                                                                                                                                                                                                                          • Driving a seven segment display using 7447 7448 driver IC
                                                                                                                                                                                                                                                          • COMPONENTS AND APPARATUS REQUIRED
                                                                                                                                                                                                                                                          • 1 Following ICs and their Datasheets
                                                                                                                                                                                                                                                          • 7447 7448 BCD to Seven Segment Driver
                                                                                                                                                                                                                                                          • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                                                            • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches
                                                                                                                                                                                                                                                              • THEORY
                                                                                                                                                                                                                                                              • Seven Segment Displays
                                                                                                                                                                                                                                                              • CIRCUIT DIAGRAM
                                                                                                                                                                                                                                                              • Figure 102 Circuit diagram for 7447driving a common-anode display
                                                                                                                                                                                                                                                                  • IMPLEMENTATION AND OBSERVATIONS
                                                                                                                                                                                                                                                                    • Decimal Digit
                                                                                                                                                                                                                                                                    • BCD Inputs
                                                                                                                                                                                                                                                                    • Seven Segment Outputs
                                                                                                                                                                                                                                                                    • D
                                                                                                                                                                                                                                                                    • C
                                                                                                                                                                                                                                                                    • B
                                                                                                                                                                                                                                                                    • A
                                                                                                                                                                                                                                                                    • a
                                                                                                                                                                                                                                                                    • b
                                                                                                                                                                                                                                                                    • c
                                                                                                                                                                                                                                                                    • d
                                                                                                                                                                                                                                                                    • e
                                                                                                                                                                                                                                                                    • f
                                                                                                                                                                                                                                                                    • g
                                                                                                                                                                                                                                                                    • 0
                                                                                                                                                                                                                                                                    • 0
                                                                                                                                                                                                                                                                    • 0
                                                                                                                                                                                                                                                                    • 0
                                                                                                                                                                                                                                                                    • 0
                                                                                                                                                                                                                                                                    • 1
                                                                                                                                                                                                                                                                    • 0
                                                                                                                                                                                                                                                                    • 0
                                                                                                                                                                                                                                                                    • 0
                                                                                                                                                                                                                                                                    • 1
                                                                                                                                                                                                                                                                    • 2
                                                                                                                                                                                                                                                                    • 0
                                                                                                                                                                                                                                                                    • 0
                                                                                                                                                                                                                                                                    • 1
                                                                                                                                                                                                                                                                    • 0
                                                                                                                                                                                                                                                                    • 3
                                                                                                                                                                                                                                                                    • 0
                                                                                                                                                                                                                                                                    • 0
                                                                                                                                                                                                                                                                    • 1
                                                                                                                                                                                                                                                                    • 1
                                                                                                                                                                                                                                                                    • 4
                                                                                                                                                                                                                                                                    • 0
                                                                                                                                                                                                                                                                    • 1
                                                                                                                                                                                                                                                                    • 0
                                                                                                                                                                                                                                                                    • 0
                                                                                                                                                                                                                                                                    • 5
                                                                                                                                                                                                                                                                    • 0
                                                                                                                                                                                                                                                                    • 1
                                                                                                                                                                                                                                                                    • 0
                                                                                                                                                                                                                                                                    • 1
                                                                                                                                                                                                                                                                    • 6
                                                                                                                                                                                                                                                                    • 0
                                                                                                                                                                                                                                                                    • 1
                                                                                                                                                                                                                                                                    • 1
                                                                                                                                                                                                                                                                    • 0
                                                                                                                                                                                                                                                                    • 7
                                                                                                                                                                                                                                                                    • 0
                                                                                                                                                                                                                                                                    • 1
                                                                                                                                                                                                                                                                    • 1
                                                                                                                                                                                                                                                                    • 1
                                                                                                                                                                                                                                                                    • 8
                                                                                                                                                                                                                                                                    • 1
                                                                                                                                                                                                                                                                    • 0
                                                                                                                                                                                                                                                                    • 0
                                                                                                                                                                                                                                                                    • 0
                                                                                                                                                                                                                                                                    • 9
                                                                                                                                                                                                                                                                    • 1
                                                                                                                                                                                                                                                                    • 0
                                                                                                                                                                                                                                                                    • 0
                                                                                                                                                                                                                                                                    • 1
                                                                                                                                                                                                                                                                      • ACTIVITY
                                                                                                                                                                                                                                                                        • 16-ldst-exp11
                                                                                                                                                                                                                                                                          • Lab Session 11
                                                                                                                                                                                                                                                                            • OBJECT
                                                                                                                                                                                                                                                                            • COMPONENTS AND APPARATUS REQUIRED
                                                                                                                                                                                                                                                                              • 1 Following ICs and their Datasheets
                                                                                                                                                                                                                                                                              • 7473 7476 JK Flip-Flop
                                                                                                                                                                                                                                                                              • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                                                                                • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                                                                                                • Connecting wires Switches
                                                                                                                                                                                                                                                                                  • THEORY
                                                                                                                                                                                                                                                                                      • Flip-Flop
                                                                                                                                                                                                                                                                                      • JK Flip-Flop
                                                                                                                                                                                                                                                                                        • Circuit Diagram
                                                                                                                                                                                                                                                                                          • Observations
                                                                                                                                                                                                                                                                                            • ACTIVITY
                                                                                                                                                                                                                                                                                                • 17-ldst-exp12
                                                                                                                                                                                                                                                                                                  • Lab Session 12
                                                                                                                                                                                                                                                                                                    • OBJECT
                                                                                                                                                                                                                                                                                                    • GIVEN STATE DIAGRAM
                                                                                                                                                                                                                                                                                                    • Figure 121 State Diagram
                                                                                                                                                                                                                                                                                                    • COMPONENTS AND APPARATUS REQUIRED
                                                                                                                                                                                                                                                                                                      • 1 Following ICs and their Datasheets
                                                                                                                                                                                                                                                                                                      • 7474 D Flip-Flop
                                                                                                                                                                                                                                                                                                      • ICs of basic gates (AND OR NOT XOR etc) as required
                                                                                                                                                                                                                                                                                                      • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                                                                                                        • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                                                                                                                        • Connecting wires Switches
                                                                                                                                                                                                                                                                                                          • THEORY
                                                                                                                                                                                                                                                                                                              • Sequential Circuits
                                                                                                                                                                                                                                                                                                                • 18-ldst-exp13
                                                                                                                                                                                                                                                                                                                  • Lab Session 13
                                                                                                                                                                                                                                                                                                                    • Designing a modulo-5 asynchronous up-counter using JK-FF
                                                                                                                                                                                                                                                                                                                      • 1 Following ICs and their Datasheets
                                                                                                                                                                                                                                                                                                                      • 7400 Quad 2-input or 7410 Triple 3-input NAND Gates
                                                                                                                                                                                                                                                                                                                      • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                                                                                                                        • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                                                                                                                                        • Connecting wires Switches
                                                                                                                                                                                                                                                                                                                          • THEORY
                                                                                                                                                                                                                                                                                                                              • Figure 131 A Mod-5 Asynchronous Up Counter
                                                                                                                                                                                                                                                                                                                              • Implementation and Observations
                                                                                                                                                                                                                                                                                                                                • ACTIVITY
                                                                                                                                                                                                                                                                                                                                    • 19-ldst-exp14
                                                                                                                                                                                                                                                                                                                                      • Experimenting with 74194 4-bit bidirectional universal shift register
                                                                                                                                                                                                                                                                                                                                      • 1 Following ICs and their Datasheets
                                                                                                                                                                                                                                                                                                                                      • 74194 4-bit bidirectional universal shift register
                                                                                                                                                                                                                                                                                                                                      • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                                                                                                                                        • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                                                                                                                                                        • Connecting wires Switches
                                                                                                                                                                                                                                                                                                                                          • THEORY
                                                                                                                                                                                                                                                                                                                                            • Shift Registers
                                                                                                                                                                                                                                                                                                                                            • Bidirectional Shift Registers
                                                                                                                                                                                                                                                                                                                                            • Universal Shift Registers
                                                                                                                                                                                                                                                                                                                                              • S1
                                                                                                                                                                                                                                                                                                                                                • Circuit Diagram
                                                                                                                                                                                                                                                                                                                                                • ACTIVITY
                                                                                                                                                                                                                                                                                                                                                    • 20-ldst-exp15
                                                                                                                                                                                                                                                                                                                                                      • COMPONENTS AND APPARATUS REQUIRED
                                                                                                                                                                                                                                                                                                                                                      • 1 Parallel Port Connectors (DB-25) with Cable
                                                                                                                                                                                                                                                                                                                                                      • 2 Personal Computer with Windows 98 and TurboC Compiler Installed
                                                                                                                                                                                                                                                                                                                                                      • 3 Following ICs and their Datasheets
                                                                                                                                                                                                                                                                                                                                                      • 74245 Octal Bus Transceivers with 3-State Outputs
                                                                                                                                                                                                                                                                                                                                                      • 4 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                                                                                                                                                        • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                                                                                                                                                                          • Connecting wires Switches
                                                                                                                                                                                                                                                                                                                                                            • THEORY
                                                                                                                                                                                                                                                                                                                                                            • 3-State Logic
                                                                                                                                                                                                                                                                                                                                                              • Serial and Parallel Port Connectors
                                                                                                                                                                                                                                                                                                                                                              • Parallel Port Connector ndash DB-25
                                                                                                                                                                                                                                                                                                                                                                • Accessing parallel port through C Language Programming
                                                                                                                                                                                                                                                                                                                                                                    • 21-ldst-appendixA
                                                                                                                                                                                                                                                                                                                                                                    • 22-ldst-appendixB
                                                                                                                                                                                                                                                                                                                                                                      • DEBOUNCING CIRCUITRY FOR MECHANICAL SWITCHES

                                                                                              Logic Design amp Switching Theory 1 Lab Session 11 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                                              49

                                                                                              TESTING OF 7473 7476 DUAL JK FLIP-FLOP

                                                                                              Both the ICs 7473 and 7476 are similar in functionality except for one difference The flip-flops in 7473 have only one type of active low asynchronous input which is the Clear input whereas the flip-flops in 7476 have both Preset and Clear inputs Both these ICs have negative edge triggered flip-flops

                                                                                              Circuit Diagram

                                                                                              Figure 112 Pin connections of 7476

                                                                                              Testing Procedure

                                                                                              bull Make connections as shown in the circuit diagram (figure 112) bull Apply different combinations of 1s and 0s at J and K inputs bull Observe the output and record your observations in the following table

                                                                                              Observations

                                                                                              J

                                                                                              K Q

                                                                                              0 0 0 1 1 0 1 1

                                                                                              ACTIVITY

                                                                                              1 Observe the output Q of JK flip-flop if the clock input is connected to VCC or GND instead of a clock source Write your observations here __________________________________________________________________________________________________________________________________________ _______________________________________________________________________________________________________________________________________________________________________________________________________________

                                                                                              Logic Design amp Switching Theory 1 Lab Session 12 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                                              50

                                                                                              Lab Session 12 OBJECT

                                                                                              Designing sequential circuit for the given state diagram using D flip-flop GIVEN STATE DIAGRAM

                                                                                              00

                                                                                              11

                                                                                              Figure 121 State Diagram COMPONENTS AND APPARATUS REQUIRED 1 Following ICs and their Datasheets

                                                                                              bull 7474 D Flip-Flop bull ICs of basic gates (AND OR NOT XOR etc) as required

                                                                                              2 Digital Trainer DT-01 or the following components Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches

                                                                                              THEORY

                                                                                              Sequential Circuits In Sequential Circuits the output not only depends on the present inputs but also on previous states of the circuit These circuits use memory elements (latches flip-flops) and the binary information stored in the memory elements at any given time defines the state of the sequential circuit Analysis of a Sequential Circuit The behavior of a sequential circuit is determined from the inputs the outputs and the states of its flip-flops Both the outputs and next state are a function of the inputs and the

                                                                                              10

                                                                                              01

                                                                                              00 11 10

                                                                                              00

                                                                                              00 11 10 00

                                                                                              Logic Design amp Switching Theory 1 Lab Session 12 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                                              51

                                                                                              present state The analysis of a sequential circuit form a state diagram comprises of the following bull Selecting a particular flip-flop to design the circuit bull Obtaining state table from the state diagram bull Finding input equations for the selected flip-flop bull Finding state equations (not required for the construction of circuit) bull Implementing the circuit using selected flip-flops and their input equations ANALYZING THE GIVEN STATE DIAGRAM D Flip-Flop D flip-flop is also called transparent flip-flop as it simply transfers the input data to the output For our design we require the graphical symbol and excitation table of D flip-flop (see figure 122)

                                                                                              Qt Qt+1 T 0 0 0 0 1 1 1 0 0 1 1 1

                                                                                              (b) Excitation table of D Flip-Flop

                                                                                              (a) Graphical Symbol

                                                                                              Figure 122 Characteristic equation of D flip-flop is Q(t+1) = D State Table The given state diagram has four states so we will need two D flip-flops (FF-0 FF-1) Form state table form the given state diagram and record the results in the following table

                                                                                              Present State Input Next State Output Input to FF-0 D0

                                                                                              Input to FF-1 D1 Q1t Q0t x Q1(t+1) Q0(t+1) z

                                                                                              Logic Design amp Switching Theory 1 Lab Session 12 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                                              52

                                                                                              Input Equations Using Karnaugh map the input equations D0 and D1 for the two flip-flops can be found

                                                                                              D0 D1 Q0x

                                                                                              Q1

                                                                                              _ _ Q0x

                                                                                              _ Q0x

                                                                                              Q0x

                                                                                              _ Q0x

                                                                                              Q0x

                                                                                              Q1

                                                                                              _ _ Q0x

                                                                                              _ Q0x

                                                                                              Q0x

                                                                                              _ Q0x

                                                                                              _ Q1

                                                                                              _ Q1

                                                                                              Q1

                                                                                              Q1

                                                                                              D0 = _________________ D1 = _________________

                                                                                              State Equations Using the characteristic equation of D flip-flop we can find the state equations Q0(t+1) and Q1(t+1) for the to flip flops Q0(t+1) = _______________________ Q1(t+1) = _______________________ _______________________ _______________________ _______________________ _______________________ Circuit Diagram

                                                                                              Logic Design amp Switching Theory 1 Lab Session 12 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                                              53

                                                                                              Implementation Procedure and Observations

                                                                                              1 Implement the circuit using digital ICs on a bread board (prepare the pin diagram (use appendix A) and refer to laboratory session 01 for procedure)

                                                                                              2 Make the clear inputs of the flip-flops low (to clear the flip-flops) The flip-flops will remain in clear state as long as the clear inputs are connected to low level

                                                                                              3 Connect output Q0 and the clock pulse to an oscilloscope 4 Apply 0 to the input x 5 Now make the clear inputs to high 6 Observe the waveform for the first 5 clock pulses and record it 7 Repeat steps 2 to 6 keeping x=1 in step 4 this time 8 Repeat steps 2 to 7 this time connecting Q1 instead of Q0 to the oscilloscope in step

                                                                                              3 Record your observations (Keep frequency of the clock pulse low (eg1Hz) so that the output waveforms can be observed easily)

                                                                                              1 2 3 4 5 Clock Pulse

                                                                                              Output Waveform for Q0 when x=0

                                                                                              Output Waveform for Q0 when x=1

                                                                                              Output Waveform for Q1 when x=0

                                                                                              Output Waveform for Q1 when x=1

                                                                                              Logic Design amp Switching Theory 1 Lab Session 13 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                                              Lab Session 13 OBJECT

                                                                                              Designing a modulo-5 asynchronous up-counter using JK-FF COMPONENTS AND APPARATUS REQUIRED

                                                                                              1 Following ICs and their Datasheets

                                                                                              bull 7400 Quad 2-input or 7410 Triple 3-input NAND Gates bull 7476 7473 JK Flip-Flop

                                                                                              2 Digital Trainer DT-01 or the following components Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches

                                                                                              THEORY

                                                                                              Digital Counters A digital counter is a set of flip-flops whose states change in response to pulses applied at the input to the counter The flip-flops are interconnected so that their combined state at any time is the binary equivalent of the total number of pulses that have occurred up to that time Every counter resets after a certain number of clock pulses Thus as it name implies a counter is used to count pulses An n stage counter can count up to a maximum of 2n states n is equal to the number of flip-flops required for the construction of counter

                                                                                              Modulus Counters The number of input pulses that causes a counter to reset to its initial count is called the modulus of the counter Thus the modulus equals to total number of distinct states (counts) including zero that a counter can store A binary counter with n stages is a modulo-2n (or mod-2n) counter The largest count a mod-N counter can achieve is N-1 ie a mod-N counter never reaches the binary number equal to its modulus N is always equal to or less than 2n Counters can be classified as bull Synchronous Counters which are clock driven All the flip-flops are driven by a

                                                                                              single clock bull Asynchronous Counters which are event driven Clock input is given to the first

                                                                                              flip-flop only Rest of the flip-flops are driven by their preceding flip-flops

                                                                                              DESIGN OF A MOD-5 ASYNCHRONOUS UP COUNTER The number of flip-flops required to construct a mod-5 counter is 3 because 5 should be less than or equal to 2n This counter will count from 0 to 4 a total of 5 distinct states Since a 3-stage counter can count up to 8 states at maximum a NAND gate is used to reset it after 5 clock pulses Figure 131 shows the logic diagram

                                                                                              54

                                                                                              Logic Design amp Switching Theory 1 Lab Session 13 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                                              55

                                                                                              Figure 131 A Mod-5 Asynchronous Up Counter

                                                                                              Implementation and Observations

                                                                                              Implement the mod-5 counter circuit (figure 131) on a bread board (prepare the pin diagram (use appendix A) and refer to laboratory session 01 for implementation procedure) and record the observations in the following table

                                                                                              Clock Pulse Q2 Q1 Q0

                                                                                              0 1 2 3 4 5 6 7

                                                                                              ACTIVITY

                                                                                              Draw the timing diagram for mod-5 counter designed in this laboratory session

                                                                                              Logic Design amp Switching Theory 1 Lab Session 14 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                                              Lab Session 14 OBJECT

                                                                                              Experimenting with 74194 4-bit bidirectional universal shift register COMPONENTS AND APPARATUS REQUIRED

                                                                                              1 Following ICs and their Datasheets

                                                                                              bull 74194 4-bit bidirectional universal shift register 2 Digital Trainer DT-01 or the following components

                                                                                              Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches

                                                                                              THEORY

                                                                                              Shift Registers

                                                                                              A Register is a set of flip-flops used to store binary data A register which is capable of shifting its binary information either to the right or left is called a shift register The logical configuration of a register consists of a chain of flip-flops connected in cascade with the output of one flip-flop connected to the input of next flip-flop All flip-flops receive a common clock pulse which causes the shift from one stage to the next

                                                                                              Bidirectional Shift Registers A bi-directional shift register is one whose bits can be shifted from left to right or from right to left

                                                                                              Universal Shift Registers A universal shift register is a bi-directional register whose input can be in either serial or parallel form and whose output can be in either serial or parallel form

                                                                                              74194 4-BIT BIDIRECTIONAL UNIVERSAL SHIFT REGISTER

                                                                                              The 74194 register provides parallel as well as serial loading in both directions Function of various pins of this IC is described below

                                                                                              bull A B C and D Active high inputs for parallel loading bull QA QB QC and QD Active high outputs bull S0 and S1 Active high mode control inputs The following table shows combinations

                                                                                              of S1 and S0 to enable various modes

                                                                                              S1 S0 Clock Action 0 0 x No change 0 1 uarr Shift right 1 0 uarr Shift left 1 1 uarr Parallel load

                                                                                              uarr shows the rising edge of the clock pulse

                                                                                              56

                                                                                              Logic Design amp Switching Theory 1 Lab Session 14 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering bull SR Active high serial input for right shifting bull SL Active high serial input for left shifting bull CLR Active low input Clears all the flip-flops of the register if set to 0 should be

                                                                                              kept high otherwise bull CLK Clock input bull VCC and GND Supply connections lines Thus A B C and D are inputs for parallel loading whereas SR and SL are inputs for serial loading with right or left shifting respectively S1 and S0 are used to select the loading mode Circuit Diagram

                                                                                              Figure 141 Pin connections of 74194 Testing Procedure

                                                                                              bull Make connections as shown in the circuit diagram bull Observe the output for the input combinations given in the following table

                                                                                              57

                                                                                              Logic Design amp Switching Theory 1 Lab Session 14 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                                              58

                                                                                              Observations

                                                                                              S1 S0 SL SR A B C D QA QB QC QD 0 0 0 1 0 0 0 0 0 1 1 0 0 0 0 1 1 0 0 0 0 0 1 0 1 1 0 0 0 0 1 1 0 0 1 1 0 1 0 0 0 1 1 1 0 1 0 1 1 0 1 0 0 1 1 0 1 1 1 0 0 1 1 1 1 1 0 0 1 1 1 1

                                                                                              ACTIVITY 1 Show connections of 74194 to convert it into a ring counter with right shifting

                                                                                              Logic Design amp Switching Theory 1 Lab Session 15 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                                              Lab Session 15

                                                                                              OBJECT

                                                                                              Experimenting with 74245 octal bus transceivers using parallel port PC interfacing COMPONENTS AND APPARATUS REQUIRED 1 Parallel Port Connectors (DB-25) with Cable 2 Personal Computer with Windows 98 and TurboC Compiler Installed 3 Following ICs and their Datasheets

                                                                                              bull 74245 Octal Bus Transceivers with 3-State Outputs 4 Digital Trainer DT-01 or the following components

                                                                                              Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches

                                                                                              THEORY

                                                                                              3-State Logic Sometimes it is necessary to isolate one part of circuit from the other part For this purpose some TTL ICs are designed with 3-state logic Such devices have three possible output states high low and high impedance The device can be put into high impedance state by a control signal applied to an appropriate pin When such a device is in high impedance state there is very high impedance at its output effectively isolating the device from whatever circuitry the output normally drives 74245 Octal Bus Transceivers A bus is any conducting path or set of paths having electrical connections to one or more devices 74245 octal bus transceivers are mainly used to control connectivity between two devices or circuits It also provides direction control for signal flow Function of various pin of this IC is given below

                                                                                              bull A1 through A8 Bus A bull B1 through B8 Bus B bull G΄ Active low enable input When high sets all the bus pins to high impedance state bull DIR Direction control for signal flow When set to high logic level transfers bus A

                                                                                              data to B bus When set to low logic level transfers bus B data to A bus bull VCC and GND Supply connections lines Serial and Parallel Port Connectors A Parallel Port can consist of only 25 pin port adapter called a DB-25 and a serial port can consist of either a 25 pin port adapter called a DB-25 or 9 pin adapter called a DB-9 port adapter Whether the port is a 9 pin or 25 pin it can accomplish all of the same tasks that serial port communications have been designed for

                                                                                              59

                                                                                              Logic Design amp Switching Theory 1 Lab Session 15 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                                              60

                                                                                              Each adapter can be a male type connector with pins or a female type adapter with tiny holes Generally a PRINTER port (called LPT1) on the back of a computer is female type adapter and we need to use MALE DB-25 pin cable on it for PRINTER connection or for parallel LAPLINK cable And a COM port on the back of a computer is male for the serial ports but it may not necessarily be Parallel Port Connector ndash DB-25 The DB-25 connector (named for its B-size D-shaped shell and 25 pins) is practically ubiquitous in the electronics industry The DB-25 connector is used for a variety of purposes Two common applications are RS-232EIA-232 (serial) connections and the parallel printer interface on the IBM PC The DB-25 connector is also used for SCSI connections Normally the parallel port is used for output to a printer or other device It sends data 8-bits or one byte at a time in parallel The other lines available on the DB-25 connector are a combination of status lines control lines and ground lines The status and control lines are used for handshaking commands and feedback when we are talking to a printer

                                                                                              Figure 152 DB-25 Female Figure 151 DB-25 Male

                                                                                              Figure 153 Pin Layout for DB-25 As can be seen form figure 153 there are four types of pins in this connector

                                                                                              bull Data pins (8 pins - D0 to D7) Active high bidirectional lines

                                                                                              Logic Design amp Switching Theory 1 Lab Session 15 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering bull Control pins (4 pins - C0 to C3) C0 C1 and C3 are active low whereas C2 is active

                                                                                              high These lines also are bidirectional bull Status pins (5 pins ndash S3 to S7) Only S7 is active low rest are active high input lines bull Ground pins (8 pins) Used as a reference signal for the low (below 05 volts) charge

                                                                                              Parallel Port Addresses A DB-25 connector at a parallel port has three address one for each kind of pins register data status and control The first or base address generally refers to data register Second address is for status register and the third one is for control register In Windows 98 the base address is usually found to be 278H 378H or 3BCH Now if 378H is the base address then it refers to the data register whereas addresses for status and control register are respectively 379H and 37AH For Windows 98 the base address can be found as follows 1 On your Desktop right-click on My Computer and select Properties 2 Click on the Device Manager tab and find LPT1 under Plug and Play BIOS 3 After selecting LPT1 click the Properties button 4 Next select the Resources tab and the address should then appear next to InputOutput

                                                                                              Range Accessing parallel port through C Language Programming There are multiple functions in C Language for accessing external ports The most commonly used are listed below

                                                                                              bull unsigned char inportb(int portid) inportb reads a byte from a hardware port

                                                                                              bull int inport(int portid) reads a word from a hardware port

                                                                                              bull void outportb(int portid unsigned char value) outputs a byte to a hardware port

                                                                                              bull void outport(int portid int value) outputs a word to a hardware port

                                                                                              portid refers to the port address whereas value refers to the data to be sent TESTING 74245 USING PARALLEL PORT PC INTERFACING At one end the parallel port connector will be connected to the PC via parallel port cable and another connector (to be plugged into the PC parallel port slot) At the other end it will be connected to the buffer IC 74245 Data lines of the connector will be used to transfer 8-bit data between the PC and the buffer Out of the 8-bits of 74245 4-bits will be used to enter data which will be displayed at the monitor through a C language

                                                                                              61

                                                                                              Logic Design amp Switching Theory 1 Lab Session 15 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering program The remaining 4-bits will receive data from PC as entered by the user via keyboard

                                                                                              Circuit Diagram

                                                                                              Figure 154 Interface of 74245 to PC via Parallel Port

                                                                                              Procedure

                                                                                              1 Connect the DB-25 connector to the PC at one end and solder it to the circuit board at the other end

                                                                                              2 Connect various pins of the connector and 74245 according to the circuit diagram shown in figure 152

                                                                                              3 Using the functions listed in the previous section write a program in C language to operate various pins of the buffer The user interface of the program should provide option to the user whether to send or receive data from the port

                                                                                              4 Set DIR switch to 1 5 Try sending some data bits to the port The result should be displayed at the LEDs 6 Set DIR switch to 0 7 Set some binary 4-bit value through the switches Try reading it via parallel port

                                                                                              C Language Program

                                                                                              A program to access parallel port for data transfers

                                                                                              use header file include ltstdiohgt main program void main() define variable

                                                                                              62

                                                                                              Logic Design amp Switching Theory 1 Lab Session 15 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering unsigned int data=0 char choice while(1) printing option menu clrscr() printf(This program will send or receive a BCD digit from the parallel portn) printf(nPress your choice numbern) printf(n1 Send Data) printf(n2 Receive Data) printf(n3 Exitn) choice = getch() sending entered digit to the port if(choice == 1) input BCD digit printf(nEnter BCD digit to be sent to the port) data = getche() masking the first four bits data = data amp 0x0f sending to the port outportb(0x378data) printf(nThe BCD digit c has been sent to the port data) printing on screen the data received from the port else if(choice == 2) receiving data from the port data = inportb(0x378) masking the last four bits data = data amp 0xf0 shifting first four bits to make them the last four bits datagtgt=4 printf(nThe BCD digit set at the port is c data) exit else if(choice == 3) break key pressed is not in the menu else printf(nEnter valid choice number) printf(nnPress any key to continue) getch()

                                                                                              63

                                                                                              Logic Design amp Switching Theory 1 Lab Session 15 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                                              ACTIVITY 1 In the above circuit DIR and G΄ inputs are hardwired Connect them to status or

                                                                                              control pins of the parallel port connector and control their function through your software program Circuit Diagram Program Code ______________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________

                                                                                              ___________________________________________________________________________________________________________________________________________________

                                                                                              64

                                                                                              Logic Design amp Switching Theory 1 Lab Session 15 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                                              65

                                                                                              _____________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ _____________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ _______________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ _________________________________________________ _________________________________________________

                                                                                              Logic Design amp Switching Theory 1 Appendix A NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                                              Appendix A

                                                                                              PIN DIAGRAMS OF THE ICS REQUIRED FOR THE LABORATORY SESSIONS Consult the TTLIC data book for internal diagrams and electrical characteristics of these ICs 7400 Quad 2-Input NAND 7402 Quad 2-Input NOR

                                                                                              7404 Hex Inverter 7408 Quad 2-Input AND

                                                                                              7410 Triple 3-Input NAND 7411 Triple 3-Input AND

                                                                                              7421 Dual 4-Input AND 7432 Quad 2-Input OR

                                                                                              66

                                                                                              Logic Design amp Switching Theory 1 Appendix A NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                                              BCD-to-Seven Segm 7448 BCD-to-Seven Segment 7447 ent

                                                                                              Decoder (15V OC) Decoder (2kΩ pull-up output)

                                                                                              7473 Dual JK Flip-Flop 7474 Dual D-Type Flip-Flop

                                                                                              7476 Dual JK Flop-Flop -Bit Binary Full Adder 7483 4 with Fast Carry

                                                                                              86 Quad 2-Inpu 74138 3-to-8 Line 74 t Exclusive OR Decoder Demultiplexer

                                                                                              67

                                                                                              Logic Design amp Switching Theory 1 Appendix A NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                                              68

                                                                                              74148 8-to-3 Line 16-to-1 Line Data

                                                                                              Priority Encoder 74150 Selector Multiplexer

                                                                                              74245 Oct nsceivers Universal Shift Register (PIPO) (3-State)

                                                                                              74194 4-Bit Bidirectional al Bus Tra

                                                                                              Logic Design amp Switching Theory 1 Appendix B NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                                              Appendix B

                                                                                              DEBOUNCING CIRCUITRY FOR MECHANICAL SWITCHES Mechanical switches form the interface between human beings and computers or other digital systems For example a keyboard is a matrix of switches used to supply alphanumeric data to a computer Whatever the switch design it is a potential source of problems due to contact bounce The contact bounce creates a sense of narrow pulses when a switch is opened or closed An example of device whose operation would be adversely affected by contact bounce is a digital counter used to count the number of times a switch is depressed Eliminating the effects of contact bounce is called debouncing When data is entered into a computer via a keyboard a software debounce is often used This type of debouncing is a program that causes the computer to sample the switch terminal (ie to input data from it) many times in succession during the interval of time that contact bounce occurs If the data is sensed to be 1s (or 0s) for a specific number of consecutive samples then it is assumed that contact bounce has ended and the last value sensed is valid Hardware debouncing is the use of electronic circuitry to eliminate the effects of contact bounce There are numerous versions of such circuitry including those that use monostable multivibrators (one-shots) but the most straightforward is simply an RS latch Figure B1 shows the circuit When the switch is in position 1 R = 0 and S = 1 so the latch is set and the output (Q) is 1 When the switch is in position 0 R = 1and S = 0 so the latch is reset and the output is 0 When the switch is moved form one position to the other the latch changes state and bouncing occurs at either the R or the S input The bouncing does not affect the latch after it has change state An RS latch will remain set for example when its R input is 0 and its S input is alternately changed form 1 to 0

                                                                                              Figure B1 Use of RS latch to debounce a mechanical switch

                                                                                              69

                                                                                              • 01-ldst-Outer title
                                                                                                • Practical Workbook
                                                                                                • Logic Design amp Switching Theory I
                                                                                                  • Dept of Computer amp Information Systems Engineering
                                                                                                    • NED University of Engineering amp Technology
                                                                                                    • Karachi ndash 75270 Pakistan
                                                                                                      • 02-ldst-inner Title
                                                                                                        • Practical Workbook
                                                                                                        • Logic Design amp Switching Theory I
                                                                                                          • Dept of Computer amp Information Systems Engineering
                                                                                                            • NED University of Engineering amp Technology
                                                                                                            • Karachi ndash 75270 Pakistan
                                                                                                              • 03-ldst-general info
                                                                                                              • 04-ldst-introduction
                                                                                                              • 05-Table of Contents
                                                                                                                • CONTENTS
                                                                                                                  • Lab Session No Object Page No
                                                                                                                  • 1
                                                                                                                  • Also implementing and testing the given circuit on a bread board
                                                                                                                    • Working with Electronics Workbench
                                                                                                                      • Driving a seven segment display using 7447 7448 driver IC
                                                                                                                        • Designing a modulus-5 asynchronous up-counter using JK-FF
                                                                                                                          • Experimenting with 74194 4-bit bidirectional universal shift register
                                                                                                                              • 13
                                                                                                                                  • 06-ldst-Exp01
                                                                                                                                    • Lab Session 01
                                                                                                                                    • OBJECT
                                                                                                                                      • 1 Bread board
                                                                                                                                      • 2 5 V - power supply
                                                                                                                                      • 3 Multimeter
                                                                                                                                      • 4 Logic probe
                                                                                                                                      • 5 LEDs with resistors
                                                                                                                                      • 6 Connecting wires
                                                                                                                                      • 8 Following ICs and their datasheets
                                                                                                                                        • THEORY
                                                                                                                                          • Logic Gates
                                                                                                                                          • 1 The AND Gate ndash An AND gatersquos output is 1 if and only if all its inputs are 1 If A and B are two inputs to an AND gate then output F of the gate is given as F = AB
                                                                                                                                          • 2 The OR Gate - An OR gatersquos output is 1 if at least one of its input is 1 If A and B are two inputs to an OR gate then output F of the gate is given as F = A+B
                                                                                                                                          • 3 The NOT Gate (Inverter) ndash Its output is 1 when its input is 0 and its output is 0 when the input is 1 ie it complements a digital variable If A is the input to a NOT gate then output F of the gate is given as
                                                                                                                                          • 4 The NAND Gate ndash Its output is 1 if at least one of its input is 0 This gate performs the same logic as an AND gate followed by an inverter If A and B are two inputs to a NAND gate then output F of the gate is given as
                                                                                                                                            • 5 The NOR Gate - The output of a NOR gate is 1 if and only if all its inputs are 0 This gate performs the same logic function as an OR gate followed by an inverter If A and B are two inputs to a NAND gate then output F of the gate is given as
                                                                                                                                                • DATA SHEETS
                                                                                                                                                  • Logic expression for the given logic diagram __________________________________
                                                                                                                                                      • 07-ldst-exp02
                                                                                                                                                        • Working with Electronics Workbench
                                                                                                                                                          • 08-ldst-exp03
                                                                                                                                                            • Designing Half and Full Adder Circuits
                                                                                                                                                              • COMPONENTS AND APPARATUS REQUIRED
                                                                                                                                                                • 1 Following ICs and their Datasheets
                                                                                                                                                                • 7408 Quad 2-input AND Gate
                                                                                                                                                                • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                  • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                  • Connecting wires Switches
                                                                                                                                                                    • THEORY
                                                                                                                                                                        • IMPLEMENTATION AND OBSERVATIONS
                                                                                                                                                                          • 09-ldst-Exp04
                                                                                                                                                                            • Lab Session 04
                                                                                                                                                                            • 1 Digital ICs and their Datasheets
                                                                                                                                                                            • 7408 Quad 2-input AND Gate
                                                                                                                                                                            • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                              • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                              • Connecting wires Switches
                                                                                                                                                                              • PROCEDURE
                                                                                                                                                                              • REDUCTION OF LOGIC EXPRESSION USING KARNAUGH MAP
                                                                                                                                                                              • OBSERVATIONS
                                                                                                                                                                              • RESULT
                                                                                                                                                                                  • 10-ldst-Exp05
                                                                                                                                                                                    • Lab Session 05
                                                                                                                                                                                    • 1 Following ICs and their Datasheets
                                                                                                                                                                                    • 7408 Quad 2-input AND Gate
                                                                                                                                                                                    • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                      • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                      • (100 Ω) Connecting wires Switches
                                                                                                                                                                                      • THEORY
                                                                                                                                                                                        • IMPLEMENTATION AND OBSERVATIONS
                                                                                                                                                                                          • 11-ldst-Exp06
                                                                                                                                                                                            • OBJECT
                                                                                                                                                                                            • 1 Following ICs and their Datasheets
                                                                                                                                                                                            • 7408 Quad 2-input AND Gates or 7411 Triple 3-input AND Gates
                                                                                                                                                                                            • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                              • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                              • Connecting wires Switches
                                                                                                                                                                                                • Figure 62 Circuit Diagram for 4 x 1 Multiplexer
                                                                                                                                                                                                • Implementation and Observations
                                                                                                                                                                                                  • Circuit Diagram
                                                                                                                                                                                                    • ACTIVITY
                                                                                                                                                                                                      • 12-ldst-exp07
                                                                                                                                                                                                        • 1 Following ICs and their Datasheets
                                                                                                                                                                                                        • 7408 Quad 2-input or 7411 Triple 3-input AND Gates
                                                                                                                                                                                                        • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                          • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                          • Connecting wires Switches
                                                                                                                                                                                                            • THEORY
                                                                                                                                                                                                                • Figure 72 Circuit Diagram for 2 x 4 Decoder 1 x 4 Demultiplexer
                                                                                                                                                                                                                • Implementation and Observations
                                                                                                                                                                                                                  • Circuit Diagram
                                                                                                                                                                                                                    • ACTIVITY
                                                                                                                                                                                                                      • 13-ldst-Exp08
                                                                                                                                                                                                                        • OBJECT
                                                                                                                                                                                                                        • 1 Following ICs and their Datasheets
                                                                                                                                                                                                                        • 7408 Quad 2-input or 7421 Dual 4-input AND Gates
                                                                                                                                                                                                                        • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                          • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                                          • Connecting wires Switches
                                                                                                                                                                                                                            • THEORY
                                                                                                                                                                                                                                • Figure 81 Circuit Diagram for 4 x 2 Priority Encoder
                                                                                                                                                                                                                                • Implementation and Observations
                                                                                                                                                                                                                                  • Therefore if GS A2 A1 and A0 are all low then it shows that line 0 is selected and if E0 A2 A1 and A0 are all low then it shows that none of the inputs selected E0 and GS cannot be in the same state provided that E1 is enabled
                                                                                                                                                                                                                                  • Circuit Diagram
                                                                                                                                                                                                                                    • ACTIVITY
                                                                                                                                                                                                                                      • 14-ldst-exp09
                                                                                                                                                                                                                                        • OBJECT
                                                                                                                                                                                                                                        • 1 Following ICs and their Datasheets
                                                                                                                                                                                                                                        • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                                          • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                                                          • Connecting wires Switches
                                                                                                                                                                                                                                            • THEORY
                                                                                                                                                                                                                                              • Parity Generator
                                                                                                                                                                                                                                                • Let x y and z be the three bits that constitute the message and are the input to the Odd Parity Generator Circuit Since it is an odd parity system the bit P is generated so as to make the total number of 1s odd (including P) The function P can be expressed as follows
                                                                                                                                                                                                                                                • Figure 91 Circuit Diagram for a 3-bit Parity Generator
                                                                                                                                                                                                                                                  • C = x Ο y Ο z Ο P
                                                                                                                                                                                                                                                    • Implementation and Observations
                                                                                                                                                                                                                                                      • ACTIVITY
                                                                                                                                                                                                                                                          • 15-ldst-exp10
                                                                                                                                                                                                                                                            • Driving a seven segment display using 7447 7448 driver IC
                                                                                                                                                                                                                                                            • COMPONENTS AND APPARATUS REQUIRED
                                                                                                                                                                                                                                                            • 1 Following ICs and their Datasheets
                                                                                                                                                                                                                                                            • 7447 7448 BCD to Seven Segment Driver
                                                                                                                                                                                                                                                            • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                                                              • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches
                                                                                                                                                                                                                                                                • THEORY
                                                                                                                                                                                                                                                                • Seven Segment Displays
                                                                                                                                                                                                                                                                • CIRCUIT DIAGRAM
                                                                                                                                                                                                                                                                • Figure 102 Circuit diagram for 7447driving a common-anode display
                                                                                                                                                                                                                                                                    • IMPLEMENTATION AND OBSERVATIONS
                                                                                                                                                                                                                                                                      • Decimal Digit
                                                                                                                                                                                                                                                                      • BCD Inputs
                                                                                                                                                                                                                                                                      • Seven Segment Outputs
                                                                                                                                                                                                                                                                      • D
                                                                                                                                                                                                                                                                      • C
                                                                                                                                                                                                                                                                      • B
                                                                                                                                                                                                                                                                      • A
                                                                                                                                                                                                                                                                      • a
                                                                                                                                                                                                                                                                      • b
                                                                                                                                                                                                                                                                      • c
                                                                                                                                                                                                                                                                      • d
                                                                                                                                                                                                                                                                      • e
                                                                                                                                                                                                                                                                      • f
                                                                                                                                                                                                                                                                      • g
                                                                                                                                                                                                                                                                      • 0
                                                                                                                                                                                                                                                                      • 0
                                                                                                                                                                                                                                                                      • 0
                                                                                                                                                                                                                                                                      • 0
                                                                                                                                                                                                                                                                      • 0
                                                                                                                                                                                                                                                                      • 1
                                                                                                                                                                                                                                                                      • 0
                                                                                                                                                                                                                                                                      • 0
                                                                                                                                                                                                                                                                      • 0
                                                                                                                                                                                                                                                                      • 1
                                                                                                                                                                                                                                                                      • 2
                                                                                                                                                                                                                                                                      • 0
                                                                                                                                                                                                                                                                      • 0
                                                                                                                                                                                                                                                                      • 1
                                                                                                                                                                                                                                                                      • 0
                                                                                                                                                                                                                                                                      • 3
                                                                                                                                                                                                                                                                      • 0
                                                                                                                                                                                                                                                                      • 0
                                                                                                                                                                                                                                                                      • 1
                                                                                                                                                                                                                                                                      • 1
                                                                                                                                                                                                                                                                      • 4
                                                                                                                                                                                                                                                                      • 0
                                                                                                                                                                                                                                                                      • 1
                                                                                                                                                                                                                                                                      • 0
                                                                                                                                                                                                                                                                      • 0
                                                                                                                                                                                                                                                                      • 5
                                                                                                                                                                                                                                                                      • 0
                                                                                                                                                                                                                                                                      • 1
                                                                                                                                                                                                                                                                      • 0
                                                                                                                                                                                                                                                                      • 1
                                                                                                                                                                                                                                                                      • 6
                                                                                                                                                                                                                                                                      • 0
                                                                                                                                                                                                                                                                      • 1
                                                                                                                                                                                                                                                                      • 1
                                                                                                                                                                                                                                                                      • 0
                                                                                                                                                                                                                                                                      • 7
                                                                                                                                                                                                                                                                      • 0
                                                                                                                                                                                                                                                                      • 1
                                                                                                                                                                                                                                                                      • 1
                                                                                                                                                                                                                                                                      • 1
                                                                                                                                                                                                                                                                      • 8
                                                                                                                                                                                                                                                                      • 1
                                                                                                                                                                                                                                                                      • 0
                                                                                                                                                                                                                                                                      • 0
                                                                                                                                                                                                                                                                      • 0
                                                                                                                                                                                                                                                                      • 9
                                                                                                                                                                                                                                                                      • 1
                                                                                                                                                                                                                                                                      • 0
                                                                                                                                                                                                                                                                      • 0
                                                                                                                                                                                                                                                                      • 1
                                                                                                                                                                                                                                                                        • ACTIVITY
                                                                                                                                                                                                                                                                          • 16-ldst-exp11
                                                                                                                                                                                                                                                                            • Lab Session 11
                                                                                                                                                                                                                                                                              • OBJECT
                                                                                                                                                                                                                                                                              • COMPONENTS AND APPARATUS REQUIRED
                                                                                                                                                                                                                                                                                • 1 Following ICs and their Datasheets
                                                                                                                                                                                                                                                                                • 7473 7476 JK Flip-Flop
                                                                                                                                                                                                                                                                                • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                                                                                  • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                                                                                                  • Connecting wires Switches
                                                                                                                                                                                                                                                                                    • THEORY
                                                                                                                                                                                                                                                                                        • Flip-Flop
                                                                                                                                                                                                                                                                                        • JK Flip-Flop
                                                                                                                                                                                                                                                                                          • Circuit Diagram
                                                                                                                                                                                                                                                                                            • Observations
                                                                                                                                                                                                                                                                                              • ACTIVITY
                                                                                                                                                                                                                                                                                                  • 17-ldst-exp12
                                                                                                                                                                                                                                                                                                    • Lab Session 12
                                                                                                                                                                                                                                                                                                      • OBJECT
                                                                                                                                                                                                                                                                                                      • GIVEN STATE DIAGRAM
                                                                                                                                                                                                                                                                                                      • Figure 121 State Diagram
                                                                                                                                                                                                                                                                                                      • COMPONENTS AND APPARATUS REQUIRED
                                                                                                                                                                                                                                                                                                        • 1 Following ICs and their Datasheets
                                                                                                                                                                                                                                                                                                        • 7474 D Flip-Flop
                                                                                                                                                                                                                                                                                                        • ICs of basic gates (AND OR NOT XOR etc) as required
                                                                                                                                                                                                                                                                                                        • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                                                                                                          • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                                                                                                                          • Connecting wires Switches
                                                                                                                                                                                                                                                                                                            • THEORY
                                                                                                                                                                                                                                                                                                                • Sequential Circuits
                                                                                                                                                                                                                                                                                                                  • 18-ldst-exp13
                                                                                                                                                                                                                                                                                                                    • Lab Session 13
                                                                                                                                                                                                                                                                                                                      • Designing a modulo-5 asynchronous up-counter using JK-FF
                                                                                                                                                                                                                                                                                                                        • 1 Following ICs and their Datasheets
                                                                                                                                                                                                                                                                                                                        • 7400 Quad 2-input or 7410 Triple 3-input NAND Gates
                                                                                                                                                                                                                                                                                                                        • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                                                                                                                          • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                                                                                                                                          • Connecting wires Switches
                                                                                                                                                                                                                                                                                                                            • THEORY
                                                                                                                                                                                                                                                                                                                                • Figure 131 A Mod-5 Asynchronous Up Counter
                                                                                                                                                                                                                                                                                                                                • Implementation and Observations
                                                                                                                                                                                                                                                                                                                                  • ACTIVITY
                                                                                                                                                                                                                                                                                                                                      • 19-ldst-exp14
                                                                                                                                                                                                                                                                                                                                        • Experimenting with 74194 4-bit bidirectional universal shift register
                                                                                                                                                                                                                                                                                                                                        • 1 Following ICs and their Datasheets
                                                                                                                                                                                                                                                                                                                                        • 74194 4-bit bidirectional universal shift register
                                                                                                                                                                                                                                                                                                                                        • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                                                                                                                                          • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                                                                                                                                                          • Connecting wires Switches
                                                                                                                                                                                                                                                                                                                                            • THEORY
                                                                                                                                                                                                                                                                                                                                              • Shift Registers
                                                                                                                                                                                                                                                                                                                                              • Bidirectional Shift Registers
                                                                                                                                                                                                                                                                                                                                              • Universal Shift Registers
                                                                                                                                                                                                                                                                                                                                                • S1
                                                                                                                                                                                                                                                                                                                                                  • Circuit Diagram
                                                                                                                                                                                                                                                                                                                                                  • ACTIVITY
                                                                                                                                                                                                                                                                                                                                                      • 20-ldst-exp15
                                                                                                                                                                                                                                                                                                                                                        • COMPONENTS AND APPARATUS REQUIRED
                                                                                                                                                                                                                                                                                                                                                        • 1 Parallel Port Connectors (DB-25) with Cable
                                                                                                                                                                                                                                                                                                                                                        • 2 Personal Computer with Windows 98 and TurboC Compiler Installed
                                                                                                                                                                                                                                                                                                                                                        • 3 Following ICs and their Datasheets
                                                                                                                                                                                                                                                                                                                                                        • 74245 Octal Bus Transceivers with 3-State Outputs
                                                                                                                                                                                                                                                                                                                                                        • 4 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                                                                                                                                                          • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                                                                                                                                                                            • Connecting wires Switches
                                                                                                                                                                                                                                                                                                                                                              • THEORY
                                                                                                                                                                                                                                                                                                                                                              • 3-State Logic
                                                                                                                                                                                                                                                                                                                                                                • Serial and Parallel Port Connectors
                                                                                                                                                                                                                                                                                                                                                                • Parallel Port Connector ndash DB-25
                                                                                                                                                                                                                                                                                                                                                                  • Accessing parallel port through C Language Programming
                                                                                                                                                                                                                                                                                                                                                                      • 21-ldst-appendixA
                                                                                                                                                                                                                                                                                                                                                                      • 22-ldst-appendixB
                                                                                                                                                                                                                                                                                                                                                                        • DEBOUNCING CIRCUITRY FOR MECHANICAL SWITCHES

                                                                                                Logic Design amp Switching Theory 1 Lab Session 12 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                                                50

                                                                                                Lab Session 12 OBJECT

                                                                                                Designing sequential circuit for the given state diagram using D flip-flop GIVEN STATE DIAGRAM

                                                                                                00

                                                                                                11

                                                                                                Figure 121 State Diagram COMPONENTS AND APPARATUS REQUIRED 1 Following ICs and their Datasheets

                                                                                                bull 7474 D Flip-Flop bull ICs of basic gates (AND OR NOT XOR etc) as required

                                                                                                2 Digital Trainer DT-01 or the following components Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches

                                                                                                THEORY

                                                                                                Sequential Circuits In Sequential Circuits the output not only depends on the present inputs but also on previous states of the circuit These circuits use memory elements (latches flip-flops) and the binary information stored in the memory elements at any given time defines the state of the sequential circuit Analysis of a Sequential Circuit The behavior of a sequential circuit is determined from the inputs the outputs and the states of its flip-flops Both the outputs and next state are a function of the inputs and the

                                                                                                10

                                                                                                01

                                                                                                00 11 10

                                                                                                00

                                                                                                00 11 10 00

                                                                                                Logic Design amp Switching Theory 1 Lab Session 12 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                                                51

                                                                                                present state The analysis of a sequential circuit form a state diagram comprises of the following bull Selecting a particular flip-flop to design the circuit bull Obtaining state table from the state diagram bull Finding input equations for the selected flip-flop bull Finding state equations (not required for the construction of circuit) bull Implementing the circuit using selected flip-flops and their input equations ANALYZING THE GIVEN STATE DIAGRAM D Flip-Flop D flip-flop is also called transparent flip-flop as it simply transfers the input data to the output For our design we require the graphical symbol and excitation table of D flip-flop (see figure 122)

                                                                                                Qt Qt+1 T 0 0 0 0 1 1 1 0 0 1 1 1

                                                                                                (b) Excitation table of D Flip-Flop

                                                                                                (a) Graphical Symbol

                                                                                                Figure 122 Characteristic equation of D flip-flop is Q(t+1) = D State Table The given state diagram has four states so we will need two D flip-flops (FF-0 FF-1) Form state table form the given state diagram and record the results in the following table

                                                                                                Present State Input Next State Output Input to FF-0 D0

                                                                                                Input to FF-1 D1 Q1t Q0t x Q1(t+1) Q0(t+1) z

                                                                                                Logic Design amp Switching Theory 1 Lab Session 12 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                                                52

                                                                                                Input Equations Using Karnaugh map the input equations D0 and D1 for the two flip-flops can be found

                                                                                                D0 D1 Q0x

                                                                                                Q1

                                                                                                _ _ Q0x

                                                                                                _ Q0x

                                                                                                Q0x

                                                                                                _ Q0x

                                                                                                Q0x

                                                                                                Q1

                                                                                                _ _ Q0x

                                                                                                _ Q0x

                                                                                                Q0x

                                                                                                _ Q0x

                                                                                                _ Q1

                                                                                                _ Q1

                                                                                                Q1

                                                                                                Q1

                                                                                                D0 = _________________ D1 = _________________

                                                                                                State Equations Using the characteristic equation of D flip-flop we can find the state equations Q0(t+1) and Q1(t+1) for the to flip flops Q0(t+1) = _______________________ Q1(t+1) = _______________________ _______________________ _______________________ _______________________ _______________________ Circuit Diagram

                                                                                                Logic Design amp Switching Theory 1 Lab Session 12 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                                                53

                                                                                                Implementation Procedure and Observations

                                                                                                1 Implement the circuit using digital ICs on a bread board (prepare the pin diagram (use appendix A) and refer to laboratory session 01 for procedure)

                                                                                                2 Make the clear inputs of the flip-flops low (to clear the flip-flops) The flip-flops will remain in clear state as long as the clear inputs are connected to low level

                                                                                                3 Connect output Q0 and the clock pulse to an oscilloscope 4 Apply 0 to the input x 5 Now make the clear inputs to high 6 Observe the waveform for the first 5 clock pulses and record it 7 Repeat steps 2 to 6 keeping x=1 in step 4 this time 8 Repeat steps 2 to 7 this time connecting Q1 instead of Q0 to the oscilloscope in step

                                                                                                3 Record your observations (Keep frequency of the clock pulse low (eg1Hz) so that the output waveforms can be observed easily)

                                                                                                1 2 3 4 5 Clock Pulse

                                                                                                Output Waveform for Q0 when x=0

                                                                                                Output Waveform for Q0 when x=1

                                                                                                Output Waveform for Q1 when x=0

                                                                                                Output Waveform for Q1 when x=1

                                                                                                Logic Design amp Switching Theory 1 Lab Session 13 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                                                Lab Session 13 OBJECT

                                                                                                Designing a modulo-5 asynchronous up-counter using JK-FF COMPONENTS AND APPARATUS REQUIRED

                                                                                                1 Following ICs and their Datasheets

                                                                                                bull 7400 Quad 2-input or 7410 Triple 3-input NAND Gates bull 7476 7473 JK Flip-Flop

                                                                                                2 Digital Trainer DT-01 or the following components Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches

                                                                                                THEORY

                                                                                                Digital Counters A digital counter is a set of flip-flops whose states change in response to pulses applied at the input to the counter The flip-flops are interconnected so that their combined state at any time is the binary equivalent of the total number of pulses that have occurred up to that time Every counter resets after a certain number of clock pulses Thus as it name implies a counter is used to count pulses An n stage counter can count up to a maximum of 2n states n is equal to the number of flip-flops required for the construction of counter

                                                                                                Modulus Counters The number of input pulses that causes a counter to reset to its initial count is called the modulus of the counter Thus the modulus equals to total number of distinct states (counts) including zero that a counter can store A binary counter with n stages is a modulo-2n (or mod-2n) counter The largest count a mod-N counter can achieve is N-1 ie a mod-N counter never reaches the binary number equal to its modulus N is always equal to or less than 2n Counters can be classified as bull Synchronous Counters which are clock driven All the flip-flops are driven by a

                                                                                                single clock bull Asynchronous Counters which are event driven Clock input is given to the first

                                                                                                flip-flop only Rest of the flip-flops are driven by their preceding flip-flops

                                                                                                DESIGN OF A MOD-5 ASYNCHRONOUS UP COUNTER The number of flip-flops required to construct a mod-5 counter is 3 because 5 should be less than or equal to 2n This counter will count from 0 to 4 a total of 5 distinct states Since a 3-stage counter can count up to 8 states at maximum a NAND gate is used to reset it after 5 clock pulses Figure 131 shows the logic diagram

                                                                                                54

                                                                                                Logic Design amp Switching Theory 1 Lab Session 13 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                                                55

                                                                                                Figure 131 A Mod-5 Asynchronous Up Counter

                                                                                                Implementation and Observations

                                                                                                Implement the mod-5 counter circuit (figure 131) on a bread board (prepare the pin diagram (use appendix A) and refer to laboratory session 01 for implementation procedure) and record the observations in the following table

                                                                                                Clock Pulse Q2 Q1 Q0

                                                                                                0 1 2 3 4 5 6 7

                                                                                                ACTIVITY

                                                                                                Draw the timing diagram for mod-5 counter designed in this laboratory session

                                                                                                Logic Design amp Switching Theory 1 Lab Session 14 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                                                Lab Session 14 OBJECT

                                                                                                Experimenting with 74194 4-bit bidirectional universal shift register COMPONENTS AND APPARATUS REQUIRED

                                                                                                1 Following ICs and their Datasheets

                                                                                                bull 74194 4-bit bidirectional universal shift register 2 Digital Trainer DT-01 or the following components

                                                                                                Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches

                                                                                                THEORY

                                                                                                Shift Registers

                                                                                                A Register is a set of flip-flops used to store binary data A register which is capable of shifting its binary information either to the right or left is called a shift register The logical configuration of a register consists of a chain of flip-flops connected in cascade with the output of one flip-flop connected to the input of next flip-flop All flip-flops receive a common clock pulse which causes the shift from one stage to the next

                                                                                                Bidirectional Shift Registers A bi-directional shift register is one whose bits can be shifted from left to right or from right to left

                                                                                                Universal Shift Registers A universal shift register is a bi-directional register whose input can be in either serial or parallel form and whose output can be in either serial or parallel form

                                                                                                74194 4-BIT BIDIRECTIONAL UNIVERSAL SHIFT REGISTER

                                                                                                The 74194 register provides parallel as well as serial loading in both directions Function of various pins of this IC is described below

                                                                                                bull A B C and D Active high inputs for parallel loading bull QA QB QC and QD Active high outputs bull S0 and S1 Active high mode control inputs The following table shows combinations

                                                                                                of S1 and S0 to enable various modes

                                                                                                S1 S0 Clock Action 0 0 x No change 0 1 uarr Shift right 1 0 uarr Shift left 1 1 uarr Parallel load

                                                                                                uarr shows the rising edge of the clock pulse

                                                                                                56

                                                                                                Logic Design amp Switching Theory 1 Lab Session 14 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering bull SR Active high serial input for right shifting bull SL Active high serial input for left shifting bull CLR Active low input Clears all the flip-flops of the register if set to 0 should be

                                                                                                kept high otherwise bull CLK Clock input bull VCC and GND Supply connections lines Thus A B C and D are inputs for parallel loading whereas SR and SL are inputs for serial loading with right or left shifting respectively S1 and S0 are used to select the loading mode Circuit Diagram

                                                                                                Figure 141 Pin connections of 74194 Testing Procedure

                                                                                                bull Make connections as shown in the circuit diagram bull Observe the output for the input combinations given in the following table

                                                                                                57

                                                                                                Logic Design amp Switching Theory 1 Lab Session 14 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                                                58

                                                                                                Observations

                                                                                                S1 S0 SL SR A B C D QA QB QC QD 0 0 0 1 0 0 0 0 0 1 1 0 0 0 0 1 1 0 0 0 0 0 1 0 1 1 0 0 0 0 1 1 0 0 1 1 0 1 0 0 0 1 1 1 0 1 0 1 1 0 1 0 0 1 1 0 1 1 1 0 0 1 1 1 1 1 0 0 1 1 1 1

                                                                                                ACTIVITY 1 Show connections of 74194 to convert it into a ring counter with right shifting

                                                                                                Logic Design amp Switching Theory 1 Lab Session 15 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                                                Lab Session 15

                                                                                                OBJECT

                                                                                                Experimenting with 74245 octal bus transceivers using parallel port PC interfacing COMPONENTS AND APPARATUS REQUIRED 1 Parallel Port Connectors (DB-25) with Cable 2 Personal Computer with Windows 98 and TurboC Compiler Installed 3 Following ICs and their Datasheets

                                                                                                bull 74245 Octal Bus Transceivers with 3-State Outputs 4 Digital Trainer DT-01 or the following components

                                                                                                Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches

                                                                                                THEORY

                                                                                                3-State Logic Sometimes it is necessary to isolate one part of circuit from the other part For this purpose some TTL ICs are designed with 3-state logic Such devices have three possible output states high low and high impedance The device can be put into high impedance state by a control signal applied to an appropriate pin When such a device is in high impedance state there is very high impedance at its output effectively isolating the device from whatever circuitry the output normally drives 74245 Octal Bus Transceivers A bus is any conducting path or set of paths having electrical connections to one or more devices 74245 octal bus transceivers are mainly used to control connectivity between two devices or circuits It also provides direction control for signal flow Function of various pin of this IC is given below

                                                                                                bull A1 through A8 Bus A bull B1 through B8 Bus B bull G΄ Active low enable input When high sets all the bus pins to high impedance state bull DIR Direction control for signal flow When set to high logic level transfers bus A

                                                                                                data to B bus When set to low logic level transfers bus B data to A bus bull VCC and GND Supply connections lines Serial and Parallel Port Connectors A Parallel Port can consist of only 25 pin port adapter called a DB-25 and a serial port can consist of either a 25 pin port adapter called a DB-25 or 9 pin adapter called a DB-9 port adapter Whether the port is a 9 pin or 25 pin it can accomplish all of the same tasks that serial port communications have been designed for

                                                                                                59

                                                                                                Logic Design amp Switching Theory 1 Lab Session 15 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                                                60

                                                                                                Each adapter can be a male type connector with pins or a female type adapter with tiny holes Generally a PRINTER port (called LPT1) on the back of a computer is female type adapter and we need to use MALE DB-25 pin cable on it for PRINTER connection or for parallel LAPLINK cable And a COM port on the back of a computer is male for the serial ports but it may not necessarily be Parallel Port Connector ndash DB-25 The DB-25 connector (named for its B-size D-shaped shell and 25 pins) is practically ubiquitous in the electronics industry The DB-25 connector is used for a variety of purposes Two common applications are RS-232EIA-232 (serial) connections and the parallel printer interface on the IBM PC The DB-25 connector is also used for SCSI connections Normally the parallel port is used for output to a printer or other device It sends data 8-bits or one byte at a time in parallel The other lines available on the DB-25 connector are a combination of status lines control lines and ground lines The status and control lines are used for handshaking commands and feedback when we are talking to a printer

                                                                                                Figure 152 DB-25 Female Figure 151 DB-25 Male

                                                                                                Figure 153 Pin Layout for DB-25 As can be seen form figure 153 there are four types of pins in this connector

                                                                                                bull Data pins (8 pins - D0 to D7) Active high bidirectional lines

                                                                                                Logic Design amp Switching Theory 1 Lab Session 15 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering bull Control pins (4 pins - C0 to C3) C0 C1 and C3 are active low whereas C2 is active

                                                                                                high These lines also are bidirectional bull Status pins (5 pins ndash S3 to S7) Only S7 is active low rest are active high input lines bull Ground pins (8 pins) Used as a reference signal for the low (below 05 volts) charge

                                                                                                Parallel Port Addresses A DB-25 connector at a parallel port has three address one for each kind of pins register data status and control The first or base address generally refers to data register Second address is for status register and the third one is for control register In Windows 98 the base address is usually found to be 278H 378H or 3BCH Now if 378H is the base address then it refers to the data register whereas addresses for status and control register are respectively 379H and 37AH For Windows 98 the base address can be found as follows 1 On your Desktop right-click on My Computer and select Properties 2 Click on the Device Manager tab and find LPT1 under Plug and Play BIOS 3 After selecting LPT1 click the Properties button 4 Next select the Resources tab and the address should then appear next to InputOutput

                                                                                                Range Accessing parallel port through C Language Programming There are multiple functions in C Language for accessing external ports The most commonly used are listed below

                                                                                                bull unsigned char inportb(int portid) inportb reads a byte from a hardware port

                                                                                                bull int inport(int portid) reads a word from a hardware port

                                                                                                bull void outportb(int portid unsigned char value) outputs a byte to a hardware port

                                                                                                bull void outport(int portid int value) outputs a word to a hardware port

                                                                                                portid refers to the port address whereas value refers to the data to be sent TESTING 74245 USING PARALLEL PORT PC INTERFACING At one end the parallel port connector will be connected to the PC via parallel port cable and another connector (to be plugged into the PC parallel port slot) At the other end it will be connected to the buffer IC 74245 Data lines of the connector will be used to transfer 8-bit data between the PC and the buffer Out of the 8-bits of 74245 4-bits will be used to enter data which will be displayed at the monitor through a C language

                                                                                                61

                                                                                                Logic Design amp Switching Theory 1 Lab Session 15 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering program The remaining 4-bits will receive data from PC as entered by the user via keyboard

                                                                                                Circuit Diagram

                                                                                                Figure 154 Interface of 74245 to PC via Parallel Port

                                                                                                Procedure

                                                                                                1 Connect the DB-25 connector to the PC at one end and solder it to the circuit board at the other end

                                                                                                2 Connect various pins of the connector and 74245 according to the circuit diagram shown in figure 152

                                                                                                3 Using the functions listed in the previous section write a program in C language to operate various pins of the buffer The user interface of the program should provide option to the user whether to send or receive data from the port

                                                                                                4 Set DIR switch to 1 5 Try sending some data bits to the port The result should be displayed at the LEDs 6 Set DIR switch to 0 7 Set some binary 4-bit value through the switches Try reading it via parallel port

                                                                                                C Language Program

                                                                                                A program to access parallel port for data transfers

                                                                                                use header file include ltstdiohgt main program void main() define variable

                                                                                                62

                                                                                                Logic Design amp Switching Theory 1 Lab Session 15 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering unsigned int data=0 char choice while(1) printing option menu clrscr() printf(This program will send or receive a BCD digit from the parallel portn) printf(nPress your choice numbern) printf(n1 Send Data) printf(n2 Receive Data) printf(n3 Exitn) choice = getch() sending entered digit to the port if(choice == 1) input BCD digit printf(nEnter BCD digit to be sent to the port) data = getche() masking the first four bits data = data amp 0x0f sending to the port outportb(0x378data) printf(nThe BCD digit c has been sent to the port data) printing on screen the data received from the port else if(choice == 2) receiving data from the port data = inportb(0x378) masking the last four bits data = data amp 0xf0 shifting first four bits to make them the last four bits datagtgt=4 printf(nThe BCD digit set at the port is c data) exit else if(choice == 3) break key pressed is not in the menu else printf(nEnter valid choice number) printf(nnPress any key to continue) getch()

                                                                                                63

                                                                                                Logic Design amp Switching Theory 1 Lab Session 15 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                                                ACTIVITY 1 In the above circuit DIR and G΄ inputs are hardwired Connect them to status or

                                                                                                control pins of the parallel port connector and control their function through your software program Circuit Diagram Program Code ______________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________

                                                                                                ___________________________________________________________________________________________________________________________________________________

                                                                                                64

                                                                                                Logic Design amp Switching Theory 1 Lab Session 15 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                                                65

                                                                                                _____________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ _____________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ _______________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ _________________________________________________ _________________________________________________

                                                                                                Logic Design amp Switching Theory 1 Appendix A NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                                                Appendix A

                                                                                                PIN DIAGRAMS OF THE ICS REQUIRED FOR THE LABORATORY SESSIONS Consult the TTLIC data book for internal diagrams and electrical characteristics of these ICs 7400 Quad 2-Input NAND 7402 Quad 2-Input NOR

                                                                                                7404 Hex Inverter 7408 Quad 2-Input AND

                                                                                                7410 Triple 3-Input NAND 7411 Triple 3-Input AND

                                                                                                7421 Dual 4-Input AND 7432 Quad 2-Input OR

                                                                                                66

                                                                                                Logic Design amp Switching Theory 1 Appendix A NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                                                BCD-to-Seven Segm 7448 BCD-to-Seven Segment 7447 ent

                                                                                                Decoder (15V OC) Decoder (2kΩ pull-up output)

                                                                                                7473 Dual JK Flip-Flop 7474 Dual D-Type Flip-Flop

                                                                                                7476 Dual JK Flop-Flop -Bit Binary Full Adder 7483 4 with Fast Carry

                                                                                                86 Quad 2-Inpu 74138 3-to-8 Line 74 t Exclusive OR Decoder Demultiplexer

                                                                                                67

                                                                                                Logic Design amp Switching Theory 1 Appendix A NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                                                68

                                                                                                74148 8-to-3 Line 16-to-1 Line Data

                                                                                                Priority Encoder 74150 Selector Multiplexer

                                                                                                74245 Oct nsceivers Universal Shift Register (PIPO) (3-State)

                                                                                                74194 4-Bit Bidirectional al Bus Tra

                                                                                                Logic Design amp Switching Theory 1 Appendix B NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                                                Appendix B

                                                                                                DEBOUNCING CIRCUITRY FOR MECHANICAL SWITCHES Mechanical switches form the interface between human beings and computers or other digital systems For example a keyboard is a matrix of switches used to supply alphanumeric data to a computer Whatever the switch design it is a potential source of problems due to contact bounce The contact bounce creates a sense of narrow pulses when a switch is opened or closed An example of device whose operation would be adversely affected by contact bounce is a digital counter used to count the number of times a switch is depressed Eliminating the effects of contact bounce is called debouncing When data is entered into a computer via a keyboard a software debounce is often used This type of debouncing is a program that causes the computer to sample the switch terminal (ie to input data from it) many times in succession during the interval of time that contact bounce occurs If the data is sensed to be 1s (or 0s) for a specific number of consecutive samples then it is assumed that contact bounce has ended and the last value sensed is valid Hardware debouncing is the use of electronic circuitry to eliminate the effects of contact bounce There are numerous versions of such circuitry including those that use monostable multivibrators (one-shots) but the most straightforward is simply an RS latch Figure B1 shows the circuit When the switch is in position 1 R = 0 and S = 1 so the latch is set and the output (Q) is 1 When the switch is in position 0 R = 1and S = 0 so the latch is reset and the output is 0 When the switch is moved form one position to the other the latch changes state and bouncing occurs at either the R or the S input The bouncing does not affect the latch after it has change state An RS latch will remain set for example when its R input is 0 and its S input is alternately changed form 1 to 0

                                                                                                Figure B1 Use of RS latch to debounce a mechanical switch

                                                                                                69

                                                                                                • 01-ldst-Outer title
                                                                                                  • Practical Workbook
                                                                                                  • Logic Design amp Switching Theory I
                                                                                                    • Dept of Computer amp Information Systems Engineering
                                                                                                      • NED University of Engineering amp Technology
                                                                                                      • Karachi ndash 75270 Pakistan
                                                                                                        • 02-ldst-inner Title
                                                                                                          • Practical Workbook
                                                                                                          • Logic Design amp Switching Theory I
                                                                                                            • Dept of Computer amp Information Systems Engineering
                                                                                                              • NED University of Engineering amp Technology
                                                                                                              • Karachi ndash 75270 Pakistan
                                                                                                                • 03-ldst-general info
                                                                                                                • 04-ldst-introduction
                                                                                                                • 05-Table of Contents
                                                                                                                  • CONTENTS
                                                                                                                    • Lab Session No Object Page No
                                                                                                                    • 1
                                                                                                                    • Also implementing and testing the given circuit on a bread board
                                                                                                                      • Working with Electronics Workbench
                                                                                                                        • Driving a seven segment display using 7447 7448 driver IC
                                                                                                                          • Designing a modulus-5 asynchronous up-counter using JK-FF
                                                                                                                            • Experimenting with 74194 4-bit bidirectional universal shift register
                                                                                                                                • 13
                                                                                                                                    • 06-ldst-Exp01
                                                                                                                                      • Lab Session 01
                                                                                                                                      • OBJECT
                                                                                                                                        • 1 Bread board
                                                                                                                                        • 2 5 V - power supply
                                                                                                                                        • 3 Multimeter
                                                                                                                                        • 4 Logic probe
                                                                                                                                        • 5 LEDs with resistors
                                                                                                                                        • 6 Connecting wires
                                                                                                                                        • 8 Following ICs and their datasheets
                                                                                                                                          • THEORY
                                                                                                                                            • Logic Gates
                                                                                                                                            • 1 The AND Gate ndash An AND gatersquos output is 1 if and only if all its inputs are 1 If A and B are two inputs to an AND gate then output F of the gate is given as F = AB
                                                                                                                                            • 2 The OR Gate - An OR gatersquos output is 1 if at least one of its input is 1 If A and B are two inputs to an OR gate then output F of the gate is given as F = A+B
                                                                                                                                            • 3 The NOT Gate (Inverter) ndash Its output is 1 when its input is 0 and its output is 0 when the input is 1 ie it complements a digital variable If A is the input to a NOT gate then output F of the gate is given as
                                                                                                                                            • 4 The NAND Gate ndash Its output is 1 if at least one of its input is 0 This gate performs the same logic as an AND gate followed by an inverter If A and B are two inputs to a NAND gate then output F of the gate is given as
                                                                                                                                              • 5 The NOR Gate - The output of a NOR gate is 1 if and only if all its inputs are 0 This gate performs the same logic function as an OR gate followed by an inverter If A and B are two inputs to a NAND gate then output F of the gate is given as
                                                                                                                                                  • DATA SHEETS
                                                                                                                                                    • Logic expression for the given logic diagram __________________________________
                                                                                                                                                        • 07-ldst-exp02
                                                                                                                                                          • Working with Electronics Workbench
                                                                                                                                                            • 08-ldst-exp03
                                                                                                                                                              • Designing Half and Full Adder Circuits
                                                                                                                                                                • COMPONENTS AND APPARATUS REQUIRED
                                                                                                                                                                  • 1 Following ICs and their Datasheets
                                                                                                                                                                  • 7408 Quad 2-input AND Gate
                                                                                                                                                                  • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                    • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                    • Connecting wires Switches
                                                                                                                                                                      • THEORY
                                                                                                                                                                          • IMPLEMENTATION AND OBSERVATIONS
                                                                                                                                                                            • 09-ldst-Exp04
                                                                                                                                                                              • Lab Session 04
                                                                                                                                                                              • 1 Digital ICs and their Datasheets
                                                                                                                                                                              • 7408 Quad 2-input AND Gate
                                                                                                                                                                              • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                • Connecting wires Switches
                                                                                                                                                                                • PROCEDURE
                                                                                                                                                                                • REDUCTION OF LOGIC EXPRESSION USING KARNAUGH MAP
                                                                                                                                                                                • OBSERVATIONS
                                                                                                                                                                                • RESULT
                                                                                                                                                                                    • 10-ldst-Exp05
                                                                                                                                                                                      • Lab Session 05
                                                                                                                                                                                      • 1 Following ICs and their Datasheets
                                                                                                                                                                                      • 7408 Quad 2-input AND Gate
                                                                                                                                                                                      • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                        • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                        • (100 Ω) Connecting wires Switches
                                                                                                                                                                                        • THEORY
                                                                                                                                                                                          • IMPLEMENTATION AND OBSERVATIONS
                                                                                                                                                                                            • 11-ldst-Exp06
                                                                                                                                                                                              • OBJECT
                                                                                                                                                                                              • 1 Following ICs and their Datasheets
                                                                                                                                                                                              • 7408 Quad 2-input AND Gates or 7411 Triple 3-input AND Gates
                                                                                                                                                                                              • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                • Connecting wires Switches
                                                                                                                                                                                                  • Figure 62 Circuit Diagram for 4 x 1 Multiplexer
                                                                                                                                                                                                  • Implementation and Observations
                                                                                                                                                                                                    • Circuit Diagram
                                                                                                                                                                                                      • ACTIVITY
                                                                                                                                                                                                        • 12-ldst-exp07
                                                                                                                                                                                                          • 1 Following ICs and their Datasheets
                                                                                                                                                                                                          • 7408 Quad 2-input or 7411 Triple 3-input AND Gates
                                                                                                                                                                                                          • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                            • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                            • Connecting wires Switches
                                                                                                                                                                                                              • THEORY
                                                                                                                                                                                                                  • Figure 72 Circuit Diagram for 2 x 4 Decoder 1 x 4 Demultiplexer
                                                                                                                                                                                                                  • Implementation and Observations
                                                                                                                                                                                                                    • Circuit Diagram
                                                                                                                                                                                                                      • ACTIVITY
                                                                                                                                                                                                                        • 13-ldst-Exp08
                                                                                                                                                                                                                          • OBJECT
                                                                                                                                                                                                                          • 1 Following ICs and their Datasheets
                                                                                                                                                                                                                          • 7408 Quad 2-input or 7421 Dual 4-input AND Gates
                                                                                                                                                                                                                          • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                            • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                                            • Connecting wires Switches
                                                                                                                                                                                                                              • THEORY
                                                                                                                                                                                                                                  • Figure 81 Circuit Diagram for 4 x 2 Priority Encoder
                                                                                                                                                                                                                                  • Implementation and Observations
                                                                                                                                                                                                                                    • Therefore if GS A2 A1 and A0 are all low then it shows that line 0 is selected and if E0 A2 A1 and A0 are all low then it shows that none of the inputs selected E0 and GS cannot be in the same state provided that E1 is enabled
                                                                                                                                                                                                                                    • Circuit Diagram
                                                                                                                                                                                                                                      • ACTIVITY
                                                                                                                                                                                                                                        • 14-ldst-exp09
                                                                                                                                                                                                                                          • OBJECT
                                                                                                                                                                                                                                          • 1 Following ICs and their Datasheets
                                                                                                                                                                                                                                          • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                                            • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                                                            • Connecting wires Switches
                                                                                                                                                                                                                                              • THEORY
                                                                                                                                                                                                                                                • Parity Generator
                                                                                                                                                                                                                                                  • Let x y and z be the three bits that constitute the message and are the input to the Odd Parity Generator Circuit Since it is an odd parity system the bit P is generated so as to make the total number of 1s odd (including P) The function P can be expressed as follows
                                                                                                                                                                                                                                                  • Figure 91 Circuit Diagram for a 3-bit Parity Generator
                                                                                                                                                                                                                                                    • C = x Ο y Ο z Ο P
                                                                                                                                                                                                                                                      • Implementation and Observations
                                                                                                                                                                                                                                                        • ACTIVITY
                                                                                                                                                                                                                                                            • 15-ldst-exp10
                                                                                                                                                                                                                                                              • Driving a seven segment display using 7447 7448 driver IC
                                                                                                                                                                                                                                                              • COMPONENTS AND APPARATUS REQUIRED
                                                                                                                                                                                                                                                              • 1 Following ICs and their Datasheets
                                                                                                                                                                                                                                                              • 7447 7448 BCD to Seven Segment Driver
                                                                                                                                                                                                                                                              • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                                                                • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches
                                                                                                                                                                                                                                                                  • THEORY
                                                                                                                                                                                                                                                                  • Seven Segment Displays
                                                                                                                                                                                                                                                                  • CIRCUIT DIAGRAM
                                                                                                                                                                                                                                                                  • Figure 102 Circuit diagram for 7447driving a common-anode display
                                                                                                                                                                                                                                                                      • IMPLEMENTATION AND OBSERVATIONS
                                                                                                                                                                                                                                                                        • Decimal Digit
                                                                                                                                                                                                                                                                        • BCD Inputs
                                                                                                                                                                                                                                                                        • Seven Segment Outputs
                                                                                                                                                                                                                                                                        • D
                                                                                                                                                                                                                                                                        • C
                                                                                                                                                                                                                                                                        • B
                                                                                                                                                                                                                                                                        • A
                                                                                                                                                                                                                                                                        • a
                                                                                                                                                                                                                                                                        • b
                                                                                                                                                                                                                                                                        • c
                                                                                                                                                                                                                                                                        • d
                                                                                                                                                                                                                                                                        • e
                                                                                                                                                                                                                                                                        • f
                                                                                                                                                                                                                                                                        • g
                                                                                                                                                                                                                                                                        • 0
                                                                                                                                                                                                                                                                        • 0
                                                                                                                                                                                                                                                                        • 0
                                                                                                                                                                                                                                                                        • 0
                                                                                                                                                                                                                                                                        • 0
                                                                                                                                                                                                                                                                        • 1
                                                                                                                                                                                                                                                                        • 0
                                                                                                                                                                                                                                                                        • 0
                                                                                                                                                                                                                                                                        • 0
                                                                                                                                                                                                                                                                        • 1
                                                                                                                                                                                                                                                                        • 2
                                                                                                                                                                                                                                                                        • 0
                                                                                                                                                                                                                                                                        • 0
                                                                                                                                                                                                                                                                        • 1
                                                                                                                                                                                                                                                                        • 0
                                                                                                                                                                                                                                                                        • 3
                                                                                                                                                                                                                                                                        • 0
                                                                                                                                                                                                                                                                        • 0
                                                                                                                                                                                                                                                                        • 1
                                                                                                                                                                                                                                                                        • 1
                                                                                                                                                                                                                                                                        • 4
                                                                                                                                                                                                                                                                        • 0
                                                                                                                                                                                                                                                                        • 1
                                                                                                                                                                                                                                                                        • 0
                                                                                                                                                                                                                                                                        • 0
                                                                                                                                                                                                                                                                        • 5
                                                                                                                                                                                                                                                                        • 0
                                                                                                                                                                                                                                                                        • 1
                                                                                                                                                                                                                                                                        • 0
                                                                                                                                                                                                                                                                        • 1
                                                                                                                                                                                                                                                                        • 6
                                                                                                                                                                                                                                                                        • 0
                                                                                                                                                                                                                                                                        • 1
                                                                                                                                                                                                                                                                        • 1
                                                                                                                                                                                                                                                                        • 0
                                                                                                                                                                                                                                                                        • 7
                                                                                                                                                                                                                                                                        • 0
                                                                                                                                                                                                                                                                        • 1
                                                                                                                                                                                                                                                                        • 1
                                                                                                                                                                                                                                                                        • 1
                                                                                                                                                                                                                                                                        • 8
                                                                                                                                                                                                                                                                        • 1
                                                                                                                                                                                                                                                                        • 0
                                                                                                                                                                                                                                                                        • 0
                                                                                                                                                                                                                                                                        • 0
                                                                                                                                                                                                                                                                        • 9
                                                                                                                                                                                                                                                                        • 1
                                                                                                                                                                                                                                                                        • 0
                                                                                                                                                                                                                                                                        • 0
                                                                                                                                                                                                                                                                        • 1
                                                                                                                                                                                                                                                                          • ACTIVITY
                                                                                                                                                                                                                                                                            • 16-ldst-exp11
                                                                                                                                                                                                                                                                              • Lab Session 11
                                                                                                                                                                                                                                                                                • OBJECT
                                                                                                                                                                                                                                                                                • COMPONENTS AND APPARATUS REQUIRED
                                                                                                                                                                                                                                                                                  • 1 Following ICs and their Datasheets
                                                                                                                                                                                                                                                                                  • 7473 7476 JK Flip-Flop
                                                                                                                                                                                                                                                                                  • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                                                                                    • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                                                                                                    • Connecting wires Switches
                                                                                                                                                                                                                                                                                      • THEORY
                                                                                                                                                                                                                                                                                          • Flip-Flop
                                                                                                                                                                                                                                                                                          • JK Flip-Flop
                                                                                                                                                                                                                                                                                            • Circuit Diagram
                                                                                                                                                                                                                                                                                              • Observations
                                                                                                                                                                                                                                                                                                • ACTIVITY
                                                                                                                                                                                                                                                                                                    • 17-ldst-exp12
                                                                                                                                                                                                                                                                                                      • Lab Session 12
                                                                                                                                                                                                                                                                                                        • OBJECT
                                                                                                                                                                                                                                                                                                        • GIVEN STATE DIAGRAM
                                                                                                                                                                                                                                                                                                        • Figure 121 State Diagram
                                                                                                                                                                                                                                                                                                        • COMPONENTS AND APPARATUS REQUIRED
                                                                                                                                                                                                                                                                                                          • 1 Following ICs and their Datasheets
                                                                                                                                                                                                                                                                                                          • 7474 D Flip-Flop
                                                                                                                                                                                                                                                                                                          • ICs of basic gates (AND OR NOT XOR etc) as required
                                                                                                                                                                                                                                                                                                          • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                                                                                                            • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                                                                                                                            • Connecting wires Switches
                                                                                                                                                                                                                                                                                                              • THEORY
                                                                                                                                                                                                                                                                                                                  • Sequential Circuits
                                                                                                                                                                                                                                                                                                                    • 18-ldst-exp13
                                                                                                                                                                                                                                                                                                                      • Lab Session 13
                                                                                                                                                                                                                                                                                                                        • Designing a modulo-5 asynchronous up-counter using JK-FF
                                                                                                                                                                                                                                                                                                                          • 1 Following ICs and their Datasheets
                                                                                                                                                                                                                                                                                                                          • 7400 Quad 2-input or 7410 Triple 3-input NAND Gates
                                                                                                                                                                                                                                                                                                                          • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                                                                                                                            • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                                                                                                                                            • Connecting wires Switches
                                                                                                                                                                                                                                                                                                                              • THEORY
                                                                                                                                                                                                                                                                                                                                  • Figure 131 A Mod-5 Asynchronous Up Counter
                                                                                                                                                                                                                                                                                                                                  • Implementation and Observations
                                                                                                                                                                                                                                                                                                                                    • ACTIVITY
                                                                                                                                                                                                                                                                                                                                        • 19-ldst-exp14
                                                                                                                                                                                                                                                                                                                                          • Experimenting with 74194 4-bit bidirectional universal shift register
                                                                                                                                                                                                                                                                                                                                          • 1 Following ICs and their Datasheets
                                                                                                                                                                                                                                                                                                                                          • 74194 4-bit bidirectional universal shift register
                                                                                                                                                                                                                                                                                                                                          • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                                                                                                                                            • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                                                                                                                                                            • Connecting wires Switches
                                                                                                                                                                                                                                                                                                                                              • THEORY
                                                                                                                                                                                                                                                                                                                                                • Shift Registers
                                                                                                                                                                                                                                                                                                                                                • Bidirectional Shift Registers
                                                                                                                                                                                                                                                                                                                                                • Universal Shift Registers
                                                                                                                                                                                                                                                                                                                                                  • S1
                                                                                                                                                                                                                                                                                                                                                    • Circuit Diagram
                                                                                                                                                                                                                                                                                                                                                    • ACTIVITY
                                                                                                                                                                                                                                                                                                                                                        • 20-ldst-exp15
                                                                                                                                                                                                                                                                                                                                                          • COMPONENTS AND APPARATUS REQUIRED
                                                                                                                                                                                                                                                                                                                                                          • 1 Parallel Port Connectors (DB-25) with Cable
                                                                                                                                                                                                                                                                                                                                                          • 2 Personal Computer with Windows 98 and TurboC Compiler Installed
                                                                                                                                                                                                                                                                                                                                                          • 3 Following ICs and their Datasheets
                                                                                                                                                                                                                                                                                                                                                          • 74245 Octal Bus Transceivers with 3-State Outputs
                                                                                                                                                                                                                                                                                                                                                          • 4 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                                                                                                                                                            • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                                                                                                                                                                              • Connecting wires Switches
                                                                                                                                                                                                                                                                                                                                                                • THEORY
                                                                                                                                                                                                                                                                                                                                                                • 3-State Logic
                                                                                                                                                                                                                                                                                                                                                                  • Serial and Parallel Port Connectors
                                                                                                                                                                                                                                                                                                                                                                  • Parallel Port Connector ndash DB-25
                                                                                                                                                                                                                                                                                                                                                                    • Accessing parallel port through C Language Programming
                                                                                                                                                                                                                                                                                                                                                                        • 21-ldst-appendixA
                                                                                                                                                                                                                                                                                                                                                                        • 22-ldst-appendixB
                                                                                                                                                                                                                                                                                                                                                                          • DEBOUNCING CIRCUITRY FOR MECHANICAL SWITCHES

                                                                                                  Logic Design amp Switching Theory 1 Lab Session 12 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                                                  51

                                                                                                  present state The analysis of a sequential circuit form a state diagram comprises of the following bull Selecting a particular flip-flop to design the circuit bull Obtaining state table from the state diagram bull Finding input equations for the selected flip-flop bull Finding state equations (not required for the construction of circuit) bull Implementing the circuit using selected flip-flops and their input equations ANALYZING THE GIVEN STATE DIAGRAM D Flip-Flop D flip-flop is also called transparent flip-flop as it simply transfers the input data to the output For our design we require the graphical symbol and excitation table of D flip-flop (see figure 122)

                                                                                                  Qt Qt+1 T 0 0 0 0 1 1 1 0 0 1 1 1

                                                                                                  (b) Excitation table of D Flip-Flop

                                                                                                  (a) Graphical Symbol

                                                                                                  Figure 122 Characteristic equation of D flip-flop is Q(t+1) = D State Table The given state diagram has four states so we will need two D flip-flops (FF-0 FF-1) Form state table form the given state diagram and record the results in the following table

                                                                                                  Present State Input Next State Output Input to FF-0 D0

                                                                                                  Input to FF-1 D1 Q1t Q0t x Q1(t+1) Q0(t+1) z

                                                                                                  Logic Design amp Switching Theory 1 Lab Session 12 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                                                  52

                                                                                                  Input Equations Using Karnaugh map the input equations D0 and D1 for the two flip-flops can be found

                                                                                                  D0 D1 Q0x

                                                                                                  Q1

                                                                                                  _ _ Q0x

                                                                                                  _ Q0x

                                                                                                  Q0x

                                                                                                  _ Q0x

                                                                                                  Q0x

                                                                                                  Q1

                                                                                                  _ _ Q0x

                                                                                                  _ Q0x

                                                                                                  Q0x

                                                                                                  _ Q0x

                                                                                                  _ Q1

                                                                                                  _ Q1

                                                                                                  Q1

                                                                                                  Q1

                                                                                                  D0 = _________________ D1 = _________________

                                                                                                  State Equations Using the characteristic equation of D flip-flop we can find the state equations Q0(t+1) and Q1(t+1) for the to flip flops Q0(t+1) = _______________________ Q1(t+1) = _______________________ _______________________ _______________________ _______________________ _______________________ Circuit Diagram

                                                                                                  Logic Design amp Switching Theory 1 Lab Session 12 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                                                  53

                                                                                                  Implementation Procedure and Observations

                                                                                                  1 Implement the circuit using digital ICs on a bread board (prepare the pin diagram (use appendix A) and refer to laboratory session 01 for procedure)

                                                                                                  2 Make the clear inputs of the flip-flops low (to clear the flip-flops) The flip-flops will remain in clear state as long as the clear inputs are connected to low level

                                                                                                  3 Connect output Q0 and the clock pulse to an oscilloscope 4 Apply 0 to the input x 5 Now make the clear inputs to high 6 Observe the waveform for the first 5 clock pulses and record it 7 Repeat steps 2 to 6 keeping x=1 in step 4 this time 8 Repeat steps 2 to 7 this time connecting Q1 instead of Q0 to the oscilloscope in step

                                                                                                  3 Record your observations (Keep frequency of the clock pulse low (eg1Hz) so that the output waveforms can be observed easily)

                                                                                                  1 2 3 4 5 Clock Pulse

                                                                                                  Output Waveform for Q0 when x=0

                                                                                                  Output Waveform for Q0 when x=1

                                                                                                  Output Waveform for Q1 when x=0

                                                                                                  Output Waveform for Q1 when x=1

                                                                                                  Logic Design amp Switching Theory 1 Lab Session 13 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                                                  Lab Session 13 OBJECT

                                                                                                  Designing a modulo-5 asynchronous up-counter using JK-FF COMPONENTS AND APPARATUS REQUIRED

                                                                                                  1 Following ICs and their Datasheets

                                                                                                  bull 7400 Quad 2-input or 7410 Triple 3-input NAND Gates bull 7476 7473 JK Flip-Flop

                                                                                                  2 Digital Trainer DT-01 or the following components Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches

                                                                                                  THEORY

                                                                                                  Digital Counters A digital counter is a set of flip-flops whose states change in response to pulses applied at the input to the counter The flip-flops are interconnected so that their combined state at any time is the binary equivalent of the total number of pulses that have occurred up to that time Every counter resets after a certain number of clock pulses Thus as it name implies a counter is used to count pulses An n stage counter can count up to a maximum of 2n states n is equal to the number of flip-flops required for the construction of counter

                                                                                                  Modulus Counters The number of input pulses that causes a counter to reset to its initial count is called the modulus of the counter Thus the modulus equals to total number of distinct states (counts) including zero that a counter can store A binary counter with n stages is a modulo-2n (or mod-2n) counter The largest count a mod-N counter can achieve is N-1 ie a mod-N counter never reaches the binary number equal to its modulus N is always equal to or less than 2n Counters can be classified as bull Synchronous Counters which are clock driven All the flip-flops are driven by a

                                                                                                  single clock bull Asynchronous Counters which are event driven Clock input is given to the first

                                                                                                  flip-flop only Rest of the flip-flops are driven by their preceding flip-flops

                                                                                                  DESIGN OF A MOD-5 ASYNCHRONOUS UP COUNTER The number of flip-flops required to construct a mod-5 counter is 3 because 5 should be less than or equal to 2n This counter will count from 0 to 4 a total of 5 distinct states Since a 3-stage counter can count up to 8 states at maximum a NAND gate is used to reset it after 5 clock pulses Figure 131 shows the logic diagram

                                                                                                  54

                                                                                                  Logic Design amp Switching Theory 1 Lab Session 13 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                                                  55

                                                                                                  Figure 131 A Mod-5 Asynchronous Up Counter

                                                                                                  Implementation and Observations

                                                                                                  Implement the mod-5 counter circuit (figure 131) on a bread board (prepare the pin diagram (use appendix A) and refer to laboratory session 01 for implementation procedure) and record the observations in the following table

                                                                                                  Clock Pulse Q2 Q1 Q0

                                                                                                  0 1 2 3 4 5 6 7

                                                                                                  ACTIVITY

                                                                                                  Draw the timing diagram for mod-5 counter designed in this laboratory session

                                                                                                  Logic Design amp Switching Theory 1 Lab Session 14 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                                                  Lab Session 14 OBJECT

                                                                                                  Experimenting with 74194 4-bit bidirectional universal shift register COMPONENTS AND APPARATUS REQUIRED

                                                                                                  1 Following ICs and their Datasheets

                                                                                                  bull 74194 4-bit bidirectional universal shift register 2 Digital Trainer DT-01 or the following components

                                                                                                  Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches

                                                                                                  THEORY

                                                                                                  Shift Registers

                                                                                                  A Register is a set of flip-flops used to store binary data A register which is capable of shifting its binary information either to the right or left is called a shift register The logical configuration of a register consists of a chain of flip-flops connected in cascade with the output of one flip-flop connected to the input of next flip-flop All flip-flops receive a common clock pulse which causes the shift from one stage to the next

                                                                                                  Bidirectional Shift Registers A bi-directional shift register is one whose bits can be shifted from left to right or from right to left

                                                                                                  Universal Shift Registers A universal shift register is a bi-directional register whose input can be in either serial or parallel form and whose output can be in either serial or parallel form

                                                                                                  74194 4-BIT BIDIRECTIONAL UNIVERSAL SHIFT REGISTER

                                                                                                  The 74194 register provides parallel as well as serial loading in both directions Function of various pins of this IC is described below

                                                                                                  bull A B C and D Active high inputs for parallel loading bull QA QB QC and QD Active high outputs bull S0 and S1 Active high mode control inputs The following table shows combinations

                                                                                                  of S1 and S0 to enable various modes

                                                                                                  S1 S0 Clock Action 0 0 x No change 0 1 uarr Shift right 1 0 uarr Shift left 1 1 uarr Parallel load

                                                                                                  uarr shows the rising edge of the clock pulse

                                                                                                  56

                                                                                                  Logic Design amp Switching Theory 1 Lab Session 14 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering bull SR Active high serial input for right shifting bull SL Active high serial input for left shifting bull CLR Active low input Clears all the flip-flops of the register if set to 0 should be

                                                                                                  kept high otherwise bull CLK Clock input bull VCC and GND Supply connections lines Thus A B C and D are inputs for parallel loading whereas SR and SL are inputs for serial loading with right or left shifting respectively S1 and S0 are used to select the loading mode Circuit Diagram

                                                                                                  Figure 141 Pin connections of 74194 Testing Procedure

                                                                                                  bull Make connections as shown in the circuit diagram bull Observe the output for the input combinations given in the following table

                                                                                                  57

                                                                                                  Logic Design amp Switching Theory 1 Lab Session 14 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                                                  58

                                                                                                  Observations

                                                                                                  S1 S0 SL SR A B C D QA QB QC QD 0 0 0 1 0 0 0 0 0 1 1 0 0 0 0 1 1 0 0 0 0 0 1 0 1 1 0 0 0 0 1 1 0 0 1 1 0 1 0 0 0 1 1 1 0 1 0 1 1 0 1 0 0 1 1 0 1 1 1 0 0 1 1 1 1 1 0 0 1 1 1 1

                                                                                                  ACTIVITY 1 Show connections of 74194 to convert it into a ring counter with right shifting

                                                                                                  Logic Design amp Switching Theory 1 Lab Session 15 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                                                  Lab Session 15

                                                                                                  OBJECT

                                                                                                  Experimenting with 74245 octal bus transceivers using parallel port PC interfacing COMPONENTS AND APPARATUS REQUIRED 1 Parallel Port Connectors (DB-25) with Cable 2 Personal Computer with Windows 98 and TurboC Compiler Installed 3 Following ICs and their Datasheets

                                                                                                  bull 74245 Octal Bus Transceivers with 3-State Outputs 4 Digital Trainer DT-01 or the following components

                                                                                                  Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches

                                                                                                  THEORY

                                                                                                  3-State Logic Sometimes it is necessary to isolate one part of circuit from the other part For this purpose some TTL ICs are designed with 3-state logic Such devices have three possible output states high low and high impedance The device can be put into high impedance state by a control signal applied to an appropriate pin When such a device is in high impedance state there is very high impedance at its output effectively isolating the device from whatever circuitry the output normally drives 74245 Octal Bus Transceivers A bus is any conducting path or set of paths having electrical connections to one or more devices 74245 octal bus transceivers are mainly used to control connectivity between two devices or circuits It also provides direction control for signal flow Function of various pin of this IC is given below

                                                                                                  bull A1 through A8 Bus A bull B1 through B8 Bus B bull G΄ Active low enable input When high sets all the bus pins to high impedance state bull DIR Direction control for signal flow When set to high logic level transfers bus A

                                                                                                  data to B bus When set to low logic level transfers bus B data to A bus bull VCC and GND Supply connections lines Serial and Parallel Port Connectors A Parallel Port can consist of only 25 pin port adapter called a DB-25 and a serial port can consist of either a 25 pin port adapter called a DB-25 or 9 pin adapter called a DB-9 port adapter Whether the port is a 9 pin or 25 pin it can accomplish all of the same tasks that serial port communications have been designed for

                                                                                                  59

                                                                                                  Logic Design amp Switching Theory 1 Lab Session 15 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                                                  60

                                                                                                  Each adapter can be a male type connector with pins or a female type adapter with tiny holes Generally a PRINTER port (called LPT1) on the back of a computer is female type adapter and we need to use MALE DB-25 pin cable on it for PRINTER connection or for parallel LAPLINK cable And a COM port on the back of a computer is male for the serial ports but it may not necessarily be Parallel Port Connector ndash DB-25 The DB-25 connector (named for its B-size D-shaped shell and 25 pins) is practically ubiquitous in the electronics industry The DB-25 connector is used for a variety of purposes Two common applications are RS-232EIA-232 (serial) connections and the parallel printer interface on the IBM PC The DB-25 connector is also used for SCSI connections Normally the parallel port is used for output to a printer or other device It sends data 8-bits or one byte at a time in parallel The other lines available on the DB-25 connector are a combination of status lines control lines and ground lines The status and control lines are used for handshaking commands and feedback when we are talking to a printer

                                                                                                  Figure 152 DB-25 Female Figure 151 DB-25 Male

                                                                                                  Figure 153 Pin Layout for DB-25 As can be seen form figure 153 there are four types of pins in this connector

                                                                                                  bull Data pins (8 pins - D0 to D7) Active high bidirectional lines

                                                                                                  Logic Design amp Switching Theory 1 Lab Session 15 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering bull Control pins (4 pins - C0 to C3) C0 C1 and C3 are active low whereas C2 is active

                                                                                                  high These lines also are bidirectional bull Status pins (5 pins ndash S3 to S7) Only S7 is active low rest are active high input lines bull Ground pins (8 pins) Used as a reference signal for the low (below 05 volts) charge

                                                                                                  Parallel Port Addresses A DB-25 connector at a parallel port has three address one for each kind of pins register data status and control The first or base address generally refers to data register Second address is for status register and the third one is for control register In Windows 98 the base address is usually found to be 278H 378H or 3BCH Now if 378H is the base address then it refers to the data register whereas addresses for status and control register are respectively 379H and 37AH For Windows 98 the base address can be found as follows 1 On your Desktop right-click on My Computer and select Properties 2 Click on the Device Manager tab and find LPT1 under Plug and Play BIOS 3 After selecting LPT1 click the Properties button 4 Next select the Resources tab and the address should then appear next to InputOutput

                                                                                                  Range Accessing parallel port through C Language Programming There are multiple functions in C Language for accessing external ports The most commonly used are listed below

                                                                                                  bull unsigned char inportb(int portid) inportb reads a byte from a hardware port

                                                                                                  bull int inport(int portid) reads a word from a hardware port

                                                                                                  bull void outportb(int portid unsigned char value) outputs a byte to a hardware port

                                                                                                  bull void outport(int portid int value) outputs a word to a hardware port

                                                                                                  portid refers to the port address whereas value refers to the data to be sent TESTING 74245 USING PARALLEL PORT PC INTERFACING At one end the parallel port connector will be connected to the PC via parallel port cable and another connector (to be plugged into the PC parallel port slot) At the other end it will be connected to the buffer IC 74245 Data lines of the connector will be used to transfer 8-bit data between the PC and the buffer Out of the 8-bits of 74245 4-bits will be used to enter data which will be displayed at the monitor through a C language

                                                                                                  61

                                                                                                  Logic Design amp Switching Theory 1 Lab Session 15 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering program The remaining 4-bits will receive data from PC as entered by the user via keyboard

                                                                                                  Circuit Diagram

                                                                                                  Figure 154 Interface of 74245 to PC via Parallel Port

                                                                                                  Procedure

                                                                                                  1 Connect the DB-25 connector to the PC at one end and solder it to the circuit board at the other end

                                                                                                  2 Connect various pins of the connector and 74245 according to the circuit diagram shown in figure 152

                                                                                                  3 Using the functions listed in the previous section write a program in C language to operate various pins of the buffer The user interface of the program should provide option to the user whether to send or receive data from the port

                                                                                                  4 Set DIR switch to 1 5 Try sending some data bits to the port The result should be displayed at the LEDs 6 Set DIR switch to 0 7 Set some binary 4-bit value through the switches Try reading it via parallel port

                                                                                                  C Language Program

                                                                                                  A program to access parallel port for data transfers

                                                                                                  use header file include ltstdiohgt main program void main() define variable

                                                                                                  62

                                                                                                  Logic Design amp Switching Theory 1 Lab Session 15 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering unsigned int data=0 char choice while(1) printing option menu clrscr() printf(This program will send or receive a BCD digit from the parallel portn) printf(nPress your choice numbern) printf(n1 Send Data) printf(n2 Receive Data) printf(n3 Exitn) choice = getch() sending entered digit to the port if(choice == 1) input BCD digit printf(nEnter BCD digit to be sent to the port) data = getche() masking the first four bits data = data amp 0x0f sending to the port outportb(0x378data) printf(nThe BCD digit c has been sent to the port data) printing on screen the data received from the port else if(choice == 2) receiving data from the port data = inportb(0x378) masking the last four bits data = data amp 0xf0 shifting first four bits to make them the last four bits datagtgt=4 printf(nThe BCD digit set at the port is c data) exit else if(choice == 3) break key pressed is not in the menu else printf(nEnter valid choice number) printf(nnPress any key to continue) getch()

                                                                                                  63

                                                                                                  Logic Design amp Switching Theory 1 Lab Session 15 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                                                  ACTIVITY 1 In the above circuit DIR and G΄ inputs are hardwired Connect them to status or

                                                                                                  control pins of the parallel port connector and control their function through your software program Circuit Diagram Program Code ______________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________

                                                                                                  ___________________________________________________________________________________________________________________________________________________

                                                                                                  64

                                                                                                  Logic Design amp Switching Theory 1 Lab Session 15 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                                                  65

                                                                                                  _____________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ _____________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ _______________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ _________________________________________________ _________________________________________________

                                                                                                  Logic Design amp Switching Theory 1 Appendix A NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                                                  Appendix A

                                                                                                  PIN DIAGRAMS OF THE ICS REQUIRED FOR THE LABORATORY SESSIONS Consult the TTLIC data book for internal diagrams and electrical characteristics of these ICs 7400 Quad 2-Input NAND 7402 Quad 2-Input NOR

                                                                                                  7404 Hex Inverter 7408 Quad 2-Input AND

                                                                                                  7410 Triple 3-Input NAND 7411 Triple 3-Input AND

                                                                                                  7421 Dual 4-Input AND 7432 Quad 2-Input OR

                                                                                                  66

                                                                                                  Logic Design amp Switching Theory 1 Appendix A NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                                                  BCD-to-Seven Segm 7448 BCD-to-Seven Segment 7447 ent

                                                                                                  Decoder (15V OC) Decoder (2kΩ pull-up output)

                                                                                                  7473 Dual JK Flip-Flop 7474 Dual D-Type Flip-Flop

                                                                                                  7476 Dual JK Flop-Flop -Bit Binary Full Adder 7483 4 with Fast Carry

                                                                                                  86 Quad 2-Inpu 74138 3-to-8 Line 74 t Exclusive OR Decoder Demultiplexer

                                                                                                  67

                                                                                                  Logic Design amp Switching Theory 1 Appendix A NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                                                  68

                                                                                                  74148 8-to-3 Line 16-to-1 Line Data

                                                                                                  Priority Encoder 74150 Selector Multiplexer

                                                                                                  74245 Oct nsceivers Universal Shift Register (PIPO) (3-State)

                                                                                                  74194 4-Bit Bidirectional al Bus Tra

                                                                                                  Logic Design amp Switching Theory 1 Appendix B NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                                                  Appendix B

                                                                                                  DEBOUNCING CIRCUITRY FOR MECHANICAL SWITCHES Mechanical switches form the interface between human beings and computers or other digital systems For example a keyboard is a matrix of switches used to supply alphanumeric data to a computer Whatever the switch design it is a potential source of problems due to contact bounce The contact bounce creates a sense of narrow pulses when a switch is opened or closed An example of device whose operation would be adversely affected by contact bounce is a digital counter used to count the number of times a switch is depressed Eliminating the effects of contact bounce is called debouncing When data is entered into a computer via a keyboard a software debounce is often used This type of debouncing is a program that causes the computer to sample the switch terminal (ie to input data from it) many times in succession during the interval of time that contact bounce occurs If the data is sensed to be 1s (or 0s) for a specific number of consecutive samples then it is assumed that contact bounce has ended and the last value sensed is valid Hardware debouncing is the use of electronic circuitry to eliminate the effects of contact bounce There are numerous versions of such circuitry including those that use monostable multivibrators (one-shots) but the most straightforward is simply an RS latch Figure B1 shows the circuit When the switch is in position 1 R = 0 and S = 1 so the latch is set and the output (Q) is 1 When the switch is in position 0 R = 1and S = 0 so the latch is reset and the output is 0 When the switch is moved form one position to the other the latch changes state and bouncing occurs at either the R or the S input The bouncing does not affect the latch after it has change state An RS latch will remain set for example when its R input is 0 and its S input is alternately changed form 1 to 0

                                                                                                  Figure B1 Use of RS latch to debounce a mechanical switch

                                                                                                  69

                                                                                                  • 01-ldst-Outer title
                                                                                                    • Practical Workbook
                                                                                                    • Logic Design amp Switching Theory I
                                                                                                      • Dept of Computer amp Information Systems Engineering
                                                                                                        • NED University of Engineering amp Technology
                                                                                                        • Karachi ndash 75270 Pakistan
                                                                                                          • 02-ldst-inner Title
                                                                                                            • Practical Workbook
                                                                                                            • Logic Design amp Switching Theory I
                                                                                                              • Dept of Computer amp Information Systems Engineering
                                                                                                                • NED University of Engineering amp Technology
                                                                                                                • Karachi ndash 75270 Pakistan
                                                                                                                  • 03-ldst-general info
                                                                                                                  • 04-ldst-introduction
                                                                                                                  • 05-Table of Contents
                                                                                                                    • CONTENTS
                                                                                                                      • Lab Session No Object Page No
                                                                                                                      • 1
                                                                                                                      • Also implementing and testing the given circuit on a bread board
                                                                                                                        • Working with Electronics Workbench
                                                                                                                          • Driving a seven segment display using 7447 7448 driver IC
                                                                                                                            • Designing a modulus-5 asynchronous up-counter using JK-FF
                                                                                                                              • Experimenting with 74194 4-bit bidirectional universal shift register
                                                                                                                                  • 13
                                                                                                                                      • 06-ldst-Exp01
                                                                                                                                        • Lab Session 01
                                                                                                                                        • OBJECT
                                                                                                                                          • 1 Bread board
                                                                                                                                          • 2 5 V - power supply
                                                                                                                                          • 3 Multimeter
                                                                                                                                          • 4 Logic probe
                                                                                                                                          • 5 LEDs with resistors
                                                                                                                                          • 6 Connecting wires
                                                                                                                                          • 8 Following ICs and their datasheets
                                                                                                                                            • THEORY
                                                                                                                                              • Logic Gates
                                                                                                                                              • 1 The AND Gate ndash An AND gatersquos output is 1 if and only if all its inputs are 1 If A and B are two inputs to an AND gate then output F of the gate is given as F = AB
                                                                                                                                              • 2 The OR Gate - An OR gatersquos output is 1 if at least one of its input is 1 If A and B are two inputs to an OR gate then output F of the gate is given as F = A+B
                                                                                                                                              • 3 The NOT Gate (Inverter) ndash Its output is 1 when its input is 0 and its output is 0 when the input is 1 ie it complements a digital variable If A is the input to a NOT gate then output F of the gate is given as
                                                                                                                                              • 4 The NAND Gate ndash Its output is 1 if at least one of its input is 0 This gate performs the same logic as an AND gate followed by an inverter If A and B are two inputs to a NAND gate then output F of the gate is given as
                                                                                                                                                • 5 The NOR Gate - The output of a NOR gate is 1 if and only if all its inputs are 0 This gate performs the same logic function as an OR gate followed by an inverter If A and B are two inputs to a NAND gate then output F of the gate is given as
                                                                                                                                                    • DATA SHEETS
                                                                                                                                                      • Logic expression for the given logic diagram __________________________________
                                                                                                                                                          • 07-ldst-exp02
                                                                                                                                                            • Working with Electronics Workbench
                                                                                                                                                              • 08-ldst-exp03
                                                                                                                                                                • Designing Half and Full Adder Circuits
                                                                                                                                                                  • COMPONENTS AND APPARATUS REQUIRED
                                                                                                                                                                    • 1 Following ICs and their Datasheets
                                                                                                                                                                    • 7408 Quad 2-input AND Gate
                                                                                                                                                                    • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                      • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                      • Connecting wires Switches
                                                                                                                                                                        • THEORY
                                                                                                                                                                            • IMPLEMENTATION AND OBSERVATIONS
                                                                                                                                                                              • 09-ldst-Exp04
                                                                                                                                                                                • Lab Session 04
                                                                                                                                                                                • 1 Digital ICs and their Datasheets
                                                                                                                                                                                • 7408 Quad 2-input AND Gate
                                                                                                                                                                                • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                  • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                  • Connecting wires Switches
                                                                                                                                                                                  • PROCEDURE
                                                                                                                                                                                  • REDUCTION OF LOGIC EXPRESSION USING KARNAUGH MAP
                                                                                                                                                                                  • OBSERVATIONS
                                                                                                                                                                                  • RESULT
                                                                                                                                                                                      • 10-ldst-Exp05
                                                                                                                                                                                        • Lab Session 05
                                                                                                                                                                                        • 1 Following ICs and their Datasheets
                                                                                                                                                                                        • 7408 Quad 2-input AND Gate
                                                                                                                                                                                        • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                          • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                          • (100 Ω) Connecting wires Switches
                                                                                                                                                                                          • THEORY
                                                                                                                                                                                            • IMPLEMENTATION AND OBSERVATIONS
                                                                                                                                                                                              • 11-ldst-Exp06
                                                                                                                                                                                                • OBJECT
                                                                                                                                                                                                • 1 Following ICs and their Datasheets
                                                                                                                                                                                                • 7408 Quad 2-input AND Gates or 7411 Triple 3-input AND Gates
                                                                                                                                                                                                • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                  • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                  • Connecting wires Switches
                                                                                                                                                                                                    • Figure 62 Circuit Diagram for 4 x 1 Multiplexer
                                                                                                                                                                                                    • Implementation and Observations
                                                                                                                                                                                                      • Circuit Diagram
                                                                                                                                                                                                        • ACTIVITY
                                                                                                                                                                                                          • 12-ldst-exp07
                                                                                                                                                                                                            • 1 Following ICs and their Datasheets
                                                                                                                                                                                                            • 7408 Quad 2-input or 7411 Triple 3-input AND Gates
                                                                                                                                                                                                            • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                              • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                              • Connecting wires Switches
                                                                                                                                                                                                                • THEORY
                                                                                                                                                                                                                    • Figure 72 Circuit Diagram for 2 x 4 Decoder 1 x 4 Demultiplexer
                                                                                                                                                                                                                    • Implementation and Observations
                                                                                                                                                                                                                      • Circuit Diagram
                                                                                                                                                                                                                        • ACTIVITY
                                                                                                                                                                                                                          • 13-ldst-Exp08
                                                                                                                                                                                                                            • OBJECT
                                                                                                                                                                                                                            • 1 Following ICs and their Datasheets
                                                                                                                                                                                                                            • 7408 Quad 2-input or 7421 Dual 4-input AND Gates
                                                                                                                                                                                                                            • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                              • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                                              • Connecting wires Switches
                                                                                                                                                                                                                                • THEORY
                                                                                                                                                                                                                                    • Figure 81 Circuit Diagram for 4 x 2 Priority Encoder
                                                                                                                                                                                                                                    • Implementation and Observations
                                                                                                                                                                                                                                      • Therefore if GS A2 A1 and A0 are all low then it shows that line 0 is selected and if E0 A2 A1 and A0 are all low then it shows that none of the inputs selected E0 and GS cannot be in the same state provided that E1 is enabled
                                                                                                                                                                                                                                      • Circuit Diagram
                                                                                                                                                                                                                                        • ACTIVITY
                                                                                                                                                                                                                                          • 14-ldst-exp09
                                                                                                                                                                                                                                            • OBJECT
                                                                                                                                                                                                                                            • 1 Following ICs and their Datasheets
                                                                                                                                                                                                                                            • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                                              • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                                                              • Connecting wires Switches
                                                                                                                                                                                                                                                • THEORY
                                                                                                                                                                                                                                                  • Parity Generator
                                                                                                                                                                                                                                                    • Let x y and z be the three bits that constitute the message and are the input to the Odd Parity Generator Circuit Since it is an odd parity system the bit P is generated so as to make the total number of 1s odd (including P) The function P can be expressed as follows
                                                                                                                                                                                                                                                    • Figure 91 Circuit Diagram for a 3-bit Parity Generator
                                                                                                                                                                                                                                                      • C = x Ο y Ο z Ο P
                                                                                                                                                                                                                                                        • Implementation and Observations
                                                                                                                                                                                                                                                          • ACTIVITY
                                                                                                                                                                                                                                                              • 15-ldst-exp10
                                                                                                                                                                                                                                                                • Driving a seven segment display using 7447 7448 driver IC
                                                                                                                                                                                                                                                                • COMPONENTS AND APPARATUS REQUIRED
                                                                                                                                                                                                                                                                • 1 Following ICs and their Datasheets
                                                                                                                                                                                                                                                                • 7447 7448 BCD to Seven Segment Driver
                                                                                                                                                                                                                                                                • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                                                                  • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches
                                                                                                                                                                                                                                                                    • THEORY
                                                                                                                                                                                                                                                                    • Seven Segment Displays
                                                                                                                                                                                                                                                                    • CIRCUIT DIAGRAM
                                                                                                                                                                                                                                                                    • Figure 102 Circuit diagram for 7447driving a common-anode display
                                                                                                                                                                                                                                                                        • IMPLEMENTATION AND OBSERVATIONS
                                                                                                                                                                                                                                                                          • Decimal Digit
                                                                                                                                                                                                                                                                          • BCD Inputs
                                                                                                                                                                                                                                                                          • Seven Segment Outputs
                                                                                                                                                                                                                                                                          • D
                                                                                                                                                                                                                                                                          • C
                                                                                                                                                                                                                                                                          • B
                                                                                                                                                                                                                                                                          • A
                                                                                                                                                                                                                                                                          • a
                                                                                                                                                                                                                                                                          • b
                                                                                                                                                                                                                                                                          • c
                                                                                                                                                                                                                                                                          • d
                                                                                                                                                                                                                                                                          • e
                                                                                                                                                                                                                                                                          • f
                                                                                                                                                                                                                                                                          • g
                                                                                                                                                                                                                                                                          • 0
                                                                                                                                                                                                                                                                          • 0
                                                                                                                                                                                                                                                                          • 0
                                                                                                                                                                                                                                                                          • 0
                                                                                                                                                                                                                                                                          • 0
                                                                                                                                                                                                                                                                          • 1
                                                                                                                                                                                                                                                                          • 0
                                                                                                                                                                                                                                                                          • 0
                                                                                                                                                                                                                                                                          • 0
                                                                                                                                                                                                                                                                          • 1
                                                                                                                                                                                                                                                                          • 2
                                                                                                                                                                                                                                                                          • 0
                                                                                                                                                                                                                                                                          • 0
                                                                                                                                                                                                                                                                          • 1
                                                                                                                                                                                                                                                                          • 0
                                                                                                                                                                                                                                                                          • 3
                                                                                                                                                                                                                                                                          • 0
                                                                                                                                                                                                                                                                          • 0
                                                                                                                                                                                                                                                                          • 1
                                                                                                                                                                                                                                                                          • 1
                                                                                                                                                                                                                                                                          • 4
                                                                                                                                                                                                                                                                          • 0
                                                                                                                                                                                                                                                                          • 1
                                                                                                                                                                                                                                                                          • 0
                                                                                                                                                                                                                                                                          • 0
                                                                                                                                                                                                                                                                          • 5
                                                                                                                                                                                                                                                                          • 0
                                                                                                                                                                                                                                                                          • 1
                                                                                                                                                                                                                                                                          • 0
                                                                                                                                                                                                                                                                          • 1
                                                                                                                                                                                                                                                                          • 6
                                                                                                                                                                                                                                                                          • 0
                                                                                                                                                                                                                                                                          • 1
                                                                                                                                                                                                                                                                          • 1
                                                                                                                                                                                                                                                                          • 0
                                                                                                                                                                                                                                                                          • 7
                                                                                                                                                                                                                                                                          • 0
                                                                                                                                                                                                                                                                          • 1
                                                                                                                                                                                                                                                                          • 1
                                                                                                                                                                                                                                                                          • 1
                                                                                                                                                                                                                                                                          • 8
                                                                                                                                                                                                                                                                          • 1
                                                                                                                                                                                                                                                                          • 0
                                                                                                                                                                                                                                                                          • 0
                                                                                                                                                                                                                                                                          • 0
                                                                                                                                                                                                                                                                          • 9
                                                                                                                                                                                                                                                                          • 1
                                                                                                                                                                                                                                                                          • 0
                                                                                                                                                                                                                                                                          • 0
                                                                                                                                                                                                                                                                          • 1
                                                                                                                                                                                                                                                                            • ACTIVITY
                                                                                                                                                                                                                                                                              • 16-ldst-exp11
                                                                                                                                                                                                                                                                                • Lab Session 11
                                                                                                                                                                                                                                                                                  • OBJECT
                                                                                                                                                                                                                                                                                  • COMPONENTS AND APPARATUS REQUIRED
                                                                                                                                                                                                                                                                                    • 1 Following ICs and their Datasheets
                                                                                                                                                                                                                                                                                    • 7473 7476 JK Flip-Flop
                                                                                                                                                                                                                                                                                    • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                                                                                      • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                                                                                                      • Connecting wires Switches
                                                                                                                                                                                                                                                                                        • THEORY
                                                                                                                                                                                                                                                                                            • Flip-Flop
                                                                                                                                                                                                                                                                                            • JK Flip-Flop
                                                                                                                                                                                                                                                                                              • Circuit Diagram
                                                                                                                                                                                                                                                                                                • Observations
                                                                                                                                                                                                                                                                                                  • ACTIVITY
                                                                                                                                                                                                                                                                                                      • 17-ldst-exp12
                                                                                                                                                                                                                                                                                                        • Lab Session 12
                                                                                                                                                                                                                                                                                                          • OBJECT
                                                                                                                                                                                                                                                                                                          • GIVEN STATE DIAGRAM
                                                                                                                                                                                                                                                                                                          • Figure 121 State Diagram
                                                                                                                                                                                                                                                                                                          • COMPONENTS AND APPARATUS REQUIRED
                                                                                                                                                                                                                                                                                                            • 1 Following ICs and their Datasheets
                                                                                                                                                                                                                                                                                                            • 7474 D Flip-Flop
                                                                                                                                                                                                                                                                                                            • ICs of basic gates (AND OR NOT XOR etc) as required
                                                                                                                                                                                                                                                                                                            • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                                                                                                              • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                                                                                                                              • Connecting wires Switches
                                                                                                                                                                                                                                                                                                                • THEORY
                                                                                                                                                                                                                                                                                                                    • Sequential Circuits
                                                                                                                                                                                                                                                                                                                      • 18-ldst-exp13
                                                                                                                                                                                                                                                                                                                        • Lab Session 13
                                                                                                                                                                                                                                                                                                                          • Designing a modulo-5 asynchronous up-counter using JK-FF
                                                                                                                                                                                                                                                                                                                            • 1 Following ICs and their Datasheets
                                                                                                                                                                                                                                                                                                                            • 7400 Quad 2-input or 7410 Triple 3-input NAND Gates
                                                                                                                                                                                                                                                                                                                            • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                                                                                                                              • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                                                                                                                                              • Connecting wires Switches
                                                                                                                                                                                                                                                                                                                                • THEORY
                                                                                                                                                                                                                                                                                                                                    • Figure 131 A Mod-5 Asynchronous Up Counter
                                                                                                                                                                                                                                                                                                                                    • Implementation and Observations
                                                                                                                                                                                                                                                                                                                                      • ACTIVITY
                                                                                                                                                                                                                                                                                                                                          • 19-ldst-exp14
                                                                                                                                                                                                                                                                                                                                            • Experimenting with 74194 4-bit bidirectional universal shift register
                                                                                                                                                                                                                                                                                                                                            • 1 Following ICs and their Datasheets
                                                                                                                                                                                                                                                                                                                                            • 74194 4-bit bidirectional universal shift register
                                                                                                                                                                                                                                                                                                                                            • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                                                                                                                                              • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                                                                                                                                                              • Connecting wires Switches
                                                                                                                                                                                                                                                                                                                                                • THEORY
                                                                                                                                                                                                                                                                                                                                                  • Shift Registers
                                                                                                                                                                                                                                                                                                                                                  • Bidirectional Shift Registers
                                                                                                                                                                                                                                                                                                                                                  • Universal Shift Registers
                                                                                                                                                                                                                                                                                                                                                    • S1
                                                                                                                                                                                                                                                                                                                                                      • Circuit Diagram
                                                                                                                                                                                                                                                                                                                                                      • ACTIVITY
                                                                                                                                                                                                                                                                                                                                                          • 20-ldst-exp15
                                                                                                                                                                                                                                                                                                                                                            • COMPONENTS AND APPARATUS REQUIRED
                                                                                                                                                                                                                                                                                                                                                            • 1 Parallel Port Connectors (DB-25) with Cable
                                                                                                                                                                                                                                                                                                                                                            • 2 Personal Computer with Windows 98 and TurboC Compiler Installed
                                                                                                                                                                                                                                                                                                                                                            • 3 Following ICs and their Datasheets
                                                                                                                                                                                                                                                                                                                                                            • 74245 Octal Bus Transceivers with 3-State Outputs
                                                                                                                                                                                                                                                                                                                                                            • 4 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                                                                                                                                                              • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                                                                                                                                                                                • Connecting wires Switches
                                                                                                                                                                                                                                                                                                                                                                  • THEORY
                                                                                                                                                                                                                                                                                                                                                                  • 3-State Logic
                                                                                                                                                                                                                                                                                                                                                                    • Serial and Parallel Port Connectors
                                                                                                                                                                                                                                                                                                                                                                    • Parallel Port Connector ndash DB-25
                                                                                                                                                                                                                                                                                                                                                                      • Accessing parallel port through C Language Programming
                                                                                                                                                                                                                                                                                                                                                                          • 21-ldst-appendixA
                                                                                                                                                                                                                                                                                                                                                                          • 22-ldst-appendixB
                                                                                                                                                                                                                                                                                                                                                                            • DEBOUNCING CIRCUITRY FOR MECHANICAL SWITCHES

                                                                                                    Logic Design amp Switching Theory 1 Lab Session 12 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                                                    52

                                                                                                    Input Equations Using Karnaugh map the input equations D0 and D1 for the two flip-flops can be found

                                                                                                    D0 D1 Q0x

                                                                                                    Q1

                                                                                                    _ _ Q0x

                                                                                                    _ Q0x

                                                                                                    Q0x

                                                                                                    _ Q0x

                                                                                                    Q0x

                                                                                                    Q1

                                                                                                    _ _ Q0x

                                                                                                    _ Q0x

                                                                                                    Q0x

                                                                                                    _ Q0x

                                                                                                    _ Q1

                                                                                                    _ Q1

                                                                                                    Q1

                                                                                                    Q1

                                                                                                    D0 = _________________ D1 = _________________

                                                                                                    State Equations Using the characteristic equation of D flip-flop we can find the state equations Q0(t+1) and Q1(t+1) for the to flip flops Q0(t+1) = _______________________ Q1(t+1) = _______________________ _______________________ _______________________ _______________________ _______________________ Circuit Diagram

                                                                                                    Logic Design amp Switching Theory 1 Lab Session 12 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                                                    53

                                                                                                    Implementation Procedure and Observations

                                                                                                    1 Implement the circuit using digital ICs on a bread board (prepare the pin diagram (use appendix A) and refer to laboratory session 01 for procedure)

                                                                                                    2 Make the clear inputs of the flip-flops low (to clear the flip-flops) The flip-flops will remain in clear state as long as the clear inputs are connected to low level

                                                                                                    3 Connect output Q0 and the clock pulse to an oscilloscope 4 Apply 0 to the input x 5 Now make the clear inputs to high 6 Observe the waveform for the first 5 clock pulses and record it 7 Repeat steps 2 to 6 keeping x=1 in step 4 this time 8 Repeat steps 2 to 7 this time connecting Q1 instead of Q0 to the oscilloscope in step

                                                                                                    3 Record your observations (Keep frequency of the clock pulse low (eg1Hz) so that the output waveforms can be observed easily)

                                                                                                    1 2 3 4 5 Clock Pulse

                                                                                                    Output Waveform for Q0 when x=0

                                                                                                    Output Waveform for Q0 when x=1

                                                                                                    Output Waveform for Q1 when x=0

                                                                                                    Output Waveform for Q1 when x=1

                                                                                                    Logic Design amp Switching Theory 1 Lab Session 13 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                                                    Lab Session 13 OBJECT

                                                                                                    Designing a modulo-5 asynchronous up-counter using JK-FF COMPONENTS AND APPARATUS REQUIRED

                                                                                                    1 Following ICs and their Datasheets

                                                                                                    bull 7400 Quad 2-input or 7410 Triple 3-input NAND Gates bull 7476 7473 JK Flip-Flop

                                                                                                    2 Digital Trainer DT-01 or the following components Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches

                                                                                                    THEORY

                                                                                                    Digital Counters A digital counter is a set of flip-flops whose states change in response to pulses applied at the input to the counter The flip-flops are interconnected so that their combined state at any time is the binary equivalent of the total number of pulses that have occurred up to that time Every counter resets after a certain number of clock pulses Thus as it name implies a counter is used to count pulses An n stage counter can count up to a maximum of 2n states n is equal to the number of flip-flops required for the construction of counter

                                                                                                    Modulus Counters The number of input pulses that causes a counter to reset to its initial count is called the modulus of the counter Thus the modulus equals to total number of distinct states (counts) including zero that a counter can store A binary counter with n stages is a modulo-2n (or mod-2n) counter The largest count a mod-N counter can achieve is N-1 ie a mod-N counter never reaches the binary number equal to its modulus N is always equal to or less than 2n Counters can be classified as bull Synchronous Counters which are clock driven All the flip-flops are driven by a

                                                                                                    single clock bull Asynchronous Counters which are event driven Clock input is given to the first

                                                                                                    flip-flop only Rest of the flip-flops are driven by their preceding flip-flops

                                                                                                    DESIGN OF A MOD-5 ASYNCHRONOUS UP COUNTER The number of flip-flops required to construct a mod-5 counter is 3 because 5 should be less than or equal to 2n This counter will count from 0 to 4 a total of 5 distinct states Since a 3-stage counter can count up to 8 states at maximum a NAND gate is used to reset it after 5 clock pulses Figure 131 shows the logic diagram

                                                                                                    54

                                                                                                    Logic Design amp Switching Theory 1 Lab Session 13 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                                                    55

                                                                                                    Figure 131 A Mod-5 Asynchronous Up Counter

                                                                                                    Implementation and Observations

                                                                                                    Implement the mod-5 counter circuit (figure 131) on a bread board (prepare the pin diagram (use appendix A) and refer to laboratory session 01 for implementation procedure) and record the observations in the following table

                                                                                                    Clock Pulse Q2 Q1 Q0

                                                                                                    0 1 2 3 4 5 6 7

                                                                                                    ACTIVITY

                                                                                                    Draw the timing diagram for mod-5 counter designed in this laboratory session

                                                                                                    Logic Design amp Switching Theory 1 Lab Session 14 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                                                    Lab Session 14 OBJECT

                                                                                                    Experimenting with 74194 4-bit bidirectional universal shift register COMPONENTS AND APPARATUS REQUIRED

                                                                                                    1 Following ICs and their Datasheets

                                                                                                    bull 74194 4-bit bidirectional universal shift register 2 Digital Trainer DT-01 or the following components

                                                                                                    Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches

                                                                                                    THEORY

                                                                                                    Shift Registers

                                                                                                    A Register is a set of flip-flops used to store binary data A register which is capable of shifting its binary information either to the right or left is called a shift register The logical configuration of a register consists of a chain of flip-flops connected in cascade with the output of one flip-flop connected to the input of next flip-flop All flip-flops receive a common clock pulse which causes the shift from one stage to the next

                                                                                                    Bidirectional Shift Registers A bi-directional shift register is one whose bits can be shifted from left to right or from right to left

                                                                                                    Universal Shift Registers A universal shift register is a bi-directional register whose input can be in either serial or parallel form and whose output can be in either serial or parallel form

                                                                                                    74194 4-BIT BIDIRECTIONAL UNIVERSAL SHIFT REGISTER

                                                                                                    The 74194 register provides parallel as well as serial loading in both directions Function of various pins of this IC is described below

                                                                                                    bull A B C and D Active high inputs for parallel loading bull QA QB QC and QD Active high outputs bull S0 and S1 Active high mode control inputs The following table shows combinations

                                                                                                    of S1 and S0 to enable various modes

                                                                                                    S1 S0 Clock Action 0 0 x No change 0 1 uarr Shift right 1 0 uarr Shift left 1 1 uarr Parallel load

                                                                                                    uarr shows the rising edge of the clock pulse

                                                                                                    56

                                                                                                    Logic Design amp Switching Theory 1 Lab Session 14 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering bull SR Active high serial input for right shifting bull SL Active high serial input for left shifting bull CLR Active low input Clears all the flip-flops of the register if set to 0 should be

                                                                                                    kept high otherwise bull CLK Clock input bull VCC and GND Supply connections lines Thus A B C and D are inputs for parallel loading whereas SR and SL are inputs for serial loading with right or left shifting respectively S1 and S0 are used to select the loading mode Circuit Diagram

                                                                                                    Figure 141 Pin connections of 74194 Testing Procedure

                                                                                                    bull Make connections as shown in the circuit diagram bull Observe the output for the input combinations given in the following table

                                                                                                    57

                                                                                                    Logic Design amp Switching Theory 1 Lab Session 14 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                                                    58

                                                                                                    Observations

                                                                                                    S1 S0 SL SR A B C D QA QB QC QD 0 0 0 1 0 0 0 0 0 1 1 0 0 0 0 1 1 0 0 0 0 0 1 0 1 1 0 0 0 0 1 1 0 0 1 1 0 1 0 0 0 1 1 1 0 1 0 1 1 0 1 0 0 1 1 0 1 1 1 0 0 1 1 1 1 1 0 0 1 1 1 1

                                                                                                    ACTIVITY 1 Show connections of 74194 to convert it into a ring counter with right shifting

                                                                                                    Logic Design amp Switching Theory 1 Lab Session 15 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                                                    Lab Session 15

                                                                                                    OBJECT

                                                                                                    Experimenting with 74245 octal bus transceivers using parallel port PC interfacing COMPONENTS AND APPARATUS REQUIRED 1 Parallel Port Connectors (DB-25) with Cable 2 Personal Computer with Windows 98 and TurboC Compiler Installed 3 Following ICs and their Datasheets

                                                                                                    bull 74245 Octal Bus Transceivers with 3-State Outputs 4 Digital Trainer DT-01 or the following components

                                                                                                    Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches

                                                                                                    THEORY

                                                                                                    3-State Logic Sometimes it is necessary to isolate one part of circuit from the other part For this purpose some TTL ICs are designed with 3-state logic Such devices have three possible output states high low and high impedance The device can be put into high impedance state by a control signal applied to an appropriate pin When such a device is in high impedance state there is very high impedance at its output effectively isolating the device from whatever circuitry the output normally drives 74245 Octal Bus Transceivers A bus is any conducting path or set of paths having electrical connections to one or more devices 74245 octal bus transceivers are mainly used to control connectivity between two devices or circuits It also provides direction control for signal flow Function of various pin of this IC is given below

                                                                                                    bull A1 through A8 Bus A bull B1 through B8 Bus B bull G΄ Active low enable input When high sets all the bus pins to high impedance state bull DIR Direction control for signal flow When set to high logic level transfers bus A

                                                                                                    data to B bus When set to low logic level transfers bus B data to A bus bull VCC and GND Supply connections lines Serial and Parallel Port Connectors A Parallel Port can consist of only 25 pin port adapter called a DB-25 and a serial port can consist of either a 25 pin port adapter called a DB-25 or 9 pin adapter called a DB-9 port adapter Whether the port is a 9 pin or 25 pin it can accomplish all of the same tasks that serial port communications have been designed for

                                                                                                    59

                                                                                                    Logic Design amp Switching Theory 1 Lab Session 15 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                                                    60

                                                                                                    Each adapter can be a male type connector with pins or a female type adapter with tiny holes Generally a PRINTER port (called LPT1) on the back of a computer is female type adapter and we need to use MALE DB-25 pin cable on it for PRINTER connection or for parallel LAPLINK cable And a COM port on the back of a computer is male for the serial ports but it may not necessarily be Parallel Port Connector ndash DB-25 The DB-25 connector (named for its B-size D-shaped shell and 25 pins) is practically ubiquitous in the electronics industry The DB-25 connector is used for a variety of purposes Two common applications are RS-232EIA-232 (serial) connections and the parallel printer interface on the IBM PC The DB-25 connector is also used for SCSI connections Normally the parallel port is used for output to a printer or other device It sends data 8-bits or one byte at a time in parallel The other lines available on the DB-25 connector are a combination of status lines control lines and ground lines The status and control lines are used for handshaking commands and feedback when we are talking to a printer

                                                                                                    Figure 152 DB-25 Female Figure 151 DB-25 Male

                                                                                                    Figure 153 Pin Layout for DB-25 As can be seen form figure 153 there are four types of pins in this connector

                                                                                                    bull Data pins (8 pins - D0 to D7) Active high bidirectional lines

                                                                                                    Logic Design amp Switching Theory 1 Lab Session 15 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering bull Control pins (4 pins - C0 to C3) C0 C1 and C3 are active low whereas C2 is active

                                                                                                    high These lines also are bidirectional bull Status pins (5 pins ndash S3 to S7) Only S7 is active low rest are active high input lines bull Ground pins (8 pins) Used as a reference signal for the low (below 05 volts) charge

                                                                                                    Parallel Port Addresses A DB-25 connector at a parallel port has three address one for each kind of pins register data status and control The first or base address generally refers to data register Second address is for status register and the third one is for control register In Windows 98 the base address is usually found to be 278H 378H or 3BCH Now if 378H is the base address then it refers to the data register whereas addresses for status and control register are respectively 379H and 37AH For Windows 98 the base address can be found as follows 1 On your Desktop right-click on My Computer and select Properties 2 Click on the Device Manager tab and find LPT1 under Plug and Play BIOS 3 After selecting LPT1 click the Properties button 4 Next select the Resources tab and the address should then appear next to InputOutput

                                                                                                    Range Accessing parallel port through C Language Programming There are multiple functions in C Language for accessing external ports The most commonly used are listed below

                                                                                                    bull unsigned char inportb(int portid) inportb reads a byte from a hardware port

                                                                                                    bull int inport(int portid) reads a word from a hardware port

                                                                                                    bull void outportb(int portid unsigned char value) outputs a byte to a hardware port

                                                                                                    bull void outport(int portid int value) outputs a word to a hardware port

                                                                                                    portid refers to the port address whereas value refers to the data to be sent TESTING 74245 USING PARALLEL PORT PC INTERFACING At one end the parallel port connector will be connected to the PC via parallel port cable and another connector (to be plugged into the PC parallel port slot) At the other end it will be connected to the buffer IC 74245 Data lines of the connector will be used to transfer 8-bit data between the PC and the buffer Out of the 8-bits of 74245 4-bits will be used to enter data which will be displayed at the monitor through a C language

                                                                                                    61

                                                                                                    Logic Design amp Switching Theory 1 Lab Session 15 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering program The remaining 4-bits will receive data from PC as entered by the user via keyboard

                                                                                                    Circuit Diagram

                                                                                                    Figure 154 Interface of 74245 to PC via Parallel Port

                                                                                                    Procedure

                                                                                                    1 Connect the DB-25 connector to the PC at one end and solder it to the circuit board at the other end

                                                                                                    2 Connect various pins of the connector and 74245 according to the circuit diagram shown in figure 152

                                                                                                    3 Using the functions listed in the previous section write a program in C language to operate various pins of the buffer The user interface of the program should provide option to the user whether to send or receive data from the port

                                                                                                    4 Set DIR switch to 1 5 Try sending some data bits to the port The result should be displayed at the LEDs 6 Set DIR switch to 0 7 Set some binary 4-bit value through the switches Try reading it via parallel port

                                                                                                    C Language Program

                                                                                                    A program to access parallel port for data transfers

                                                                                                    use header file include ltstdiohgt main program void main() define variable

                                                                                                    62

                                                                                                    Logic Design amp Switching Theory 1 Lab Session 15 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering unsigned int data=0 char choice while(1) printing option menu clrscr() printf(This program will send or receive a BCD digit from the parallel portn) printf(nPress your choice numbern) printf(n1 Send Data) printf(n2 Receive Data) printf(n3 Exitn) choice = getch() sending entered digit to the port if(choice == 1) input BCD digit printf(nEnter BCD digit to be sent to the port) data = getche() masking the first four bits data = data amp 0x0f sending to the port outportb(0x378data) printf(nThe BCD digit c has been sent to the port data) printing on screen the data received from the port else if(choice == 2) receiving data from the port data = inportb(0x378) masking the last four bits data = data amp 0xf0 shifting first four bits to make them the last four bits datagtgt=4 printf(nThe BCD digit set at the port is c data) exit else if(choice == 3) break key pressed is not in the menu else printf(nEnter valid choice number) printf(nnPress any key to continue) getch()

                                                                                                    63

                                                                                                    Logic Design amp Switching Theory 1 Lab Session 15 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                                                    ACTIVITY 1 In the above circuit DIR and G΄ inputs are hardwired Connect them to status or

                                                                                                    control pins of the parallel port connector and control their function through your software program Circuit Diagram Program Code ______________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________

                                                                                                    ___________________________________________________________________________________________________________________________________________________

                                                                                                    64

                                                                                                    Logic Design amp Switching Theory 1 Lab Session 15 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                                                    65

                                                                                                    _____________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ _____________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ _______________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ _________________________________________________ _________________________________________________

                                                                                                    Logic Design amp Switching Theory 1 Appendix A NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                                                    Appendix A

                                                                                                    PIN DIAGRAMS OF THE ICS REQUIRED FOR THE LABORATORY SESSIONS Consult the TTLIC data book for internal diagrams and electrical characteristics of these ICs 7400 Quad 2-Input NAND 7402 Quad 2-Input NOR

                                                                                                    7404 Hex Inverter 7408 Quad 2-Input AND

                                                                                                    7410 Triple 3-Input NAND 7411 Triple 3-Input AND

                                                                                                    7421 Dual 4-Input AND 7432 Quad 2-Input OR

                                                                                                    66

                                                                                                    Logic Design amp Switching Theory 1 Appendix A NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                                                    BCD-to-Seven Segm 7448 BCD-to-Seven Segment 7447 ent

                                                                                                    Decoder (15V OC) Decoder (2kΩ pull-up output)

                                                                                                    7473 Dual JK Flip-Flop 7474 Dual D-Type Flip-Flop

                                                                                                    7476 Dual JK Flop-Flop -Bit Binary Full Adder 7483 4 with Fast Carry

                                                                                                    86 Quad 2-Inpu 74138 3-to-8 Line 74 t Exclusive OR Decoder Demultiplexer

                                                                                                    67

                                                                                                    Logic Design amp Switching Theory 1 Appendix A NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                                                    68

                                                                                                    74148 8-to-3 Line 16-to-1 Line Data

                                                                                                    Priority Encoder 74150 Selector Multiplexer

                                                                                                    74245 Oct nsceivers Universal Shift Register (PIPO) (3-State)

                                                                                                    74194 4-Bit Bidirectional al Bus Tra

                                                                                                    Logic Design amp Switching Theory 1 Appendix B NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                                                    Appendix B

                                                                                                    DEBOUNCING CIRCUITRY FOR MECHANICAL SWITCHES Mechanical switches form the interface between human beings and computers or other digital systems For example a keyboard is a matrix of switches used to supply alphanumeric data to a computer Whatever the switch design it is a potential source of problems due to contact bounce The contact bounce creates a sense of narrow pulses when a switch is opened or closed An example of device whose operation would be adversely affected by contact bounce is a digital counter used to count the number of times a switch is depressed Eliminating the effects of contact bounce is called debouncing When data is entered into a computer via a keyboard a software debounce is often used This type of debouncing is a program that causes the computer to sample the switch terminal (ie to input data from it) many times in succession during the interval of time that contact bounce occurs If the data is sensed to be 1s (or 0s) for a specific number of consecutive samples then it is assumed that contact bounce has ended and the last value sensed is valid Hardware debouncing is the use of electronic circuitry to eliminate the effects of contact bounce There are numerous versions of such circuitry including those that use monostable multivibrators (one-shots) but the most straightforward is simply an RS latch Figure B1 shows the circuit When the switch is in position 1 R = 0 and S = 1 so the latch is set and the output (Q) is 1 When the switch is in position 0 R = 1and S = 0 so the latch is reset and the output is 0 When the switch is moved form one position to the other the latch changes state and bouncing occurs at either the R or the S input The bouncing does not affect the latch after it has change state An RS latch will remain set for example when its R input is 0 and its S input is alternately changed form 1 to 0

                                                                                                    Figure B1 Use of RS latch to debounce a mechanical switch

                                                                                                    69

                                                                                                    • 01-ldst-Outer title
                                                                                                      • Practical Workbook
                                                                                                      • Logic Design amp Switching Theory I
                                                                                                        • Dept of Computer amp Information Systems Engineering
                                                                                                          • NED University of Engineering amp Technology
                                                                                                          • Karachi ndash 75270 Pakistan
                                                                                                            • 02-ldst-inner Title
                                                                                                              • Practical Workbook
                                                                                                              • Logic Design amp Switching Theory I
                                                                                                                • Dept of Computer amp Information Systems Engineering
                                                                                                                  • NED University of Engineering amp Technology
                                                                                                                  • Karachi ndash 75270 Pakistan
                                                                                                                    • 03-ldst-general info
                                                                                                                    • 04-ldst-introduction
                                                                                                                    • 05-Table of Contents
                                                                                                                      • CONTENTS
                                                                                                                        • Lab Session No Object Page No
                                                                                                                        • 1
                                                                                                                        • Also implementing and testing the given circuit on a bread board
                                                                                                                          • Working with Electronics Workbench
                                                                                                                            • Driving a seven segment display using 7447 7448 driver IC
                                                                                                                              • Designing a modulus-5 asynchronous up-counter using JK-FF
                                                                                                                                • Experimenting with 74194 4-bit bidirectional universal shift register
                                                                                                                                    • 13
                                                                                                                                        • 06-ldst-Exp01
                                                                                                                                          • Lab Session 01
                                                                                                                                          • OBJECT
                                                                                                                                            • 1 Bread board
                                                                                                                                            • 2 5 V - power supply
                                                                                                                                            • 3 Multimeter
                                                                                                                                            • 4 Logic probe
                                                                                                                                            • 5 LEDs with resistors
                                                                                                                                            • 6 Connecting wires
                                                                                                                                            • 8 Following ICs and their datasheets
                                                                                                                                              • THEORY
                                                                                                                                                • Logic Gates
                                                                                                                                                • 1 The AND Gate ndash An AND gatersquos output is 1 if and only if all its inputs are 1 If A and B are two inputs to an AND gate then output F of the gate is given as F = AB
                                                                                                                                                • 2 The OR Gate - An OR gatersquos output is 1 if at least one of its input is 1 If A and B are two inputs to an OR gate then output F of the gate is given as F = A+B
                                                                                                                                                • 3 The NOT Gate (Inverter) ndash Its output is 1 when its input is 0 and its output is 0 when the input is 1 ie it complements a digital variable If A is the input to a NOT gate then output F of the gate is given as
                                                                                                                                                • 4 The NAND Gate ndash Its output is 1 if at least one of its input is 0 This gate performs the same logic as an AND gate followed by an inverter If A and B are two inputs to a NAND gate then output F of the gate is given as
                                                                                                                                                  • 5 The NOR Gate - The output of a NOR gate is 1 if and only if all its inputs are 0 This gate performs the same logic function as an OR gate followed by an inverter If A and B are two inputs to a NAND gate then output F of the gate is given as
                                                                                                                                                      • DATA SHEETS
                                                                                                                                                        • Logic expression for the given logic diagram __________________________________
                                                                                                                                                            • 07-ldst-exp02
                                                                                                                                                              • Working with Electronics Workbench
                                                                                                                                                                • 08-ldst-exp03
                                                                                                                                                                  • Designing Half and Full Adder Circuits
                                                                                                                                                                    • COMPONENTS AND APPARATUS REQUIRED
                                                                                                                                                                      • 1 Following ICs and their Datasheets
                                                                                                                                                                      • 7408 Quad 2-input AND Gate
                                                                                                                                                                      • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                        • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                        • Connecting wires Switches
                                                                                                                                                                          • THEORY
                                                                                                                                                                              • IMPLEMENTATION AND OBSERVATIONS
                                                                                                                                                                                • 09-ldst-Exp04
                                                                                                                                                                                  • Lab Session 04
                                                                                                                                                                                  • 1 Digital ICs and their Datasheets
                                                                                                                                                                                  • 7408 Quad 2-input AND Gate
                                                                                                                                                                                  • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                    • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                    • Connecting wires Switches
                                                                                                                                                                                    • PROCEDURE
                                                                                                                                                                                    • REDUCTION OF LOGIC EXPRESSION USING KARNAUGH MAP
                                                                                                                                                                                    • OBSERVATIONS
                                                                                                                                                                                    • RESULT
                                                                                                                                                                                        • 10-ldst-Exp05
                                                                                                                                                                                          • Lab Session 05
                                                                                                                                                                                          • 1 Following ICs and their Datasheets
                                                                                                                                                                                          • 7408 Quad 2-input AND Gate
                                                                                                                                                                                          • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                            • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                            • (100 Ω) Connecting wires Switches
                                                                                                                                                                                            • THEORY
                                                                                                                                                                                              • IMPLEMENTATION AND OBSERVATIONS
                                                                                                                                                                                                • 11-ldst-Exp06
                                                                                                                                                                                                  • OBJECT
                                                                                                                                                                                                  • 1 Following ICs and their Datasheets
                                                                                                                                                                                                  • 7408 Quad 2-input AND Gates or 7411 Triple 3-input AND Gates
                                                                                                                                                                                                  • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                    • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                    • Connecting wires Switches
                                                                                                                                                                                                      • Figure 62 Circuit Diagram for 4 x 1 Multiplexer
                                                                                                                                                                                                      • Implementation and Observations
                                                                                                                                                                                                        • Circuit Diagram
                                                                                                                                                                                                          • ACTIVITY
                                                                                                                                                                                                            • 12-ldst-exp07
                                                                                                                                                                                                              • 1 Following ICs and their Datasheets
                                                                                                                                                                                                              • 7408 Quad 2-input or 7411 Triple 3-input AND Gates
                                                                                                                                                                                                              • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                                • Connecting wires Switches
                                                                                                                                                                                                                  • THEORY
                                                                                                                                                                                                                      • Figure 72 Circuit Diagram for 2 x 4 Decoder 1 x 4 Demultiplexer
                                                                                                                                                                                                                      • Implementation and Observations
                                                                                                                                                                                                                        • Circuit Diagram
                                                                                                                                                                                                                          • ACTIVITY
                                                                                                                                                                                                                            • 13-ldst-Exp08
                                                                                                                                                                                                                              • OBJECT
                                                                                                                                                                                                                              • 1 Following ICs and their Datasheets
                                                                                                                                                                                                                              • 7408 Quad 2-input or 7421 Dual 4-input AND Gates
                                                                                                                                                                                                                              • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                                • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                                                • Connecting wires Switches
                                                                                                                                                                                                                                  • THEORY
                                                                                                                                                                                                                                      • Figure 81 Circuit Diagram for 4 x 2 Priority Encoder
                                                                                                                                                                                                                                      • Implementation and Observations
                                                                                                                                                                                                                                        • Therefore if GS A2 A1 and A0 are all low then it shows that line 0 is selected and if E0 A2 A1 and A0 are all low then it shows that none of the inputs selected E0 and GS cannot be in the same state provided that E1 is enabled
                                                                                                                                                                                                                                        • Circuit Diagram
                                                                                                                                                                                                                                          • ACTIVITY
                                                                                                                                                                                                                                            • 14-ldst-exp09
                                                                                                                                                                                                                                              • OBJECT
                                                                                                                                                                                                                                              • 1 Following ICs and their Datasheets
                                                                                                                                                                                                                                              • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                                                • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                                                                • Connecting wires Switches
                                                                                                                                                                                                                                                  • THEORY
                                                                                                                                                                                                                                                    • Parity Generator
                                                                                                                                                                                                                                                      • Let x y and z be the three bits that constitute the message and are the input to the Odd Parity Generator Circuit Since it is an odd parity system the bit P is generated so as to make the total number of 1s odd (including P) The function P can be expressed as follows
                                                                                                                                                                                                                                                      • Figure 91 Circuit Diagram for a 3-bit Parity Generator
                                                                                                                                                                                                                                                        • C = x Ο y Ο z Ο P
                                                                                                                                                                                                                                                          • Implementation and Observations
                                                                                                                                                                                                                                                            • ACTIVITY
                                                                                                                                                                                                                                                                • 15-ldst-exp10
                                                                                                                                                                                                                                                                  • Driving a seven segment display using 7447 7448 driver IC
                                                                                                                                                                                                                                                                  • COMPONENTS AND APPARATUS REQUIRED
                                                                                                                                                                                                                                                                  • 1 Following ICs and their Datasheets
                                                                                                                                                                                                                                                                  • 7447 7448 BCD to Seven Segment Driver
                                                                                                                                                                                                                                                                  • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                                                                    • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches
                                                                                                                                                                                                                                                                      • THEORY
                                                                                                                                                                                                                                                                      • Seven Segment Displays
                                                                                                                                                                                                                                                                      • CIRCUIT DIAGRAM
                                                                                                                                                                                                                                                                      • Figure 102 Circuit diagram for 7447driving a common-anode display
                                                                                                                                                                                                                                                                          • IMPLEMENTATION AND OBSERVATIONS
                                                                                                                                                                                                                                                                            • Decimal Digit
                                                                                                                                                                                                                                                                            • BCD Inputs
                                                                                                                                                                                                                                                                            • Seven Segment Outputs
                                                                                                                                                                                                                                                                            • D
                                                                                                                                                                                                                                                                            • C
                                                                                                                                                                                                                                                                            • B
                                                                                                                                                                                                                                                                            • A
                                                                                                                                                                                                                                                                            • a
                                                                                                                                                                                                                                                                            • b
                                                                                                                                                                                                                                                                            • c
                                                                                                                                                                                                                                                                            • d
                                                                                                                                                                                                                                                                            • e
                                                                                                                                                                                                                                                                            • f
                                                                                                                                                                                                                                                                            • g
                                                                                                                                                                                                                                                                            • 0
                                                                                                                                                                                                                                                                            • 0
                                                                                                                                                                                                                                                                            • 0
                                                                                                                                                                                                                                                                            • 0
                                                                                                                                                                                                                                                                            • 0
                                                                                                                                                                                                                                                                            • 1
                                                                                                                                                                                                                                                                            • 0
                                                                                                                                                                                                                                                                            • 0
                                                                                                                                                                                                                                                                            • 0
                                                                                                                                                                                                                                                                            • 1
                                                                                                                                                                                                                                                                            • 2
                                                                                                                                                                                                                                                                            • 0
                                                                                                                                                                                                                                                                            • 0
                                                                                                                                                                                                                                                                            • 1
                                                                                                                                                                                                                                                                            • 0
                                                                                                                                                                                                                                                                            • 3
                                                                                                                                                                                                                                                                            • 0
                                                                                                                                                                                                                                                                            • 0
                                                                                                                                                                                                                                                                            • 1
                                                                                                                                                                                                                                                                            • 1
                                                                                                                                                                                                                                                                            • 4
                                                                                                                                                                                                                                                                            • 0
                                                                                                                                                                                                                                                                            • 1
                                                                                                                                                                                                                                                                            • 0
                                                                                                                                                                                                                                                                            • 0
                                                                                                                                                                                                                                                                            • 5
                                                                                                                                                                                                                                                                            • 0
                                                                                                                                                                                                                                                                            • 1
                                                                                                                                                                                                                                                                            • 0
                                                                                                                                                                                                                                                                            • 1
                                                                                                                                                                                                                                                                            • 6
                                                                                                                                                                                                                                                                            • 0
                                                                                                                                                                                                                                                                            • 1
                                                                                                                                                                                                                                                                            • 1
                                                                                                                                                                                                                                                                            • 0
                                                                                                                                                                                                                                                                            • 7
                                                                                                                                                                                                                                                                            • 0
                                                                                                                                                                                                                                                                            • 1
                                                                                                                                                                                                                                                                            • 1
                                                                                                                                                                                                                                                                            • 1
                                                                                                                                                                                                                                                                            • 8
                                                                                                                                                                                                                                                                            • 1
                                                                                                                                                                                                                                                                            • 0
                                                                                                                                                                                                                                                                            • 0
                                                                                                                                                                                                                                                                            • 0
                                                                                                                                                                                                                                                                            • 9
                                                                                                                                                                                                                                                                            • 1
                                                                                                                                                                                                                                                                            • 0
                                                                                                                                                                                                                                                                            • 0
                                                                                                                                                                                                                                                                            • 1
                                                                                                                                                                                                                                                                              • ACTIVITY
                                                                                                                                                                                                                                                                                • 16-ldst-exp11
                                                                                                                                                                                                                                                                                  • Lab Session 11
                                                                                                                                                                                                                                                                                    • OBJECT
                                                                                                                                                                                                                                                                                    • COMPONENTS AND APPARATUS REQUIRED
                                                                                                                                                                                                                                                                                      • 1 Following ICs and their Datasheets
                                                                                                                                                                                                                                                                                      • 7473 7476 JK Flip-Flop
                                                                                                                                                                                                                                                                                      • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                                                                                        • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                                                                                                        • Connecting wires Switches
                                                                                                                                                                                                                                                                                          • THEORY
                                                                                                                                                                                                                                                                                              • Flip-Flop
                                                                                                                                                                                                                                                                                              • JK Flip-Flop
                                                                                                                                                                                                                                                                                                • Circuit Diagram
                                                                                                                                                                                                                                                                                                  • Observations
                                                                                                                                                                                                                                                                                                    • ACTIVITY
                                                                                                                                                                                                                                                                                                        • 17-ldst-exp12
                                                                                                                                                                                                                                                                                                          • Lab Session 12
                                                                                                                                                                                                                                                                                                            • OBJECT
                                                                                                                                                                                                                                                                                                            • GIVEN STATE DIAGRAM
                                                                                                                                                                                                                                                                                                            • Figure 121 State Diagram
                                                                                                                                                                                                                                                                                                            • COMPONENTS AND APPARATUS REQUIRED
                                                                                                                                                                                                                                                                                                              • 1 Following ICs and their Datasheets
                                                                                                                                                                                                                                                                                                              • 7474 D Flip-Flop
                                                                                                                                                                                                                                                                                                              • ICs of basic gates (AND OR NOT XOR etc) as required
                                                                                                                                                                                                                                                                                                              • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                                                                                                                • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                                                                                                                                • Connecting wires Switches
                                                                                                                                                                                                                                                                                                                  • THEORY
                                                                                                                                                                                                                                                                                                                      • Sequential Circuits
                                                                                                                                                                                                                                                                                                                        • 18-ldst-exp13
                                                                                                                                                                                                                                                                                                                          • Lab Session 13
                                                                                                                                                                                                                                                                                                                            • Designing a modulo-5 asynchronous up-counter using JK-FF
                                                                                                                                                                                                                                                                                                                              • 1 Following ICs and their Datasheets
                                                                                                                                                                                                                                                                                                                              • 7400 Quad 2-input or 7410 Triple 3-input NAND Gates
                                                                                                                                                                                                                                                                                                                              • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                                                                                                                                • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                                                                                                                                                • Connecting wires Switches
                                                                                                                                                                                                                                                                                                                                  • THEORY
                                                                                                                                                                                                                                                                                                                                      • Figure 131 A Mod-5 Asynchronous Up Counter
                                                                                                                                                                                                                                                                                                                                      • Implementation and Observations
                                                                                                                                                                                                                                                                                                                                        • ACTIVITY
                                                                                                                                                                                                                                                                                                                                            • 19-ldst-exp14
                                                                                                                                                                                                                                                                                                                                              • Experimenting with 74194 4-bit bidirectional universal shift register
                                                                                                                                                                                                                                                                                                                                              • 1 Following ICs and their Datasheets
                                                                                                                                                                                                                                                                                                                                              • 74194 4-bit bidirectional universal shift register
                                                                                                                                                                                                                                                                                                                                              • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                                                                                                                                                • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                                                                                                                                                                • Connecting wires Switches
                                                                                                                                                                                                                                                                                                                                                  • THEORY
                                                                                                                                                                                                                                                                                                                                                    • Shift Registers
                                                                                                                                                                                                                                                                                                                                                    • Bidirectional Shift Registers
                                                                                                                                                                                                                                                                                                                                                    • Universal Shift Registers
                                                                                                                                                                                                                                                                                                                                                      • S1
                                                                                                                                                                                                                                                                                                                                                        • Circuit Diagram
                                                                                                                                                                                                                                                                                                                                                        • ACTIVITY
                                                                                                                                                                                                                                                                                                                                                            • 20-ldst-exp15
                                                                                                                                                                                                                                                                                                                                                              • COMPONENTS AND APPARATUS REQUIRED
                                                                                                                                                                                                                                                                                                                                                              • 1 Parallel Port Connectors (DB-25) with Cable
                                                                                                                                                                                                                                                                                                                                                              • 2 Personal Computer with Windows 98 and TurboC Compiler Installed
                                                                                                                                                                                                                                                                                                                                                              • 3 Following ICs and their Datasheets
                                                                                                                                                                                                                                                                                                                                                              • 74245 Octal Bus Transceivers with 3-State Outputs
                                                                                                                                                                                                                                                                                                                                                              • 4 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                                                                                                                                                                • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                                                                                                                                                                                  • Connecting wires Switches
                                                                                                                                                                                                                                                                                                                                                                    • THEORY
                                                                                                                                                                                                                                                                                                                                                                    • 3-State Logic
                                                                                                                                                                                                                                                                                                                                                                      • Serial and Parallel Port Connectors
                                                                                                                                                                                                                                                                                                                                                                      • Parallel Port Connector ndash DB-25
                                                                                                                                                                                                                                                                                                                                                                        • Accessing parallel port through C Language Programming
                                                                                                                                                                                                                                                                                                                                                                            • 21-ldst-appendixA
                                                                                                                                                                                                                                                                                                                                                                            • 22-ldst-appendixB
                                                                                                                                                                                                                                                                                                                                                                              • DEBOUNCING CIRCUITRY FOR MECHANICAL SWITCHES

                                                                                                      Logic Design amp Switching Theory 1 Lab Session 12 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                                                      53

                                                                                                      Implementation Procedure and Observations

                                                                                                      1 Implement the circuit using digital ICs on a bread board (prepare the pin diagram (use appendix A) and refer to laboratory session 01 for procedure)

                                                                                                      2 Make the clear inputs of the flip-flops low (to clear the flip-flops) The flip-flops will remain in clear state as long as the clear inputs are connected to low level

                                                                                                      3 Connect output Q0 and the clock pulse to an oscilloscope 4 Apply 0 to the input x 5 Now make the clear inputs to high 6 Observe the waveform for the first 5 clock pulses and record it 7 Repeat steps 2 to 6 keeping x=1 in step 4 this time 8 Repeat steps 2 to 7 this time connecting Q1 instead of Q0 to the oscilloscope in step

                                                                                                      3 Record your observations (Keep frequency of the clock pulse low (eg1Hz) so that the output waveforms can be observed easily)

                                                                                                      1 2 3 4 5 Clock Pulse

                                                                                                      Output Waveform for Q0 when x=0

                                                                                                      Output Waveform for Q0 when x=1

                                                                                                      Output Waveform for Q1 when x=0

                                                                                                      Output Waveform for Q1 when x=1

                                                                                                      Logic Design amp Switching Theory 1 Lab Session 13 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                                                      Lab Session 13 OBJECT

                                                                                                      Designing a modulo-5 asynchronous up-counter using JK-FF COMPONENTS AND APPARATUS REQUIRED

                                                                                                      1 Following ICs and their Datasheets

                                                                                                      bull 7400 Quad 2-input or 7410 Triple 3-input NAND Gates bull 7476 7473 JK Flip-Flop

                                                                                                      2 Digital Trainer DT-01 or the following components Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches

                                                                                                      THEORY

                                                                                                      Digital Counters A digital counter is a set of flip-flops whose states change in response to pulses applied at the input to the counter The flip-flops are interconnected so that their combined state at any time is the binary equivalent of the total number of pulses that have occurred up to that time Every counter resets after a certain number of clock pulses Thus as it name implies a counter is used to count pulses An n stage counter can count up to a maximum of 2n states n is equal to the number of flip-flops required for the construction of counter

                                                                                                      Modulus Counters The number of input pulses that causes a counter to reset to its initial count is called the modulus of the counter Thus the modulus equals to total number of distinct states (counts) including zero that a counter can store A binary counter with n stages is a modulo-2n (or mod-2n) counter The largest count a mod-N counter can achieve is N-1 ie a mod-N counter never reaches the binary number equal to its modulus N is always equal to or less than 2n Counters can be classified as bull Synchronous Counters which are clock driven All the flip-flops are driven by a

                                                                                                      single clock bull Asynchronous Counters which are event driven Clock input is given to the first

                                                                                                      flip-flop only Rest of the flip-flops are driven by their preceding flip-flops

                                                                                                      DESIGN OF A MOD-5 ASYNCHRONOUS UP COUNTER The number of flip-flops required to construct a mod-5 counter is 3 because 5 should be less than or equal to 2n This counter will count from 0 to 4 a total of 5 distinct states Since a 3-stage counter can count up to 8 states at maximum a NAND gate is used to reset it after 5 clock pulses Figure 131 shows the logic diagram

                                                                                                      54

                                                                                                      Logic Design amp Switching Theory 1 Lab Session 13 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                                                      55

                                                                                                      Figure 131 A Mod-5 Asynchronous Up Counter

                                                                                                      Implementation and Observations

                                                                                                      Implement the mod-5 counter circuit (figure 131) on a bread board (prepare the pin diagram (use appendix A) and refer to laboratory session 01 for implementation procedure) and record the observations in the following table

                                                                                                      Clock Pulse Q2 Q1 Q0

                                                                                                      0 1 2 3 4 5 6 7

                                                                                                      ACTIVITY

                                                                                                      Draw the timing diagram for mod-5 counter designed in this laboratory session

                                                                                                      Logic Design amp Switching Theory 1 Lab Session 14 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                                                      Lab Session 14 OBJECT

                                                                                                      Experimenting with 74194 4-bit bidirectional universal shift register COMPONENTS AND APPARATUS REQUIRED

                                                                                                      1 Following ICs and their Datasheets

                                                                                                      bull 74194 4-bit bidirectional universal shift register 2 Digital Trainer DT-01 or the following components

                                                                                                      Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches

                                                                                                      THEORY

                                                                                                      Shift Registers

                                                                                                      A Register is a set of flip-flops used to store binary data A register which is capable of shifting its binary information either to the right or left is called a shift register The logical configuration of a register consists of a chain of flip-flops connected in cascade with the output of one flip-flop connected to the input of next flip-flop All flip-flops receive a common clock pulse which causes the shift from one stage to the next

                                                                                                      Bidirectional Shift Registers A bi-directional shift register is one whose bits can be shifted from left to right or from right to left

                                                                                                      Universal Shift Registers A universal shift register is a bi-directional register whose input can be in either serial or parallel form and whose output can be in either serial or parallel form

                                                                                                      74194 4-BIT BIDIRECTIONAL UNIVERSAL SHIFT REGISTER

                                                                                                      The 74194 register provides parallel as well as serial loading in both directions Function of various pins of this IC is described below

                                                                                                      bull A B C and D Active high inputs for parallel loading bull QA QB QC and QD Active high outputs bull S0 and S1 Active high mode control inputs The following table shows combinations

                                                                                                      of S1 and S0 to enable various modes

                                                                                                      S1 S0 Clock Action 0 0 x No change 0 1 uarr Shift right 1 0 uarr Shift left 1 1 uarr Parallel load

                                                                                                      uarr shows the rising edge of the clock pulse

                                                                                                      56

                                                                                                      Logic Design amp Switching Theory 1 Lab Session 14 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering bull SR Active high serial input for right shifting bull SL Active high serial input for left shifting bull CLR Active low input Clears all the flip-flops of the register if set to 0 should be

                                                                                                      kept high otherwise bull CLK Clock input bull VCC and GND Supply connections lines Thus A B C and D are inputs for parallel loading whereas SR and SL are inputs for serial loading with right or left shifting respectively S1 and S0 are used to select the loading mode Circuit Diagram

                                                                                                      Figure 141 Pin connections of 74194 Testing Procedure

                                                                                                      bull Make connections as shown in the circuit diagram bull Observe the output for the input combinations given in the following table

                                                                                                      57

                                                                                                      Logic Design amp Switching Theory 1 Lab Session 14 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                                                      58

                                                                                                      Observations

                                                                                                      S1 S0 SL SR A B C D QA QB QC QD 0 0 0 1 0 0 0 0 0 1 1 0 0 0 0 1 1 0 0 0 0 0 1 0 1 1 0 0 0 0 1 1 0 0 1 1 0 1 0 0 0 1 1 1 0 1 0 1 1 0 1 0 0 1 1 0 1 1 1 0 0 1 1 1 1 1 0 0 1 1 1 1

                                                                                                      ACTIVITY 1 Show connections of 74194 to convert it into a ring counter with right shifting

                                                                                                      Logic Design amp Switching Theory 1 Lab Session 15 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                                                      Lab Session 15

                                                                                                      OBJECT

                                                                                                      Experimenting with 74245 octal bus transceivers using parallel port PC interfacing COMPONENTS AND APPARATUS REQUIRED 1 Parallel Port Connectors (DB-25) with Cable 2 Personal Computer with Windows 98 and TurboC Compiler Installed 3 Following ICs and their Datasheets

                                                                                                      bull 74245 Octal Bus Transceivers with 3-State Outputs 4 Digital Trainer DT-01 or the following components

                                                                                                      Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches

                                                                                                      THEORY

                                                                                                      3-State Logic Sometimes it is necessary to isolate one part of circuit from the other part For this purpose some TTL ICs are designed with 3-state logic Such devices have three possible output states high low and high impedance The device can be put into high impedance state by a control signal applied to an appropriate pin When such a device is in high impedance state there is very high impedance at its output effectively isolating the device from whatever circuitry the output normally drives 74245 Octal Bus Transceivers A bus is any conducting path or set of paths having electrical connections to one or more devices 74245 octal bus transceivers are mainly used to control connectivity between two devices or circuits It also provides direction control for signal flow Function of various pin of this IC is given below

                                                                                                      bull A1 through A8 Bus A bull B1 through B8 Bus B bull G΄ Active low enable input When high sets all the bus pins to high impedance state bull DIR Direction control for signal flow When set to high logic level transfers bus A

                                                                                                      data to B bus When set to low logic level transfers bus B data to A bus bull VCC and GND Supply connections lines Serial and Parallel Port Connectors A Parallel Port can consist of only 25 pin port adapter called a DB-25 and a serial port can consist of either a 25 pin port adapter called a DB-25 or 9 pin adapter called a DB-9 port adapter Whether the port is a 9 pin or 25 pin it can accomplish all of the same tasks that serial port communications have been designed for

                                                                                                      59

                                                                                                      Logic Design amp Switching Theory 1 Lab Session 15 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                                                      60

                                                                                                      Each adapter can be a male type connector with pins or a female type adapter with tiny holes Generally a PRINTER port (called LPT1) on the back of a computer is female type adapter and we need to use MALE DB-25 pin cable on it for PRINTER connection or for parallel LAPLINK cable And a COM port on the back of a computer is male for the serial ports but it may not necessarily be Parallel Port Connector ndash DB-25 The DB-25 connector (named for its B-size D-shaped shell and 25 pins) is practically ubiquitous in the electronics industry The DB-25 connector is used for a variety of purposes Two common applications are RS-232EIA-232 (serial) connections and the parallel printer interface on the IBM PC The DB-25 connector is also used for SCSI connections Normally the parallel port is used for output to a printer or other device It sends data 8-bits or one byte at a time in parallel The other lines available on the DB-25 connector are a combination of status lines control lines and ground lines The status and control lines are used for handshaking commands and feedback when we are talking to a printer

                                                                                                      Figure 152 DB-25 Female Figure 151 DB-25 Male

                                                                                                      Figure 153 Pin Layout for DB-25 As can be seen form figure 153 there are four types of pins in this connector

                                                                                                      bull Data pins (8 pins - D0 to D7) Active high bidirectional lines

                                                                                                      Logic Design amp Switching Theory 1 Lab Session 15 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering bull Control pins (4 pins - C0 to C3) C0 C1 and C3 are active low whereas C2 is active

                                                                                                      high These lines also are bidirectional bull Status pins (5 pins ndash S3 to S7) Only S7 is active low rest are active high input lines bull Ground pins (8 pins) Used as a reference signal for the low (below 05 volts) charge

                                                                                                      Parallel Port Addresses A DB-25 connector at a parallel port has three address one for each kind of pins register data status and control The first or base address generally refers to data register Second address is for status register and the third one is for control register In Windows 98 the base address is usually found to be 278H 378H or 3BCH Now if 378H is the base address then it refers to the data register whereas addresses for status and control register are respectively 379H and 37AH For Windows 98 the base address can be found as follows 1 On your Desktop right-click on My Computer and select Properties 2 Click on the Device Manager tab and find LPT1 under Plug and Play BIOS 3 After selecting LPT1 click the Properties button 4 Next select the Resources tab and the address should then appear next to InputOutput

                                                                                                      Range Accessing parallel port through C Language Programming There are multiple functions in C Language for accessing external ports The most commonly used are listed below

                                                                                                      bull unsigned char inportb(int portid) inportb reads a byte from a hardware port

                                                                                                      bull int inport(int portid) reads a word from a hardware port

                                                                                                      bull void outportb(int portid unsigned char value) outputs a byte to a hardware port

                                                                                                      bull void outport(int portid int value) outputs a word to a hardware port

                                                                                                      portid refers to the port address whereas value refers to the data to be sent TESTING 74245 USING PARALLEL PORT PC INTERFACING At one end the parallel port connector will be connected to the PC via parallel port cable and another connector (to be plugged into the PC parallel port slot) At the other end it will be connected to the buffer IC 74245 Data lines of the connector will be used to transfer 8-bit data between the PC and the buffer Out of the 8-bits of 74245 4-bits will be used to enter data which will be displayed at the monitor through a C language

                                                                                                      61

                                                                                                      Logic Design amp Switching Theory 1 Lab Session 15 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering program The remaining 4-bits will receive data from PC as entered by the user via keyboard

                                                                                                      Circuit Diagram

                                                                                                      Figure 154 Interface of 74245 to PC via Parallel Port

                                                                                                      Procedure

                                                                                                      1 Connect the DB-25 connector to the PC at one end and solder it to the circuit board at the other end

                                                                                                      2 Connect various pins of the connector and 74245 according to the circuit diagram shown in figure 152

                                                                                                      3 Using the functions listed in the previous section write a program in C language to operate various pins of the buffer The user interface of the program should provide option to the user whether to send or receive data from the port

                                                                                                      4 Set DIR switch to 1 5 Try sending some data bits to the port The result should be displayed at the LEDs 6 Set DIR switch to 0 7 Set some binary 4-bit value through the switches Try reading it via parallel port

                                                                                                      C Language Program

                                                                                                      A program to access parallel port for data transfers

                                                                                                      use header file include ltstdiohgt main program void main() define variable

                                                                                                      62

                                                                                                      Logic Design amp Switching Theory 1 Lab Session 15 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering unsigned int data=0 char choice while(1) printing option menu clrscr() printf(This program will send or receive a BCD digit from the parallel portn) printf(nPress your choice numbern) printf(n1 Send Data) printf(n2 Receive Data) printf(n3 Exitn) choice = getch() sending entered digit to the port if(choice == 1) input BCD digit printf(nEnter BCD digit to be sent to the port) data = getche() masking the first four bits data = data amp 0x0f sending to the port outportb(0x378data) printf(nThe BCD digit c has been sent to the port data) printing on screen the data received from the port else if(choice == 2) receiving data from the port data = inportb(0x378) masking the last four bits data = data amp 0xf0 shifting first four bits to make them the last four bits datagtgt=4 printf(nThe BCD digit set at the port is c data) exit else if(choice == 3) break key pressed is not in the menu else printf(nEnter valid choice number) printf(nnPress any key to continue) getch()

                                                                                                      63

                                                                                                      Logic Design amp Switching Theory 1 Lab Session 15 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                                                      ACTIVITY 1 In the above circuit DIR and G΄ inputs are hardwired Connect them to status or

                                                                                                      control pins of the parallel port connector and control their function through your software program Circuit Diagram Program Code ______________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________

                                                                                                      ___________________________________________________________________________________________________________________________________________________

                                                                                                      64

                                                                                                      Logic Design amp Switching Theory 1 Lab Session 15 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                                                      65

                                                                                                      _____________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ _____________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ _______________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ _________________________________________________ _________________________________________________

                                                                                                      Logic Design amp Switching Theory 1 Appendix A NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                                                      Appendix A

                                                                                                      PIN DIAGRAMS OF THE ICS REQUIRED FOR THE LABORATORY SESSIONS Consult the TTLIC data book for internal diagrams and electrical characteristics of these ICs 7400 Quad 2-Input NAND 7402 Quad 2-Input NOR

                                                                                                      7404 Hex Inverter 7408 Quad 2-Input AND

                                                                                                      7410 Triple 3-Input NAND 7411 Triple 3-Input AND

                                                                                                      7421 Dual 4-Input AND 7432 Quad 2-Input OR

                                                                                                      66

                                                                                                      Logic Design amp Switching Theory 1 Appendix A NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                                                      BCD-to-Seven Segm 7448 BCD-to-Seven Segment 7447 ent

                                                                                                      Decoder (15V OC) Decoder (2kΩ pull-up output)

                                                                                                      7473 Dual JK Flip-Flop 7474 Dual D-Type Flip-Flop

                                                                                                      7476 Dual JK Flop-Flop -Bit Binary Full Adder 7483 4 with Fast Carry

                                                                                                      86 Quad 2-Inpu 74138 3-to-8 Line 74 t Exclusive OR Decoder Demultiplexer

                                                                                                      67

                                                                                                      Logic Design amp Switching Theory 1 Appendix A NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                                                      68

                                                                                                      74148 8-to-3 Line 16-to-1 Line Data

                                                                                                      Priority Encoder 74150 Selector Multiplexer

                                                                                                      74245 Oct nsceivers Universal Shift Register (PIPO) (3-State)

                                                                                                      74194 4-Bit Bidirectional al Bus Tra

                                                                                                      Logic Design amp Switching Theory 1 Appendix B NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                                                      Appendix B

                                                                                                      DEBOUNCING CIRCUITRY FOR MECHANICAL SWITCHES Mechanical switches form the interface between human beings and computers or other digital systems For example a keyboard is a matrix of switches used to supply alphanumeric data to a computer Whatever the switch design it is a potential source of problems due to contact bounce The contact bounce creates a sense of narrow pulses when a switch is opened or closed An example of device whose operation would be adversely affected by contact bounce is a digital counter used to count the number of times a switch is depressed Eliminating the effects of contact bounce is called debouncing When data is entered into a computer via a keyboard a software debounce is often used This type of debouncing is a program that causes the computer to sample the switch terminal (ie to input data from it) many times in succession during the interval of time that contact bounce occurs If the data is sensed to be 1s (or 0s) for a specific number of consecutive samples then it is assumed that contact bounce has ended and the last value sensed is valid Hardware debouncing is the use of electronic circuitry to eliminate the effects of contact bounce There are numerous versions of such circuitry including those that use monostable multivibrators (one-shots) but the most straightforward is simply an RS latch Figure B1 shows the circuit When the switch is in position 1 R = 0 and S = 1 so the latch is set and the output (Q) is 1 When the switch is in position 0 R = 1and S = 0 so the latch is reset and the output is 0 When the switch is moved form one position to the other the latch changes state and bouncing occurs at either the R or the S input The bouncing does not affect the latch after it has change state An RS latch will remain set for example when its R input is 0 and its S input is alternately changed form 1 to 0

                                                                                                      Figure B1 Use of RS latch to debounce a mechanical switch

                                                                                                      69

                                                                                                      • 01-ldst-Outer title
                                                                                                        • Practical Workbook
                                                                                                        • Logic Design amp Switching Theory I
                                                                                                          • Dept of Computer amp Information Systems Engineering
                                                                                                            • NED University of Engineering amp Technology
                                                                                                            • Karachi ndash 75270 Pakistan
                                                                                                              • 02-ldst-inner Title
                                                                                                                • Practical Workbook
                                                                                                                • Logic Design amp Switching Theory I
                                                                                                                  • Dept of Computer amp Information Systems Engineering
                                                                                                                    • NED University of Engineering amp Technology
                                                                                                                    • Karachi ndash 75270 Pakistan
                                                                                                                      • 03-ldst-general info
                                                                                                                      • 04-ldst-introduction
                                                                                                                      • 05-Table of Contents
                                                                                                                        • CONTENTS
                                                                                                                          • Lab Session No Object Page No
                                                                                                                          • 1
                                                                                                                          • Also implementing and testing the given circuit on a bread board
                                                                                                                            • Working with Electronics Workbench
                                                                                                                              • Driving a seven segment display using 7447 7448 driver IC
                                                                                                                                • Designing a modulus-5 asynchronous up-counter using JK-FF
                                                                                                                                  • Experimenting with 74194 4-bit bidirectional universal shift register
                                                                                                                                      • 13
                                                                                                                                          • 06-ldst-Exp01
                                                                                                                                            • Lab Session 01
                                                                                                                                            • OBJECT
                                                                                                                                              • 1 Bread board
                                                                                                                                              • 2 5 V - power supply
                                                                                                                                              • 3 Multimeter
                                                                                                                                              • 4 Logic probe
                                                                                                                                              • 5 LEDs with resistors
                                                                                                                                              • 6 Connecting wires
                                                                                                                                              • 8 Following ICs and their datasheets
                                                                                                                                                • THEORY
                                                                                                                                                  • Logic Gates
                                                                                                                                                  • 1 The AND Gate ndash An AND gatersquos output is 1 if and only if all its inputs are 1 If A and B are two inputs to an AND gate then output F of the gate is given as F = AB
                                                                                                                                                  • 2 The OR Gate - An OR gatersquos output is 1 if at least one of its input is 1 If A and B are two inputs to an OR gate then output F of the gate is given as F = A+B
                                                                                                                                                  • 3 The NOT Gate (Inverter) ndash Its output is 1 when its input is 0 and its output is 0 when the input is 1 ie it complements a digital variable If A is the input to a NOT gate then output F of the gate is given as
                                                                                                                                                  • 4 The NAND Gate ndash Its output is 1 if at least one of its input is 0 This gate performs the same logic as an AND gate followed by an inverter If A and B are two inputs to a NAND gate then output F of the gate is given as
                                                                                                                                                    • 5 The NOR Gate - The output of a NOR gate is 1 if and only if all its inputs are 0 This gate performs the same logic function as an OR gate followed by an inverter If A and B are two inputs to a NAND gate then output F of the gate is given as
                                                                                                                                                        • DATA SHEETS
                                                                                                                                                          • Logic expression for the given logic diagram __________________________________
                                                                                                                                                              • 07-ldst-exp02
                                                                                                                                                                • Working with Electronics Workbench
                                                                                                                                                                  • 08-ldst-exp03
                                                                                                                                                                    • Designing Half and Full Adder Circuits
                                                                                                                                                                      • COMPONENTS AND APPARATUS REQUIRED
                                                                                                                                                                        • 1 Following ICs and their Datasheets
                                                                                                                                                                        • 7408 Quad 2-input AND Gate
                                                                                                                                                                        • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                          • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                          • Connecting wires Switches
                                                                                                                                                                            • THEORY
                                                                                                                                                                                • IMPLEMENTATION AND OBSERVATIONS
                                                                                                                                                                                  • 09-ldst-Exp04
                                                                                                                                                                                    • Lab Session 04
                                                                                                                                                                                    • 1 Digital ICs and their Datasheets
                                                                                                                                                                                    • 7408 Quad 2-input AND Gate
                                                                                                                                                                                    • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                      • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                      • Connecting wires Switches
                                                                                                                                                                                      • PROCEDURE
                                                                                                                                                                                      • REDUCTION OF LOGIC EXPRESSION USING KARNAUGH MAP
                                                                                                                                                                                      • OBSERVATIONS
                                                                                                                                                                                      • RESULT
                                                                                                                                                                                          • 10-ldst-Exp05
                                                                                                                                                                                            • Lab Session 05
                                                                                                                                                                                            • 1 Following ICs and their Datasheets
                                                                                                                                                                                            • 7408 Quad 2-input AND Gate
                                                                                                                                                                                            • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                              • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                              • (100 Ω) Connecting wires Switches
                                                                                                                                                                                              • THEORY
                                                                                                                                                                                                • IMPLEMENTATION AND OBSERVATIONS
                                                                                                                                                                                                  • 11-ldst-Exp06
                                                                                                                                                                                                    • OBJECT
                                                                                                                                                                                                    • 1 Following ICs and their Datasheets
                                                                                                                                                                                                    • 7408 Quad 2-input AND Gates or 7411 Triple 3-input AND Gates
                                                                                                                                                                                                    • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                      • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                      • Connecting wires Switches
                                                                                                                                                                                                        • Figure 62 Circuit Diagram for 4 x 1 Multiplexer
                                                                                                                                                                                                        • Implementation and Observations
                                                                                                                                                                                                          • Circuit Diagram
                                                                                                                                                                                                            • ACTIVITY
                                                                                                                                                                                                              • 12-ldst-exp07
                                                                                                                                                                                                                • 1 Following ICs and their Datasheets
                                                                                                                                                                                                                • 7408 Quad 2-input or 7411 Triple 3-input AND Gates
                                                                                                                                                                                                                • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                  • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                                  • Connecting wires Switches
                                                                                                                                                                                                                    • THEORY
                                                                                                                                                                                                                        • Figure 72 Circuit Diagram for 2 x 4 Decoder 1 x 4 Demultiplexer
                                                                                                                                                                                                                        • Implementation and Observations
                                                                                                                                                                                                                          • Circuit Diagram
                                                                                                                                                                                                                            • ACTIVITY
                                                                                                                                                                                                                              • 13-ldst-Exp08
                                                                                                                                                                                                                                • OBJECT
                                                                                                                                                                                                                                • 1 Following ICs and their Datasheets
                                                                                                                                                                                                                                • 7408 Quad 2-input or 7421 Dual 4-input AND Gates
                                                                                                                                                                                                                                • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                                  • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                                                  • Connecting wires Switches
                                                                                                                                                                                                                                    • THEORY
                                                                                                                                                                                                                                        • Figure 81 Circuit Diagram for 4 x 2 Priority Encoder
                                                                                                                                                                                                                                        • Implementation and Observations
                                                                                                                                                                                                                                          • Therefore if GS A2 A1 and A0 are all low then it shows that line 0 is selected and if E0 A2 A1 and A0 are all low then it shows that none of the inputs selected E0 and GS cannot be in the same state provided that E1 is enabled
                                                                                                                                                                                                                                          • Circuit Diagram
                                                                                                                                                                                                                                            • ACTIVITY
                                                                                                                                                                                                                                              • 14-ldst-exp09
                                                                                                                                                                                                                                                • OBJECT
                                                                                                                                                                                                                                                • 1 Following ICs and their Datasheets
                                                                                                                                                                                                                                                • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                                                  • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                                                                  • Connecting wires Switches
                                                                                                                                                                                                                                                    • THEORY
                                                                                                                                                                                                                                                      • Parity Generator
                                                                                                                                                                                                                                                        • Let x y and z be the three bits that constitute the message and are the input to the Odd Parity Generator Circuit Since it is an odd parity system the bit P is generated so as to make the total number of 1s odd (including P) The function P can be expressed as follows
                                                                                                                                                                                                                                                        • Figure 91 Circuit Diagram for a 3-bit Parity Generator
                                                                                                                                                                                                                                                          • C = x Ο y Ο z Ο P
                                                                                                                                                                                                                                                            • Implementation and Observations
                                                                                                                                                                                                                                                              • ACTIVITY
                                                                                                                                                                                                                                                                  • 15-ldst-exp10
                                                                                                                                                                                                                                                                    • Driving a seven segment display using 7447 7448 driver IC
                                                                                                                                                                                                                                                                    • COMPONENTS AND APPARATUS REQUIRED
                                                                                                                                                                                                                                                                    • 1 Following ICs and their Datasheets
                                                                                                                                                                                                                                                                    • 7447 7448 BCD to Seven Segment Driver
                                                                                                                                                                                                                                                                    • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                                                                      • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches
                                                                                                                                                                                                                                                                        • THEORY
                                                                                                                                                                                                                                                                        • Seven Segment Displays
                                                                                                                                                                                                                                                                        • CIRCUIT DIAGRAM
                                                                                                                                                                                                                                                                        • Figure 102 Circuit diagram for 7447driving a common-anode display
                                                                                                                                                                                                                                                                            • IMPLEMENTATION AND OBSERVATIONS
                                                                                                                                                                                                                                                                              • Decimal Digit
                                                                                                                                                                                                                                                                              • BCD Inputs
                                                                                                                                                                                                                                                                              • Seven Segment Outputs
                                                                                                                                                                                                                                                                              • D
                                                                                                                                                                                                                                                                              • C
                                                                                                                                                                                                                                                                              • B
                                                                                                                                                                                                                                                                              • A
                                                                                                                                                                                                                                                                              • a
                                                                                                                                                                                                                                                                              • b
                                                                                                                                                                                                                                                                              • c
                                                                                                                                                                                                                                                                              • d
                                                                                                                                                                                                                                                                              • e
                                                                                                                                                                                                                                                                              • f
                                                                                                                                                                                                                                                                              • g
                                                                                                                                                                                                                                                                              • 0
                                                                                                                                                                                                                                                                              • 0
                                                                                                                                                                                                                                                                              • 0
                                                                                                                                                                                                                                                                              • 0
                                                                                                                                                                                                                                                                              • 0
                                                                                                                                                                                                                                                                              • 1
                                                                                                                                                                                                                                                                              • 0
                                                                                                                                                                                                                                                                              • 0
                                                                                                                                                                                                                                                                              • 0
                                                                                                                                                                                                                                                                              • 1
                                                                                                                                                                                                                                                                              • 2
                                                                                                                                                                                                                                                                              • 0
                                                                                                                                                                                                                                                                              • 0
                                                                                                                                                                                                                                                                              • 1
                                                                                                                                                                                                                                                                              • 0
                                                                                                                                                                                                                                                                              • 3
                                                                                                                                                                                                                                                                              • 0
                                                                                                                                                                                                                                                                              • 0
                                                                                                                                                                                                                                                                              • 1
                                                                                                                                                                                                                                                                              • 1
                                                                                                                                                                                                                                                                              • 4
                                                                                                                                                                                                                                                                              • 0
                                                                                                                                                                                                                                                                              • 1
                                                                                                                                                                                                                                                                              • 0
                                                                                                                                                                                                                                                                              • 0
                                                                                                                                                                                                                                                                              • 5
                                                                                                                                                                                                                                                                              • 0
                                                                                                                                                                                                                                                                              • 1
                                                                                                                                                                                                                                                                              • 0
                                                                                                                                                                                                                                                                              • 1
                                                                                                                                                                                                                                                                              • 6
                                                                                                                                                                                                                                                                              • 0
                                                                                                                                                                                                                                                                              • 1
                                                                                                                                                                                                                                                                              • 1
                                                                                                                                                                                                                                                                              • 0
                                                                                                                                                                                                                                                                              • 7
                                                                                                                                                                                                                                                                              • 0
                                                                                                                                                                                                                                                                              • 1
                                                                                                                                                                                                                                                                              • 1
                                                                                                                                                                                                                                                                              • 1
                                                                                                                                                                                                                                                                              • 8
                                                                                                                                                                                                                                                                              • 1
                                                                                                                                                                                                                                                                              • 0
                                                                                                                                                                                                                                                                              • 0
                                                                                                                                                                                                                                                                              • 0
                                                                                                                                                                                                                                                                              • 9
                                                                                                                                                                                                                                                                              • 1
                                                                                                                                                                                                                                                                              • 0
                                                                                                                                                                                                                                                                              • 0
                                                                                                                                                                                                                                                                              • 1
                                                                                                                                                                                                                                                                                • ACTIVITY
                                                                                                                                                                                                                                                                                  • 16-ldst-exp11
                                                                                                                                                                                                                                                                                    • Lab Session 11
                                                                                                                                                                                                                                                                                      • OBJECT
                                                                                                                                                                                                                                                                                      • COMPONENTS AND APPARATUS REQUIRED
                                                                                                                                                                                                                                                                                        • 1 Following ICs and their Datasheets
                                                                                                                                                                                                                                                                                        • 7473 7476 JK Flip-Flop
                                                                                                                                                                                                                                                                                        • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                                                                                          • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                                                                                                          • Connecting wires Switches
                                                                                                                                                                                                                                                                                            • THEORY
                                                                                                                                                                                                                                                                                                • Flip-Flop
                                                                                                                                                                                                                                                                                                • JK Flip-Flop
                                                                                                                                                                                                                                                                                                  • Circuit Diagram
                                                                                                                                                                                                                                                                                                    • Observations
                                                                                                                                                                                                                                                                                                      • ACTIVITY
                                                                                                                                                                                                                                                                                                          • 17-ldst-exp12
                                                                                                                                                                                                                                                                                                            • Lab Session 12
                                                                                                                                                                                                                                                                                                              • OBJECT
                                                                                                                                                                                                                                                                                                              • GIVEN STATE DIAGRAM
                                                                                                                                                                                                                                                                                                              • Figure 121 State Diagram
                                                                                                                                                                                                                                                                                                              • COMPONENTS AND APPARATUS REQUIRED
                                                                                                                                                                                                                                                                                                                • 1 Following ICs and their Datasheets
                                                                                                                                                                                                                                                                                                                • 7474 D Flip-Flop
                                                                                                                                                                                                                                                                                                                • ICs of basic gates (AND OR NOT XOR etc) as required
                                                                                                                                                                                                                                                                                                                • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                                                                                                                  • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                                                                                                                                  • Connecting wires Switches
                                                                                                                                                                                                                                                                                                                    • THEORY
                                                                                                                                                                                                                                                                                                                        • Sequential Circuits
                                                                                                                                                                                                                                                                                                                          • 18-ldst-exp13
                                                                                                                                                                                                                                                                                                                            • Lab Session 13
                                                                                                                                                                                                                                                                                                                              • Designing a modulo-5 asynchronous up-counter using JK-FF
                                                                                                                                                                                                                                                                                                                                • 1 Following ICs and their Datasheets
                                                                                                                                                                                                                                                                                                                                • 7400 Quad 2-input or 7410 Triple 3-input NAND Gates
                                                                                                                                                                                                                                                                                                                                • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                                                                                                                                  • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                                                                                                                                                  • Connecting wires Switches
                                                                                                                                                                                                                                                                                                                                    • THEORY
                                                                                                                                                                                                                                                                                                                                        • Figure 131 A Mod-5 Asynchronous Up Counter
                                                                                                                                                                                                                                                                                                                                        • Implementation and Observations
                                                                                                                                                                                                                                                                                                                                          • ACTIVITY
                                                                                                                                                                                                                                                                                                                                              • 19-ldst-exp14
                                                                                                                                                                                                                                                                                                                                                • Experimenting with 74194 4-bit bidirectional universal shift register
                                                                                                                                                                                                                                                                                                                                                • 1 Following ICs and their Datasheets
                                                                                                                                                                                                                                                                                                                                                • 74194 4-bit bidirectional universal shift register
                                                                                                                                                                                                                                                                                                                                                • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                                                                                                                                                  • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                                                                                                                                                                  • Connecting wires Switches
                                                                                                                                                                                                                                                                                                                                                    • THEORY
                                                                                                                                                                                                                                                                                                                                                      • Shift Registers
                                                                                                                                                                                                                                                                                                                                                      • Bidirectional Shift Registers
                                                                                                                                                                                                                                                                                                                                                      • Universal Shift Registers
                                                                                                                                                                                                                                                                                                                                                        • S1
                                                                                                                                                                                                                                                                                                                                                          • Circuit Diagram
                                                                                                                                                                                                                                                                                                                                                          • ACTIVITY
                                                                                                                                                                                                                                                                                                                                                              • 20-ldst-exp15
                                                                                                                                                                                                                                                                                                                                                                • COMPONENTS AND APPARATUS REQUIRED
                                                                                                                                                                                                                                                                                                                                                                • 1 Parallel Port Connectors (DB-25) with Cable
                                                                                                                                                                                                                                                                                                                                                                • 2 Personal Computer with Windows 98 and TurboC Compiler Installed
                                                                                                                                                                                                                                                                                                                                                                • 3 Following ICs and their Datasheets
                                                                                                                                                                                                                                                                                                                                                                • 74245 Octal Bus Transceivers with 3-State Outputs
                                                                                                                                                                                                                                                                                                                                                                • 4 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                                                                                                                                                                  • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                                                                                                                                                                                    • Connecting wires Switches
                                                                                                                                                                                                                                                                                                                                                                      • THEORY
                                                                                                                                                                                                                                                                                                                                                                      • 3-State Logic
                                                                                                                                                                                                                                                                                                                                                                        • Serial and Parallel Port Connectors
                                                                                                                                                                                                                                                                                                                                                                        • Parallel Port Connector ndash DB-25
                                                                                                                                                                                                                                                                                                                                                                          • Accessing parallel port through C Language Programming
                                                                                                                                                                                                                                                                                                                                                                              • 21-ldst-appendixA
                                                                                                                                                                                                                                                                                                                                                                              • 22-ldst-appendixB
                                                                                                                                                                                                                                                                                                                                                                                • DEBOUNCING CIRCUITRY FOR MECHANICAL SWITCHES

                                                                                                        Logic Design amp Switching Theory 1 Lab Session 13 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                                                        Lab Session 13 OBJECT

                                                                                                        Designing a modulo-5 asynchronous up-counter using JK-FF COMPONENTS AND APPARATUS REQUIRED

                                                                                                        1 Following ICs and their Datasheets

                                                                                                        bull 7400 Quad 2-input or 7410 Triple 3-input NAND Gates bull 7476 7473 JK Flip-Flop

                                                                                                        2 Digital Trainer DT-01 or the following components Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches

                                                                                                        THEORY

                                                                                                        Digital Counters A digital counter is a set of flip-flops whose states change in response to pulses applied at the input to the counter The flip-flops are interconnected so that their combined state at any time is the binary equivalent of the total number of pulses that have occurred up to that time Every counter resets after a certain number of clock pulses Thus as it name implies a counter is used to count pulses An n stage counter can count up to a maximum of 2n states n is equal to the number of flip-flops required for the construction of counter

                                                                                                        Modulus Counters The number of input pulses that causes a counter to reset to its initial count is called the modulus of the counter Thus the modulus equals to total number of distinct states (counts) including zero that a counter can store A binary counter with n stages is a modulo-2n (or mod-2n) counter The largest count a mod-N counter can achieve is N-1 ie a mod-N counter never reaches the binary number equal to its modulus N is always equal to or less than 2n Counters can be classified as bull Synchronous Counters which are clock driven All the flip-flops are driven by a

                                                                                                        single clock bull Asynchronous Counters which are event driven Clock input is given to the first

                                                                                                        flip-flop only Rest of the flip-flops are driven by their preceding flip-flops

                                                                                                        DESIGN OF A MOD-5 ASYNCHRONOUS UP COUNTER The number of flip-flops required to construct a mod-5 counter is 3 because 5 should be less than or equal to 2n This counter will count from 0 to 4 a total of 5 distinct states Since a 3-stage counter can count up to 8 states at maximum a NAND gate is used to reset it after 5 clock pulses Figure 131 shows the logic diagram

                                                                                                        54

                                                                                                        Logic Design amp Switching Theory 1 Lab Session 13 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                                                        55

                                                                                                        Figure 131 A Mod-5 Asynchronous Up Counter

                                                                                                        Implementation and Observations

                                                                                                        Implement the mod-5 counter circuit (figure 131) on a bread board (prepare the pin diagram (use appendix A) and refer to laboratory session 01 for implementation procedure) and record the observations in the following table

                                                                                                        Clock Pulse Q2 Q1 Q0

                                                                                                        0 1 2 3 4 5 6 7

                                                                                                        ACTIVITY

                                                                                                        Draw the timing diagram for mod-5 counter designed in this laboratory session

                                                                                                        Logic Design amp Switching Theory 1 Lab Session 14 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                                                        Lab Session 14 OBJECT

                                                                                                        Experimenting with 74194 4-bit bidirectional universal shift register COMPONENTS AND APPARATUS REQUIRED

                                                                                                        1 Following ICs and their Datasheets

                                                                                                        bull 74194 4-bit bidirectional universal shift register 2 Digital Trainer DT-01 or the following components

                                                                                                        Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches

                                                                                                        THEORY

                                                                                                        Shift Registers

                                                                                                        A Register is a set of flip-flops used to store binary data A register which is capable of shifting its binary information either to the right or left is called a shift register The logical configuration of a register consists of a chain of flip-flops connected in cascade with the output of one flip-flop connected to the input of next flip-flop All flip-flops receive a common clock pulse which causes the shift from one stage to the next

                                                                                                        Bidirectional Shift Registers A bi-directional shift register is one whose bits can be shifted from left to right or from right to left

                                                                                                        Universal Shift Registers A universal shift register is a bi-directional register whose input can be in either serial or parallel form and whose output can be in either serial or parallel form

                                                                                                        74194 4-BIT BIDIRECTIONAL UNIVERSAL SHIFT REGISTER

                                                                                                        The 74194 register provides parallel as well as serial loading in both directions Function of various pins of this IC is described below

                                                                                                        bull A B C and D Active high inputs for parallel loading bull QA QB QC and QD Active high outputs bull S0 and S1 Active high mode control inputs The following table shows combinations

                                                                                                        of S1 and S0 to enable various modes

                                                                                                        S1 S0 Clock Action 0 0 x No change 0 1 uarr Shift right 1 0 uarr Shift left 1 1 uarr Parallel load

                                                                                                        uarr shows the rising edge of the clock pulse

                                                                                                        56

                                                                                                        Logic Design amp Switching Theory 1 Lab Session 14 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering bull SR Active high serial input for right shifting bull SL Active high serial input for left shifting bull CLR Active low input Clears all the flip-flops of the register if set to 0 should be

                                                                                                        kept high otherwise bull CLK Clock input bull VCC and GND Supply connections lines Thus A B C and D are inputs for parallel loading whereas SR and SL are inputs for serial loading with right or left shifting respectively S1 and S0 are used to select the loading mode Circuit Diagram

                                                                                                        Figure 141 Pin connections of 74194 Testing Procedure

                                                                                                        bull Make connections as shown in the circuit diagram bull Observe the output for the input combinations given in the following table

                                                                                                        57

                                                                                                        Logic Design amp Switching Theory 1 Lab Session 14 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                                                        58

                                                                                                        Observations

                                                                                                        S1 S0 SL SR A B C D QA QB QC QD 0 0 0 1 0 0 0 0 0 1 1 0 0 0 0 1 1 0 0 0 0 0 1 0 1 1 0 0 0 0 1 1 0 0 1 1 0 1 0 0 0 1 1 1 0 1 0 1 1 0 1 0 0 1 1 0 1 1 1 0 0 1 1 1 1 1 0 0 1 1 1 1

                                                                                                        ACTIVITY 1 Show connections of 74194 to convert it into a ring counter with right shifting

                                                                                                        Logic Design amp Switching Theory 1 Lab Session 15 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                                                        Lab Session 15

                                                                                                        OBJECT

                                                                                                        Experimenting with 74245 octal bus transceivers using parallel port PC interfacing COMPONENTS AND APPARATUS REQUIRED 1 Parallel Port Connectors (DB-25) with Cable 2 Personal Computer with Windows 98 and TurboC Compiler Installed 3 Following ICs and their Datasheets

                                                                                                        bull 74245 Octal Bus Transceivers with 3-State Outputs 4 Digital Trainer DT-01 or the following components

                                                                                                        Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches

                                                                                                        THEORY

                                                                                                        3-State Logic Sometimes it is necessary to isolate one part of circuit from the other part For this purpose some TTL ICs are designed with 3-state logic Such devices have three possible output states high low and high impedance The device can be put into high impedance state by a control signal applied to an appropriate pin When such a device is in high impedance state there is very high impedance at its output effectively isolating the device from whatever circuitry the output normally drives 74245 Octal Bus Transceivers A bus is any conducting path or set of paths having electrical connections to one or more devices 74245 octal bus transceivers are mainly used to control connectivity between two devices or circuits It also provides direction control for signal flow Function of various pin of this IC is given below

                                                                                                        bull A1 through A8 Bus A bull B1 through B8 Bus B bull G΄ Active low enable input When high sets all the bus pins to high impedance state bull DIR Direction control for signal flow When set to high logic level transfers bus A

                                                                                                        data to B bus When set to low logic level transfers bus B data to A bus bull VCC and GND Supply connections lines Serial and Parallel Port Connectors A Parallel Port can consist of only 25 pin port adapter called a DB-25 and a serial port can consist of either a 25 pin port adapter called a DB-25 or 9 pin adapter called a DB-9 port adapter Whether the port is a 9 pin or 25 pin it can accomplish all of the same tasks that serial port communications have been designed for

                                                                                                        59

                                                                                                        Logic Design amp Switching Theory 1 Lab Session 15 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                                                        60

                                                                                                        Each adapter can be a male type connector with pins or a female type adapter with tiny holes Generally a PRINTER port (called LPT1) on the back of a computer is female type adapter and we need to use MALE DB-25 pin cable on it for PRINTER connection or for parallel LAPLINK cable And a COM port on the back of a computer is male for the serial ports but it may not necessarily be Parallel Port Connector ndash DB-25 The DB-25 connector (named for its B-size D-shaped shell and 25 pins) is practically ubiquitous in the electronics industry The DB-25 connector is used for a variety of purposes Two common applications are RS-232EIA-232 (serial) connections and the parallel printer interface on the IBM PC The DB-25 connector is also used for SCSI connections Normally the parallel port is used for output to a printer or other device It sends data 8-bits or one byte at a time in parallel The other lines available on the DB-25 connector are a combination of status lines control lines and ground lines The status and control lines are used for handshaking commands and feedback when we are talking to a printer

                                                                                                        Figure 152 DB-25 Female Figure 151 DB-25 Male

                                                                                                        Figure 153 Pin Layout for DB-25 As can be seen form figure 153 there are four types of pins in this connector

                                                                                                        bull Data pins (8 pins - D0 to D7) Active high bidirectional lines

                                                                                                        Logic Design amp Switching Theory 1 Lab Session 15 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering bull Control pins (4 pins - C0 to C3) C0 C1 and C3 are active low whereas C2 is active

                                                                                                        high These lines also are bidirectional bull Status pins (5 pins ndash S3 to S7) Only S7 is active low rest are active high input lines bull Ground pins (8 pins) Used as a reference signal for the low (below 05 volts) charge

                                                                                                        Parallel Port Addresses A DB-25 connector at a parallel port has three address one for each kind of pins register data status and control The first or base address generally refers to data register Second address is for status register and the third one is for control register In Windows 98 the base address is usually found to be 278H 378H or 3BCH Now if 378H is the base address then it refers to the data register whereas addresses for status and control register are respectively 379H and 37AH For Windows 98 the base address can be found as follows 1 On your Desktop right-click on My Computer and select Properties 2 Click on the Device Manager tab and find LPT1 under Plug and Play BIOS 3 After selecting LPT1 click the Properties button 4 Next select the Resources tab and the address should then appear next to InputOutput

                                                                                                        Range Accessing parallel port through C Language Programming There are multiple functions in C Language for accessing external ports The most commonly used are listed below

                                                                                                        bull unsigned char inportb(int portid) inportb reads a byte from a hardware port

                                                                                                        bull int inport(int portid) reads a word from a hardware port

                                                                                                        bull void outportb(int portid unsigned char value) outputs a byte to a hardware port

                                                                                                        bull void outport(int portid int value) outputs a word to a hardware port

                                                                                                        portid refers to the port address whereas value refers to the data to be sent TESTING 74245 USING PARALLEL PORT PC INTERFACING At one end the parallel port connector will be connected to the PC via parallel port cable and another connector (to be plugged into the PC parallel port slot) At the other end it will be connected to the buffer IC 74245 Data lines of the connector will be used to transfer 8-bit data between the PC and the buffer Out of the 8-bits of 74245 4-bits will be used to enter data which will be displayed at the monitor through a C language

                                                                                                        61

                                                                                                        Logic Design amp Switching Theory 1 Lab Session 15 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering program The remaining 4-bits will receive data from PC as entered by the user via keyboard

                                                                                                        Circuit Diagram

                                                                                                        Figure 154 Interface of 74245 to PC via Parallel Port

                                                                                                        Procedure

                                                                                                        1 Connect the DB-25 connector to the PC at one end and solder it to the circuit board at the other end

                                                                                                        2 Connect various pins of the connector and 74245 according to the circuit diagram shown in figure 152

                                                                                                        3 Using the functions listed in the previous section write a program in C language to operate various pins of the buffer The user interface of the program should provide option to the user whether to send or receive data from the port

                                                                                                        4 Set DIR switch to 1 5 Try sending some data bits to the port The result should be displayed at the LEDs 6 Set DIR switch to 0 7 Set some binary 4-bit value through the switches Try reading it via parallel port

                                                                                                        C Language Program

                                                                                                        A program to access parallel port for data transfers

                                                                                                        use header file include ltstdiohgt main program void main() define variable

                                                                                                        62

                                                                                                        Logic Design amp Switching Theory 1 Lab Session 15 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering unsigned int data=0 char choice while(1) printing option menu clrscr() printf(This program will send or receive a BCD digit from the parallel portn) printf(nPress your choice numbern) printf(n1 Send Data) printf(n2 Receive Data) printf(n3 Exitn) choice = getch() sending entered digit to the port if(choice == 1) input BCD digit printf(nEnter BCD digit to be sent to the port) data = getche() masking the first four bits data = data amp 0x0f sending to the port outportb(0x378data) printf(nThe BCD digit c has been sent to the port data) printing on screen the data received from the port else if(choice == 2) receiving data from the port data = inportb(0x378) masking the last four bits data = data amp 0xf0 shifting first four bits to make them the last four bits datagtgt=4 printf(nThe BCD digit set at the port is c data) exit else if(choice == 3) break key pressed is not in the menu else printf(nEnter valid choice number) printf(nnPress any key to continue) getch()

                                                                                                        63

                                                                                                        Logic Design amp Switching Theory 1 Lab Session 15 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                                                        ACTIVITY 1 In the above circuit DIR and G΄ inputs are hardwired Connect them to status or

                                                                                                        control pins of the parallel port connector and control their function through your software program Circuit Diagram Program Code ______________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________

                                                                                                        ___________________________________________________________________________________________________________________________________________________

                                                                                                        64

                                                                                                        Logic Design amp Switching Theory 1 Lab Session 15 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                                                        65

                                                                                                        _____________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ _____________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ _______________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ _________________________________________________ _________________________________________________

                                                                                                        Logic Design amp Switching Theory 1 Appendix A NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                                                        Appendix A

                                                                                                        PIN DIAGRAMS OF THE ICS REQUIRED FOR THE LABORATORY SESSIONS Consult the TTLIC data book for internal diagrams and electrical characteristics of these ICs 7400 Quad 2-Input NAND 7402 Quad 2-Input NOR

                                                                                                        7404 Hex Inverter 7408 Quad 2-Input AND

                                                                                                        7410 Triple 3-Input NAND 7411 Triple 3-Input AND

                                                                                                        7421 Dual 4-Input AND 7432 Quad 2-Input OR

                                                                                                        66

                                                                                                        Logic Design amp Switching Theory 1 Appendix A NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                                                        BCD-to-Seven Segm 7448 BCD-to-Seven Segment 7447 ent

                                                                                                        Decoder (15V OC) Decoder (2kΩ pull-up output)

                                                                                                        7473 Dual JK Flip-Flop 7474 Dual D-Type Flip-Flop

                                                                                                        7476 Dual JK Flop-Flop -Bit Binary Full Adder 7483 4 with Fast Carry

                                                                                                        86 Quad 2-Inpu 74138 3-to-8 Line 74 t Exclusive OR Decoder Demultiplexer

                                                                                                        67

                                                                                                        Logic Design amp Switching Theory 1 Appendix A NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                                                        68

                                                                                                        74148 8-to-3 Line 16-to-1 Line Data

                                                                                                        Priority Encoder 74150 Selector Multiplexer

                                                                                                        74245 Oct nsceivers Universal Shift Register (PIPO) (3-State)

                                                                                                        74194 4-Bit Bidirectional al Bus Tra

                                                                                                        Logic Design amp Switching Theory 1 Appendix B NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                                                        Appendix B

                                                                                                        DEBOUNCING CIRCUITRY FOR MECHANICAL SWITCHES Mechanical switches form the interface between human beings and computers or other digital systems For example a keyboard is a matrix of switches used to supply alphanumeric data to a computer Whatever the switch design it is a potential source of problems due to contact bounce The contact bounce creates a sense of narrow pulses when a switch is opened or closed An example of device whose operation would be adversely affected by contact bounce is a digital counter used to count the number of times a switch is depressed Eliminating the effects of contact bounce is called debouncing When data is entered into a computer via a keyboard a software debounce is often used This type of debouncing is a program that causes the computer to sample the switch terminal (ie to input data from it) many times in succession during the interval of time that contact bounce occurs If the data is sensed to be 1s (or 0s) for a specific number of consecutive samples then it is assumed that contact bounce has ended and the last value sensed is valid Hardware debouncing is the use of electronic circuitry to eliminate the effects of contact bounce There are numerous versions of such circuitry including those that use monostable multivibrators (one-shots) but the most straightforward is simply an RS latch Figure B1 shows the circuit When the switch is in position 1 R = 0 and S = 1 so the latch is set and the output (Q) is 1 When the switch is in position 0 R = 1and S = 0 so the latch is reset and the output is 0 When the switch is moved form one position to the other the latch changes state and bouncing occurs at either the R or the S input The bouncing does not affect the latch after it has change state An RS latch will remain set for example when its R input is 0 and its S input is alternately changed form 1 to 0

                                                                                                        Figure B1 Use of RS latch to debounce a mechanical switch

                                                                                                        69

                                                                                                        • 01-ldst-Outer title
                                                                                                          • Practical Workbook
                                                                                                          • Logic Design amp Switching Theory I
                                                                                                            • Dept of Computer amp Information Systems Engineering
                                                                                                              • NED University of Engineering amp Technology
                                                                                                              • Karachi ndash 75270 Pakistan
                                                                                                                • 02-ldst-inner Title
                                                                                                                  • Practical Workbook
                                                                                                                  • Logic Design amp Switching Theory I
                                                                                                                    • Dept of Computer amp Information Systems Engineering
                                                                                                                      • NED University of Engineering amp Technology
                                                                                                                      • Karachi ndash 75270 Pakistan
                                                                                                                        • 03-ldst-general info
                                                                                                                        • 04-ldst-introduction
                                                                                                                        • 05-Table of Contents
                                                                                                                          • CONTENTS
                                                                                                                            • Lab Session No Object Page No
                                                                                                                            • 1
                                                                                                                            • Also implementing and testing the given circuit on a bread board
                                                                                                                              • Working with Electronics Workbench
                                                                                                                                • Driving a seven segment display using 7447 7448 driver IC
                                                                                                                                  • Designing a modulus-5 asynchronous up-counter using JK-FF
                                                                                                                                    • Experimenting with 74194 4-bit bidirectional universal shift register
                                                                                                                                        • 13
                                                                                                                                            • 06-ldst-Exp01
                                                                                                                                              • Lab Session 01
                                                                                                                                              • OBJECT
                                                                                                                                                • 1 Bread board
                                                                                                                                                • 2 5 V - power supply
                                                                                                                                                • 3 Multimeter
                                                                                                                                                • 4 Logic probe
                                                                                                                                                • 5 LEDs with resistors
                                                                                                                                                • 6 Connecting wires
                                                                                                                                                • 8 Following ICs and their datasheets
                                                                                                                                                  • THEORY
                                                                                                                                                    • Logic Gates
                                                                                                                                                    • 1 The AND Gate ndash An AND gatersquos output is 1 if and only if all its inputs are 1 If A and B are two inputs to an AND gate then output F of the gate is given as F = AB
                                                                                                                                                    • 2 The OR Gate - An OR gatersquos output is 1 if at least one of its input is 1 If A and B are two inputs to an OR gate then output F of the gate is given as F = A+B
                                                                                                                                                    • 3 The NOT Gate (Inverter) ndash Its output is 1 when its input is 0 and its output is 0 when the input is 1 ie it complements a digital variable If A is the input to a NOT gate then output F of the gate is given as
                                                                                                                                                    • 4 The NAND Gate ndash Its output is 1 if at least one of its input is 0 This gate performs the same logic as an AND gate followed by an inverter If A and B are two inputs to a NAND gate then output F of the gate is given as
                                                                                                                                                      • 5 The NOR Gate - The output of a NOR gate is 1 if and only if all its inputs are 0 This gate performs the same logic function as an OR gate followed by an inverter If A and B are two inputs to a NAND gate then output F of the gate is given as
                                                                                                                                                          • DATA SHEETS
                                                                                                                                                            • Logic expression for the given logic diagram __________________________________
                                                                                                                                                                • 07-ldst-exp02
                                                                                                                                                                  • Working with Electronics Workbench
                                                                                                                                                                    • 08-ldst-exp03
                                                                                                                                                                      • Designing Half and Full Adder Circuits
                                                                                                                                                                        • COMPONENTS AND APPARATUS REQUIRED
                                                                                                                                                                          • 1 Following ICs and their Datasheets
                                                                                                                                                                          • 7408 Quad 2-input AND Gate
                                                                                                                                                                          • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                            • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                            • Connecting wires Switches
                                                                                                                                                                              • THEORY
                                                                                                                                                                                  • IMPLEMENTATION AND OBSERVATIONS
                                                                                                                                                                                    • 09-ldst-Exp04
                                                                                                                                                                                      • Lab Session 04
                                                                                                                                                                                      • 1 Digital ICs and their Datasheets
                                                                                                                                                                                      • 7408 Quad 2-input AND Gate
                                                                                                                                                                                      • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                        • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                        • Connecting wires Switches
                                                                                                                                                                                        • PROCEDURE
                                                                                                                                                                                        • REDUCTION OF LOGIC EXPRESSION USING KARNAUGH MAP
                                                                                                                                                                                        • OBSERVATIONS
                                                                                                                                                                                        • RESULT
                                                                                                                                                                                            • 10-ldst-Exp05
                                                                                                                                                                                              • Lab Session 05
                                                                                                                                                                                              • 1 Following ICs and their Datasheets
                                                                                                                                                                                              • 7408 Quad 2-input AND Gate
                                                                                                                                                                                              • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                • (100 Ω) Connecting wires Switches
                                                                                                                                                                                                • THEORY
                                                                                                                                                                                                  • IMPLEMENTATION AND OBSERVATIONS
                                                                                                                                                                                                    • 11-ldst-Exp06
                                                                                                                                                                                                      • OBJECT
                                                                                                                                                                                                      • 1 Following ICs and their Datasheets
                                                                                                                                                                                                      • 7408 Quad 2-input AND Gates or 7411 Triple 3-input AND Gates
                                                                                                                                                                                                      • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                        • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                        • Connecting wires Switches
                                                                                                                                                                                                          • Figure 62 Circuit Diagram for 4 x 1 Multiplexer
                                                                                                                                                                                                          • Implementation and Observations
                                                                                                                                                                                                            • Circuit Diagram
                                                                                                                                                                                                              • ACTIVITY
                                                                                                                                                                                                                • 12-ldst-exp07
                                                                                                                                                                                                                  • 1 Following ICs and their Datasheets
                                                                                                                                                                                                                  • 7408 Quad 2-input or 7411 Triple 3-input AND Gates
                                                                                                                                                                                                                  • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                    • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                                    • Connecting wires Switches
                                                                                                                                                                                                                      • THEORY
                                                                                                                                                                                                                          • Figure 72 Circuit Diagram for 2 x 4 Decoder 1 x 4 Demultiplexer
                                                                                                                                                                                                                          • Implementation and Observations
                                                                                                                                                                                                                            • Circuit Diagram
                                                                                                                                                                                                                              • ACTIVITY
                                                                                                                                                                                                                                • 13-ldst-Exp08
                                                                                                                                                                                                                                  • OBJECT
                                                                                                                                                                                                                                  • 1 Following ICs and their Datasheets
                                                                                                                                                                                                                                  • 7408 Quad 2-input or 7421 Dual 4-input AND Gates
                                                                                                                                                                                                                                  • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                                    • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                                                    • Connecting wires Switches
                                                                                                                                                                                                                                      • THEORY
                                                                                                                                                                                                                                          • Figure 81 Circuit Diagram for 4 x 2 Priority Encoder
                                                                                                                                                                                                                                          • Implementation and Observations
                                                                                                                                                                                                                                            • Therefore if GS A2 A1 and A0 are all low then it shows that line 0 is selected and if E0 A2 A1 and A0 are all low then it shows that none of the inputs selected E0 and GS cannot be in the same state provided that E1 is enabled
                                                                                                                                                                                                                                            • Circuit Diagram
                                                                                                                                                                                                                                              • ACTIVITY
                                                                                                                                                                                                                                                • 14-ldst-exp09
                                                                                                                                                                                                                                                  • OBJECT
                                                                                                                                                                                                                                                  • 1 Following ICs and their Datasheets
                                                                                                                                                                                                                                                  • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                                                    • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                                                                    • Connecting wires Switches
                                                                                                                                                                                                                                                      • THEORY
                                                                                                                                                                                                                                                        • Parity Generator
                                                                                                                                                                                                                                                          • Let x y and z be the three bits that constitute the message and are the input to the Odd Parity Generator Circuit Since it is an odd parity system the bit P is generated so as to make the total number of 1s odd (including P) The function P can be expressed as follows
                                                                                                                                                                                                                                                          • Figure 91 Circuit Diagram for a 3-bit Parity Generator
                                                                                                                                                                                                                                                            • C = x Ο y Ο z Ο P
                                                                                                                                                                                                                                                              • Implementation and Observations
                                                                                                                                                                                                                                                                • ACTIVITY
                                                                                                                                                                                                                                                                    • 15-ldst-exp10
                                                                                                                                                                                                                                                                      • Driving a seven segment display using 7447 7448 driver IC
                                                                                                                                                                                                                                                                      • COMPONENTS AND APPARATUS REQUIRED
                                                                                                                                                                                                                                                                      • 1 Following ICs and their Datasheets
                                                                                                                                                                                                                                                                      • 7447 7448 BCD to Seven Segment Driver
                                                                                                                                                                                                                                                                      • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                                                                        • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches
                                                                                                                                                                                                                                                                          • THEORY
                                                                                                                                                                                                                                                                          • Seven Segment Displays
                                                                                                                                                                                                                                                                          • CIRCUIT DIAGRAM
                                                                                                                                                                                                                                                                          • Figure 102 Circuit diagram for 7447driving a common-anode display
                                                                                                                                                                                                                                                                              • IMPLEMENTATION AND OBSERVATIONS
                                                                                                                                                                                                                                                                                • Decimal Digit
                                                                                                                                                                                                                                                                                • BCD Inputs
                                                                                                                                                                                                                                                                                • Seven Segment Outputs
                                                                                                                                                                                                                                                                                • D
                                                                                                                                                                                                                                                                                • C
                                                                                                                                                                                                                                                                                • B
                                                                                                                                                                                                                                                                                • A
                                                                                                                                                                                                                                                                                • a
                                                                                                                                                                                                                                                                                • b
                                                                                                                                                                                                                                                                                • c
                                                                                                                                                                                                                                                                                • d
                                                                                                                                                                                                                                                                                • e
                                                                                                                                                                                                                                                                                • f
                                                                                                                                                                                                                                                                                • g
                                                                                                                                                                                                                                                                                • 0
                                                                                                                                                                                                                                                                                • 0
                                                                                                                                                                                                                                                                                • 0
                                                                                                                                                                                                                                                                                • 0
                                                                                                                                                                                                                                                                                • 0
                                                                                                                                                                                                                                                                                • 1
                                                                                                                                                                                                                                                                                • 0
                                                                                                                                                                                                                                                                                • 0
                                                                                                                                                                                                                                                                                • 0
                                                                                                                                                                                                                                                                                • 1
                                                                                                                                                                                                                                                                                • 2
                                                                                                                                                                                                                                                                                • 0
                                                                                                                                                                                                                                                                                • 0
                                                                                                                                                                                                                                                                                • 1
                                                                                                                                                                                                                                                                                • 0
                                                                                                                                                                                                                                                                                • 3
                                                                                                                                                                                                                                                                                • 0
                                                                                                                                                                                                                                                                                • 0
                                                                                                                                                                                                                                                                                • 1
                                                                                                                                                                                                                                                                                • 1
                                                                                                                                                                                                                                                                                • 4
                                                                                                                                                                                                                                                                                • 0
                                                                                                                                                                                                                                                                                • 1
                                                                                                                                                                                                                                                                                • 0
                                                                                                                                                                                                                                                                                • 0
                                                                                                                                                                                                                                                                                • 5
                                                                                                                                                                                                                                                                                • 0
                                                                                                                                                                                                                                                                                • 1
                                                                                                                                                                                                                                                                                • 0
                                                                                                                                                                                                                                                                                • 1
                                                                                                                                                                                                                                                                                • 6
                                                                                                                                                                                                                                                                                • 0
                                                                                                                                                                                                                                                                                • 1
                                                                                                                                                                                                                                                                                • 1
                                                                                                                                                                                                                                                                                • 0
                                                                                                                                                                                                                                                                                • 7
                                                                                                                                                                                                                                                                                • 0
                                                                                                                                                                                                                                                                                • 1
                                                                                                                                                                                                                                                                                • 1
                                                                                                                                                                                                                                                                                • 1
                                                                                                                                                                                                                                                                                • 8
                                                                                                                                                                                                                                                                                • 1
                                                                                                                                                                                                                                                                                • 0
                                                                                                                                                                                                                                                                                • 0
                                                                                                                                                                                                                                                                                • 0
                                                                                                                                                                                                                                                                                • 9
                                                                                                                                                                                                                                                                                • 1
                                                                                                                                                                                                                                                                                • 0
                                                                                                                                                                                                                                                                                • 0
                                                                                                                                                                                                                                                                                • 1
                                                                                                                                                                                                                                                                                  • ACTIVITY
                                                                                                                                                                                                                                                                                    • 16-ldst-exp11
                                                                                                                                                                                                                                                                                      • Lab Session 11
                                                                                                                                                                                                                                                                                        • OBJECT
                                                                                                                                                                                                                                                                                        • COMPONENTS AND APPARATUS REQUIRED
                                                                                                                                                                                                                                                                                          • 1 Following ICs and their Datasheets
                                                                                                                                                                                                                                                                                          • 7473 7476 JK Flip-Flop
                                                                                                                                                                                                                                                                                          • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                                                                                            • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                                                                                                            • Connecting wires Switches
                                                                                                                                                                                                                                                                                              • THEORY
                                                                                                                                                                                                                                                                                                  • Flip-Flop
                                                                                                                                                                                                                                                                                                  • JK Flip-Flop
                                                                                                                                                                                                                                                                                                    • Circuit Diagram
                                                                                                                                                                                                                                                                                                      • Observations
                                                                                                                                                                                                                                                                                                        • ACTIVITY
                                                                                                                                                                                                                                                                                                            • 17-ldst-exp12
                                                                                                                                                                                                                                                                                                              • Lab Session 12
                                                                                                                                                                                                                                                                                                                • OBJECT
                                                                                                                                                                                                                                                                                                                • GIVEN STATE DIAGRAM
                                                                                                                                                                                                                                                                                                                • Figure 121 State Diagram
                                                                                                                                                                                                                                                                                                                • COMPONENTS AND APPARATUS REQUIRED
                                                                                                                                                                                                                                                                                                                  • 1 Following ICs and their Datasheets
                                                                                                                                                                                                                                                                                                                  • 7474 D Flip-Flop
                                                                                                                                                                                                                                                                                                                  • ICs of basic gates (AND OR NOT XOR etc) as required
                                                                                                                                                                                                                                                                                                                  • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                                                                                                                    • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                                                                                                                                    • Connecting wires Switches
                                                                                                                                                                                                                                                                                                                      • THEORY
                                                                                                                                                                                                                                                                                                                          • Sequential Circuits
                                                                                                                                                                                                                                                                                                                            • 18-ldst-exp13
                                                                                                                                                                                                                                                                                                                              • Lab Session 13
                                                                                                                                                                                                                                                                                                                                • Designing a modulo-5 asynchronous up-counter using JK-FF
                                                                                                                                                                                                                                                                                                                                  • 1 Following ICs and their Datasheets
                                                                                                                                                                                                                                                                                                                                  • 7400 Quad 2-input or 7410 Triple 3-input NAND Gates
                                                                                                                                                                                                                                                                                                                                  • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                                                                                                                                    • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                                                                                                                                                    • Connecting wires Switches
                                                                                                                                                                                                                                                                                                                                      • THEORY
                                                                                                                                                                                                                                                                                                                                          • Figure 131 A Mod-5 Asynchronous Up Counter
                                                                                                                                                                                                                                                                                                                                          • Implementation and Observations
                                                                                                                                                                                                                                                                                                                                            • ACTIVITY
                                                                                                                                                                                                                                                                                                                                                • 19-ldst-exp14
                                                                                                                                                                                                                                                                                                                                                  • Experimenting with 74194 4-bit bidirectional universal shift register
                                                                                                                                                                                                                                                                                                                                                  • 1 Following ICs and their Datasheets
                                                                                                                                                                                                                                                                                                                                                  • 74194 4-bit bidirectional universal shift register
                                                                                                                                                                                                                                                                                                                                                  • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                                                                                                                                                    • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                                                                                                                                                                    • Connecting wires Switches
                                                                                                                                                                                                                                                                                                                                                      • THEORY
                                                                                                                                                                                                                                                                                                                                                        • Shift Registers
                                                                                                                                                                                                                                                                                                                                                        • Bidirectional Shift Registers
                                                                                                                                                                                                                                                                                                                                                        • Universal Shift Registers
                                                                                                                                                                                                                                                                                                                                                          • S1
                                                                                                                                                                                                                                                                                                                                                            • Circuit Diagram
                                                                                                                                                                                                                                                                                                                                                            • ACTIVITY
                                                                                                                                                                                                                                                                                                                                                                • 20-ldst-exp15
                                                                                                                                                                                                                                                                                                                                                                  • COMPONENTS AND APPARATUS REQUIRED
                                                                                                                                                                                                                                                                                                                                                                  • 1 Parallel Port Connectors (DB-25) with Cable
                                                                                                                                                                                                                                                                                                                                                                  • 2 Personal Computer with Windows 98 and TurboC Compiler Installed
                                                                                                                                                                                                                                                                                                                                                                  • 3 Following ICs and their Datasheets
                                                                                                                                                                                                                                                                                                                                                                  • 74245 Octal Bus Transceivers with 3-State Outputs
                                                                                                                                                                                                                                                                                                                                                                  • 4 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                                                                                                                                                                    • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                                                                                                                                                                                      • Connecting wires Switches
                                                                                                                                                                                                                                                                                                                                                                        • THEORY
                                                                                                                                                                                                                                                                                                                                                                        • 3-State Logic
                                                                                                                                                                                                                                                                                                                                                                          • Serial and Parallel Port Connectors
                                                                                                                                                                                                                                                                                                                                                                          • Parallel Port Connector ndash DB-25
                                                                                                                                                                                                                                                                                                                                                                            • Accessing parallel port through C Language Programming
                                                                                                                                                                                                                                                                                                                                                                                • 21-ldst-appendixA
                                                                                                                                                                                                                                                                                                                                                                                • 22-ldst-appendixB
                                                                                                                                                                                                                                                                                                                                                                                  • DEBOUNCING CIRCUITRY FOR MECHANICAL SWITCHES

                                                                                                          Logic Design amp Switching Theory 1 Lab Session 13 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                                                          55

                                                                                                          Figure 131 A Mod-5 Asynchronous Up Counter

                                                                                                          Implementation and Observations

                                                                                                          Implement the mod-5 counter circuit (figure 131) on a bread board (prepare the pin diagram (use appendix A) and refer to laboratory session 01 for implementation procedure) and record the observations in the following table

                                                                                                          Clock Pulse Q2 Q1 Q0

                                                                                                          0 1 2 3 4 5 6 7

                                                                                                          ACTIVITY

                                                                                                          Draw the timing diagram for mod-5 counter designed in this laboratory session

                                                                                                          Logic Design amp Switching Theory 1 Lab Session 14 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                                                          Lab Session 14 OBJECT

                                                                                                          Experimenting with 74194 4-bit bidirectional universal shift register COMPONENTS AND APPARATUS REQUIRED

                                                                                                          1 Following ICs and their Datasheets

                                                                                                          bull 74194 4-bit bidirectional universal shift register 2 Digital Trainer DT-01 or the following components

                                                                                                          Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches

                                                                                                          THEORY

                                                                                                          Shift Registers

                                                                                                          A Register is a set of flip-flops used to store binary data A register which is capable of shifting its binary information either to the right or left is called a shift register The logical configuration of a register consists of a chain of flip-flops connected in cascade with the output of one flip-flop connected to the input of next flip-flop All flip-flops receive a common clock pulse which causes the shift from one stage to the next

                                                                                                          Bidirectional Shift Registers A bi-directional shift register is one whose bits can be shifted from left to right or from right to left

                                                                                                          Universal Shift Registers A universal shift register is a bi-directional register whose input can be in either serial or parallel form and whose output can be in either serial or parallel form

                                                                                                          74194 4-BIT BIDIRECTIONAL UNIVERSAL SHIFT REGISTER

                                                                                                          The 74194 register provides parallel as well as serial loading in both directions Function of various pins of this IC is described below

                                                                                                          bull A B C and D Active high inputs for parallel loading bull QA QB QC and QD Active high outputs bull S0 and S1 Active high mode control inputs The following table shows combinations

                                                                                                          of S1 and S0 to enable various modes

                                                                                                          S1 S0 Clock Action 0 0 x No change 0 1 uarr Shift right 1 0 uarr Shift left 1 1 uarr Parallel load

                                                                                                          uarr shows the rising edge of the clock pulse

                                                                                                          56

                                                                                                          Logic Design amp Switching Theory 1 Lab Session 14 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering bull SR Active high serial input for right shifting bull SL Active high serial input for left shifting bull CLR Active low input Clears all the flip-flops of the register if set to 0 should be

                                                                                                          kept high otherwise bull CLK Clock input bull VCC and GND Supply connections lines Thus A B C and D are inputs for parallel loading whereas SR and SL are inputs for serial loading with right or left shifting respectively S1 and S0 are used to select the loading mode Circuit Diagram

                                                                                                          Figure 141 Pin connections of 74194 Testing Procedure

                                                                                                          bull Make connections as shown in the circuit diagram bull Observe the output for the input combinations given in the following table

                                                                                                          57

                                                                                                          Logic Design amp Switching Theory 1 Lab Session 14 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                                                          58

                                                                                                          Observations

                                                                                                          S1 S0 SL SR A B C D QA QB QC QD 0 0 0 1 0 0 0 0 0 1 1 0 0 0 0 1 1 0 0 0 0 0 1 0 1 1 0 0 0 0 1 1 0 0 1 1 0 1 0 0 0 1 1 1 0 1 0 1 1 0 1 0 0 1 1 0 1 1 1 0 0 1 1 1 1 1 0 0 1 1 1 1

                                                                                                          ACTIVITY 1 Show connections of 74194 to convert it into a ring counter with right shifting

                                                                                                          Logic Design amp Switching Theory 1 Lab Session 15 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                                                          Lab Session 15

                                                                                                          OBJECT

                                                                                                          Experimenting with 74245 octal bus transceivers using parallel port PC interfacing COMPONENTS AND APPARATUS REQUIRED 1 Parallel Port Connectors (DB-25) with Cable 2 Personal Computer with Windows 98 and TurboC Compiler Installed 3 Following ICs and their Datasheets

                                                                                                          bull 74245 Octal Bus Transceivers with 3-State Outputs 4 Digital Trainer DT-01 or the following components

                                                                                                          Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches

                                                                                                          THEORY

                                                                                                          3-State Logic Sometimes it is necessary to isolate one part of circuit from the other part For this purpose some TTL ICs are designed with 3-state logic Such devices have three possible output states high low and high impedance The device can be put into high impedance state by a control signal applied to an appropriate pin When such a device is in high impedance state there is very high impedance at its output effectively isolating the device from whatever circuitry the output normally drives 74245 Octal Bus Transceivers A bus is any conducting path or set of paths having electrical connections to one or more devices 74245 octal bus transceivers are mainly used to control connectivity between two devices or circuits It also provides direction control for signal flow Function of various pin of this IC is given below

                                                                                                          bull A1 through A8 Bus A bull B1 through B8 Bus B bull G΄ Active low enable input When high sets all the bus pins to high impedance state bull DIR Direction control for signal flow When set to high logic level transfers bus A

                                                                                                          data to B bus When set to low logic level transfers bus B data to A bus bull VCC and GND Supply connections lines Serial and Parallel Port Connectors A Parallel Port can consist of only 25 pin port adapter called a DB-25 and a serial port can consist of either a 25 pin port adapter called a DB-25 or 9 pin adapter called a DB-9 port adapter Whether the port is a 9 pin or 25 pin it can accomplish all of the same tasks that serial port communications have been designed for

                                                                                                          59

                                                                                                          Logic Design amp Switching Theory 1 Lab Session 15 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                                                          60

                                                                                                          Each adapter can be a male type connector with pins or a female type adapter with tiny holes Generally a PRINTER port (called LPT1) on the back of a computer is female type adapter and we need to use MALE DB-25 pin cable on it for PRINTER connection or for parallel LAPLINK cable And a COM port on the back of a computer is male for the serial ports but it may not necessarily be Parallel Port Connector ndash DB-25 The DB-25 connector (named for its B-size D-shaped shell and 25 pins) is practically ubiquitous in the electronics industry The DB-25 connector is used for a variety of purposes Two common applications are RS-232EIA-232 (serial) connections and the parallel printer interface on the IBM PC The DB-25 connector is also used for SCSI connections Normally the parallel port is used for output to a printer or other device It sends data 8-bits or one byte at a time in parallel The other lines available on the DB-25 connector are a combination of status lines control lines and ground lines The status and control lines are used for handshaking commands and feedback when we are talking to a printer

                                                                                                          Figure 152 DB-25 Female Figure 151 DB-25 Male

                                                                                                          Figure 153 Pin Layout for DB-25 As can be seen form figure 153 there are four types of pins in this connector

                                                                                                          bull Data pins (8 pins - D0 to D7) Active high bidirectional lines

                                                                                                          Logic Design amp Switching Theory 1 Lab Session 15 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering bull Control pins (4 pins - C0 to C3) C0 C1 and C3 are active low whereas C2 is active

                                                                                                          high These lines also are bidirectional bull Status pins (5 pins ndash S3 to S7) Only S7 is active low rest are active high input lines bull Ground pins (8 pins) Used as a reference signal for the low (below 05 volts) charge

                                                                                                          Parallel Port Addresses A DB-25 connector at a parallel port has three address one for each kind of pins register data status and control The first or base address generally refers to data register Second address is for status register and the third one is for control register In Windows 98 the base address is usually found to be 278H 378H or 3BCH Now if 378H is the base address then it refers to the data register whereas addresses for status and control register are respectively 379H and 37AH For Windows 98 the base address can be found as follows 1 On your Desktop right-click on My Computer and select Properties 2 Click on the Device Manager tab and find LPT1 under Plug and Play BIOS 3 After selecting LPT1 click the Properties button 4 Next select the Resources tab and the address should then appear next to InputOutput

                                                                                                          Range Accessing parallel port through C Language Programming There are multiple functions in C Language for accessing external ports The most commonly used are listed below

                                                                                                          bull unsigned char inportb(int portid) inportb reads a byte from a hardware port

                                                                                                          bull int inport(int portid) reads a word from a hardware port

                                                                                                          bull void outportb(int portid unsigned char value) outputs a byte to a hardware port

                                                                                                          bull void outport(int portid int value) outputs a word to a hardware port

                                                                                                          portid refers to the port address whereas value refers to the data to be sent TESTING 74245 USING PARALLEL PORT PC INTERFACING At one end the parallel port connector will be connected to the PC via parallel port cable and another connector (to be plugged into the PC parallel port slot) At the other end it will be connected to the buffer IC 74245 Data lines of the connector will be used to transfer 8-bit data between the PC and the buffer Out of the 8-bits of 74245 4-bits will be used to enter data which will be displayed at the monitor through a C language

                                                                                                          61

                                                                                                          Logic Design amp Switching Theory 1 Lab Session 15 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering program The remaining 4-bits will receive data from PC as entered by the user via keyboard

                                                                                                          Circuit Diagram

                                                                                                          Figure 154 Interface of 74245 to PC via Parallel Port

                                                                                                          Procedure

                                                                                                          1 Connect the DB-25 connector to the PC at one end and solder it to the circuit board at the other end

                                                                                                          2 Connect various pins of the connector and 74245 according to the circuit diagram shown in figure 152

                                                                                                          3 Using the functions listed in the previous section write a program in C language to operate various pins of the buffer The user interface of the program should provide option to the user whether to send or receive data from the port

                                                                                                          4 Set DIR switch to 1 5 Try sending some data bits to the port The result should be displayed at the LEDs 6 Set DIR switch to 0 7 Set some binary 4-bit value through the switches Try reading it via parallel port

                                                                                                          C Language Program

                                                                                                          A program to access parallel port for data transfers

                                                                                                          use header file include ltstdiohgt main program void main() define variable

                                                                                                          62

                                                                                                          Logic Design amp Switching Theory 1 Lab Session 15 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering unsigned int data=0 char choice while(1) printing option menu clrscr() printf(This program will send or receive a BCD digit from the parallel portn) printf(nPress your choice numbern) printf(n1 Send Data) printf(n2 Receive Data) printf(n3 Exitn) choice = getch() sending entered digit to the port if(choice == 1) input BCD digit printf(nEnter BCD digit to be sent to the port) data = getche() masking the first four bits data = data amp 0x0f sending to the port outportb(0x378data) printf(nThe BCD digit c has been sent to the port data) printing on screen the data received from the port else if(choice == 2) receiving data from the port data = inportb(0x378) masking the last four bits data = data amp 0xf0 shifting first four bits to make them the last four bits datagtgt=4 printf(nThe BCD digit set at the port is c data) exit else if(choice == 3) break key pressed is not in the menu else printf(nEnter valid choice number) printf(nnPress any key to continue) getch()

                                                                                                          63

                                                                                                          Logic Design amp Switching Theory 1 Lab Session 15 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                                                          ACTIVITY 1 In the above circuit DIR and G΄ inputs are hardwired Connect them to status or

                                                                                                          control pins of the parallel port connector and control their function through your software program Circuit Diagram Program Code ______________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________

                                                                                                          ___________________________________________________________________________________________________________________________________________________

                                                                                                          64

                                                                                                          Logic Design amp Switching Theory 1 Lab Session 15 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                                                          65

                                                                                                          _____________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ _____________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ _______________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ _________________________________________________ _________________________________________________

                                                                                                          Logic Design amp Switching Theory 1 Appendix A NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                                                          Appendix A

                                                                                                          PIN DIAGRAMS OF THE ICS REQUIRED FOR THE LABORATORY SESSIONS Consult the TTLIC data book for internal diagrams and electrical characteristics of these ICs 7400 Quad 2-Input NAND 7402 Quad 2-Input NOR

                                                                                                          7404 Hex Inverter 7408 Quad 2-Input AND

                                                                                                          7410 Triple 3-Input NAND 7411 Triple 3-Input AND

                                                                                                          7421 Dual 4-Input AND 7432 Quad 2-Input OR

                                                                                                          66

                                                                                                          Logic Design amp Switching Theory 1 Appendix A NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                                                          BCD-to-Seven Segm 7448 BCD-to-Seven Segment 7447 ent

                                                                                                          Decoder (15V OC) Decoder (2kΩ pull-up output)

                                                                                                          7473 Dual JK Flip-Flop 7474 Dual D-Type Flip-Flop

                                                                                                          7476 Dual JK Flop-Flop -Bit Binary Full Adder 7483 4 with Fast Carry

                                                                                                          86 Quad 2-Inpu 74138 3-to-8 Line 74 t Exclusive OR Decoder Demultiplexer

                                                                                                          67

                                                                                                          Logic Design amp Switching Theory 1 Appendix A NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                                                          68

                                                                                                          74148 8-to-3 Line 16-to-1 Line Data

                                                                                                          Priority Encoder 74150 Selector Multiplexer

                                                                                                          74245 Oct nsceivers Universal Shift Register (PIPO) (3-State)

                                                                                                          74194 4-Bit Bidirectional al Bus Tra

                                                                                                          Logic Design amp Switching Theory 1 Appendix B NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                                                          Appendix B

                                                                                                          DEBOUNCING CIRCUITRY FOR MECHANICAL SWITCHES Mechanical switches form the interface between human beings and computers or other digital systems For example a keyboard is a matrix of switches used to supply alphanumeric data to a computer Whatever the switch design it is a potential source of problems due to contact bounce The contact bounce creates a sense of narrow pulses when a switch is opened or closed An example of device whose operation would be adversely affected by contact bounce is a digital counter used to count the number of times a switch is depressed Eliminating the effects of contact bounce is called debouncing When data is entered into a computer via a keyboard a software debounce is often used This type of debouncing is a program that causes the computer to sample the switch terminal (ie to input data from it) many times in succession during the interval of time that contact bounce occurs If the data is sensed to be 1s (or 0s) for a specific number of consecutive samples then it is assumed that contact bounce has ended and the last value sensed is valid Hardware debouncing is the use of electronic circuitry to eliminate the effects of contact bounce There are numerous versions of such circuitry including those that use monostable multivibrators (one-shots) but the most straightforward is simply an RS latch Figure B1 shows the circuit When the switch is in position 1 R = 0 and S = 1 so the latch is set and the output (Q) is 1 When the switch is in position 0 R = 1and S = 0 so the latch is reset and the output is 0 When the switch is moved form one position to the other the latch changes state and bouncing occurs at either the R or the S input The bouncing does not affect the latch after it has change state An RS latch will remain set for example when its R input is 0 and its S input is alternately changed form 1 to 0

                                                                                                          Figure B1 Use of RS latch to debounce a mechanical switch

                                                                                                          69

                                                                                                          • 01-ldst-Outer title
                                                                                                            • Practical Workbook
                                                                                                            • Logic Design amp Switching Theory I
                                                                                                              • Dept of Computer amp Information Systems Engineering
                                                                                                                • NED University of Engineering amp Technology
                                                                                                                • Karachi ndash 75270 Pakistan
                                                                                                                  • 02-ldst-inner Title
                                                                                                                    • Practical Workbook
                                                                                                                    • Logic Design amp Switching Theory I
                                                                                                                      • Dept of Computer amp Information Systems Engineering
                                                                                                                        • NED University of Engineering amp Technology
                                                                                                                        • Karachi ndash 75270 Pakistan
                                                                                                                          • 03-ldst-general info
                                                                                                                          • 04-ldst-introduction
                                                                                                                          • 05-Table of Contents
                                                                                                                            • CONTENTS
                                                                                                                              • Lab Session No Object Page No
                                                                                                                              • 1
                                                                                                                              • Also implementing and testing the given circuit on a bread board
                                                                                                                                • Working with Electronics Workbench
                                                                                                                                  • Driving a seven segment display using 7447 7448 driver IC
                                                                                                                                    • Designing a modulus-5 asynchronous up-counter using JK-FF
                                                                                                                                      • Experimenting with 74194 4-bit bidirectional universal shift register
                                                                                                                                          • 13
                                                                                                                                              • 06-ldst-Exp01
                                                                                                                                                • Lab Session 01
                                                                                                                                                • OBJECT
                                                                                                                                                  • 1 Bread board
                                                                                                                                                  • 2 5 V - power supply
                                                                                                                                                  • 3 Multimeter
                                                                                                                                                  • 4 Logic probe
                                                                                                                                                  • 5 LEDs with resistors
                                                                                                                                                  • 6 Connecting wires
                                                                                                                                                  • 8 Following ICs and their datasheets
                                                                                                                                                    • THEORY
                                                                                                                                                      • Logic Gates
                                                                                                                                                      • 1 The AND Gate ndash An AND gatersquos output is 1 if and only if all its inputs are 1 If A and B are two inputs to an AND gate then output F of the gate is given as F = AB
                                                                                                                                                      • 2 The OR Gate - An OR gatersquos output is 1 if at least one of its input is 1 If A and B are two inputs to an OR gate then output F of the gate is given as F = A+B
                                                                                                                                                      • 3 The NOT Gate (Inverter) ndash Its output is 1 when its input is 0 and its output is 0 when the input is 1 ie it complements a digital variable If A is the input to a NOT gate then output F of the gate is given as
                                                                                                                                                      • 4 The NAND Gate ndash Its output is 1 if at least one of its input is 0 This gate performs the same logic as an AND gate followed by an inverter If A and B are two inputs to a NAND gate then output F of the gate is given as
                                                                                                                                                        • 5 The NOR Gate - The output of a NOR gate is 1 if and only if all its inputs are 0 This gate performs the same logic function as an OR gate followed by an inverter If A and B are two inputs to a NAND gate then output F of the gate is given as
                                                                                                                                                            • DATA SHEETS
                                                                                                                                                              • Logic expression for the given logic diagram __________________________________
                                                                                                                                                                  • 07-ldst-exp02
                                                                                                                                                                    • Working with Electronics Workbench
                                                                                                                                                                      • 08-ldst-exp03
                                                                                                                                                                        • Designing Half and Full Adder Circuits
                                                                                                                                                                          • COMPONENTS AND APPARATUS REQUIRED
                                                                                                                                                                            • 1 Following ICs and their Datasheets
                                                                                                                                                                            • 7408 Quad 2-input AND Gate
                                                                                                                                                                            • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                              • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                              • Connecting wires Switches
                                                                                                                                                                                • THEORY
                                                                                                                                                                                    • IMPLEMENTATION AND OBSERVATIONS
                                                                                                                                                                                      • 09-ldst-Exp04
                                                                                                                                                                                        • Lab Session 04
                                                                                                                                                                                        • 1 Digital ICs and their Datasheets
                                                                                                                                                                                        • 7408 Quad 2-input AND Gate
                                                                                                                                                                                        • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                          • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                          • Connecting wires Switches
                                                                                                                                                                                          • PROCEDURE
                                                                                                                                                                                          • REDUCTION OF LOGIC EXPRESSION USING KARNAUGH MAP
                                                                                                                                                                                          • OBSERVATIONS
                                                                                                                                                                                          • RESULT
                                                                                                                                                                                              • 10-ldst-Exp05
                                                                                                                                                                                                • Lab Session 05
                                                                                                                                                                                                • 1 Following ICs and their Datasheets
                                                                                                                                                                                                • 7408 Quad 2-input AND Gate
                                                                                                                                                                                                • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                  • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                  • (100 Ω) Connecting wires Switches
                                                                                                                                                                                                  • THEORY
                                                                                                                                                                                                    • IMPLEMENTATION AND OBSERVATIONS
                                                                                                                                                                                                      • 11-ldst-Exp06
                                                                                                                                                                                                        • OBJECT
                                                                                                                                                                                                        • 1 Following ICs and their Datasheets
                                                                                                                                                                                                        • 7408 Quad 2-input AND Gates or 7411 Triple 3-input AND Gates
                                                                                                                                                                                                        • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                          • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                          • Connecting wires Switches
                                                                                                                                                                                                            • Figure 62 Circuit Diagram for 4 x 1 Multiplexer
                                                                                                                                                                                                            • Implementation and Observations
                                                                                                                                                                                                              • Circuit Diagram
                                                                                                                                                                                                                • ACTIVITY
                                                                                                                                                                                                                  • 12-ldst-exp07
                                                                                                                                                                                                                    • 1 Following ICs and their Datasheets
                                                                                                                                                                                                                    • 7408 Quad 2-input or 7411 Triple 3-input AND Gates
                                                                                                                                                                                                                    • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                      • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                                      • Connecting wires Switches
                                                                                                                                                                                                                        • THEORY
                                                                                                                                                                                                                            • Figure 72 Circuit Diagram for 2 x 4 Decoder 1 x 4 Demultiplexer
                                                                                                                                                                                                                            • Implementation and Observations
                                                                                                                                                                                                                              • Circuit Diagram
                                                                                                                                                                                                                                • ACTIVITY
                                                                                                                                                                                                                                  • 13-ldst-Exp08
                                                                                                                                                                                                                                    • OBJECT
                                                                                                                                                                                                                                    • 1 Following ICs and their Datasheets
                                                                                                                                                                                                                                    • 7408 Quad 2-input or 7421 Dual 4-input AND Gates
                                                                                                                                                                                                                                    • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                                      • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                                                      • Connecting wires Switches
                                                                                                                                                                                                                                        • THEORY
                                                                                                                                                                                                                                            • Figure 81 Circuit Diagram for 4 x 2 Priority Encoder
                                                                                                                                                                                                                                            • Implementation and Observations
                                                                                                                                                                                                                                              • Therefore if GS A2 A1 and A0 are all low then it shows that line 0 is selected and if E0 A2 A1 and A0 are all low then it shows that none of the inputs selected E0 and GS cannot be in the same state provided that E1 is enabled
                                                                                                                                                                                                                                              • Circuit Diagram
                                                                                                                                                                                                                                                • ACTIVITY
                                                                                                                                                                                                                                                  • 14-ldst-exp09
                                                                                                                                                                                                                                                    • OBJECT
                                                                                                                                                                                                                                                    • 1 Following ICs and their Datasheets
                                                                                                                                                                                                                                                    • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                                                      • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                                                                      • Connecting wires Switches
                                                                                                                                                                                                                                                        • THEORY
                                                                                                                                                                                                                                                          • Parity Generator
                                                                                                                                                                                                                                                            • Let x y and z be the three bits that constitute the message and are the input to the Odd Parity Generator Circuit Since it is an odd parity system the bit P is generated so as to make the total number of 1s odd (including P) The function P can be expressed as follows
                                                                                                                                                                                                                                                            • Figure 91 Circuit Diagram for a 3-bit Parity Generator
                                                                                                                                                                                                                                                              • C = x Ο y Ο z Ο P
                                                                                                                                                                                                                                                                • Implementation and Observations
                                                                                                                                                                                                                                                                  • ACTIVITY
                                                                                                                                                                                                                                                                      • 15-ldst-exp10
                                                                                                                                                                                                                                                                        • Driving a seven segment display using 7447 7448 driver IC
                                                                                                                                                                                                                                                                        • COMPONENTS AND APPARATUS REQUIRED
                                                                                                                                                                                                                                                                        • 1 Following ICs and their Datasheets
                                                                                                                                                                                                                                                                        • 7447 7448 BCD to Seven Segment Driver
                                                                                                                                                                                                                                                                        • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                                                                          • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches
                                                                                                                                                                                                                                                                            • THEORY
                                                                                                                                                                                                                                                                            • Seven Segment Displays
                                                                                                                                                                                                                                                                            • CIRCUIT DIAGRAM
                                                                                                                                                                                                                                                                            • Figure 102 Circuit diagram for 7447driving a common-anode display
                                                                                                                                                                                                                                                                                • IMPLEMENTATION AND OBSERVATIONS
                                                                                                                                                                                                                                                                                  • Decimal Digit
                                                                                                                                                                                                                                                                                  • BCD Inputs
                                                                                                                                                                                                                                                                                  • Seven Segment Outputs
                                                                                                                                                                                                                                                                                  • D
                                                                                                                                                                                                                                                                                  • C
                                                                                                                                                                                                                                                                                  • B
                                                                                                                                                                                                                                                                                  • A
                                                                                                                                                                                                                                                                                  • a
                                                                                                                                                                                                                                                                                  • b
                                                                                                                                                                                                                                                                                  • c
                                                                                                                                                                                                                                                                                  • d
                                                                                                                                                                                                                                                                                  • e
                                                                                                                                                                                                                                                                                  • f
                                                                                                                                                                                                                                                                                  • g
                                                                                                                                                                                                                                                                                  • 0
                                                                                                                                                                                                                                                                                  • 0
                                                                                                                                                                                                                                                                                  • 0
                                                                                                                                                                                                                                                                                  • 0
                                                                                                                                                                                                                                                                                  • 0
                                                                                                                                                                                                                                                                                  • 1
                                                                                                                                                                                                                                                                                  • 0
                                                                                                                                                                                                                                                                                  • 0
                                                                                                                                                                                                                                                                                  • 0
                                                                                                                                                                                                                                                                                  • 1
                                                                                                                                                                                                                                                                                  • 2
                                                                                                                                                                                                                                                                                  • 0
                                                                                                                                                                                                                                                                                  • 0
                                                                                                                                                                                                                                                                                  • 1
                                                                                                                                                                                                                                                                                  • 0
                                                                                                                                                                                                                                                                                  • 3
                                                                                                                                                                                                                                                                                  • 0
                                                                                                                                                                                                                                                                                  • 0
                                                                                                                                                                                                                                                                                  • 1
                                                                                                                                                                                                                                                                                  • 1
                                                                                                                                                                                                                                                                                  • 4
                                                                                                                                                                                                                                                                                  • 0
                                                                                                                                                                                                                                                                                  • 1
                                                                                                                                                                                                                                                                                  • 0
                                                                                                                                                                                                                                                                                  • 0
                                                                                                                                                                                                                                                                                  • 5
                                                                                                                                                                                                                                                                                  • 0
                                                                                                                                                                                                                                                                                  • 1
                                                                                                                                                                                                                                                                                  • 0
                                                                                                                                                                                                                                                                                  • 1
                                                                                                                                                                                                                                                                                  • 6
                                                                                                                                                                                                                                                                                  • 0
                                                                                                                                                                                                                                                                                  • 1
                                                                                                                                                                                                                                                                                  • 1
                                                                                                                                                                                                                                                                                  • 0
                                                                                                                                                                                                                                                                                  • 7
                                                                                                                                                                                                                                                                                  • 0
                                                                                                                                                                                                                                                                                  • 1
                                                                                                                                                                                                                                                                                  • 1
                                                                                                                                                                                                                                                                                  • 1
                                                                                                                                                                                                                                                                                  • 8
                                                                                                                                                                                                                                                                                  • 1
                                                                                                                                                                                                                                                                                  • 0
                                                                                                                                                                                                                                                                                  • 0
                                                                                                                                                                                                                                                                                  • 0
                                                                                                                                                                                                                                                                                  • 9
                                                                                                                                                                                                                                                                                  • 1
                                                                                                                                                                                                                                                                                  • 0
                                                                                                                                                                                                                                                                                  • 0
                                                                                                                                                                                                                                                                                  • 1
                                                                                                                                                                                                                                                                                    • ACTIVITY
                                                                                                                                                                                                                                                                                      • 16-ldst-exp11
                                                                                                                                                                                                                                                                                        • Lab Session 11
                                                                                                                                                                                                                                                                                          • OBJECT
                                                                                                                                                                                                                                                                                          • COMPONENTS AND APPARATUS REQUIRED
                                                                                                                                                                                                                                                                                            • 1 Following ICs and their Datasheets
                                                                                                                                                                                                                                                                                            • 7473 7476 JK Flip-Flop
                                                                                                                                                                                                                                                                                            • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                                                                                              • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                                                                                                              • Connecting wires Switches
                                                                                                                                                                                                                                                                                                • THEORY
                                                                                                                                                                                                                                                                                                    • Flip-Flop
                                                                                                                                                                                                                                                                                                    • JK Flip-Flop
                                                                                                                                                                                                                                                                                                      • Circuit Diagram
                                                                                                                                                                                                                                                                                                        • Observations
                                                                                                                                                                                                                                                                                                          • ACTIVITY
                                                                                                                                                                                                                                                                                                              • 17-ldst-exp12
                                                                                                                                                                                                                                                                                                                • Lab Session 12
                                                                                                                                                                                                                                                                                                                  • OBJECT
                                                                                                                                                                                                                                                                                                                  • GIVEN STATE DIAGRAM
                                                                                                                                                                                                                                                                                                                  • Figure 121 State Diagram
                                                                                                                                                                                                                                                                                                                  • COMPONENTS AND APPARATUS REQUIRED
                                                                                                                                                                                                                                                                                                                    • 1 Following ICs and their Datasheets
                                                                                                                                                                                                                                                                                                                    • 7474 D Flip-Flop
                                                                                                                                                                                                                                                                                                                    • ICs of basic gates (AND OR NOT XOR etc) as required
                                                                                                                                                                                                                                                                                                                    • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                                                                                                                      • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                                                                                                                                      • Connecting wires Switches
                                                                                                                                                                                                                                                                                                                        • THEORY
                                                                                                                                                                                                                                                                                                                            • Sequential Circuits
                                                                                                                                                                                                                                                                                                                              • 18-ldst-exp13
                                                                                                                                                                                                                                                                                                                                • Lab Session 13
                                                                                                                                                                                                                                                                                                                                  • Designing a modulo-5 asynchronous up-counter using JK-FF
                                                                                                                                                                                                                                                                                                                                    • 1 Following ICs and their Datasheets
                                                                                                                                                                                                                                                                                                                                    • 7400 Quad 2-input or 7410 Triple 3-input NAND Gates
                                                                                                                                                                                                                                                                                                                                    • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                                                                                                                                      • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                                                                                                                                                      • Connecting wires Switches
                                                                                                                                                                                                                                                                                                                                        • THEORY
                                                                                                                                                                                                                                                                                                                                            • Figure 131 A Mod-5 Asynchronous Up Counter
                                                                                                                                                                                                                                                                                                                                            • Implementation and Observations
                                                                                                                                                                                                                                                                                                                                              • ACTIVITY
                                                                                                                                                                                                                                                                                                                                                  • 19-ldst-exp14
                                                                                                                                                                                                                                                                                                                                                    • Experimenting with 74194 4-bit bidirectional universal shift register
                                                                                                                                                                                                                                                                                                                                                    • 1 Following ICs and their Datasheets
                                                                                                                                                                                                                                                                                                                                                    • 74194 4-bit bidirectional universal shift register
                                                                                                                                                                                                                                                                                                                                                    • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                                                                                                                                                      • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                                                                                                                                                                      • Connecting wires Switches
                                                                                                                                                                                                                                                                                                                                                        • THEORY
                                                                                                                                                                                                                                                                                                                                                          • Shift Registers
                                                                                                                                                                                                                                                                                                                                                          • Bidirectional Shift Registers
                                                                                                                                                                                                                                                                                                                                                          • Universal Shift Registers
                                                                                                                                                                                                                                                                                                                                                            • S1
                                                                                                                                                                                                                                                                                                                                                              • Circuit Diagram
                                                                                                                                                                                                                                                                                                                                                              • ACTIVITY
                                                                                                                                                                                                                                                                                                                                                                  • 20-ldst-exp15
                                                                                                                                                                                                                                                                                                                                                                    • COMPONENTS AND APPARATUS REQUIRED
                                                                                                                                                                                                                                                                                                                                                                    • 1 Parallel Port Connectors (DB-25) with Cable
                                                                                                                                                                                                                                                                                                                                                                    • 2 Personal Computer with Windows 98 and TurboC Compiler Installed
                                                                                                                                                                                                                                                                                                                                                                    • 3 Following ICs and their Datasheets
                                                                                                                                                                                                                                                                                                                                                                    • 74245 Octal Bus Transceivers with 3-State Outputs
                                                                                                                                                                                                                                                                                                                                                                    • 4 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                                                                                                                                                                      • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                                                                                                                                                                                        • Connecting wires Switches
                                                                                                                                                                                                                                                                                                                                                                          • THEORY
                                                                                                                                                                                                                                                                                                                                                                          • 3-State Logic
                                                                                                                                                                                                                                                                                                                                                                            • Serial and Parallel Port Connectors
                                                                                                                                                                                                                                                                                                                                                                            • Parallel Port Connector ndash DB-25
                                                                                                                                                                                                                                                                                                                                                                              • Accessing parallel port through C Language Programming
                                                                                                                                                                                                                                                                                                                                                                                  • 21-ldst-appendixA
                                                                                                                                                                                                                                                                                                                                                                                  • 22-ldst-appendixB
                                                                                                                                                                                                                                                                                                                                                                                    • DEBOUNCING CIRCUITRY FOR MECHANICAL SWITCHES

                                                                                                            Logic Design amp Switching Theory 1 Lab Session 14 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                                                            Lab Session 14 OBJECT

                                                                                                            Experimenting with 74194 4-bit bidirectional universal shift register COMPONENTS AND APPARATUS REQUIRED

                                                                                                            1 Following ICs and their Datasheets

                                                                                                            bull 74194 4-bit bidirectional universal shift register 2 Digital Trainer DT-01 or the following components

                                                                                                            Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches

                                                                                                            THEORY

                                                                                                            Shift Registers

                                                                                                            A Register is a set of flip-flops used to store binary data A register which is capable of shifting its binary information either to the right or left is called a shift register The logical configuration of a register consists of a chain of flip-flops connected in cascade with the output of one flip-flop connected to the input of next flip-flop All flip-flops receive a common clock pulse which causes the shift from one stage to the next

                                                                                                            Bidirectional Shift Registers A bi-directional shift register is one whose bits can be shifted from left to right or from right to left

                                                                                                            Universal Shift Registers A universal shift register is a bi-directional register whose input can be in either serial or parallel form and whose output can be in either serial or parallel form

                                                                                                            74194 4-BIT BIDIRECTIONAL UNIVERSAL SHIFT REGISTER

                                                                                                            The 74194 register provides parallel as well as serial loading in both directions Function of various pins of this IC is described below

                                                                                                            bull A B C and D Active high inputs for parallel loading bull QA QB QC and QD Active high outputs bull S0 and S1 Active high mode control inputs The following table shows combinations

                                                                                                            of S1 and S0 to enable various modes

                                                                                                            S1 S0 Clock Action 0 0 x No change 0 1 uarr Shift right 1 0 uarr Shift left 1 1 uarr Parallel load

                                                                                                            uarr shows the rising edge of the clock pulse

                                                                                                            56

                                                                                                            Logic Design amp Switching Theory 1 Lab Session 14 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering bull SR Active high serial input for right shifting bull SL Active high serial input for left shifting bull CLR Active low input Clears all the flip-flops of the register if set to 0 should be

                                                                                                            kept high otherwise bull CLK Clock input bull VCC and GND Supply connections lines Thus A B C and D are inputs for parallel loading whereas SR and SL are inputs for serial loading with right or left shifting respectively S1 and S0 are used to select the loading mode Circuit Diagram

                                                                                                            Figure 141 Pin connections of 74194 Testing Procedure

                                                                                                            bull Make connections as shown in the circuit diagram bull Observe the output for the input combinations given in the following table

                                                                                                            57

                                                                                                            Logic Design amp Switching Theory 1 Lab Session 14 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                                                            58

                                                                                                            Observations

                                                                                                            S1 S0 SL SR A B C D QA QB QC QD 0 0 0 1 0 0 0 0 0 1 1 0 0 0 0 1 1 0 0 0 0 0 1 0 1 1 0 0 0 0 1 1 0 0 1 1 0 1 0 0 0 1 1 1 0 1 0 1 1 0 1 0 0 1 1 0 1 1 1 0 0 1 1 1 1 1 0 0 1 1 1 1

                                                                                                            ACTIVITY 1 Show connections of 74194 to convert it into a ring counter with right shifting

                                                                                                            Logic Design amp Switching Theory 1 Lab Session 15 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                                                            Lab Session 15

                                                                                                            OBJECT

                                                                                                            Experimenting with 74245 octal bus transceivers using parallel port PC interfacing COMPONENTS AND APPARATUS REQUIRED 1 Parallel Port Connectors (DB-25) with Cable 2 Personal Computer with Windows 98 and TurboC Compiler Installed 3 Following ICs and their Datasheets

                                                                                                            bull 74245 Octal Bus Transceivers with 3-State Outputs 4 Digital Trainer DT-01 or the following components

                                                                                                            Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches

                                                                                                            THEORY

                                                                                                            3-State Logic Sometimes it is necessary to isolate one part of circuit from the other part For this purpose some TTL ICs are designed with 3-state logic Such devices have three possible output states high low and high impedance The device can be put into high impedance state by a control signal applied to an appropriate pin When such a device is in high impedance state there is very high impedance at its output effectively isolating the device from whatever circuitry the output normally drives 74245 Octal Bus Transceivers A bus is any conducting path or set of paths having electrical connections to one or more devices 74245 octal bus transceivers are mainly used to control connectivity between two devices or circuits It also provides direction control for signal flow Function of various pin of this IC is given below

                                                                                                            bull A1 through A8 Bus A bull B1 through B8 Bus B bull G΄ Active low enable input When high sets all the bus pins to high impedance state bull DIR Direction control for signal flow When set to high logic level transfers bus A

                                                                                                            data to B bus When set to low logic level transfers bus B data to A bus bull VCC and GND Supply connections lines Serial and Parallel Port Connectors A Parallel Port can consist of only 25 pin port adapter called a DB-25 and a serial port can consist of either a 25 pin port adapter called a DB-25 or 9 pin adapter called a DB-9 port adapter Whether the port is a 9 pin or 25 pin it can accomplish all of the same tasks that serial port communications have been designed for

                                                                                                            59

                                                                                                            Logic Design amp Switching Theory 1 Lab Session 15 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                                                            60

                                                                                                            Each adapter can be a male type connector with pins or a female type adapter with tiny holes Generally a PRINTER port (called LPT1) on the back of a computer is female type adapter and we need to use MALE DB-25 pin cable on it for PRINTER connection or for parallel LAPLINK cable And a COM port on the back of a computer is male for the serial ports but it may not necessarily be Parallel Port Connector ndash DB-25 The DB-25 connector (named for its B-size D-shaped shell and 25 pins) is practically ubiquitous in the electronics industry The DB-25 connector is used for a variety of purposes Two common applications are RS-232EIA-232 (serial) connections and the parallel printer interface on the IBM PC The DB-25 connector is also used for SCSI connections Normally the parallel port is used for output to a printer or other device It sends data 8-bits or one byte at a time in parallel The other lines available on the DB-25 connector are a combination of status lines control lines and ground lines The status and control lines are used for handshaking commands and feedback when we are talking to a printer

                                                                                                            Figure 152 DB-25 Female Figure 151 DB-25 Male

                                                                                                            Figure 153 Pin Layout for DB-25 As can be seen form figure 153 there are four types of pins in this connector

                                                                                                            bull Data pins (8 pins - D0 to D7) Active high bidirectional lines

                                                                                                            Logic Design amp Switching Theory 1 Lab Session 15 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering bull Control pins (4 pins - C0 to C3) C0 C1 and C3 are active low whereas C2 is active

                                                                                                            high These lines also are bidirectional bull Status pins (5 pins ndash S3 to S7) Only S7 is active low rest are active high input lines bull Ground pins (8 pins) Used as a reference signal for the low (below 05 volts) charge

                                                                                                            Parallel Port Addresses A DB-25 connector at a parallel port has three address one for each kind of pins register data status and control The first or base address generally refers to data register Second address is for status register and the third one is for control register In Windows 98 the base address is usually found to be 278H 378H or 3BCH Now if 378H is the base address then it refers to the data register whereas addresses for status and control register are respectively 379H and 37AH For Windows 98 the base address can be found as follows 1 On your Desktop right-click on My Computer and select Properties 2 Click on the Device Manager tab and find LPT1 under Plug and Play BIOS 3 After selecting LPT1 click the Properties button 4 Next select the Resources tab and the address should then appear next to InputOutput

                                                                                                            Range Accessing parallel port through C Language Programming There are multiple functions in C Language for accessing external ports The most commonly used are listed below

                                                                                                            bull unsigned char inportb(int portid) inportb reads a byte from a hardware port

                                                                                                            bull int inport(int portid) reads a word from a hardware port

                                                                                                            bull void outportb(int portid unsigned char value) outputs a byte to a hardware port

                                                                                                            bull void outport(int portid int value) outputs a word to a hardware port

                                                                                                            portid refers to the port address whereas value refers to the data to be sent TESTING 74245 USING PARALLEL PORT PC INTERFACING At one end the parallel port connector will be connected to the PC via parallel port cable and another connector (to be plugged into the PC parallel port slot) At the other end it will be connected to the buffer IC 74245 Data lines of the connector will be used to transfer 8-bit data between the PC and the buffer Out of the 8-bits of 74245 4-bits will be used to enter data which will be displayed at the monitor through a C language

                                                                                                            61

                                                                                                            Logic Design amp Switching Theory 1 Lab Session 15 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering program The remaining 4-bits will receive data from PC as entered by the user via keyboard

                                                                                                            Circuit Diagram

                                                                                                            Figure 154 Interface of 74245 to PC via Parallel Port

                                                                                                            Procedure

                                                                                                            1 Connect the DB-25 connector to the PC at one end and solder it to the circuit board at the other end

                                                                                                            2 Connect various pins of the connector and 74245 according to the circuit diagram shown in figure 152

                                                                                                            3 Using the functions listed in the previous section write a program in C language to operate various pins of the buffer The user interface of the program should provide option to the user whether to send or receive data from the port

                                                                                                            4 Set DIR switch to 1 5 Try sending some data bits to the port The result should be displayed at the LEDs 6 Set DIR switch to 0 7 Set some binary 4-bit value through the switches Try reading it via parallel port

                                                                                                            C Language Program

                                                                                                            A program to access parallel port for data transfers

                                                                                                            use header file include ltstdiohgt main program void main() define variable

                                                                                                            62

                                                                                                            Logic Design amp Switching Theory 1 Lab Session 15 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering unsigned int data=0 char choice while(1) printing option menu clrscr() printf(This program will send or receive a BCD digit from the parallel portn) printf(nPress your choice numbern) printf(n1 Send Data) printf(n2 Receive Data) printf(n3 Exitn) choice = getch() sending entered digit to the port if(choice == 1) input BCD digit printf(nEnter BCD digit to be sent to the port) data = getche() masking the first four bits data = data amp 0x0f sending to the port outportb(0x378data) printf(nThe BCD digit c has been sent to the port data) printing on screen the data received from the port else if(choice == 2) receiving data from the port data = inportb(0x378) masking the last four bits data = data amp 0xf0 shifting first four bits to make them the last four bits datagtgt=4 printf(nThe BCD digit set at the port is c data) exit else if(choice == 3) break key pressed is not in the menu else printf(nEnter valid choice number) printf(nnPress any key to continue) getch()

                                                                                                            63

                                                                                                            Logic Design amp Switching Theory 1 Lab Session 15 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                                                            ACTIVITY 1 In the above circuit DIR and G΄ inputs are hardwired Connect them to status or

                                                                                                            control pins of the parallel port connector and control their function through your software program Circuit Diagram Program Code ______________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________

                                                                                                            ___________________________________________________________________________________________________________________________________________________

                                                                                                            64

                                                                                                            Logic Design amp Switching Theory 1 Lab Session 15 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                                                            65

                                                                                                            _____________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ _____________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ _______________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ _________________________________________________ _________________________________________________

                                                                                                            Logic Design amp Switching Theory 1 Appendix A NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                                                            Appendix A

                                                                                                            PIN DIAGRAMS OF THE ICS REQUIRED FOR THE LABORATORY SESSIONS Consult the TTLIC data book for internal diagrams and electrical characteristics of these ICs 7400 Quad 2-Input NAND 7402 Quad 2-Input NOR

                                                                                                            7404 Hex Inverter 7408 Quad 2-Input AND

                                                                                                            7410 Triple 3-Input NAND 7411 Triple 3-Input AND

                                                                                                            7421 Dual 4-Input AND 7432 Quad 2-Input OR

                                                                                                            66

                                                                                                            Logic Design amp Switching Theory 1 Appendix A NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                                                            BCD-to-Seven Segm 7448 BCD-to-Seven Segment 7447 ent

                                                                                                            Decoder (15V OC) Decoder (2kΩ pull-up output)

                                                                                                            7473 Dual JK Flip-Flop 7474 Dual D-Type Flip-Flop

                                                                                                            7476 Dual JK Flop-Flop -Bit Binary Full Adder 7483 4 with Fast Carry

                                                                                                            86 Quad 2-Inpu 74138 3-to-8 Line 74 t Exclusive OR Decoder Demultiplexer

                                                                                                            67

                                                                                                            Logic Design amp Switching Theory 1 Appendix A NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                                                            68

                                                                                                            74148 8-to-3 Line 16-to-1 Line Data

                                                                                                            Priority Encoder 74150 Selector Multiplexer

                                                                                                            74245 Oct nsceivers Universal Shift Register (PIPO) (3-State)

                                                                                                            74194 4-Bit Bidirectional al Bus Tra

                                                                                                            Logic Design amp Switching Theory 1 Appendix B NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                                                            Appendix B

                                                                                                            DEBOUNCING CIRCUITRY FOR MECHANICAL SWITCHES Mechanical switches form the interface between human beings and computers or other digital systems For example a keyboard is a matrix of switches used to supply alphanumeric data to a computer Whatever the switch design it is a potential source of problems due to contact bounce The contact bounce creates a sense of narrow pulses when a switch is opened or closed An example of device whose operation would be adversely affected by contact bounce is a digital counter used to count the number of times a switch is depressed Eliminating the effects of contact bounce is called debouncing When data is entered into a computer via a keyboard a software debounce is often used This type of debouncing is a program that causes the computer to sample the switch terminal (ie to input data from it) many times in succession during the interval of time that contact bounce occurs If the data is sensed to be 1s (or 0s) for a specific number of consecutive samples then it is assumed that contact bounce has ended and the last value sensed is valid Hardware debouncing is the use of electronic circuitry to eliminate the effects of contact bounce There are numerous versions of such circuitry including those that use monostable multivibrators (one-shots) but the most straightforward is simply an RS latch Figure B1 shows the circuit When the switch is in position 1 R = 0 and S = 1 so the latch is set and the output (Q) is 1 When the switch is in position 0 R = 1and S = 0 so the latch is reset and the output is 0 When the switch is moved form one position to the other the latch changes state and bouncing occurs at either the R or the S input The bouncing does not affect the latch after it has change state An RS latch will remain set for example when its R input is 0 and its S input is alternately changed form 1 to 0

                                                                                                            Figure B1 Use of RS latch to debounce a mechanical switch

                                                                                                            69

                                                                                                            • 01-ldst-Outer title
                                                                                                              • Practical Workbook
                                                                                                              • Logic Design amp Switching Theory I
                                                                                                                • Dept of Computer amp Information Systems Engineering
                                                                                                                  • NED University of Engineering amp Technology
                                                                                                                  • Karachi ndash 75270 Pakistan
                                                                                                                    • 02-ldst-inner Title
                                                                                                                      • Practical Workbook
                                                                                                                      • Logic Design amp Switching Theory I
                                                                                                                        • Dept of Computer amp Information Systems Engineering
                                                                                                                          • NED University of Engineering amp Technology
                                                                                                                          • Karachi ndash 75270 Pakistan
                                                                                                                            • 03-ldst-general info
                                                                                                                            • 04-ldst-introduction
                                                                                                                            • 05-Table of Contents
                                                                                                                              • CONTENTS
                                                                                                                                • Lab Session No Object Page No
                                                                                                                                • 1
                                                                                                                                • Also implementing and testing the given circuit on a bread board
                                                                                                                                  • Working with Electronics Workbench
                                                                                                                                    • Driving a seven segment display using 7447 7448 driver IC
                                                                                                                                      • Designing a modulus-5 asynchronous up-counter using JK-FF
                                                                                                                                        • Experimenting with 74194 4-bit bidirectional universal shift register
                                                                                                                                            • 13
                                                                                                                                                • 06-ldst-Exp01
                                                                                                                                                  • Lab Session 01
                                                                                                                                                  • OBJECT
                                                                                                                                                    • 1 Bread board
                                                                                                                                                    • 2 5 V - power supply
                                                                                                                                                    • 3 Multimeter
                                                                                                                                                    • 4 Logic probe
                                                                                                                                                    • 5 LEDs with resistors
                                                                                                                                                    • 6 Connecting wires
                                                                                                                                                    • 8 Following ICs and their datasheets
                                                                                                                                                      • THEORY
                                                                                                                                                        • Logic Gates
                                                                                                                                                        • 1 The AND Gate ndash An AND gatersquos output is 1 if and only if all its inputs are 1 If A and B are two inputs to an AND gate then output F of the gate is given as F = AB
                                                                                                                                                        • 2 The OR Gate - An OR gatersquos output is 1 if at least one of its input is 1 If A and B are two inputs to an OR gate then output F of the gate is given as F = A+B
                                                                                                                                                        • 3 The NOT Gate (Inverter) ndash Its output is 1 when its input is 0 and its output is 0 when the input is 1 ie it complements a digital variable If A is the input to a NOT gate then output F of the gate is given as
                                                                                                                                                        • 4 The NAND Gate ndash Its output is 1 if at least one of its input is 0 This gate performs the same logic as an AND gate followed by an inverter If A and B are two inputs to a NAND gate then output F of the gate is given as
                                                                                                                                                          • 5 The NOR Gate - The output of a NOR gate is 1 if and only if all its inputs are 0 This gate performs the same logic function as an OR gate followed by an inverter If A and B are two inputs to a NAND gate then output F of the gate is given as
                                                                                                                                                              • DATA SHEETS
                                                                                                                                                                • Logic expression for the given logic diagram __________________________________
                                                                                                                                                                    • 07-ldst-exp02
                                                                                                                                                                      • Working with Electronics Workbench
                                                                                                                                                                        • 08-ldst-exp03
                                                                                                                                                                          • Designing Half and Full Adder Circuits
                                                                                                                                                                            • COMPONENTS AND APPARATUS REQUIRED
                                                                                                                                                                              • 1 Following ICs and their Datasheets
                                                                                                                                                                              • 7408 Quad 2-input AND Gate
                                                                                                                                                                              • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                • Connecting wires Switches
                                                                                                                                                                                  • THEORY
                                                                                                                                                                                      • IMPLEMENTATION AND OBSERVATIONS
                                                                                                                                                                                        • 09-ldst-Exp04
                                                                                                                                                                                          • Lab Session 04
                                                                                                                                                                                          • 1 Digital ICs and their Datasheets
                                                                                                                                                                                          • 7408 Quad 2-input AND Gate
                                                                                                                                                                                          • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                            • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                            • Connecting wires Switches
                                                                                                                                                                                            • PROCEDURE
                                                                                                                                                                                            • REDUCTION OF LOGIC EXPRESSION USING KARNAUGH MAP
                                                                                                                                                                                            • OBSERVATIONS
                                                                                                                                                                                            • RESULT
                                                                                                                                                                                                • 10-ldst-Exp05
                                                                                                                                                                                                  • Lab Session 05
                                                                                                                                                                                                  • 1 Following ICs and their Datasheets
                                                                                                                                                                                                  • 7408 Quad 2-input AND Gate
                                                                                                                                                                                                  • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                    • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                    • (100 Ω) Connecting wires Switches
                                                                                                                                                                                                    • THEORY
                                                                                                                                                                                                      • IMPLEMENTATION AND OBSERVATIONS
                                                                                                                                                                                                        • 11-ldst-Exp06
                                                                                                                                                                                                          • OBJECT
                                                                                                                                                                                                          • 1 Following ICs and their Datasheets
                                                                                                                                                                                                          • 7408 Quad 2-input AND Gates or 7411 Triple 3-input AND Gates
                                                                                                                                                                                                          • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                            • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                            • Connecting wires Switches
                                                                                                                                                                                                              • Figure 62 Circuit Diagram for 4 x 1 Multiplexer
                                                                                                                                                                                                              • Implementation and Observations
                                                                                                                                                                                                                • Circuit Diagram
                                                                                                                                                                                                                  • ACTIVITY
                                                                                                                                                                                                                    • 12-ldst-exp07
                                                                                                                                                                                                                      • 1 Following ICs and their Datasheets
                                                                                                                                                                                                                      • 7408 Quad 2-input or 7411 Triple 3-input AND Gates
                                                                                                                                                                                                                      • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                        • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                                        • Connecting wires Switches
                                                                                                                                                                                                                          • THEORY
                                                                                                                                                                                                                              • Figure 72 Circuit Diagram for 2 x 4 Decoder 1 x 4 Demultiplexer
                                                                                                                                                                                                                              • Implementation and Observations
                                                                                                                                                                                                                                • Circuit Diagram
                                                                                                                                                                                                                                  • ACTIVITY
                                                                                                                                                                                                                                    • 13-ldst-Exp08
                                                                                                                                                                                                                                      • OBJECT
                                                                                                                                                                                                                                      • 1 Following ICs and their Datasheets
                                                                                                                                                                                                                                      • 7408 Quad 2-input or 7421 Dual 4-input AND Gates
                                                                                                                                                                                                                                      • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                                        • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                                                        • Connecting wires Switches
                                                                                                                                                                                                                                          • THEORY
                                                                                                                                                                                                                                              • Figure 81 Circuit Diagram for 4 x 2 Priority Encoder
                                                                                                                                                                                                                                              • Implementation and Observations
                                                                                                                                                                                                                                                • Therefore if GS A2 A1 and A0 are all low then it shows that line 0 is selected and if E0 A2 A1 and A0 are all low then it shows that none of the inputs selected E0 and GS cannot be in the same state provided that E1 is enabled
                                                                                                                                                                                                                                                • Circuit Diagram
                                                                                                                                                                                                                                                  • ACTIVITY
                                                                                                                                                                                                                                                    • 14-ldst-exp09
                                                                                                                                                                                                                                                      • OBJECT
                                                                                                                                                                                                                                                      • 1 Following ICs and their Datasheets
                                                                                                                                                                                                                                                      • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                                                        • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                                                                        • Connecting wires Switches
                                                                                                                                                                                                                                                          • THEORY
                                                                                                                                                                                                                                                            • Parity Generator
                                                                                                                                                                                                                                                              • Let x y and z be the three bits that constitute the message and are the input to the Odd Parity Generator Circuit Since it is an odd parity system the bit P is generated so as to make the total number of 1s odd (including P) The function P can be expressed as follows
                                                                                                                                                                                                                                                              • Figure 91 Circuit Diagram for a 3-bit Parity Generator
                                                                                                                                                                                                                                                                • C = x Ο y Ο z Ο P
                                                                                                                                                                                                                                                                  • Implementation and Observations
                                                                                                                                                                                                                                                                    • ACTIVITY
                                                                                                                                                                                                                                                                        • 15-ldst-exp10
                                                                                                                                                                                                                                                                          • Driving a seven segment display using 7447 7448 driver IC
                                                                                                                                                                                                                                                                          • COMPONENTS AND APPARATUS REQUIRED
                                                                                                                                                                                                                                                                          • 1 Following ICs and their Datasheets
                                                                                                                                                                                                                                                                          • 7447 7448 BCD to Seven Segment Driver
                                                                                                                                                                                                                                                                          • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                                                                            • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches
                                                                                                                                                                                                                                                                              • THEORY
                                                                                                                                                                                                                                                                              • Seven Segment Displays
                                                                                                                                                                                                                                                                              • CIRCUIT DIAGRAM
                                                                                                                                                                                                                                                                              • Figure 102 Circuit diagram for 7447driving a common-anode display
                                                                                                                                                                                                                                                                                  • IMPLEMENTATION AND OBSERVATIONS
                                                                                                                                                                                                                                                                                    • Decimal Digit
                                                                                                                                                                                                                                                                                    • BCD Inputs
                                                                                                                                                                                                                                                                                    • Seven Segment Outputs
                                                                                                                                                                                                                                                                                    • D
                                                                                                                                                                                                                                                                                    • C
                                                                                                                                                                                                                                                                                    • B
                                                                                                                                                                                                                                                                                    • A
                                                                                                                                                                                                                                                                                    • a
                                                                                                                                                                                                                                                                                    • b
                                                                                                                                                                                                                                                                                    • c
                                                                                                                                                                                                                                                                                    • d
                                                                                                                                                                                                                                                                                    • e
                                                                                                                                                                                                                                                                                    • f
                                                                                                                                                                                                                                                                                    • g
                                                                                                                                                                                                                                                                                    • 0
                                                                                                                                                                                                                                                                                    • 0
                                                                                                                                                                                                                                                                                    • 0
                                                                                                                                                                                                                                                                                    • 0
                                                                                                                                                                                                                                                                                    • 0
                                                                                                                                                                                                                                                                                    • 1
                                                                                                                                                                                                                                                                                    • 0
                                                                                                                                                                                                                                                                                    • 0
                                                                                                                                                                                                                                                                                    • 0
                                                                                                                                                                                                                                                                                    • 1
                                                                                                                                                                                                                                                                                    • 2
                                                                                                                                                                                                                                                                                    • 0
                                                                                                                                                                                                                                                                                    • 0
                                                                                                                                                                                                                                                                                    • 1
                                                                                                                                                                                                                                                                                    • 0
                                                                                                                                                                                                                                                                                    • 3
                                                                                                                                                                                                                                                                                    • 0
                                                                                                                                                                                                                                                                                    • 0
                                                                                                                                                                                                                                                                                    • 1
                                                                                                                                                                                                                                                                                    • 1
                                                                                                                                                                                                                                                                                    • 4
                                                                                                                                                                                                                                                                                    • 0
                                                                                                                                                                                                                                                                                    • 1
                                                                                                                                                                                                                                                                                    • 0
                                                                                                                                                                                                                                                                                    • 0
                                                                                                                                                                                                                                                                                    • 5
                                                                                                                                                                                                                                                                                    • 0
                                                                                                                                                                                                                                                                                    • 1
                                                                                                                                                                                                                                                                                    • 0
                                                                                                                                                                                                                                                                                    • 1
                                                                                                                                                                                                                                                                                    • 6
                                                                                                                                                                                                                                                                                    • 0
                                                                                                                                                                                                                                                                                    • 1
                                                                                                                                                                                                                                                                                    • 1
                                                                                                                                                                                                                                                                                    • 0
                                                                                                                                                                                                                                                                                    • 7
                                                                                                                                                                                                                                                                                    • 0
                                                                                                                                                                                                                                                                                    • 1
                                                                                                                                                                                                                                                                                    • 1
                                                                                                                                                                                                                                                                                    • 1
                                                                                                                                                                                                                                                                                    • 8
                                                                                                                                                                                                                                                                                    • 1
                                                                                                                                                                                                                                                                                    • 0
                                                                                                                                                                                                                                                                                    • 0
                                                                                                                                                                                                                                                                                    • 0
                                                                                                                                                                                                                                                                                    • 9
                                                                                                                                                                                                                                                                                    • 1
                                                                                                                                                                                                                                                                                    • 0
                                                                                                                                                                                                                                                                                    • 0
                                                                                                                                                                                                                                                                                    • 1
                                                                                                                                                                                                                                                                                      • ACTIVITY
                                                                                                                                                                                                                                                                                        • 16-ldst-exp11
                                                                                                                                                                                                                                                                                          • Lab Session 11
                                                                                                                                                                                                                                                                                            • OBJECT
                                                                                                                                                                                                                                                                                            • COMPONENTS AND APPARATUS REQUIRED
                                                                                                                                                                                                                                                                                              • 1 Following ICs and their Datasheets
                                                                                                                                                                                                                                                                                              • 7473 7476 JK Flip-Flop
                                                                                                                                                                                                                                                                                              • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                                                                                                • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                                                                                                                • Connecting wires Switches
                                                                                                                                                                                                                                                                                                  • THEORY
                                                                                                                                                                                                                                                                                                      • Flip-Flop
                                                                                                                                                                                                                                                                                                      • JK Flip-Flop
                                                                                                                                                                                                                                                                                                        • Circuit Diagram
                                                                                                                                                                                                                                                                                                          • Observations
                                                                                                                                                                                                                                                                                                            • ACTIVITY
                                                                                                                                                                                                                                                                                                                • 17-ldst-exp12
                                                                                                                                                                                                                                                                                                                  • Lab Session 12
                                                                                                                                                                                                                                                                                                                    • OBJECT
                                                                                                                                                                                                                                                                                                                    • GIVEN STATE DIAGRAM
                                                                                                                                                                                                                                                                                                                    • Figure 121 State Diagram
                                                                                                                                                                                                                                                                                                                    • COMPONENTS AND APPARATUS REQUIRED
                                                                                                                                                                                                                                                                                                                      • 1 Following ICs and their Datasheets
                                                                                                                                                                                                                                                                                                                      • 7474 D Flip-Flop
                                                                                                                                                                                                                                                                                                                      • ICs of basic gates (AND OR NOT XOR etc) as required
                                                                                                                                                                                                                                                                                                                      • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                                                                                                                        • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                                                                                                                                        • Connecting wires Switches
                                                                                                                                                                                                                                                                                                                          • THEORY
                                                                                                                                                                                                                                                                                                                              • Sequential Circuits
                                                                                                                                                                                                                                                                                                                                • 18-ldst-exp13
                                                                                                                                                                                                                                                                                                                                  • Lab Session 13
                                                                                                                                                                                                                                                                                                                                    • Designing a modulo-5 asynchronous up-counter using JK-FF
                                                                                                                                                                                                                                                                                                                                      • 1 Following ICs and their Datasheets
                                                                                                                                                                                                                                                                                                                                      • 7400 Quad 2-input or 7410 Triple 3-input NAND Gates
                                                                                                                                                                                                                                                                                                                                      • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                                                                                                                                        • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                                                                                                                                                        • Connecting wires Switches
                                                                                                                                                                                                                                                                                                                                          • THEORY
                                                                                                                                                                                                                                                                                                                                              • Figure 131 A Mod-5 Asynchronous Up Counter
                                                                                                                                                                                                                                                                                                                                              • Implementation and Observations
                                                                                                                                                                                                                                                                                                                                                • ACTIVITY
                                                                                                                                                                                                                                                                                                                                                    • 19-ldst-exp14
                                                                                                                                                                                                                                                                                                                                                      • Experimenting with 74194 4-bit bidirectional universal shift register
                                                                                                                                                                                                                                                                                                                                                      • 1 Following ICs and their Datasheets
                                                                                                                                                                                                                                                                                                                                                      • 74194 4-bit bidirectional universal shift register
                                                                                                                                                                                                                                                                                                                                                      • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                                                                                                                                                        • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                                                                                                                                                                        • Connecting wires Switches
                                                                                                                                                                                                                                                                                                                                                          • THEORY
                                                                                                                                                                                                                                                                                                                                                            • Shift Registers
                                                                                                                                                                                                                                                                                                                                                            • Bidirectional Shift Registers
                                                                                                                                                                                                                                                                                                                                                            • Universal Shift Registers
                                                                                                                                                                                                                                                                                                                                                              • S1
                                                                                                                                                                                                                                                                                                                                                                • Circuit Diagram
                                                                                                                                                                                                                                                                                                                                                                • ACTIVITY
                                                                                                                                                                                                                                                                                                                                                                    • 20-ldst-exp15
                                                                                                                                                                                                                                                                                                                                                                      • COMPONENTS AND APPARATUS REQUIRED
                                                                                                                                                                                                                                                                                                                                                                      • 1 Parallel Port Connectors (DB-25) with Cable
                                                                                                                                                                                                                                                                                                                                                                      • 2 Personal Computer with Windows 98 and TurboC Compiler Installed
                                                                                                                                                                                                                                                                                                                                                                      • 3 Following ICs and their Datasheets
                                                                                                                                                                                                                                                                                                                                                                      • 74245 Octal Bus Transceivers with 3-State Outputs
                                                                                                                                                                                                                                                                                                                                                                      • 4 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                                                                                                                                                                        • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                                                                                                                                                                                          • Connecting wires Switches
                                                                                                                                                                                                                                                                                                                                                                            • THEORY
                                                                                                                                                                                                                                                                                                                                                                            • 3-State Logic
                                                                                                                                                                                                                                                                                                                                                                              • Serial and Parallel Port Connectors
                                                                                                                                                                                                                                                                                                                                                                              • Parallel Port Connector ndash DB-25
                                                                                                                                                                                                                                                                                                                                                                                • Accessing parallel port through C Language Programming
                                                                                                                                                                                                                                                                                                                                                                                    • 21-ldst-appendixA
                                                                                                                                                                                                                                                                                                                                                                                    • 22-ldst-appendixB
                                                                                                                                                                                                                                                                                                                                                                                      • DEBOUNCING CIRCUITRY FOR MECHANICAL SWITCHES

                                                                                                              Logic Design amp Switching Theory 1 Lab Session 14 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering bull SR Active high serial input for right shifting bull SL Active high serial input for left shifting bull CLR Active low input Clears all the flip-flops of the register if set to 0 should be

                                                                                                              kept high otherwise bull CLK Clock input bull VCC and GND Supply connections lines Thus A B C and D are inputs for parallel loading whereas SR and SL are inputs for serial loading with right or left shifting respectively S1 and S0 are used to select the loading mode Circuit Diagram

                                                                                                              Figure 141 Pin connections of 74194 Testing Procedure

                                                                                                              bull Make connections as shown in the circuit diagram bull Observe the output for the input combinations given in the following table

                                                                                                              57

                                                                                                              Logic Design amp Switching Theory 1 Lab Session 14 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                                                              58

                                                                                                              Observations

                                                                                                              S1 S0 SL SR A B C D QA QB QC QD 0 0 0 1 0 0 0 0 0 1 1 0 0 0 0 1 1 0 0 0 0 0 1 0 1 1 0 0 0 0 1 1 0 0 1 1 0 1 0 0 0 1 1 1 0 1 0 1 1 0 1 0 0 1 1 0 1 1 1 0 0 1 1 1 1 1 0 0 1 1 1 1

                                                                                                              ACTIVITY 1 Show connections of 74194 to convert it into a ring counter with right shifting

                                                                                                              Logic Design amp Switching Theory 1 Lab Session 15 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                                                              Lab Session 15

                                                                                                              OBJECT

                                                                                                              Experimenting with 74245 octal bus transceivers using parallel port PC interfacing COMPONENTS AND APPARATUS REQUIRED 1 Parallel Port Connectors (DB-25) with Cable 2 Personal Computer with Windows 98 and TurboC Compiler Installed 3 Following ICs and their Datasheets

                                                                                                              bull 74245 Octal Bus Transceivers with 3-State Outputs 4 Digital Trainer DT-01 or the following components

                                                                                                              Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches

                                                                                                              THEORY

                                                                                                              3-State Logic Sometimes it is necessary to isolate one part of circuit from the other part For this purpose some TTL ICs are designed with 3-state logic Such devices have three possible output states high low and high impedance The device can be put into high impedance state by a control signal applied to an appropriate pin When such a device is in high impedance state there is very high impedance at its output effectively isolating the device from whatever circuitry the output normally drives 74245 Octal Bus Transceivers A bus is any conducting path or set of paths having electrical connections to one or more devices 74245 octal bus transceivers are mainly used to control connectivity between two devices or circuits It also provides direction control for signal flow Function of various pin of this IC is given below

                                                                                                              bull A1 through A8 Bus A bull B1 through B8 Bus B bull G΄ Active low enable input When high sets all the bus pins to high impedance state bull DIR Direction control for signal flow When set to high logic level transfers bus A

                                                                                                              data to B bus When set to low logic level transfers bus B data to A bus bull VCC and GND Supply connections lines Serial and Parallel Port Connectors A Parallel Port can consist of only 25 pin port adapter called a DB-25 and a serial port can consist of either a 25 pin port adapter called a DB-25 or 9 pin adapter called a DB-9 port adapter Whether the port is a 9 pin or 25 pin it can accomplish all of the same tasks that serial port communications have been designed for

                                                                                                              59

                                                                                                              Logic Design amp Switching Theory 1 Lab Session 15 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                                                              60

                                                                                                              Each adapter can be a male type connector with pins or a female type adapter with tiny holes Generally a PRINTER port (called LPT1) on the back of a computer is female type adapter and we need to use MALE DB-25 pin cable on it for PRINTER connection or for parallel LAPLINK cable And a COM port on the back of a computer is male for the serial ports but it may not necessarily be Parallel Port Connector ndash DB-25 The DB-25 connector (named for its B-size D-shaped shell and 25 pins) is practically ubiquitous in the electronics industry The DB-25 connector is used for a variety of purposes Two common applications are RS-232EIA-232 (serial) connections and the parallel printer interface on the IBM PC The DB-25 connector is also used for SCSI connections Normally the parallel port is used for output to a printer or other device It sends data 8-bits or one byte at a time in parallel The other lines available on the DB-25 connector are a combination of status lines control lines and ground lines The status and control lines are used for handshaking commands and feedback when we are talking to a printer

                                                                                                              Figure 152 DB-25 Female Figure 151 DB-25 Male

                                                                                                              Figure 153 Pin Layout for DB-25 As can be seen form figure 153 there are four types of pins in this connector

                                                                                                              bull Data pins (8 pins - D0 to D7) Active high bidirectional lines

                                                                                                              Logic Design amp Switching Theory 1 Lab Session 15 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering bull Control pins (4 pins - C0 to C3) C0 C1 and C3 are active low whereas C2 is active

                                                                                                              high These lines also are bidirectional bull Status pins (5 pins ndash S3 to S7) Only S7 is active low rest are active high input lines bull Ground pins (8 pins) Used as a reference signal for the low (below 05 volts) charge

                                                                                                              Parallel Port Addresses A DB-25 connector at a parallel port has three address one for each kind of pins register data status and control The first or base address generally refers to data register Second address is for status register and the third one is for control register In Windows 98 the base address is usually found to be 278H 378H or 3BCH Now if 378H is the base address then it refers to the data register whereas addresses for status and control register are respectively 379H and 37AH For Windows 98 the base address can be found as follows 1 On your Desktop right-click on My Computer and select Properties 2 Click on the Device Manager tab and find LPT1 under Plug and Play BIOS 3 After selecting LPT1 click the Properties button 4 Next select the Resources tab and the address should then appear next to InputOutput

                                                                                                              Range Accessing parallel port through C Language Programming There are multiple functions in C Language for accessing external ports The most commonly used are listed below

                                                                                                              bull unsigned char inportb(int portid) inportb reads a byte from a hardware port

                                                                                                              bull int inport(int portid) reads a word from a hardware port

                                                                                                              bull void outportb(int portid unsigned char value) outputs a byte to a hardware port

                                                                                                              bull void outport(int portid int value) outputs a word to a hardware port

                                                                                                              portid refers to the port address whereas value refers to the data to be sent TESTING 74245 USING PARALLEL PORT PC INTERFACING At one end the parallel port connector will be connected to the PC via parallel port cable and another connector (to be plugged into the PC parallel port slot) At the other end it will be connected to the buffer IC 74245 Data lines of the connector will be used to transfer 8-bit data between the PC and the buffer Out of the 8-bits of 74245 4-bits will be used to enter data which will be displayed at the monitor through a C language

                                                                                                              61

                                                                                                              Logic Design amp Switching Theory 1 Lab Session 15 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering program The remaining 4-bits will receive data from PC as entered by the user via keyboard

                                                                                                              Circuit Diagram

                                                                                                              Figure 154 Interface of 74245 to PC via Parallel Port

                                                                                                              Procedure

                                                                                                              1 Connect the DB-25 connector to the PC at one end and solder it to the circuit board at the other end

                                                                                                              2 Connect various pins of the connector and 74245 according to the circuit diagram shown in figure 152

                                                                                                              3 Using the functions listed in the previous section write a program in C language to operate various pins of the buffer The user interface of the program should provide option to the user whether to send or receive data from the port

                                                                                                              4 Set DIR switch to 1 5 Try sending some data bits to the port The result should be displayed at the LEDs 6 Set DIR switch to 0 7 Set some binary 4-bit value through the switches Try reading it via parallel port

                                                                                                              C Language Program

                                                                                                              A program to access parallel port for data transfers

                                                                                                              use header file include ltstdiohgt main program void main() define variable

                                                                                                              62

                                                                                                              Logic Design amp Switching Theory 1 Lab Session 15 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering unsigned int data=0 char choice while(1) printing option menu clrscr() printf(This program will send or receive a BCD digit from the parallel portn) printf(nPress your choice numbern) printf(n1 Send Data) printf(n2 Receive Data) printf(n3 Exitn) choice = getch() sending entered digit to the port if(choice == 1) input BCD digit printf(nEnter BCD digit to be sent to the port) data = getche() masking the first four bits data = data amp 0x0f sending to the port outportb(0x378data) printf(nThe BCD digit c has been sent to the port data) printing on screen the data received from the port else if(choice == 2) receiving data from the port data = inportb(0x378) masking the last four bits data = data amp 0xf0 shifting first four bits to make them the last four bits datagtgt=4 printf(nThe BCD digit set at the port is c data) exit else if(choice == 3) break key pressed is not in the menu else printf(nEnter valid choice number) printf(nnPress any key to continue) getch()

                                                                                                              63

                                                                                                              Logic Design amp Switching Theory 1 Lab Session 15 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                                                              ACTIVITY 1 In the above circuit DIR and G΄ inputs are hardwired Connect them to status or

                                                                                                              control pins of the parallel port connector and control their function through your software program Circuit Diagram Program Code ______________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________

                                                                                                              ___________________________________________________________________________________________________________________________________________________

                                                                                                              64

                                                                                                              Logic Design amp Switching Theory 1 Lab Session 15 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                                                              65

                                                                                                              _____________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ _____________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ _______________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ _________________________________________________ _________________________________________________

                                                                                                              Logic Design amp Switching Theory 1 Appendix A NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                                                              Appendix A

                                                                                                              PIN DIAGRAMS OF THE ICS REQUIRED FOR THE LABORATORY SESSIONS Consult the TTLIC data book for internal diagrams and electrical characteristics of these ICs 7400 Quad 2-Input NAND 7402 Quad 2-Input NOR

                                                                                                              7404 Hex Inverter 7408 Quad 2-Input AND

                                                                                                              7410 Triple 3-Input NAND 7411 Triple 3-Input AND

                                                                                                              7421 Dual 4-Input AND 7432 Quad 2-Input OR

                                                                                                              66

                                                                                                              Logic Design amp Switching Theory 1 Appendix A NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                                                              BCD-to-Seven Segm 7448 BCD-to-Seven Segment 7447 ent

                                                                                                              Decoder (15V OC) Decoder (2kΩ pull-up output)

                                                                                                              7473 Dual JK Flip-Flop 7474 Dual D-Type Flip-Flop

                                                                                                              7476 Dual JK Flop-Flop -Bit Binary Full Adder 7483 4 with Fast Carry

                                                                                                              86 Quad 2-Inpu 74138 3-to-8 Line 74 t Exclusive OR Decoder Demultiplexer

                                                                                                              67

                                                                                                              Logic Design amp Switching Theory 1 Appendix A NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                                                              68

                                                                                                              74148 8-to-3 Line 16-to-1 Line Data

                                                                                                              Priority Encoder 74150 Selector Multiplexer

                                                                                                              74245 Oct nsceivers Universal Shift Register (PIPO) (3-State)

                                                                                                              74194 4-Bit Bidirectional al Bus Tra

                                                                                                              Logic Design amp Switching Theory 1 Appendix B NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                                                              Appendix B

                                                                                                              DEBOUNCING CIRCUITRY FOR MECHANICAL SWITCHES Mechanical switches form the interface between human beings and computers or other digital systems For example a keyboard is a matrix of switches used to supply alphanumeric data to a computer Whatever the switch design it is a potential source of problems due to contact bounce The contact bounce creates a sense of narrow pulses when a switch is opened or closed An example of device whose operation would be adversely affected by contact bounce is a digital counter used to count the number of times a switch is depressed Eliminating the effects of contact bounce is called debouncing When data is entered into a computer via a keyboard a software debounce is often used This type of debouncing is a program that causes the computer to sample the switch terminal (ie to input data from it) many times in succession during the interval of time that contact bounce occurs If the data is sensed to be 1s (or 0s) for a specific number of consecutive samples then it is assumed that contact bounce has ended and the last value sensed is valid Hardware debouncing is the use of electronic circuitry to eliminate the effects of contact bounce There are numerous versions of such circuitry including those that use monostable multivibrators (one-shots) but the most straightforward is simply an RS latch Figure B1 shows the circuit When the switch is in position 1 R = 0 and S = 1 so the latch is set and the output (Q) is 1 When the switch is in position 0 R = 1and S = 0 so the latch is reset and the output is 0 When the switch is moved form one position to the other the latch changes state and bouncing occurs at either the R or the S input The bouncing does not affect the latch after it has change state An RS latch will remain set for example when its R input is 0 and its S input is alternately changed form 1 to 0

                                                                                                              Figure B1 Use of RS latch to debounce a mechanical switch

                                                                                                              69

                                                                                                              • 01-ldst-Outer title
                                                                                                                • Practical Workbook
                                                                                                                • Logic Design amp Switching Theory I
                                                                                                                  • Dept of Computer amp Information Systems Engineering
                                                                                                                    • NED University of Engineering amp Technology
                                                                                                                    • Karachi ndash 75270 Pakistan
                                                                                                                      • 02-ldst-inner Title
                                                                                                                        • Practical Workbook
                                                                                                                        • Logic Design amp Switching Theory I
                                                                                                                          • Dept of Computer amp Information Systems Engineering
                                                                                                                            • NED University of Engineering amp Technology
                                                                                                                            • Karachi ndash 75270 Pakistan
                                                                                                                              • 03-ldst-general info
                                                                                                                              • 04-ldst-introduction
                                                                                                                              • 05-Table of Contents
                                                                                                                                • CONTENTS
                                                                                                                                  • Lab Session No Object Page No
                                                                                                                                  • 1
                                                                                                                                  • Also implementing and testing the given circuit on a bread board
                                                                                                                                    • Working with Electronics Workbench
                                                                                                                                      • Driving a seven segment display using 7447 7448 driver IC
                                                                                                                                        • Designing a modulus-5 asynchronous up-counter using JK-FF
                                                                                                                                          • Experimenting with 74194 4-bit bidirectional universal shift register
                                                                                                                                              • 13
                                                                                                                                                  • 06-ldst-Exp01
                                                                                                                                                    • Lab Session 01
                                                                                                                                                    • OBJECT
                                                                                                                                                      • 1 Bread board
                                                                                                                                                      • 2 5 V - power supply
                                                                                                                                                      • 3 Multimeter
                                                                                                                                                      • 4 Logic probe
                                                                                                                                                      • 5 LEDs with resistors
                                                                                                                                                      • 6 Connecting wires
                                                                                                                                                      • 8 Following ICs and their datasheets
                                                                                                                                                        • THEORY
                                                                                                                                                          • Logic Gates
                                                                                                                                                          • 1 The AND Gate ndash An AND gatersquos output is 1 if and only if all its inputs are 1 If A and B are two inputs to an AND gate then output F of the gate is given as F = AB
                                                                                                                                                          • 2 The OR Gate - An OR gatersquos output is 1 if at least one of its input is 1 If A and B are two inputs to an OR gate then output F of the gate is given as F = A+B
                                                                                                                                                          • 3 The NOT Gate (Inverter) ndash Its output is 1 when its input is 0 and its output is 0 when the input is 1 ie it complements a digital variable If A is the input to a NOT gate then output F of the gate is given as
                                                                                                                                                          • 4 The NAND Gate ndash Its output is 1 if at least one of its input is 0 This gate performs the same logic as an AND gate followed by an inverter If A and B are two inputs to a NAND gate then output F of the gate is given as
                                                                                                                                                            • 5 The NOR Gate - The output of a NOR gate is 1 if and only if all its inputs are 0 This gate performs the same logic function as an OR gate followed by an inverter If A and B are two inputs to a NAND gate then output F of the gate is given as
                                                                                                                                                                • DATA SHEETS
                                                                                                                                                                  • Logic expression for the given logic diagram __________________________________
                                                                                                                                                                      • 07-ldst-exp02
                                                                                                                                                                        • Working with Electronics Workbench
                                                                                                                                                                          • 08-ldst-exp03
                                                                                                                                                                            • Designing Half and Full Adder Circuits
                                                                                                                                                                              • COMPONENTS AND APPARATUS REQUIRED
                                                                                                                                                                                • 1 Following ICs and their Datasheets
                                                                                                                                                                                • 7408 Quad 2-input AND Gate
                                                                                                                                                                                • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                  • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                  • Connecting wires Switches
                                                                                                                                                                                    • THEORY
                                                                                                                                                                                        • IMPLEMENTATION AND OBSERVATIONS
                                                                                                                                                                                          • 09-ldst-Exp04
                                                                                                                                                                                            • Lab Session 04
                                                                                                                                                                                            • 1 Digital ICs and their Datasheets
                                                                                                                                                                                            • 7408 Quad 2-input AND Gate
                                                                                                                                                                                            • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                              • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                              • Connecting wires Switches
                                                                                                                                                                                              • PROCEDURE
                                                                                                                                                                                              • REDUCTION OF LOGIC EXPRESSION USING KARNAUGH MAP
                                                                                                                                                                                              • OBSERVATIONS
                                                                                                                                                                                              • RESULT
                                                                                                                                                                                                  • 10-ldst-Exp05
                                                                                                                                                                                                    • Lab Session 05
                                                                                                                                                                                                    • 1 Following ICs and their Datasheets
                                                                                                                                                                                                    • 7408 Quad 2-input AND Gate
                                                                                                                                                                                                    • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                      • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                      • (100 Ω) Connecting wires Switches
                                                                                                                                                                                                      • THEORY
                                                                                                                                                                                                        • IMPLEMENTATION AND OBSERVATIONS
                                                                                                                                                                                                          • 11-ldst-Exp06
                                                                                                                                                                                                            • OBJECT
                                                                                                                                                                                                            • 1 Following ICs and their Datasheets
                                                                                                                                                                                                            • 7408 Quad 2-input AND Gates or 7411 Triple 3-input AND Gates
                                                                                                                                                                                                            • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                              • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                              • Connecting wires Switches
                                                                                                                                                                                                                • Figure 62 Circuit Diagram for 4 x 1 Multiplexer
                                                                                                                                                                                                                • Implementation and Observations
                                                                                                                                                                                                                  • Circuit Diagram
                                                                                                                                                                                                                    • ACTIVITY
                                                                                                                                                                                                                      • 12-ldst-exp07
                                                                                                                                                                                                                        • 1 Following ICs and their Datasheets
                                                                                                                                                                                                                        • 7408 Quad 2-input or 7411 Triple 3-input AND Gates
                                                                                                                                                                                                                        • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                          • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                                          • Connecting wires Switches
                                                                                                                                                                                                                            • THEORY
                                                                                                                                                                                                                                • Figure 72 Circuit Diagram for 2 x 4 Decoder 1 x 4 Demultiplexer
                                                                                                                                                                                                                                • Implementation and Observations
                                                                                                                                                                                                                                  • Circuit Diagram
                                                                                                                                                                                                                                    • ACTIVITY
                                                                                                                                                                                                                                      • 13-ldst-Exp08
                                                                                                                                                                                                                                        • OBJECT
                                                                                                                                                                                                                                        • 1 Following ICs and their Datasheets
                                                                                                                                                                                                                                        • 7408 Quad 2-input or 7421 Dual 4-input AND Gates
                                                                                                                                                                                                                                        • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                                          • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                                                          • Connecting wires Switches
                                                                                                                                                                                                                                            • THEORY
                                                                                                                                                                                                                                                • Figure 81 Circuit Diagram for 4 x 2 Priority Encoder
                                                                                                                                                                                                                                                • Implementation and Observations
                                                                                                                                                                                                                                                  • Therefore if GS A2 A1 and A0 are all low then it shows that line 0 is selected and if E0 A2 A1 and A0 are all low then it shows that none of the inputs selected E0 and GS cannot be in the same state provided that E1 is enabled
                                                                                                                                                                                                                                                  • Circuit Diagram
                                                                                                                                                                                                                                                    • ACTIVITY
                                                                                                                                                                                                                                                      • 14-ldst-exp09
                                                                                                                                                                                                                                                        • OBJECT
                                                                                                                                                                                                                                                        • 1 Following ICs and their Datasheets
                                                                                                                                                                                                                                                        • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                                                          • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                                                                          • Connecting wires Switches
                                                                                                                                                                                                                                                            • THEORY
                                                                                                                                                                                                                                                              • Parity Generator
                                                                                                                                                                                                                                                                • Let x y and z be the three bits that constitute the message and are the input to the Odd Parity Generator Circuit Since it is an odd parity system the bit P is generated so as to make the total number of 1s odd (including P) The function P can be expressed as follows
                                                                                                                                                                                                                                                                • Figure 91 Circuit Diagram for a 3-bit Parity Generator
                                                                                                                                                                                                                                                                  • C = x Ο y Ο z Ο P
                                                                                                                                                                                                                                                                    • Implementation and Observations
                                                                                                                                                                                                                                                                      • ACTIVITY
                                                                                                                                                                                                                                                                          • 15-ldst-exp10
                                                                                                                                                                                                                                                                            • Driving a seven segment display using 7447 7448 driver IC
                                                                                                                                                                                                                                                                            • COMPONENTS AND APPARATUS REQUIRED
                                                                                                                                                                                                                                                                            • 1 Following ICs and their Datasheets
                                                                                                                                                                                                                                                                            • 7447 7448 BCD to Seven Segment Driver
                                                                                                                                                                                                                                                                            • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                                                                              • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches
                                                                                                                                                                                                                                                                                • THEORY
                                                                                                                                                                                                                                                                                • Seven Segment Displays
                                                                                                                                                                                                                                                                                • CIRCUIT DIAGRAM
                                                                                                                                                                                                                                                                                • Figure 102 Circuit diagram for 7447driving a common-anode display
                                                                                                                                                                                                                                                                                    • IMPLEMENTATION AND OBSERVATIONS
                                                                                                                                                                                                                                                                                      • Decimal Digit
                                                                                                                                                                                                                                                                                      • BCD Inputs
                                                                                                                                                                                                                                                                                      • Seven Segment Outputs
                                                                                                                                                                                                                                                                                      • D
                                                                                                                                                                                                                                                                                      • C
                                                                                                                                                                                                                                                                                      • B
                                                                                                                                                                                                                                                                                      • A
                                                                                                                                                                                                                                                                                      • a
                                                                                                                                                                                                                                                                                      • b
                                                                                                                                                                                                                                                                                      • c
                                                                                                                                                                                                                                                                                      • d
                                                                                                                                                                                                                                                                                      • e
                                                                                                                                                                                                                                                                                      • f
                                                                                                                                                                                                                                                                                      • g
                                                                                                                                                                                                                                                                                      • 0
                                                                                                                                                                                                                                                                                      • 0
                                                                                                                                                                                                                                                                                      • 0
                                                                                                                                                                                                                                                                                      • 0
                                                                                                                                                                                                                                                                                      • 0
                                                                                                                                                                                                                                                                                      • 1
                                                                                                                                                                                                                                                                                      • 0
                                                                                                                                                                                                                                                                                      • 0
                                                                                                                                                                                                                                                                                      • 0
                                                                                                                                                                                                                                                                                      • 1
                                                                                                                                                                                                                                                                                      • 2
                                                                                                                                                                                                                                                                                      • 0
                                                                                                                                                                                                                                                                                      • 0
                                                                                                                                                                                                                                                                                      • 1
                                                                                                                                                                                                                                                                                      • 0
                                                                                                                                                                                                                                                                                      • 3
                                                                                                                                                                                                                                                                                      • 0
                                                                                                                                                                                                                                                                                      • 0
                                                                                                                                                                                                                                                                                      • 1
                                                                                                                                                                                                                                                                                      • 1
                                                                                                                                                                                                                                                                                      • 4
                                                                                                                                                                                                                                                                                      • 0
                                                                                                                                                                                                                                                                                      • 1
                                                                                                                                                                                                                                                                                      • 0
                                                                                                                                                                                                                                                                                      • 0
                                                                                                                                                                                                                                                                                      • 5
                                                                                                                                                                                                                                                                                      • 0
                                                                                                                                                                                                                                                                                      • 1
                                                                                                                                                                                                                                                                                      • 0
                                                                                                                                                                                                                                                                                      • 1
                                                                                                                                                                                                                                                                                      • 6
                                                                                                                                                                                                                                                                                      • 0
                                                                                                                                                                                                                                                                                      • 1
                                                                                                                                                                                                                                                                                      • 1
                                                                                                                                                                                                                                                                                      • 0
                                                                                                                                                                                                                                                                                      • 7
                                                                                                                                                                                                                                                                                      • 0
                                                                                                                                                                                                                                                                                      • 1
                                                                                                                                                                                                                                                                                      • 1
                                                                                                                                                                                                                                                                                      • 1
                                                                                                                                                                                                                                                                                      • 8
                                                                                                                                                                                                                                                                                      • 1
                                                                                                                                                                                                                                                                                      • 0
                                                                                                                                                                                                                                                                                      • 0
                                                                                                                                                                                                                                                                                      • 0
                                                                                                                                                                                                                                                                                      • 9
                                                                                                                                                                                                                                                                                      • 1
                                                                                                                                                                                                                                                                                      • 0
                                                                                                                                                                                                                                                                                      • 0
                                                                                                                                                                                                                                                                                      • 1
                                                                                                                                                                                                                                                                                        • ACTIVITY
                                                                                                                                                                                                                                                                                          • 16-ldst-exp11
                                                                                                                                                                                                                                                                                            • Lab Session 11
                                                                                                                                                                                                                                                                                              • OBJECT
                                                                                                                                                                                                                                                                                              • COMPONENTS AND APPARATUS REQUIRED
                                                                                                                                                                                                                                                                                                • 1 Following ICs and their Datasheets
                                                                                                                                                                                                                                                                                                • 7473 7476 JK Flip-Flop
                                                                                                                                                                                                                                                                                                • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                                                                                                  • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                                                                                                                  • Connecting wires Switches
                                                                                                                                                                                                                                                                                                    • THEORY
                                                                                                                                                                                                                                                                                                        • Flip-Flop
                                                                                                                                                                                                                                                                                                        • JK Flip-Flop
                                                                                                                                                                                                                                                                                                          • Circuit Diagram
                                                                                                                                                                                                                                                                                                            • Observations
                                                                                                                                                                                                                                                                                                              • ACTIVITY
                                                                                                                                                                                                                                                                                                                  • 17-ldst-exp12
                                                                                                                                                                                                                                                                                                                    • Lab Session 12
                                                                                                                                                                                                                                                                                                                      • OBJECT
                                                                                                                                                                                                                                                                                                                      • GIVEN STATE DIAGRAM
                                                                                                                                                                                                                                                                                                                      • Figure 121 State Diagram
                                                                                                                                                                                                                                                                                                                      • COMPONENTS AND APPARATUS REQUIRED
                                                                                                                                                                                                                                                                                                                        • 1 Following ICs and their Datasheets
                                                                                                                                                                                                                                                                                                                        • 7474 D Flip-Flop
                                                                                                                                                                                                                                                                                                                        • ICs of basic gates (AND OR NOT XOR etc) as required
                                                                                                                                                                                                                                                                                                                        • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                                                                                                                          • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                                                                                                                                          • Connecting wires Switches
                                                                                                                                                                                                                                                                                                                            • THEORY
                                                                                                                                                                                                                                                                                                                                • Sequential Circuits
                                                                                                                                                                                                                                                                                                                                  • 18-ldst-exp13
                                                                                                                                                                                                                                                                                                                                    • Lab Session 13
                                                                                                                                                                                                                                                                                                                                      • Designing a modulo-5 asynchronous up-counter using JK-FF
                                                                                                                                                                                                                                                                                                                                        • 1 Following ICs and their Datasheets
                                                                                                                                                                                                                                                                                                                                        • 7400 Quad 2-input or 7410 Triple 3-input NAND Gates
                                                                                                                                                                                                                                                                                                                                        • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                                                                                                                                          • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                                                                                                                                                          • Connecting wires Switches
                                                                                                                                                                                                                                                                                                                                            • THEORY
                                                                                                                                                                                                                                                                                                                                                • Figure 131 A Mod-5 Asynchronous Up Counter
                                                                                                                                                                                                                                                                                                                                                • Implementation and Observations
                                                                                                                                                                                                                                                                                                                                                  • ACTIVITY
                                                                                                                                                                                                                                                                                                                                                      • 19-ldst-exp14
                                                                                                                                                                                                                                                                                                                                                        • Experimenting with 74194 4-bit bidirectional universal shift register
                                                                                                                                                                                                                                                                                                                                                        • 1 Following ICs and their Datasheets
                                                                                                                                                                                                                                                                                                                                                        • 74194 4-bit bidirectional universal shift register
                                                                                                                                                                                                                                                                                                                                                        • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                                                                                                                                                          • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                                                                                                                                                                          • Connecting wires Switches
                                                                                                                                                                                                                                                                                                                                                            • THEORY
                                                                                                                                                                                                                                                                                                                                                              • Shift Registers
                                                                                                                                                                                                                                                                                                                                                              • Bidirectional Shift Registers
                                                                                                                                                                                                                                                                                                                                                              • Universal Shift Registers
                                                                                                                                                                                                                                                                                                                                                                • S1
                                                                                                                                                                                                                                                                                                                                                                  • Circuit Diagram
                                                                                                                                                                                                                                                                                                                                                                  • ACTIVITY
                                                                                                                                                                                                                                                                                                                                                                      • 20-ldst-exp15
                                                                                                                                                                                                                                                                                                                                                                        • COMPONENTS AND APPARATUS REQUIRED
                                                                                                                                                                                                                                                                                                                                                                        • 1 Parallel Port Connectors (DB-25) with Cable
                                                                                                                                                                                                                                                                                                                                                                        • 2 Personal Computer with Windows 98 and TurboC Compiler Installed
                                                                                                                                                                                                                                                                                                                                                                        • 3 Following ICs and their Datasheets
                                                                                                                                                                                                                                                                                                                                                                        • 74245 Octal Bus Transceivers with 3-State Outputs
                                                                                                                                                                                                                                                                                                                                                                        • 4 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                                                                                                                                                                          • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                                                                                                                                                                                            • Connecting wires Switches
                                                                                                                                                                                                                                                                                                                                                                              • THEORY
                                                                                                                                                                                                                                                                                                                                                                              • 3-State Logic
                                                                                                                                                                                                                                                                                                                                                                                • Serial and Parallel Port Connectors
                                                                                                                                                                                                                                                                                                                                                                                • Parallel Port Connector ndash DB-25
                                                                                                                                                                                                                                                                                                                                                                                  • Accessing parallel port through C Language Programming
                                                                                                                                                                                                                                                                                                                                                                                      • 21-ldst-appendixA
                                                                                                                                                                                                                                                                                                                                                                                      • 22-ldst-appendixB
                                                                                                                                                                                                                                                                                                                                                                                        • DEBOUNCING CIRCUITRY FOR MECHANICAL SWITCHES

                                                                                                                Logic Design amp Switching Theory 1 Lab Session 14 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                                                                58

                                                                                                                Observations

                                                                                                                S1 S0 SL SR A B C D QA QB QC QD 0 0 0 1 0 0 0 0 0 1 1 0 0 0 0 1 1 0 0 0 0 0 1 0 1 1 0 0 0 0 1 1 0 0 1 1 0 1 0 0 0 1 1 1 0 1 0 1 1 0 1 0 0 1 1 0 1 1 1 0 0 1 1 1 1 1 0 0 1 1 1 1

                                                                                                                ACTIVITY 1 Show connections of 74194 to convert it into a ring counter with right shifting

                                                                                                                Logic Design amp Switching Theory 1 Lab Session 15 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                                                                Lab Session 15

                                                                                                                OBJECT

                                                                                                                Experimenting with 74245 octal bus transceivers using parallel port PC interfacing COMPONENTS AND APPARATUS REQUIRED 1 Parallel Port Connectors (DB-25) with Cable 2 Personal Computer with Windows 98 and TurboC Compiler Installed 3 Following ICs and their Datasheets

                                                                                                                bull 74245 Octal Bus Transceivers with 3-State Outputs 4 Digital Trainer DT-01 or the following components

                                                                                                                Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches

                                                                                                                THEORY

                                                                                                                3-State Logic Sometimes it is necessary to isolate one part of circuit from the other part For this purpose some TTL ICs are designed with 3-state logic Such devices have three possible output states high low and high impedance The device can be put into high impedance state by a control signal applied to an appropriate pin When such a device is in high impedance state there is very high impedance at its output effectively isolating the device from whatever circuitry the output normally drives 74245 Octal Bus Transceivers A bus is any conducting path or set of paths having electrical connections to one or more devices 74245 octal bus transceivers are mainly used to control connectivity between two devices or circuits It also provides direction control for signal flow Function of various pin of this IC is given below

                                                                                                                bull A1 through A8 Bus A bull B1 through B8 Bus B bull G΄ Active low enable input When high sets all the bus pins to high impedance state bull DIR Direction control for signal flow When set to high logic level transfers bus A

                                                                                                                data to B bus When set to low logic level transfers bus B data to A bus bull VCC and GND Supply connections lines Serial and Parallel Port Connectors A Parallel Port can consist of only 25 pin port adapter called a DB-25 and a serial port can consist of either a 25 pin port adapter called a DB-25 or 9 pin adapter called a DB-9 port adapter Whether the port is a 9 pin or 25 pin it can accomplish all of the same tasks that serial port communications have been designed for

                                                                                                                59

                                                                                                                Logic Design amp Switching Theory 1 Lab Session 15 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                                                                60

                                                                                                                Each adapter can be a male type connector with pins or a female type adapter with tiny holes Generally a PRINTER port (called LPT1) on the back of a computer is female type adapter and we need to use MALE DB-25 pin cable on it for PRINTER connection or for parallel LAPLINK cable And a COM port on the back of a computer is male for the serial ports but it may not necessarily be Parallel Port Connector ndash DB-25 The DB-25 connector (named for its B-size D-shaped shell and 25 pins) is practically ubiquitous in the electronics industry The DB-25 connector is used for a variety of purposes Two common applications are RS-232EIA-232 (serial) connections and the parallel printer interface on the IBM PC The DB-25 connector is also used for SCSI connections Normally the parallel port is used for output to a printer or other device It sends data 8-bits or one byte at a time in parallel The other lines available on the DB-25 connector are a combination of status lines control lines and ground lines The status and control lines are used for handshaking commands and feedback when we are talking to a printer

                                                                                                                Figure 152 DB-25 Female Figure 151 DB-25 Male

                                                                                                                Figure 153 Pin Layout for DB-25 As can be seen form figure 153 there are four types of pins in this connector

                                                                                                                bull Data pins (8 pins - D0 to D7) Active high bidirectional lines

                                                                                                                Logic Design amp Switching Theory 1 Lab Session 15 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering bull Control pins (4 pins - C0 to C3) C0 C1 and C3 are active low whereas C2 is active

                                                                                                                high These lines also are bidirectional bull Status pins (5 pins ndash S3 to S7) Only S7 is active low rest are active high input lines bull Ground pins (8 pins) Used as a reference signal for the low (below 05 volts) charge

                                                                                                                Parallel Port Addresses A DB-25 connector at a parallel port has three address one for each kind of pins register data status and control The first or base address generally refers to data register Second address is for status register and the third one is for control register In Windows 98 the base address is usually found to be 278H 378H or 3BCH Now if 378H is the base address then it refers to the data register whereas addresses for status and control register are respectively 379H and 37AH For Windows 98 the base address can be found as follows 1 On your Desktop right-click on My Computer and select Properties 2 Click on the Device Manager tab and find LPT1 under Plug and Play BIOS 3 After selecting LPT1 click the Properties button 4 Next select the Resources tab and the address should then appear next to InputOutput

                                                                                                                Range Accessing parallel port through C Language Programming There are multiple functions in C Language for accessing external ports The most commonly used are listed below

                                                                                                                bull unsigned char inportb(int portid) inportb reads a byte from a hardware port

                                                                                                                bull int inport(int portid) reads a word from a hardware port

                                                                                                                bull void outportb(int portid unsigned char value) outputs a byte to a hardware port

                                                                                                                bull void outport(int portid int value) outputs a word to a hardware port

                                                                                                                portid refers to the port address whereas value refers to the data to be sent TESTING 74245 USING PARALLEL PORT PC INTERFACING At one end the parallel port connector will be connected to the PC via parallel port cable and another connector (to be plugged into the PC parallel port slot) At the other end it will be connected to the buffer IC 74245 Data lines of the connector will be used to transfer 8-bit data between the PC and the buffer Out of the 8-bits of 74245 4-bits will be used to enter data which will be displayed at the monitor through a C language

                                                                                                                61

                                                                                                                Logic Design amp Switching Theory 1 Lab Session 15 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering program The remaining 4-bits will receive data from PC as entered by the user via keyboard

                                                                                                                Circuit Diagram

                                                                                                                Figure 154 Interface of 74245 to PC via Parallel Port

                                                                                                                Procedure

                                                                                                                1 Connect the DB-25 connector to the PC at one end and solder it to the circuit board at the other end

                                                                                                                2 Connect various pins of the connector and 74245 according to the circuit diagram shown in figure 152

                                                                                                                3 Using the functions listed in the previous section write a program in C language to operate various pins of the buffer The user interface of the program should provide option to the user whether to send or receive data from the port

                                                                                                                4 Set DIR switch to 1 5 Try sending some data bits to the port The result should be displayed at the LEDs 6 Set DIR switch to 0 7 Set some binary 4-bit value through the switches Try reading it via parallel port

                                                                                                                C Language Program

                                                                                                                A program to access parallel port for data transfers

                                                                                                                use header file include ltstdiohgt main program void main() define variable

                                                                                                                62

                                                                                                                Logic Design amp Switching Theory 1 Lab Session 15 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering unsigned int data=0 char choice while(1) printing option menu clrscr() printf(This program will send or receive a BCD digit from the parallel portn) printf(nPress your choice numbern) printf(n1 Send Data) printf(n2 Receive Data) printf(n3 Exitn) choice = getch() sending entered digit to the port if(choice == 1) input BCD digit printf(nEnter BCD digit to be sent to the port) data = getche() masking the first four bits data = data amp 0x0f sending to the port outportb(0x378data) printf(nThe BCD digit c has been sent to the port data) printing on screen the data received from the port else if(choice == 2) receiving data from the port data = inportb(0x378) masking the last four bits data = data amp 0xf0 shifting first four bits to make them the last four bits datagtgt=4 printf(nThe BCD digit set at the port is c data) exit else if(choice == 3) break key pressed is not in the menu else printf(nEnter valid choice number) printf(nnPress any key to continue) getch()

                                                                                                                63

                                                                                                                Logic Design amp Switching Theory 1 Lab Session 15 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                                                                ACTIVITY 1 In the above circuit DIR and G΄ inputs are hardwired Connect them to status or

                                                                                                                control pins of the parallel port connector and control their function through your software program Circuit Diagram Program Code ______________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________

                                                                                                                ___________________________________________________________________________________________________________________________________________________

                                                                                                                64

                                                                                                                Logic Design amp Switching Theory 1 Lab Session 15 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                                                                65

                                                                                                                _____________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ _____________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ _______________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ _________________________________________________ _________________________________________________

                                                                                                                Logic Design amp Switching Theory 1 Appendix A NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                                                                Appendix A

                                                                                                                PIN DIAGRAMS OF THE ICS REQUIRED FOR THE LABORATORY SESSIONS Consult the TTLIC data book for internal diagrams and electrical characteristics of these ICs 7400 Quad 2-Input NAND 7402 Quad 2-Input NOR

                                                                                                                7404 Hex Inverter 7408 Quad 2-Input AND

                                                                                                                7410 Triple 3-Input NAND 7411 Triple 3-Input AND

                                                                                                                7421 Dual 4-Input AND 7432 Quad 2-Input OR

                                                                                                                66

                                                                                                                Logic Design amp Switching Theory 1 Appendix A NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                                                                BCD-to-Seven Segm 7448 BCD-to-Seven Segment 7447 ent

                                                                                                                Decoder (15V OC) Decoder (2kΩ pull-up output)

                                                                                                                7473 Dual JK Flip-Flop 7474 Dual D-Type Flip-Flop

                                                                                                                7476 Dual JK Flop-Flop -Bit Binary Full Adder 7483 4 with Fast Carry

                                                                                                                86 Quad 2-Inpu 74138 3-to-8 Line 74 t Exclusive OR Decoder Demultiplexer

                                                                                                                67

                                                                                                                Logic Design amp Switching Theory 1 Appendix A NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                                                                68

                                                                                                                74148 8-to-3 Line 16-to-1 Line Data

                                                                                                                Priority Encoder 74150 Selector Multiplexer

                                                                                                                74245 Oct nsceivers Universal Shift Register (PIPO) (3-State)

                                                                                                                74194 4-Bit Bidirectional al Bus Tra

                                                                                                                Logic Design amp Switching Theory 1 Appendix B NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                                                                Appendix B

                                                                                                                DEBOUNCING CIRCUITRY FOR MECHANICAL SWITCHES Mechanical switches form the interface between human beings and computers or other digital systems For example a keyboard is a matrix of switches used to supply alphanumeric data to a computer Whatever the switch design it is a potential source of problems due to contact bounce The contact bounce creates a sense of narrow pulses when a switch is opened or closed An example of device whose operation would be adversely affected by contact bounce is a digital counter used to count the number of times a switch is depressed Eliminating the effects of contact bounce is called debouncing When data is entered into a computer via a keyboard a software debounce is often used This type of debouncing is a program that causes the computer to sample the switch terminal (ie to input data from it) many times in succession during the interval of time that contact bounce occurs If the data is sensed to be 1s (or 0s) for a specific number of consecutive samples then it is assumed that contact bounce has ended and the last value sensed is valid Hardware debouncing is the use of electronic circuitry to eliminate the effects of contact bounce There are numerous versions of such circuitry including those that use monostable multivibrators (one-shots) but the most straightforward is simply an RS latch Figure B1 shows the circuit When the switch is in position 1 R = 0 and S = 1 so the latch is set and the output (Q) is 1 When the switch is in position 0 R = 1and S = 0 so the latch is reset and the output is 0 When the switch is moved form one position to the other the latch changes state and bouncing occurs at either the R or the S input The bouncing does not affect the latch after it has change state An RS latch will remain set for example when its R input is 0 and its S input is alternately changed form 1 to 0

                                                                                                                Figure B1 Use of RS latch to debounce a mechanical switch

                                                                                                                69

                                                                                                                • 01-ldst-Outer title
                                                                                                                  • Practical Workbook
                                                                                                                  • Logic Design amp Switching Theory I
                                                                                                                    • Dept of Computer amp Information Systems Engineering
                                                                                                                      • NED University of Engineering amp Technology
                                                                                                                      • Karachi ndash 75270 Pakistan
                                                                                                                        • 02-ldst-inner Title
                                                                                                                          • Practical Workbook
                                                                                                                          • Logic Design amp Switching Theory I
                                                                                                                            • Dept of Computer amp Information Systems Engineering
                                                                                                                              • NED University of Engineering amp Technology
                                                                                                                              • Karachi ndash 75270 Pakistan
                                                                                                                                • 03-ldst-general info
                                                                                                                                • 04-ldst-introduction
                                                                                                                                • 05-Table of Contents
                                                                                                                                  • CONTENTS
                                                                                                                                    • Lab Session No Object Page No
                                                                                                                                    • 1
                                                                                                                                    • Also implementing and testing the given circuit on a bread board
                                                                                                                                      • Working with Electronics Workbench
                                                                                                                                        • Driving a seven segment display using 7447 7448 driver IC
                                                                                                                                          • Designing a modulus-5 asynchronous up-counter using JK-FF
                                                                                                                                            • Experimenting with 74194 4-bit bidirectional universal shift register
                                                                                                                                                • 13
                                                                                                                                                    • 06-ldst-Exp01
                                                                                                                                                      • Lab Session 01
                                                                                                                                                      • OBJECT
                                                                                                                                                        • 1 Bread board
                                                                                                                                                        • 2 5 V - power supply
                                                                                                                                                        • 3 Multimeter
                                                                                                                                                        • 4 Logic probe
                                                                                                                                                        • 5 LEDs with resistors
                                                                                                                                                        • 6 Connecting wires
                                                                                                                                                        • 8 Following ICs and their datasheets
                                                                                                                                                          • THEORY
                                                                                                                                                            • Logic Gates
                                                                                                                                                            • 1 The AND Gate ndash An AND gatersquos output is 1 if and only if all its inputs are 1 If A and B are two inputs to an AND gate then output F of the gate is given as F = AB
                                                                                                                                                            • 2 The OR Gate - An OR gatersquos output is 1 if at least one of its input is 1 If A and B are two inputs to an OR gate then output F of the gate is given as F = A+B
                                                                                                                                                            • 3 The NOT Gate (Inverter) ndash Its output is 1 when its input is 0 and its output is 0 when the input is 1 ie it complements a digital variable If A is the input to a NOT gate then output F of the gate is given as
                                                                                                                                                            • 4 The NAND Gate ndash Its output is 1 if at least one of its input is 0 This gate performs the same logic as an AND gate followed by an inverter If A and B are two inputs to a NAND gate then output F of the gate is given as
                                                                                                                                                              • 5 The NOR Gate - The output of a NOR gate is 1 if and only if all its inputs are 0 This gate performs the same logic function as an OR gate followed by an inverter If A and B are two inputs to a NAND gate then output F of the gate is given as
                                                                                                                                                                  • DATA SHEETS
                                                                                                                                                                    • Logic expression for the given logic diagram __________________________________
                                                                                                                                                                        • 07-ldst-exp02
                                                                                                                                                                          • Working with Electronics Workbench
                                                                                                                                                                            • 08-ldst-exp03
                                                                                                                                                                              • Designing Half and Full Adder Circuits
                                                                                                                                                                                • COMPONENTS AND APPARATUS REQUIRED
                                                                                                                                                                                  • 1 Following ICs and their Datasheets
                                                                                                                                                                                  • 7408 Quad 2-input AND Gate
                                                                                                                                                                                  • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                    • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                    • Connecting wires Switches
                                                                                                                                                                                      • THEORY
                                                                                                                                                                                          • IMPLEMENTATION AND OBSERVATIONS
                                                                                                                                                                                            • 09-ldst-Exp04
                                                                                                                                                                                              • Lab Session 04
                                                                                                                                                                                              • 1 Digital ICs and their Datasheets
                                                                                                                                                                                              • 7408 Quad 2-input AND Gate
                                                                                                                                                                                              • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                • Connecting wires Switches
                                                                                                                                                                                                • PROCEDURE
                                                                                                                                                                                                • REDUCTION OF LOGIC EXPRESSION USING KARNAUGH MAP
                                                                                                                                                                                                • OBSERVATIONS
                                                                                                                                                                                                • RESULT
                                                                                                                                                                                                    • 10-ldst-Exp05
                                                                                                                                                                                                      • Lab Session 05
                                                                                                                                                                                                      • 1 Following ICs and their Datasheets
                                                                                                                                                                                                      • 7408 Quad 2-input AND Gate
                                                                                                                                                                                                      • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                        • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                        • (100 Ω) Connecting wires Switches
                                                                                                                                                                                                        • THEORY
                                                                                                                                                                                                          • IMPLEMENTATION AND OBSERVATIONS
                                                                                                                                                                                                            • 11-ldst-Exp06
                                                                                                                                                                                                              • OBJECT
                                                                                                                                                                                                              • 1 Following ICs and their Datasheets
                                                                                                                                                                                                              • 7408 Quad 2-input AND Gates or 7411 Triple 3-input AND Gates
                                                                                                                                                                                                              • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                                • Connecting wires Switches
                                                                                                                                                                                                                  • Figure 62 Circuit Diagram for 4 x 1 Multiplexer
                                                                                                                                                                                                                  • Implementation and Observations
                                                                                                                                                                                                                    • Circuit Diagram
                                                                                                                                                                                                                      • ACTIVITY
                                                                                                                                                                                                                        • 12-ldst-exp07
                                                                                                                                                                                                                          • 1 Following ICs and their Datasheets
                                                                                                                                                                                                                          • 7408 Quad 2-input or 7411 Triple 3-input AND Gates
                                                                                                                                                                                                                          • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                            • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                                            • Connecting wires Switches
                                                                                                                                                                                                                              • THEORY
                                                                                                                                                                                                                                  • Figure 72 Circuit Diagram for 2 x 4 Decoder 1 x 4 Demultiplexer
                                                                                                                                                                                                                                  • Implementation and Observations
                                                                                                                                                                                                                                    • Circuit Diagram
                                                                                                                                                                                                                                      • ACTIVITY
                                                                                                                                                                                                                                        • 13-ldst-Exp08
                                                                                                                                                                                                                                          • OBJECT
                                                                                                                                                                                                                                          • 1 Following ICs and their Datasheets
                                                                                                                                                                                                                                          • 7408 Quad 2-input or 7421 Dual 4-input AND Gates
                                                                                                                                                                                                                                          • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                                            • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                                                            • Connecting wires Switches
                                                                                                                                                                                                                                              • THEORY
                                                                                                                                                                                                                                                  • Figure 81 Circuit Diagram for 4 x 2 Priority Encoder
                                                                                                                                                                                                                                                  • Implementation and Observations
                                                                                                                                                                                                                                                    • Therefore if GS A2 A1 and A0 are all low then it shows that line 0 is selected and if E0 A2 A1 and A0 are all low then it shows that none of the inputs selected E0 and GS cannot be in the same state provided that E1 is enabled
                                                                                                                                                                                                                                                    • Circuit Diagram
                                                                                                                                                                                                                                                      • ACTIVITY
                                                                                                                                                                                                                                                        • 14-ldst-exp09
                                                                                                                                                                                                                                                          • OBJECT
                                                                                                                                                                                                                                                          • 1 Following ICs and their Datasheets
                                                                                                                                                                                                                                                          • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                                                            • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                                                                            • Connecting wires Switches
                                                                                                                                                                                                                                                              • THEORY
                                                                                                                                                                                                                                                                • Parity Generator
                                                                                                                                                                                                                                                                  • Let x y and z be the three bits that constitute the message and are the input to the Odd Parity Generator Circuit Since it is an odd parity system the bit P is generated so as to make the total number of 1s odd (including P) The function P can be expressed as follows
                                                                                                                                                                                                                                                                  • Figure 91 Circuit Diagram for a 3-bit Parity Generator
                                                                                                                                                                                                                                                                    • C = x Ο y Ο z Ο P
                                                                                                                                                                                                                                                                      • Implementation and Observations
                                                                                                                                                                                                                                                                        • ACTIVITY
                                                                                                                                                                                                                                                                            • 15-ldst-exp10
                                                                                                                                                                                                                                                                              • Driving a seven segment display using 7447 7448 driver IC
                                                                                                                                                                                                                                                                              • COMPONENTS AND APPARATUS REQUIRED
                                                                                                                                                                                                                                                                              • 1 Following ICs and their Datasheets
                                                                                                                                                                                                                                                                              • 7447 7448 BCD to Seven Segment Driver
                                                                                                                                                                                                                                                                              • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                                                                                • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches
                                                                                                                                                                                                                                                                                  • THEORY
                                                                                                                                                                                                                                                                                  • Seven Segment Displays
                                                                                                                                                                                                                                                                                  • CIRCUIT DIAGRAM
                                                                                                                                                                                                                                                                                  • Figure 102 Circuit diagram for 7447driving a common-anode display
                                                                                                                                                                                                                                                                                      • IMPLEMENTATION AND OBSERVATIONS
                                                                                                                                                                                                                                                                                        • Decimal Digit
                                                                                                                                                                                                                                                                                        • BCD Inputs
                                                                                                                                                                                                                                                                                        • Seven Segment Outputs
                                                                                                                                                                                                                                                                                        • D
                                                                                                                                                                                                                                                                                        • C
                                                                                                                                                                                                                                                                                        • B
                                                                                                                                                                                                                                                                                        • A
                                                                                                                                                                                                                                                                                        • a
                                                                                                                                                                                                                                                                                        • b
                                                                                                                                                                                                                                                                                        • c
                                                                                                                                                                                                                                                                                        • d
                                                                                                                                                                                                                                                                                        • e
                                                                                                                                                                                                                                                                                        • f
                                                                                                                                                                                                                                                                                        • g
                                                                                                                                                                                                                                                                                        • 0
                                                                                                                                                                                                                                                                                        • 0
                                                                                                                                                                                                                                                                                        • 0
                                                                                                                                                                                                                                                                                        • 0
                                                                                                                                                                                                                                                                                        • 0
                                                                                                                                                                                                                                                                                        • 1
                                                                                                                                                                                                                                                                                        • 0
                                                                                                                                                                                                                                                                                        • 0
                                                                                                                                                                                                                                                                                        • 0
                                                                                                                                                                                                                                                                                        • 1
                                                                                                                                                                                                                                                                                        • 2
                                                                                                                                                                                                                                                                                        • 0
                                                                                                                                                                                                                                                                                        • 0
                                                                                                                                                                                                                                                                                        • 1
                                                                                                                                                                                                                                                                                        • 0
                                                                                                                                                                                                                                                                                        • 3
                                                                                                                                                                                                                                                                                        • 0
                                                                                                                                                                                                                                                                                        • 0
                                                                                                                                                                                                                                                                                        • 1
                                                                                                                                                                                                                                                                                        • 1
                                                                                                                                                                                                                                                                                        • 4
                                                                                                                                                                                                                                                                                        • 0
                                                                                                                                                                                                                                                                                        • 1
                                                                                                                                                                                                                                                                                        • 0
                                                                                                                                                                                                                                                                                        • 0
                                                                                                                                                                                                                                                                                        • 5
                                                                                                                                                                                                                                                                                        • 0
                                                                                                                                                                                                                                                                                        • 1
                                                                                                                                                                                                                                                                                        • 0
                                                                                                                                                                                                                                                                                        • 1
                                                                                                                                                                                                                                                                                        • 6
                                                                                                                                                                                                                                                                                        • 0
                                                                                                                                                                                                                                                                                        • 1
                                                                                                                                                                                                                                                                                        • 1
                                                                                                                                                                                                                                                                                        • 0
                                                                                                                                                                                                                                                                                        • 7
                                                                                                                                                                                                                                                                                        • 0
                                                                                                                                                                                                                                                                                        • 1
                                                                                                                                                                                                                                                                                        • 1
                                                                                                                                                                                                                                                                                        • 1
                                                                                                                                                                                                                                                                                        • 8
                                                                                                                                                                                                                                                                                        • 1
                                                                                                                                                                                                                                                                                        • 0
                                                                                                                                                                                                                                                                                        • 0
                                                                                                                                                                                                                                                                                        • 0
                                                                                                                                                                                                                                                                                        • 9
                                                                                                                                                                                                                                                                                        • 1
                                                                                                                                                                                                                                                                                        • 0
                                                                                                                                                                                                                                                                                        • 0
                                                                                                                                                                                                                                                                                        • 1
                                                                                                                                                                                                                                                                                          • ACTIVITY
                                                                                                                                                                                                                                                                                            • 16-ldst-exp11
                                                                                                                                                                                                                                                                                              • Lab Session 11
                                                                                                                                                                                                                                                                                                • OBJECT
                                                                                                                                                                                                                                                                                                • COMPONENTS AND APPARATUS REQUIRED
                                                                                                                                                                                                                                                                                                  • 1 Following ICs and their Datasheets
                                                                                                                                                                                                                                                                                                  • 7473 7476 JK Flip-Flop
                                                                                                                                                                                                                                                                                                  • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                                                                                                    • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                                                                                                                    • Connecting wires Switches
                                                                                                                                                                                                                                                                                                      • THEORY
                                                                                                                                                                                                                                                                                                          • Flip-Flop
                                                                                                                                                                                                                                                                                                          • JK Flip-Flop
                                                                                                                                                                                                                                                                                                            • Circuit Diagram
                                                                                                                                                                                                                                                                                                              • Observations
                                                                                                                                                                                                                                                                                                                • ACTIVITY
                                                                                                                                                                                                                                                                                                                    • 17-ldst-exp12
                                                                                                                                                                                                                                                                                                                      • Lab Session 12
                                                                                                                                                                                                                                                                                                                        • OBJECT
                                                                                                                                                                                                                                                                                                                        • GIVEN STATE DIAGRAM
                                                                                                                                                                                                                                                                                                                        • Figure 121 State Diagram
                                                                                                                                                                                                                                                                                                                        • COMPONENTS AND APPARATUS REQUIRED
                                                                                                                                                                                                                                                                                                                          • 1 Following ICs and their Datasheets
                                                                                                                                                                                                                                                                                                                          • 7474 D Flip-Flop
                                                                                                                                                                                                                                                                                                                          • ICs of basic gates (AND OR NOT XOR etc) as required
                                                                                                                                                                                                                                                                                                                          • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                                                                                                                            • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                                                                                                                                            • Connecting wires Switches
                                                                                                                                                                                                                                                                                                                              • THEORY
                                                                                                                                                                                                                                                                                                                                  • Sequential Circuits
                                                                                                                                                                                                                                                                                                                                    • 18-ldst-exp13
                                                                                                                                                                                                                                                                                                                                      • Lab Session 13
                                                                                                                                                                                                                                                                                                                                        • Designing a modulo-5 asynchronous up-counter using JK-FF
                                                                                                                                                                                                                                                                                                                                          • 1 Following ICs and their Datasheets
                                                                                                                                                                                                                                                                                                                                          • 7400 Quad 2-input or 7410 Triple 3-input NAND Gates
                                                                                                                                                                                                                                                                                                                                          • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                                                                                                                                            • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                                                                                                                                                            • Connecting wires Switches
                                                                                                                                                                                                                                                                                                                                              • THEORY
                                                                                                                                                                                                                                                                                                                                                  • Figure 131 A Mod-5 Asynchronous Up Counter
                                                                                                                                                                                                                                                                                                                                                  • Implementation and Observations
                                                                                                                                                                                                                                                                                                                                                    • ACTIVITY
                                                                                                                                                                                                                                                                                                                                                        • 19-ldst-exp14
                                                                                                                                                                                                                                                                                                                                                          • Experimenting with 74194 4-bit bidirectional universal shift register
                                                                                                                                                                                                                                                                                                                                                          • 1 Following ICs and their Datasheets
                                                                                                                                                                                                                                                                                                                                                          • 74194 4-bit bidirectional universal shift register
                                                                                                                                                                                                                                                                                                                                                          • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                                                                                                                                                            • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                                                                                                                                                                            • Connecting wires Switches
                                                                                                                                                                                                                                                                                                                                                              • THEORY
                                                                                                                                                                                                                                                                                                                                                                • Shift Registers
                                                                                                                                                                                                                                                                                                                                                                • Bidirectional Shift Registers
                                                                                                                                                                                                                                                                                                                                                                • Universal Shift Registers
                                                                                                                                                                                                                                                                                                                                                                  • S1
                                                                                                                                                                                                                                                                                                                                                                    • Circuit Diagram
                                                                                                                                                                                                                                                                                                                                                                    • ACTIVITY
                                                                                                                                                                                                                                                                                                                                                                        • 20-ldst-exp15
                                                                                                                                                                                                                                                                                                                                                                          • COMPONENTS AND APPARATUS REQUIRED
                                                                                                                                                                                                                                                                                                                                                                          • 1 Parallel Port Connectors (DB-25) with Cable
                                                                                                                                                                                                                                                                                                                                                                          • 2 Personal Computer with Windows 98 and TurboC Compiler Installed
                                                                                                                                                                                                                                                                                                                                                                          • 3 Following ICs and their Datasheets
                                                                                                                                                                                                                                                                                                                                                                          • 74245 Octal Bus Transceivers with 3-State Outputs
                                                                                                                                                                                                                                                                                                                                                                          • 4 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                                                                                                                                                                            • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                                                                                                                                                                                              • Connecting wires Switches
                                                                                                                                                                                                                                                                                                                                                                                • THEORY
                                                                                                                                                                                                                                                                                                                                                                                • 3-State Logic
                                                                                                                                                                                                                                                                                                                                                                                  • Serial and Parallel Port Connectors
                                                                                                                                                                                                                                                                                                                                                                                  • Parallel Port Connector ndash DB-25
                                                                                                                                                                                                                                                                                                                                                                                    • Accessing parallel port through C Language Programming
                                                                                                                                                                                                                                                                                                                                                                                        • 21-ldst-appendixA
                                                                                                                                                                                                                                                                                                                                                                                        • 22-ldst-appendixB
                                                                                                                                                                                                                                                                                                                                                                                          • DEBOUNCING CIRCUITRY FOR MECHANICAL SWITCHES

                                                                                                                  Logic Design amp Switching Theory 1 Lab Session 15 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                                                                  Lab Session 15

                                                                                                                  OBJECT

                                                                                                                  Experimenting with 74245 octal bus transceivers using parallel port PC interfacing COMPONENTS AND APPARATUS REQUIRED 1 Parallel Port Connectors (DB-25) with Cable 2 Personal Computer with Windows 98 and TurboC Compiler Installed 3 Following ICs and their Datasheets

                                                                                                                  bull 74245 Octal Bus Transceivers with 3-State Outputs 4 Digital Trainer DT-01 or the following components

                                                                                                                  Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches

                                                                                                                  THEORY

                                                                                                                  3-State Logic Sometimes it is necessary to isolate one part of circuit from the other part For this purpose some TTL ICs are designed with 3-state logic Such devices have three possible output states high low and high impedance The device can be put into high impedance state by a control signal applied to an appropriate pin When such a device is in high impedance state there is very high impedance at its output effectively isolating the device from whatever circuitry the output normally drives 74245 Octal Bus Transceivers A bus is any conducting path or set of paths having electrical connections to one or more devices 74245 octal bus transceivers are mainly used to control connectivity between two devices or circuits It also provides direction control for signal flow Function of various pin of this IC is given below

                                                                                                                  bull A1 through A8 Bus A bull B1 through B8 Bus B bull G΄ Active low enable input When high sets all the bus pins to high impedance state bull DIR Direction control for signal flow When set to high logic level transfers bus A

                                                                                                                  data to B bus When set to low logic level transfers bus B data to A bus bull VCC and GND Supply connections lines Serial and Parallel Port Connectors A Parallel Port can consist of only 25 pin port adapter called a DB-25 and a serial port can consist of either a 25 pin port adapter called a DB-25 or 9 pin adapter called a DB-9 port adapter Whether the port is a 9 pin or 25 pin it can accomplish all of the same tasks that serial port communications have been designed for

                                                                                                                  59

                                                                                                                  Logic Design amp Switching Theory 1 Lab Session 15 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                                                                  60

                                                                                                                  Each adapter can be a male type connector with pins or a female type adapter with tiny holes Generally a PRINTER port (called LPT1) on the back of a computer is female type adapter and we need to use MALE DB-25 pin cable on it for PRINTER connection or for parallel LAPLINK cable And a COM port on the back of a computer is male for the serial ports but it may not necessarily be Parallel Port Connector ndash DB-25 The DB-25 connector (named for its B-size D-shaped shell and 25 pins) is practically ubiquitous in the electronics industry The DB-25 connector is used for a variety of purposes Two common applications are RS-232EIA-232 (serial) connections and the parallel printer interface on the IBM PC The DB-25 connector is also used for SCSI connections Normally the parallel port is used for output to a printer or other device It sends data 8-bits or one byte at a time in parallel The other lines available on the DB-25 connector are a combination of status lines control lines and ground lines The status and control lines are used for handshaking commands and feedback when we are talking to a printer

                                                                                                                  Figure 152 DB-25 Female Figure 151 DB-25 Male

                                                                                                                  Figure 153 Pin Layout for DB-25 As can be seen form figure 153 there are four types of pins in this connector

                                                                                                                  bull Data pins (8 pins - D0 to D7) Active high bidirectional lines

                                                                                                                  Logic Design amp Switching Theory 1 Lab Session 15 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering bull Control pins (4 pins - C0 to C3) C0 C1 and C3 are active low whereas C2 is active

                                                                                                                  high These lines also are bidirectional bull Status pins (5 pins ndash S3 to S7) Only S7 is active low rest are active high input lines bull Ground pins (8 pins) Used as a reference signal for the low (below 05 volts) charge

                                                                                                                  Parallel Port Addresses A DB-25 connector at a parallel port has three address one for each kind of pins register data status and control The first or base address generally refers to data register Second address is for status register and the third one is for control register In Windows 98 the base address is usually found to be 278H 378H or 3BCH Now if 378H is the base address then it refers to the data register whereas addresses for status and control register are respectively 379H and 37AH For Windows 98 the base address can be found as follows 1 On your Desktop right-click on My Computer and select Properties 2 Click on the Device Manager tab and find LPT1 under Plug and Play BIOS 3 After selecting LPT1 click the Properties button 4 Next select the Resources tab and the address should then appear next to InputOutput

                                                                                                                  Range Accessing parallel port through C Language Programming There are multiple functions in C Language for accessing external ports The most commonly used are listed below

                                                                                                                  bull unsigned char inportb(int portid) inportb reads a byte from a hardware port

                                                                                                                  bull int inport(int portid) reads a word from a hardware port

                                                                                                                  bull void outportb(int portid unsigned char value) outputs a byte to a hardware port

                                                                                                                  bull void outport(int portid int value) outputs a word to a hardware port

                                                                                                                  portid refers to the port address whereas value refers to the data to be sent TESTING 74245 USING PARALLEL PORT PC INTERFACING At one end the parallel port connector will be connected to the PC via parallel port cable and another connector (to be plugged into the PC parallel port slot) At the other end it will be connected to the buffer IC 74245 Data lines of the connector will be used to transfer 8-bit data between the PC and the buffer Out of the 8-bits of 74245 4-bits will be used to enter data which will be displayed at the monitor through a C language

                                                                                                                  61

                                                                                                                  Logic Design amp Switching Theory 1 Lab Session 15 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering program The remaining 4-bits will receive data from PC as entered by the user via keyboard

                                                                                                                  Circuit Diagram

                                                                                                                  Figure 154 Interface of 74245 to PC via Parallel Port

                                                                                                                  Procedure

                                                                                                                  1 Connect the DB-25 connector to the PC at one end and solder it to the circuit board at the other end

                                                                                                                  2 Connect various pins of the connector and 74245 according to the circuit diagram shown in figure 152

                                                                                                                  3 Using the functions listed in the previous section write a program in C language to operate various pins of the buffer The user interface of the program should provide option to the user whether to send or receive data from the port

                                                                                                                  4 Set DIR switch to 1 5 Try sending some data bits to the port The result should be displayed at the LEDs 6 Set DIR switch to 0 7 Set some binary 4-bit value through the switches Try reading it via parallel port

                                                                                                                  C Language Program

                                                                                                                  A program to access parallel port for data transfers

                                                                                                                  use header file include ltstdiohgt main program void main() define variable

                                                                                                                  62

                                                                                                                  Logic Design amp Switching Theory 1 Lab Session 15 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering unsigned int data=0 char choice while(1) printing option menu clrscr() printf(This program will send or receive a BCD digit from the parallel portn) printf(nPress your choice numbern) printf(n1 Send Data) printf(n2 Receive Data) printf(n3 Exitn) choice = getch() sending entered digit to the port if(choice == 1) input BCD digit printf(nEnter BCD digit to be sent to the port) data = getche() masking the first four bits data = data amp 0x0f sending to the port outportb(0x378data) printf(nThe BCD digit c has been sent to the port data) printing on screen the data received from the port else if(choice == 2) receiving data from the port data = inportb(0x378) masking the last four bits data = data amp 0xf0 shifting first four bits to make them the last four bits datagtgt=4 printf(nThe BCD digit set at the port is c data) exit else if(choice == 3) break key pressed is not in the menu else printf(nEnter valid choice number) printf(nnPress any key to continue) getch()

                                                                                                                  63

                                                                                                                  Logic Design amp Switching Theory 1 Lab Session 15 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                                                                  ACTIVITY 1 In the above circuit DIR and G΄ inputs are hardwired Connect them to status or

                                                                                                                  control pins of the parallel port connector and control their function through your software program Circuit Diagram Program Code ______________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________

                                                                                                                  ___________________________________________________________________________________________________________________________________________________

                                                                                                                  64

                                                                                                                  Logic Design amp Switching Theory 1 Lab Session 15 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                                                                  65

                                                                                                                  _____________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ _____________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ _______________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ _________________________________________________ _________________________________________________

                                                                                                                  Logic Design amp Switching Theory 1 Appendix A NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                                                                  Appendix A

                                                                                                                  PIN DIAGRAMS OF THE ICS REQUIRED FOR THE LABORATORY SESSIONS Consult the TTLIC data book for internal diagrams and electrical characteristics of these ICs 7400 Quad 2-Input NAND 7402 Quad 2-Input NOR

                                                                                                                  7404 Hex Inverter 7408 Quad 2-Input AND

                                                                                                                  7410 Triple 3-Input NAND 7411 Triple 3-Input AND

                                                                                                                  7421 Dual 4-Input AND 7432 Quad 2-Input OR

                                                                                                                  66

                                                                                                                  Logic Design amp Switching Theory 1 Appendix A NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                                                                  BCD-to-Seven Segm 7448 BCD-to-Seven Segment 7447 ent

                                                                                                                  Decoder (15V OC) Decoder (2kΩ pull-up output)

                                                                                                                  7473 Dual JK Flip-Flop 7474 Dual D-Type Flip-Flop

                                                                                                                  7476 Dual JK Flop-Flop -Bit Binary Full Adder 7483 4 with Fast Carry

                                                                                                                  86 Quad 2-Inpu 74138 3-to-8 Line 74 t Exclusive OR Decoder Demultiplexer

                                                                                                                  67

                                                                                                                  Logic Design amp Switching Theory 1 Appendix A NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                                                                  68

                                                                                                                  74148 8-to-3 Line 16-to-1 Line Data

                                                                                                                  Priority Encoder 74150 Selector Multiplexer

                                                                                                                  74245 Oct nsceivers Universal Shift Register (PIPO) (3-State)

                                                                                                                  74194 4-Bit Bidirectional al Bus Tra

                                                                                                                  Logic Design amp Switching Theory 1 Appendix B NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                                                                  Appendix B

                                                                                                                  DEBOUNCING CIRCUITRY FOR MECHANICAL SWITCHES Mechanical switches form the interface between human beings and computers or other digital systems For example a keyboard is a matrix of switches used to supply alphanumeric data to a computer Whatever the switch design it is a potential source of problems due to contact bounce The contact bounce creates a sense of narrow pulses when a switch is opened or closed An example of device whose operation would be adversely affected by contact bounce is a digital counter used to count the number of times a switch is depressed Eliminating the effects of contact bounce is called debouncing When data is entered into a computer via a keyboard a software debounce is often used This type of debouncing is a program that causes the computer to sample the switch terminal (ie to input data from it) many times in succession during the interval of time that contact bounce occurs If the data is sensed to be 1s (or 0s) for a specific number of consecutive samples then it is assumed that contact bounce has ended and the last value sensed is valid Hardware debouncing is the use of electronic circuitry to eliminate the effects of contact bounce There are numerous versions of such circuitry including those that use monostable multivibrators (one-shots) but the most straightforward is simply an RS latch Figure B1 shows the circuit When the switch is in position 1 R = 0 and S = 1 so the latch is set and the output (Q) is 1 When the switch is in position 0 R = 1and S = 0 so the latch is reset and the output is 0 When the switch is moved form one position to the other the latch changes state and bouncing occurs at either the R or the S input The bouncing does not affect the latch after it has change state An RS latch will remain set for example when its R input is 0 and its S input is alternately changed form 1 to 0

                                                                                                                  Figure B1 Use of RS latch to debounce a mechanical switch

                                                                                                                  69

                                                                                                                  • 01-ldst-Outer title
                                                                                                                    • Practical Workbook
                                                                                                                    • Logic Design amp Switching Theory I
                                                                                                                      • Dept of Computer amp Information Systems Engineering
                                                                                                                        • NED University of Engineering amp Technology
                                                                                                                        • Karachi ndash 75270 Pakistan
                                                                                                                          • 02-ldst-inner Title
                                                                                                                            • Practical Workbook
                                                                                                                            • Logic Design amp Switching Theory I
                                                                                                                              • Dept of Computer amp Information Systems Engineering
                                                                                                                                • NED University of Engineering amp Technology
                                                                                                                                • Karachi ndash 75270 Pakistan
                                                                                                                                  • 03-ldst-general info
                                                                                                                                  • 04-ldst-introduction
                                                                                                                                  • 05-Table of Contents
                                                                                                                                    • CONTENTS
                                                                                                                                      • Lab Session No Object Page No
                                                                                                                                      • 1
                                                                                                                                      • Also implementing and testing the given circuit on a bread board
                                                                                                                                        • Working with Electronics Workbench
                                                                                                                                          • Driving a seven segment display using 7447 7448 driver IC
                                                                                                                                            • Designing a modulus-5 asynchronous up-counter using JK-FF
                                                                                                                                              • Experimenting with 74194 4-bit bidirectional universal shift register
                                                                                                                                                  • 13
                                                                                                                                                      • 06-ldst-Exp01
                                                                                                                                                        • Lab Session 01
                                                                                                                                                        • OBJECT
                                                                                                                                                          • 1 Bread board
                                                                                                                                                          • 2 5 V - power supply
                                                                                                                                                          • 3 Multimeter
                                                                                                                                                          • 4 Logic probe
                                                                                                                                                          • 5 LEDs with resistors
                                                                                                                                                          • 6 Connecting wires
                                                                                                                                                          • 8 Following ICs and their datasheets
                                                                                                                                                            • THEORY
                                                                                                                                                              • Logic Gates
                                                                                                                                                              • 1 The AND Gate ndash An AND gatersquos output is 1 if and only if all its inputs are 1 If A and B are two inputs to an AND gate then output F of the gate is given as F = AB
                                                                                                                                                              • 2 The OR Gate - An OR gatersquos output is 1 if at least one of its input is 1 If A and B are two inputs to an OR gate then output F of the gate is given as F = A+B
                                                                                                                                                              • 3 The NOT Gate (Inverter) ndash Its output is 1 when its input is 0 and its output is 0 when the input is 1 ie it complements a digital variable If A is the input to a NOT gate then output F of the gate is given as
                                                                                                                                                              • 4 The NAND Gate ndash Its output is 1 if at least one of its input is 0 This gate performs the same logic as an AND gate followed by an inverter If A and B are two inputs to a NAND gate then output F of the gate is given as
                                                                                                                                                                • 5 The NOR Gate - The output of a NOR gate is 1 if and only if all its inputs are 0 This gate performs the same logic function as an OR gate followed by an inverter If A and B are two inputs to a NAND gate then output F of the gate is given as
                                                                                                                                                                    • DATA SHEETS
                                                                                                                                                                      • Logic expression for the given logic diagram __________________________________
                                                                                                                                                                          • 07-ldst-exp02
                                                                                                                                                                            • Working with Electronics Workbench
                                                                                                                                                                              • 08-ldst-exp03
                                                                                                                                                                                • Designing Half and Full Adder Circuits
                                                                                                                                                                                  • COMPONENTS AND APPARATUS REQUIRED
                                                                                                                                                                                    • 1 Following ICs and their Datasheets
                                                                                                                                                                                    • 7408 Quad 2-input AND Gate
                                                                                                                                                                                    • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                      • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                      • Connecting wires Switches
                                                                                                                                                                                        • THEORY
                                                                                                                                                                                            • IMPLEMENTATION AND OBSERVATIONS
                                                                                                                                                                                              • 09-ldst-Exp04
                                                                                                                                                                                                • Lab Session 04
                                                                                                                                                                                                • 1 Digital ICs and their Datasheets
                                                                                                                                                                                                • 7408 Quad 2-input AND Gate
                                                                                                                                                                                                • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                  • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                  • Connecting wires Switches
                                                                                                                                                                                                  • PROCEDURE
                                                                                                                                                                                                  • REDUCTION OF LOGIC EXPRESSION USING KARNAUGH MAP
                                                                                                                                                                                                  • OBSERVATIONS
                                                                                                                                                                                                  • RESULT
                                                                                                                                                                                                      • 10-ldst-Exp05
                                                                                                                                                                                                        • Lab Session 05
                                                                                                                                                                                                        • 1 Following ICs and their Datasheets
                                                                                                                                                                                                        • 7408 Quad 2-input AND Gate
                                                                                                                                                                                                        • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                          • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                          • (100 Ω) Connecting wires Switches
                                                                                                                                                                                                          • THEORY
                                                                                                                                                                                                            • IMPLEMENTATION AND OBSERVATIONS
                                                                                                                                                                                                              • 11-ldst-Exp06
                                                                                                                                                                                                                • OBJECT
                                                                                                                                                                                                                • 1 Following ICs and their Datasheets
                                                                                                                                                                                                                • 7408 Quad 2-input AND Gates or 7411 Triple 3-input AND Gates
                                                                                                                                                                                                                • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                  • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                                  • Connecting wires Switches
                                                                                                                                                                                                                    • Figure 62 Circuit Diagram for 4 x 1 Multiplexer
                                                                                                                                                                                                                    • Implementation and Observations
                                                                                                                                                                                                                      • Circuit Diagram
                                                                                                                                                                                                                        • ACTIVITY
                                                                                                                                                                                                                          • 12-ldst-exp07
                                                                                                                                                                                                                            • 1 Following ICs and their Datasheets
                                                                                                                                                                                                                            • 7408 Quad 2-input or 7411 Triple 3-input AND Gates
                                                                                                                                                                                                                            • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                              • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                                              • Connecting wires Switches
                                                                                                                                                                                                                                • THEORY
                                                                                                                                                                                                                                    • Figure 72 Circuit Diagram for 2 x 4 Decoder 1 x 4 Demultiplexer
                                                                                                                                                                                                                                    • Implementation and Observations
                                                                                                                                                                                                                                      • Circuit Diagram
                                                                                                                                                                                                                                        • ACTIVITY
                                                                                                                                                                                                                                          • 13-ldst-Exp08
                                                                                                                                                                                                                                            • OBJECT
                                                                                                                                                                                                                                            • 1 Following ICs and their Datasheets
                                                                                                                                                                                                                                            • 7408 Quad 2-input or 7421 Dual 4-input AND Gates
                                                                                                                                                                                                                                            • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                                              • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                                                              • Connecting wires Switches
                                                                                                                                                                                                                                                • THEORY
                                                                                                                                                                                                                                                    • Figure 81 Circuit Diagram for 4 x 2 Priority Encoder
                                                                                                                                                                                                                                                    • Implementation and Observations
                                                                                                                                                                                                                                                      • Therefore if GS A2 A1 and A0 are all low then it shows that line 0 is selected and if E0 A2 A1 and A0 are all low then it shows that none of the inputs selected E0 and GS cannot be in the same state provided that E1 is enabled
                                                                                                                                                                                                                                                      • Circuit Diagram
                                                                                                                                                                                                                                                        • ACTIVITY
                                                                                                                                                                                                                                                          • 14-ldst-exp09
                                                                                                                                                                                                                                                            • OBJECT
                                                                                                                                                                                                                                                            • 1 Following ICs and their Datasheets
                                                                                                                                                                                                                                                            • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                                                              • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                                                                              • Connecting wires Switches
                                                                                                                                                                                                                                                                • THEORY
                                                                                                                                                                                                                                                                  • Parity Generator
                                                                                                                                                                                                                                                                    • Let x y and z be the three bits that constitute the message and are the input to the Odd Parity Generator Circuit Since it is an odd parity system the bit P is generated so as to make the total number of 1s odd (including P) The function P can be expressed as follows
                                                                                                                                                                                                                                                                    • Figure 91 Circuit Diagram for a 3-bit Parity Generator
                                                                                                                                                                                                                                                                      • C = x Ο y Ο z Ο P
                                                                                                                                                                                                                                                                        • Implementation and Observations
                                                                                                                                                                                                                                                                          • ACTIVITY
                                                                                                                                                                                                                                                                              • 15-ldst-exp10
                                                                                                                                                                                                                                                                                • Driving a seven segment display using 7447 7448 driver IC
                                                                                                                                                                                                                                                                                • COMPONENTS AND APPARATUS REQUIRED
                                                                                                                                                                                                                                                                                • 1 Following ICs and their Datasheets
                                                                                                                                                                                                                                                                                • 7447 7448 BCD to Seven Segment Driver
                                                                                                                                                                                                                                                                                • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                                                                                  • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches
                                                                                                                                                                                                                                                                                    • THEORY
                                                                                                                                                                                                                                                                                    • Seven Segment Displays
                                                                                                                                                                                                                                                                                    • CIRCUIT DIAGRAM
                                                                                                                                                                                                                                                                                    • Figure 102 Circuit diagram for 7447driving a common-anode display
                                                                                                                                                                                                                                                                                        • IMPLEMENTATION AND OBSERVATIONS
                                                                                                                                                                                                                                                                                          • Decimal Digit
                                                                                                                                                                                                                                                                                          • BCD Inputs
                                                                                                                                                                                                                                                                                          • Seven Segment Outputs
                                                                                                                                                                                                                                                                                          • D
                                                                                                                                                                                                                                                                                          • C
                                                                                                                                                                                                                                                                                          • B
                                                                                                                                                                                                                                                                                          • A
                                                                                                                                                                                                                                                                                          • a
                                                                                                                                                                                                                                                                                          • b
                                                                                                                                                                                                                                                                                          • c
                                                                                                                                                                                                                                                                                          • d
                                                                                                                                                                                                                                                                                          • e
                                                                                                                                                                                                                                                                                          • f
                                                                                                                                                                                                                                                                                          • g
                                                                                                                                                                                                                                                                                          • 0
                                                                                                                                                                                                                                                                                          • 0
                                                                                                                                                                                                                                                                                          • 0
                                                                                                                                                                                                                                                                                          • 0
                                                                                                                                                                                                                                                                                          • 0
                                                                                                                                                                                                                                                                                          • 1
                                                                                                                                                                                                                                                                                          • 0
                                                                                                                                                                                                                                                                                          • 0
                                                                                                                                                                                                                                                                                          • 0
                                                                                                                                                                                                                                                                                          • 1
                                                                                                                                                                                                                                                                                          • 2
                                                                                                                                                                                                                                                                                          • 0
                                                                                                                                                                                                                                                                                          • 0
                                                                                                                                                                                                                                                                                          • 1
                                                                                                                                                                                                                                                                                          • 0
                                                                                                                                                                                                                                                                                          • 3
                                                                                                                                                                                                                                                                                          • 0
                                                                                                                                                                                                                                                                                          • 0
                                                                                                                                                                                                                                                                                          • 1
                                                                                                                                                                                                                                                                                          • 1
                                                                                                                                                                                                                                                                                          • 4
                                                                                                                                                                                                                                                                                          • 0
                                                                                                                                                                                                                                                                                          • 1
                                                                                                                                                                                                                                                                                          • 0
                                                                                                                                                                                                                                                                                          • 0
                                                                                                                                                                                                                                                                                          • 5
                                                                                                                                                                                                                                                                                          • 0
                                                                                                                                                                                                                                                                                          • 1
                                                                                                                                                                                                                                                                                          • 0
                                                                                                                                                                                                                                                                                          • 1
                                                                                                                                                                                                                                                                                          • 6
                                                                                                                                                                                                                                                                                          • 0
                                                                                                                                                                                                                                                                                          • 1
                                                                                                                                                                                                                                                                                          • 1
                                                                                                                                                                                                                                                                                          • 0
                                                                                                                                                                                                                                                                                          • 7
                                                                                                                                                                                                                                                                                          • 0
                                                                                                                                                                                                                                                                                          • 1
                                                                                                                                                                                                                                                                                          • 1
                                                                                                                                                                                                                                                                                          • 1
                                                                                                                                                                                                                                                                                          • 8
                                                                                                                                                                                                                                                                                          • 1
                                                                                                                                                                                                                                                                                          • 0
                                                                                                                                                                                                                                                                                          • 0
                                                                                                                                                                                                                                                                                          • 0
                                                                                                                                                                                                                                                                                          • 9
                                                                                                                                                                                                                                                                                          • 1
                                                                                                                                                                                                                                                                                          • 0
                                                                                                                                                                                                                                                                                          • 0
                                                                                                                                                                                                                                                                                          • 1
                                                                                                                                                                                                                                                                                            • ACTIVITY
                                                                                                                                                                                                                                                                                              • 16-ldst-exp11
                                                                                                                                                                                                                                                                                                • Lab Session 11
                                                                                                                                                                                                                                                                                                  • OBJECT
                                                                                                                                                                                                                                                                                                  • COMPONENTS AND APPARATUS REQUIRED
                                                                                                                                                                                                                                                                                                    • 1 Following ICs and their Datasheets
                                                                                                                                                                                                                                                                                                    • 7473 7476 JK Flip-Flop
                                                                                                                                                                                                                                                                                                    • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                                                                                                      • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                                                                                                                      • Connecting wires Switches
                                                                                                                                                                                                                                                                                                        • THEORY
                                                                                                                                                                                                                                                                                                            • Flip-Flop
                                                                                                                                                                                                                                                                                                            • JK Flip-Flop
                                                                                                                                                                                                                                                                                                              • Circuit Diagram
                                                                                                                                                                                                                                                                                                                • Observations
                                                                                                                                                                                                                                                                                                                  • ACTIVITY
                                                                                                                                                                                                                                                                                                                      • 17-ldst-exp12
                                                                                                                                                                                                                                                                                                                        • Lab Session 12
                                                                                                                                                                                                                                                                                                                          • OBJECT
                                                                                                                                                                                                                                                                                                                          • GIVEN STATE DIAGRAM
                                                                                                                                                                                                                                                                                                                          • Figure 121 State Diagram
                                                                                                                                                                                                                                                                                                                          • COMPONENTS AND APPARATUS REQUIRED
                                                                                                                                                                                                                                                                                                                            • 1 Following ICs and their Datasheets
                                                                                                                                                                                                                                                                                                                            • 7474 D Flip-Flop
                                                                                                                                                                                                                                                                                                                            • ICs of basic gates (AND OR NOT XOR etc) as required
                                                                                                                                                                                                                                                                                                                            • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                                                                                                                              • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                                                                                                                                              • Connecting wires Switches
                                                                                                                                                                                                                                                                                                                                • THEORY
                                                                                                                                                                                                                                                                                                                                    • Sequential Circuits
                                                                                                                                                                                                                                                                                                                                      • 18-ldst-exp13
                                                                                                                                                                                                                                                                                                                                        • Lab Session 13
                                                                                                                                                                                                                                                                                                                                          • Designing a modulo-5 asynchronous up-counter using JK-FF
                                                                                                                                                                                                                                                                                                                                            • 1 Following ICs and their Datasheets
                                                                                                                                                                                                                                                                                                                                            • 7400 Quad 2-input or 7410 Triple 3-input NAND Gates
                                                                                                                                                                                                                                                                                                                                            • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                                                                                                                                              • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                                                                                                                                                              • Connecting wires Switches
                                                                                                                                                                                                                                                                                                                                                • THEORY
                                                                                                                                                                                                                                                                                                                                                    • Figure 131 A Mod-5 Asynchronous Up Counter
                                                                                                                                                                                                                                                                                                                                                    • Implementation and Observations
                                                                                                                                                                                                                                                                                                                                                      • ACTIVITY
                                                                                                                                                                                                                                                                                                                                                          • 19-ldst-exp14
                                                                                                                                                                                                                                                                                                                                                            • Experimenting with 74194 4-bit bidirectional universal shift register
                                                                                                                                                                                                                                                                                                                                                            • 1 Following ICs and their Datasheets
                                                                                                                                                                                                                                                                                                                                                            • 74194 4-bit bidirectional universal shift register
                                                                                                                                                                                                                                                                                                                                                            • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                                                                                                                                                              • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                                                                                                                                                                              • Connecting wires Switches
                                                                                                                                                                                                                                                                                                                                                                • THEORY
                                                                                                                                                                                                                                                                                                                                                                  • Shift Registers
                                                                                                                                                                                                                                                                                                                                                                  • Bidirectional Shift Registers
                                                                                                                                                                                                                                                                                                                                                                  • Universal Shift Registers
                                                                                                                                                                                                                                                                                                                                                                    • S1
                                                                                                                                                                                                                                                                                                                                                                      • Circuit Diagram
                                                                                                                                                                                                                                                                                                                                                                      • ACTIVITY
                                                                                                                                                                                                                                                                                                                                                                          • 20-ldst-exp15
                                                                                                                                                                                                                                                                                                                                                                            • COMPONENTS AND APPARATUS REQUIRED
                                                                                                                                                                                                                                                                                                                                                                            • 1 Parallel Port Connectors (DB-25) with Cable
                                                                                                                                                                                                                                                                                                                                                                            • 2 Personal Computer with Windows 98 and TurboC Compiler Installed
                                                                                                                                                                                                                                                                                                                                                                            • 3 Following ICs and their Datasheets
                                                                                                                                                                                                                                                                                                                                                                            • 74245 Octal Bus Transceivers with 3-State Outputs
                                                                                                                                                                                                                                                                                                                                                                            • 4 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                                                                                                                                                                              • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                                                                                                                                                                                                • Connecting wires Switches
                                                                                                                                                                                                                                                                                                                                                                                  • THEORY
                                                                                                                                                                                                                                                                                                                                                                                  • 3-State Logic
                                                                                                                                                                                                                                                                                                                                                                                    • Serial and Parallel Port Connectors
                                                                                                                                                                                                                                                                                                                                                                                    • Parallel Port Connector ndash DB-25
                                                                                                                                                                                                                                                                                                                                                                                      • Accessing parallel port through C Language Programming
                                                                                                                                                                                                                                                                                                                                                                                          • 21-ldst-appendixA
                                                                                                                                                                                                                                                                                                                                                                                          • 22-ldst-appendixB
                                                                                                                                                                                                                                                                                                                                                                                            • DEBOUNCING CIRCUITRY FOR MECHANICAL SWITCHES

                                                                                                                    Logic Design amp Switching Theory 1 Lab Session 15 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                                                                    60

                                                                                                                    Each adapter can be a male type connector with pins or a female type adapter with tiny holes Generally a PRINTER port (called LPT1) on the back of a computer is female type adapter and we need to use MALE DB-25 pin cable on it for PRINTER connection or for parallel LAPLINK cable And a COM port on the back of a computer is male for the serial ports but it may not necessarily be Parallel Port Connector ndash DB-25 The DB-25 connector (named for its B-size D-shaped shell and 25 pins) is practically ubiquitous in the electronics industry The DB-25 connector is used for a variety of purposes Two common applications are RS-232EIA-232 (serial) connections and the parallel printer interface on the IBM PC The DB-25 connector is also used for SCSI connections Normally the parallel port is used for output to a printer or other device It sends data 8-bits or one byte at a time in parallel The other lines available on the DB-25 connector are a combination of status lines control lines and ground lines The status and control lines are used for handshaking commands and feedback when we are talking to a printer

                                                                                                                    Figure 152 DB-25 Female Figure 151 DB-25 Male

                                                                                                                    Figure 153 Pin Layout for DB-25 As can be seen form figure 153 there are four types of pins in this connector

                                                                                                                    bull Data pins (8 pins - D0 to D7) Active high bidirectional lines

                                                                                                                    Logic Design amp Switching Theory 1 Lab Session 15 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering bull Control pins (4 pins - C0 to C3) C0 C1 and C3 are active low whereas C2 is active

                                                                                                                    high These lines also are bidirectional bull Status pins (5 pins ndash S3 to S7) Only S7 is active low rest are active high input lines bull Ground pins (8 pins) Used as a reference signal for the low (below 05 volts) charge

                                                                                                                    Parallel Port Addresses A DB-25 connector at a parallel port has three address one for each kind of pins register data status and control The first or base address generally refers to data register Second address is for status register and the third one is for control register In Windows 98 the base address is usually found to be 278H 378H or 3BCH Now if 378H is the base address then it refers to the data register whereas addresses for status and control register are respectively 379H and 37AH For Windows 98 the base address can be found as follows 1 On your Desktop right-click on My Computer and select Properties 2 Click on the Device Manager tab and find LPT1 under Plug and Play BIOS 3 After selecting LPT1 click the Properties button 4 Next select the Resources tab and the address should then appear next to InputOutput

                                                                                                                    Range Accessing parallel port through C Language Programming There are multiple functions in C Language for accessing external ports The most commonly used are listed below

                                                                                                                    bull unsigned char inportb(int portid) inportb reads a byte from a hardware port

                                                                                                                    bull int inport(int portid) reads a word from a hardware port

                                                                                                                    bull void outportb(int portid unsigned char value) outputs a byte to a hardware port

                                                                                                                    bull void outport(int portid int value) outputs a word to a hardware port

                                                                                                                    portid refers to the port address whereas value refers to the data to be sent TESTING 74245 USING PARALLEL PORT PC INTERFACING At one end the parallel port connector will be connected to the PC via parallel port cable and another connector (to be plugged into the PC parallel port slot) At the other end it will be connected to the buffer IC 74245 Data lines of the connector will be used to transfer 8-bit data between the PC and the buffer Out of the 8-bits of 74245 4-bits will be used to enter data which will be displayed at the monitor through a C language

                                                                                                                    61

                                                                                                                    Logic Design amp Switching Theory 1 Lab Session 15 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering program The remaining 4-bits will receive data from PC as entered by the user via keyboard

                                                                                                                    Circuit Diagram

                                                                                                                    Figure 154 Interface of 74245 to PC via Parallel Port

                                                                                                                    Procedure

                                                                                                                    1 Connect the DB-25 connector to the PC at one end and solder it to the circuit board at the other end

                                                                                                                    2 Connect various pins of the connector and 74245 according to the circuit diagram shown in figure 152

                                                                                                                    3 Using the functions listed in the previous section write a program in C language to operate various pins of the buffer The user interface of the program should provide option to the user whether to send or receive data from the port

                                                                                                                    4 Set DIR switch to 1 5 Try sending some data bits to the port The result should be displayed at the LEDs 6 Set DIR switch to 0 7 Set some binary 4-bit value through the switches Try reading it via parallel port

                                                                                                                    C Language Program

                                                                                                                    A program to access parallel port for data transfers

                                                                                                                    use header file include ltstdiohgt main program void main() define variable

                                                                                                                    62

                                                                                                                    Logic Design amp Switching Theory 1 Lab Session 15 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering unsigned int data=0 char choice while(1) printing option menu clrscr() printf(This program will send or receive a BCD digit from the parallel portn) printf(nPress your choice numbern) printf(n1 Send Data) printf(n2 Receive Data) printf(n3 Exitn) choice = getch() sending entered digit to the port if(choice == 1) input BCD digit printf(nEnter BCD digit to be sent to the port) data = getche() masking the first four bits data = data amp 0x0f sending to the port outportb(0x378data) printf(nThe BCD digit c has been sent to the port data) printing on screen the data received from the port else if(choice == 2) receiving data from the port data = inportb(0x378) masking the last four bits data = data amp 0xf0 shifting first four bits to make them the last four bits datagtgt=4 printf(nThe BCD digit set at the port is c data) exit else if(choice == 3) break key pressed is not in the menu else printf(nEnter valid choice number) printf(nnPress any key to continue) getch()

                                                                                                                    63

                                                                                                                    Logic Design amp Switching Theory 1 Lab Session 15 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                                                                    ACTIVITY 1 In the above circuit DIR and G΄ inputs are hardwired Connect them to status or

                                                                                                                    control pins of the parallel port connector and control their function through your software program Circuit Diagram Program Code ______________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________

                                                                                                                    ___________________________________________________________________________________________________________________________________________________

                                                                                                                    64

                                                                                                                    Logic Design amp Switching Theory 1 Lab Session 15 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                                                                    65

                                                                                                                    _____________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ _____________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ _______________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ _________________________________________________ _________________________________________________

                                                                                                                    Logic Design amp Switching Theory 1 Appendix A NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                                                                    Appendix A

                                                                                                                    PIN DIAGRAMS OF THE ICS REQUIRED FOR THE LABORATORY SESSIONS Consult the TTLIC data book for internal diagrams and electrical characteristics of these ICs 7400 Quad 2-Input NAND 7402 Quad 2-Input NOR

                                                                                                                    7404 Hex Inverter 7408 Quad 2-Input AND

                                                                                                                    7410 Triple 3-Input NAND 7411 Triple 3-Input AND

                                                                                                                    7421 Dual 4-Input AND 7432 Quad 2-Input OR

                                                                                                                    66

                                                                                                                    Logic Design amp Switching Theory 1 Appendix A NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                                                                    BCD-to-Seven Segm 7448 BCD-to-Seven Segment 7447 ent

                                                                                                                    Decoder (15V OC) Decoder (2kΩ pull-up output)

                                                                                                                    7473 Dual JK Flip-Flop 7474 Dual D-Type Flip-Flop

                                                                                                                    7476 Dual JK Flop-Flop -Bit Binary Full Adder 7483 4 with Fast Carry

                                                                                                                    86 Quad 2-Inpu 74138 3-to-8 Line 74 t Exclusive OR Decoder Demultiplexer

                                                                                                                    67

                                                                                                                    Logic Design amp Switching Theory 1 Appendix A NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                                                                    68

                                                                                                                    74148 8-to-3 Line 16-to-1 Line Data

                                                                                                                    Priority Encoder 74150 Selector Multiplexer

                                                                                                                    74245 Oct nsceivers Universal Shift Register (PIPO) (3-State)

                                                                                                                    74194 4-Bit Bidirectional al Bus Tra

                                                                                                                    Logic Design amp Switching Theory 1 Appendix B NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                                                                    Appendix B

                                                                                                                    DEBOUNCING CIRCUITRY FOR MECHANICAL SWITCHES Mechanical switches form the interface between human beings and computers or other digital systems For example a keyboard is a matrix of switches used to supply alphanumeric data to a computer Whatever the switch design it is a potential source of problems due to contact bounce The contact bounce creates a sense of narrow pulses when a switch is opened or closed An example of device whose operation would be adversely affected by contact bounce is a digital counter used to count the number of times a switch is depressed Eliminating the effects of contact bounce is called debouncing When data is entered into a computer via a keyboard a software debounce is often used This type of debouncing is a program that causes the computer to sample the switch terminal (ie to input data from it) many times in succession during the interval of time that contact bounce occurs If the data is sensed to be 1s (or 0s) for a specific number of consecutive samples then it is assumed that contact bounce has ended and the last value sensed is valid Hardware debouncing is the use of electronic circuitry to eliminate the effects of contact bounce There are numerous versions of such circuitry including those that use monostable multivibrators (one-shots) but the most straightforward is simply an RS latch Figure B1 shows the circuit When the switch is in position 1 R = 0 and S = 1 so the latch is set and the output (Q) is 1 When the switch is in position 0 R = 1and S = 0 so the latch is reset and the output is 0 When the switch is moved form one position to the other the latch changes state and bouncing occurs at either the R or the S input The bouncing does not affect the latch after it has change state An RS latch will remain set for example when its R input is 0 and its S input is alternately changed form 1 to 0

                                                                                                                    Figure B1 Use of RS latch to debounce a mechanical switch

                                                                                                                    69

                                                                                                                    • 01-ldst-Outer title
                                                                                                                      • Practical Workbook
                                                                                                                      • Logic Design amp Switching Theory I
                                                                                                                        • Dept of Computer amp Information Systems Engineering
                                                                                                                          • NED University of Engineering amp Technology
                                                                                                                          • Karachi ndash 75270 Pakistan
                                                                                                                            • 02-ldst-inner Title
                                                                                                                              • Practical Workbook
                                                                                                                              • Logic Design amp Switching Theory I
                                                                                                                                • Dept of Computer amp Information Systems Engineering
                                                                                                                                  • NED University of Engineering amp Technology
                                                                                                                                  • Karachi ndash 75270 Pakistan
                                                                                                                                    • 03-ldst-general info
                                                                                                                                    • 04-ldst-introduction
                                                                                                                                    • 05-Table of Contents
                                                                                                                                      • CONTENTS
                                                                                                                                        • Lab Session No Object Page No
                                                                                                                                        • 1
                                                                                                                                        • Also implementing and testing the given circuit on a bread board
                                                                                                                                          • Working with Electronics Workbench
                                                                                                                                            • Driving a seven segment display using 7447 7448 driver IC
                                                                                                                                              • Designing a modulus-5 asynchronous up-counter using JK-FF
                                                                                                                                                • Experimenting with 74194 4-bit bidirectional universal shift register
                                                                                                                                                    • 13
                                                                                                                                                        • 06-ldst-Exp01
                                                                                                                                                          • Lab Session 01
                                                                                                                                                          • OBJECT
                                                                                                                                                            • 1 Bread board
                                                                                                                                                            • 2 5 V - power supply
                                                                                                                                                            • 3 Multimeter
                                                                                                                                                            • 4 Logic probe
                                                                                                                                                            • 5 LEDs with resistors
                                                                                                                                                            • 6 Connecting wires
                                                                                                                                                            • 8 Following ICs and their datasheets
                                                                                                                                                              • THEORY
                                                                                                                                                                • Logic Gates
                                                                                                                                                                • 1 The AND Gate ndash An AND gatersquos output is 1 if and only if all its inputs are 1 If A and B are two inputs to an AND gate then output F of the gate is given as F = AB
                                                                                                                                                                • 2 The OR Gate - An OR gatersquos output is 1 if at least one of its input is 1 If A and B are two inputs to an OR gate then output F of the gate is given as F = A+B
                                                                                                                                                                • 3 The NOT Gate (Inverter) ndash Its output is 1 when its input is 0 and its output is 0 when the input is 1 ie it complements a digital variable If A is the input to a NOT gate then output F of the gate is given as
                                                                                                                                                                • 4 The NAND Gate ndash Its output is 1 if at least one of its input is 0 This gate performs the same logic as an AND gate followed by an inverter If A and B are two inputs to a NAND gate then output F of the gate is given as
                                                                                                                                                                  • 5 The NOR Gate - The output of a NOR gate is 1 if and only if all its inputs are 0 This gate performs the same logic function as an OR gate followed by an inverter If A and B are two inputs to a NAND gate then output F of the gate is given as
                                                                                                                                                                      • DATA SHEETS
                                                                                                                                                                        • Logic expression for the given logic diagram __________________________________
                                                                                                                                                                            • 07-ldst-exp02
                                                                                                                                                                              • Working with Electronics Workbench
                                                                                                                                                                                • 08-ldst-exp03
                                                                                                                                                                                  • Designing Half and Full Adder Circuits
                                                                                                                                                                                    • COMPONENTS AND APPARATUS REQUIRED
                                                                                                                                                                                      • 1 Following ICs and their Datasheets
                                                                                                                                                                                      • 7408 Quad 2-input AND Gate
                                                                                                                                                                                      • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                        • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                        • Connecting wires Switches
                                                                                                                                                                                          • THEORY
                                                                                                                                                                                              • IMPLEMENTATION AND OBSERVATIONS
                                                                                                                                                                                                • 09-ldst-Exp04
                                                                                                                                                                                                  • Lab Session 04
                                                                                                                                                                                                  • 1 Digital ICs and their Datasheets
                                                                                                                                                                                                  • 7408 Quad 2-input AND Gate
                                                                                                                                                                                                  • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                    • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                    • Connecting wires Switches
                                                                                                                                                                                                    • PROCEDURE
                                                                                                                                                                                                    • REDUCTION OF LOGIC EXPRESSION USING KARNAUGH MAP
                                                                                                                                                                                                    • OBSERVATIONS
                                                                                                                                                                                                    • RESULT
                                                                                                                                                                                                        • 10-ldst-Exp05
                                                                                                                                                                                                          • Lab Session 05
                                                                                                                                                                                                          • 1 Following ICs and their Datasheets
                                                                                                                                                                                                          • 7408 Quad 2-input AND Gate
                                                                                                                                                                                                          • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                            • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                            • (100 Ω) Connecting wires Switches
                                                                                                                                                                                                            • THEORY
                                                                                                                                                                                                              • IMPLEMENTATION AND OBSERVATIONS
                                                                                                                                                                                                                • 11-ldst-Exp06
                                                                                                                                                                                                                  • OBJECT
                                                                                                                                                                                                                  • 1 Following ICs and their Datasheets
                                                                                                                                                                                                                  • 7408 Quad 2-input AND Gates or 7411 Triple 3-input AND Gates
                                                                                                                                                                                                                  • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                    • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                                    • Connecting wires Switches
                                                                                                                                                                                                                      • Figure 62 Circuit Diagram for 4 x 1 Multiplexer
                                                                                                                                                                                                                      • Implementation and Observations
                                                                                                                                                                                                                        • Circuit Diagram
                                                                                                                                                                                                                          • ACTIVITY
                                                                                                                                                                                                                            • 12-ldst-exp07
                                                                                                                                                                                                                              • 1 Following ICs and their Datasheets
                                                                                                                                                                                                                              • 7408 Quad 2-input or 7411 Triple 3-input AND Gates
                                                                                                                                                                                                                              • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                                • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                                                • Connecting wires Switches
                                                                                                                                                                                                                                  • THEORY
                                                                                                                                                                                                                                      • Figure 72 Circuit Diagram for 2 x 4 Decoder 1 x 4 Demultiplexer
                                                                                                                                                                                                                                      • Implementation and Observations
                                                                                                                                                                                                                                        • Circuit Diagram
                                                                                                                                                                                                                                          • ACTIVITY
                                                                                                                                                                                                                                            • 13-ldst-Exp08
                                                                                                                                                                                                                                              • OBJECT
                                                                                                                                                                                                                                              • 1 Following ICs and their Datasheets
                                                                                                                                                                                                                                              • 7408 Quad 2-input or 7421 Dual 4-input AND Gates
                                                                                                                                                                                                                                              • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                                                • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                                                                • Connecting wires Switches
                                                                                                                                                                                                                                                  • THEORY
                                                                                                                                                                                                                                                      • Figure 81 Circuit Diagram for 4 x 2 Priority Encoder
                                                                                                                                                                                                                                                      • Implementation and Observations
                                                                                                                                                                                                                                                        • Therefore if GS A2 A1 and A0 are all low then it shows that line 0 is selected and if E0 A2 A1 and A0 are all low then it shows that none of the inputs selected E0 and GS cannot be in the same state provided that E1 is enabled
                                                                                                                                                                                                                                                        • Circuit Diagram
                                                                                                                                                                                                                                                          • ACTIVITY
                                                                                                                                                                                                                                                            • 14-ldst-exp09
                                                                                                                                                                                                                                                              • OBJECT
                                                                                                                                                                                                                                                              • 1 Following ICs and their Datasheets
                                                                                                                                                                                                                                                              • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                                                                • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                                                                                • Connecting wires Switches
                                                                                                                                                                                                                                                                  • THEORY
                                                                                                                                                                                                                                                                    • Parity Generator
                                                                                                                                                                                                                                                                      • Let x y and z be the three bits that constitute the message and are the input to the Odd Parity Generator Circuit Since it is an odd parity system the bit P is generated so as to make the total number of 1s odd (including P) The function P can be expressed as follows
                                                                                                                                                                                                                                                                      • Figure 91 Circuit Diagram for a 3-bit Parity Generator
                                                                                                                                                                                                                                                                        • C = x Ο y Ο z Ο P
                                                                                                                                                                                                                                                                          • Implementation and Observations
                                                                                                                                                                                                                                                                            • ACTIVITY
                                                                                                                                                                                                                                                                                • 15-ldst-exp10
                                                                                                                                                                                                                                                                                  • Driving a seven segment display using 7447 7448 driver IC
                                                                                                                                                                                                                                                                                  • COMPONENTS AND APPARATUS REQUIRED
                                                                                                                                                                                                                                                                                  • 1 Following ICs and their Datasheets
                                                                                                                                                                                                                                                                                  • 7447 7448 BCD to Seven Segment Driver
                                                                                                                                                                                                                                                                                  • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                                                                                    • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches
                                                                                                                                                                                                                                                                                      • THEORY
                                                                                                                                                                                                                                                                                      • Seven Segment Displays
                                                                                                                                                                                                                                                                                      • CIRCUIT DIAGRAM
                                                                                                                                                                                                                                                                                      • Figure 102 Circuit diagram for 7447driving a common-anode display
                                                                                                                                                                                                                                                                                          • IMPLEMENTATION AND OBSERVATIONS
                                                                                                                                                                                                                                                                                            • Decimal Digit
                                                                                                                                                                                                                                                                                            • BCD Inputs
                                                                                                                                                                                                                                                                                            • Seven Segment Outputs
                                                                                                                                                                                                                                                                                            • D
                                                                                                                                                                                                                                                                                            • C
                                                                                                                                                                                                                                                                                            • B
                                                                                                                                                                                                                                                                                            • A
                                                                                                                                                                                                                                                                                            • a
                                                                                                                                                                                                                                                                                            • b
                                                                                                                                                                                                                                                                                            • c
                                                                                                                                                                                                                                                                                            • d
                                                                                                                                                                                                                                                                                            • e
                                                                                                                                                                                                                                                                                            • f
                                                                                                                                                                                                                                                                                            • g
                                                                                                                                                                                                                                                                                            • 0
                                                                                                                                                                                                                                                                                            • 0
                                                                                                                                                                                                                                                                                            • 0
                                                                                                                                                                                                                                                                                            • 0
                                                                                                                                                                                                                                                                                            • 0
                                                                                                                                                                                                                                                                                            • 1
                                                                                                                                                                                                                                                                                            • 0
                                                                                                                                                                                                                                                                                            • 0
                                                                                                                                                                                                                                                                                            • 0
                                                                                                                                                                                                                                                                                            • 1
                                                                                                                                                                                                                                                                                            • 2
                                                                                                                                                                                                                                                                                            • 0
                                                                                                                                                                                                                                                                                            • 0
                                                                                                                                                                                                                                                                                            • 1
                                                                                                                                                                                                                                                                                            • 0
                                                                                                                                                                                                                                                                                            • 3
                                                                                                                                                                                                                                                                                            • 0
                                                                                                                                                                                                                                                                                            • 0
                                                                                                                                                                                                                                                                                            • 1
                                                                                                                                                                                                                                                                                            • 1
                                                                                                                                                                                                                                                                                            • 4
                                                                                                                                                                                                                                                                                            • 0
                                                                                                                                                                                                                                                                                            • 1
                                                                                                                                                                                                                                                                                            • 0
                                                                                                                                                                                                                                                                                            • 0
                                                                                                                                                                                                                                                                                            • 5
                                                                                                                                                                                                                                                                                            • 0
                                                                                                                                                                                                                                                                                            • 1
                                                                                                                                                                                                                                                                                            • 0
                                                                                                                                                                                                                                                                                            • 1
                                                                                                                                                                                                                                                                                            • 6
                                                                                                                                                                                                                                                                                            • 0
                                                                                                                                                                                                                                                                                            • 1
                                                                                                                                                                                                                                                                                            • 1
                                                                                                                                                                                                                                                                                            • 0
                                                                                                                                                                                                                                                                                            • 7
                                                                                                                                                                                                                                                                                            • 0
                                                                                                                                                                                                                                                                                            • 1
                                                                                                                                                                                                                                                                                            • 1
                                                                                                                                                                                                                                                                                            • 1
                                                                                                                                                                                                                                                                                            • 8
                                                                                                                                                                                                                                                                                            • 1
                                                                                                                                                                                                                                                                                            • 0
                                                                                                                                                                                                                                                                                            • 0
                                                                                                                                                                                                                                                                                            • 0
                                                                                                                                                                                                                                                                                            • 9
                                                                                                                                                                                                                                                                                            • 1
                                                                                                                                                                                                                                                                                            • 0
                                                                                                                                                                                                                                                                                            • 0
                                                                                                                                                                                                                                                                                            • 1
                                                                                                                                                                                                                                                                                              • ACTIVITY
                                                                                                                                                                                                                                                                                                • 16-ldst-exp11
                                                                                                                                                                                                                                                                                                  • Lab Session 11
                                                                                                                                                                                                                                                                                                    • OBJECT
                                                                                                                                                                                                                                                                                                    • COMPONENTS AND APPARATUS REQUIRED
                                                                                                                                                                                                                                                                                                      • 1 Following ICs and their Datasheets
                                                                                                                                                                                                                                                                                                      • 7473 7476 JK Flip-Flop
                                                                                                                                                                                                                                                                                                      • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                                                                                                        • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                                                                                                                        • Connecting wires Switches
                                                                                                                                                                                                                                                                                                          • THEORY
                                                                                                                                                                                                                                                                                                              • Flip-Flop
                                                                                                                                                                                                                                                                                                              • JK Flip-Flop
                                                                                                                                                                                                                                                                                                                • Circuit Diagram
                                                                                                                                                                                                                                                                                                                  • Observations
                                                                                                                                                                                                                                                                                                                    • ACTIVITY
                                                                                                                                                                                                                                                                                                                        • 17-ldst-exp12
                                                                                                                                                                                                                                                                                                                          • Lab Session 12
                                                                                                                                                                                                                                                                                                                            • OBJECT
                                                                                                                                                                                                                                                                                                                            • GIVEN STATE DIAGRAM
                                                                                                                                                                                                                                                                                                                            • Figure 121 State Diagram
                                                                                                                                                                                                                                                                                                                            • COMPONENTS AND APPARATUS REQUIRED
                                                                                                                                                                                                                                                                                                                              • 1 Following ICs and their Datasheets
                                                                                                                                                                                                                                                                                                                              • 7474 D Flip-Flop
                                                                                                                                                                                                                                                                                                                              • ICs of basic gates (AND OR NOT XOR etc) as required
                                                                                                                                                                                                                                                                                                                              • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                                                                                                                                • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                                                                                                                                                • Connecting wires Switches
                                                                                                                                                                                                                                                                                                                                  • THEORY
                                                                                                                                                                                                                                                                                                                                      • Sequential Circuits
                                                                                                                                                                                                                                                                                                                                        • 18-ldst-exp13
                                                                                                                                                                                                                                                                                                                                          • Lab Session 13
                                                                                                                                                                                                                                                                                                                                            • Designing a modulo-5 asynchronous up-counter using JK-FF
                                                                                                                                                                                                                                                                                                                                              • 1 Following ICs and their Datasheets
                                                                                                                                                                                                                                                                                                                                              • 7400 Quad 2-input or 7410 Triple 3-input NAND Gates
                                                                                                                                                                                                                                                                                                                                              • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                                                                                                                                                • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                                                                                                                                                                • Connecting wires Switches
                                                                                                                                                                                                                                                                                                                                                  • THEORY
                                                                                                                                                                                                                                                                                                                                                      • Figure 131 A Mod-5 Asynchronous Up Counter
                                                                                                                                                                                                                                                                                                                                                      • Implementation and Observations
                                                                                                                                                                                                                                                                                                                                                        • ACTIVITY
                                                                                                                                                                                                                                                                                                                                                            • 19-ldst-exp14
                                                                                                                                                                                                                                                                                                                                                              • Experimenting with 74194 4-bit bidirectional universal shift register
                                                                                                                                                                                                                                                                                                                                                              • 1 Following ICs and their Datasheets
                                                                                                                                                                                                                                                                                                                                                              • 74194 4-bit bidirectional universal shift register
                                                                                                                                                                                                                                                                                                                                                              • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                                                                                                                                                                • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                                                                                                                                                                                • Connecting wires Switches
                                                                                                                                                                                                                                                                                                                                                                  • THEORY
                                                                                                                                                                                                                                                                                                                                                                    • Shift Registers
                                                                                                                                                                                                                                                                                                                                                                    • Bidirectional Shift Registers
                                                                                                                                                                                                                                                                                                                                                                    • Universal Shift Registers
                                                                                                                                                                                                                                                                                                                                                                      • S1
                                                                                                                                                                                                                                                                                                                                                                        • Circuit Diagram
                                                                                                                                                                                                                                                                                                                                                                        • ACTIVITY
                                                                                                                                                                                                                                                                                                                                                                            • 20-ldst-exp15
                                                                                                                                                                                                                                                                                                                                                                              • COMPONENTS AND APPARATUS REQUIRED
                                                                                                                                                                                                                                                                                                                                                                              • 1 Parallel Port Connectors (DB-25) with Cable
                                                                                                                                                                                                                                                                                                                                                                              • 2 Personal Computer with Windows 98 and TurboC Compiler Installed
                                                                                                                                                                                                                                                                                                                                                                              • 3 Following ICs and their Datasheets
                                                                                                                                                                                                                                                                                                                                                                              • 74245 Octal Bus Transceivers with 3-State Outputs
                                                                                                                                                                                                                                                                                                                                                                              • 4 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                                                                                                                                                                                • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                                                                                                                                                                                                  • Connecting wires Switches
                                                                                                                                                                                                                                                                                                                                                                                    • THEORY
                                                                                                                                                                                                                                                                                                                                                                                    • 3-State Logic
                                                                                                                                                                                                                                                                                                                                                                                      • Serial and Parallel Port Connectors
                                                                                                                                                                                                                                                                                                                                                                                      • Parallel Port Connector ndash DB-25
                                                                                                                                                                                                                                                                                                                                                                                        • Accessing parallel port through C Language Programming
                                                                                                                                                                                                                                                                                                                                                                                            • 21-ldst-appendixA
                                                                                                                                                                                                                                                                                                                                                                                            • 22-ldst-appendixB
                                                                                                                                                                                                                                                                                                                                                                                              • DEBOUNCING CIRCUITRY FOR MECHANICAL SWITCHES

                                                                                                                      Logic Design amp Switching Theory 1 Lab Session 15 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering bull Control pins (4 pins - C0 to C3) C0 C1 and C3 are active low whereas C2 is active

                                                                                                                      high These lines also are bidirectional bull Status pins (5 pins ndash S3 to S7) Only S7 is active low rest are active high input lines bull Ground pins (8 pins) Used as a reference signal for the low (below 05 volts) charge

                                                                                                                      Parallel Port Addresses A DB-25 connector at a parallel port has three address one for each kind of pins register data status and control The first or base address generally refers to data register Second address is for status register and the third one is for control register In Windows 98 the base address is usually found to be 278H 378H or 3BCH Now if 378H is the base address then it refers to the data register whereas addresses for status and control register are respectively 379H and 37AH For Windows 98 the base address can be found as follows 1 On your Desktop right-click on My Computer and select Properties 2 Click on the Device Manager tab and find LPT1 under Plug and Play BIOS 3 After selecting LPT1 click the Properties button 4 Next select the Resources tab and the address should then appear next to InputOutput

                                                                                                                      Range Accessing parallel port through C Language Programming There are multiple functions in C Language for accessing external ports The most commonly used are listed below

                                                                                                                      bull unsigned char inportb(int portid) inportb reads a byte from a hardware port

                                                                                                                      bull int inport(int portid) reads a word from a hardware port

                                                                                                                      bull void outportb(int portid unsigned char value) outputs a byte to a hardware port

                                                                                                                      bull void outport(int portid int value) outputs a word to a hardware port

                                                                                                                      portid refers to the port address whereas value refers to the data to be sent TESTING 74245 USING PARALLEL PORT PC INTERFACING At one end the parallel port connector will be connected to the PC via parallel port cable and another connector (to be plugged into the PC parallel port slot) At the other end it will be connected to the buffer IC 74245 Data lines of the connector will be used to transfer 8-bit data between the PC and the buffer Out of the 8-bits of 74245 4-bits will be used to enter data which will be displayed at the monitor through a C language

                                                                                                                      61

                                                                                                                      Logic Design amp Switching Theory 1 Lab Session 15 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering program The remaining 4-bits will receive data from PC as entered by the user via keyboard

                                                                                                                      Circuit Diagram

                                                                                                                      Figure 154 Interface of 74245 to PC via Parallel Port

                                                                                                                      Procedure

                                                                                                                      1 Connect the DB-25 connector to the PC at one end and solder it to the circuit board at the other end

                                                                                                                      2 Connect various pins of the connector and 74245 according to the circuit diagram shown in figure 152

                                                                                                                      3 Using the functions listed in the previous section write a program in C language to operate various pins of the buffer The user interface of the program should provide option to the user whether to send or receive data from the port

                                                                                                                      4 Set DIR switch to 1 5 Try sending some data bits to the port The result should be displayed at the LEDs 6 Set DIR switch to 0 7 Set some binary 4-bit value through the switches Try reading it via parallel port

                                                                                                                      C Language Program

                                                                                                                      A program to access parallel port for data transfers

                                                                                                                      use header file include ltstdiohgt main program void main() define variable

                                                                                                                      62

                                                                                                                      Logic Design amp Switching Theory 1 Lab Session 15 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering unsigned int data=0 char choice while(1) printing option menu clrscr() printf(This program will send or receive a BCD digit from the parallel portn) printf(nPress your choice numbern) printf(n1 Send Data) printf(n2 Receive Data) printf(n3 Exitn) choice = getch() sending entered digit to the port if(choice == 1) input BCD digit printf(nEnter BCD digit to be sent to the port) data = getche() masking the first four bits data = data amp 0x0f sending to the port outportb(0x378data) printf(nThe BCD digit c has been sent to the port data) printing on screen the data received from the port else if(choice == 2) receiving data from the port data = inportb(0x378) masking the last four bits data = data amp 0xf0 shifting first four bits to make them the last four bits datagtgt=4 printf(nThe BCD digit set at the port is c data) exit else if(choice == 3) break key pressed is not in the menu else printf(nEnter valid choice number) printf(nnPress any key to continue) getch()

                                                                                                                      63

                                                                                                                      Logic Design amp Switching Theory 1 Lab Session 15 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                                                                      ACTIVITY 1 In the above circuit DIR and G΄ inputs are hardwired Connect them to status or

                                                                                                                      control pins of the parallel port connector and control their function through your software program Circuit Diagram Program Code ______________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________

                                                                                                                      ___________________________________________________________________________________________________________________________________________________

                                                                                                                      64

                                                                                                                      Logic Design amp Switching Theory 1 Lab Session 15 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                                                                      65

                                                                                                                      _____________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ _____________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ _______________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ _________________________________________________ _________________________________________________

                                                                                                                      Logic Design amp Switching Theory 1 Appendix A NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                                                                      Appendix A

                                                                                                                      PIN DIAGRAMS OF THE ICS REQUIRED FOR THE LABORATORY SESSIONS Consult the TTLIC data book for internal diagrams and electrical characteristics of these ICs 7400 Quad 2-Input NAND 7402 Quad 2-Input NOR

                                                                                                                      7404 Hex Inverter 7408 Quad 2-Input AND

                                                                                                                      7410 Triple 3-Input NAND 7411 Triple 3-Input AND

                                                                                                                      7421 Dual 4-Input AND 7432 Quad 2-Input OR

                                                                                                                      66

                                                                                                                      Logic Design amp Switching Theory 1 Appendix A NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                                                                      BCD-to-Seven Segm 7448 BCD-to-Seven Segment 7447 ent

                                                                                                                      Decoder (15V OC) Decoder (2kΩ pull-up output)

                                                                                                                      7473 Dual JK Flip-Flop 7474 Dual D-Type Flip-Flop

                                                                                                                      7476 Dual JK Flop-Flop -Bit Binary Full Adder 7483 4 with Fast Carry

                                                                                                                      86 Quad 2-Inpu 74138 3-to-8 Line 74 t Exclusive OR Decoder Demultiplexer

                                                                                                                      67

                                                                                                                      Logic Design amp Switching Theory 1 Appendix A NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                                                                      68

                                                                                                                      74148 8-to-3 Line 16-to-1 Line Data

                                                                                                                      Priority Encoder 74150 Selector Multiplexer

                                                                                                                      74245 Oct nsceivers Universal Shift Register (PIPO) (3-State)

                                                                                                                      74194 4-Bit Bidirectional al Bus Tra

                                                                                                                      Logic Design amp Switching Theory 1 Appendix B NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                                                                      Appendix B

                                                                                                                      DEBOUNCING CIRCUITRY FOR MECHANICAL SWITCHES Mechanical switches form the interface between human beings and computers or other digital systems For example a keyboard is a matrix of switches used to supply alphanumeric data to a computer Whatever the switch design it is a potential source of problems due to contact bounce The contact bounce creates a sense of narrow pulses when a switch is opened or closed An example of device whose operation would be adversely affected by contact bounce is a digital counter used to count the number of times a switch is depressed Eliminating the effects of contact bounce is called debouncing When data is entered into a computer via a keyboard a software debounce is often used This type of debouncing is a program that causes the computer to sample the switch terminal (ie to input data from it) many times in succession during the interval of time that contact bounce occurs If the data is sensed to be 1s (or 0s) for a specific number of consecutive samples then it is assumed that contact bounce has ended and the last value sensed is valid Hardware debouncing is the use of electronic circuitry to eliminate the effects of contact bounce There are numerous versions of such circuitry including those that use monostable multivibrators (one-shots) but the most straightforward is simply an RS latch Figure B1 shows the circuit When the switch is in position 1 R = 0 and S = 1 so the latch is set and the output (Q) is 1 When the switch is in position 0 R = 1and S = 0 so the latch is reset and the output is 0 When the switch is moved form one position to the other the latch changes state and bouncing occurs at either the R or the S input The bouncing does not affect the latch after it has change state An RS latch will remain set for example when its R input is 0 and its S input is alternately changed form 1 to 0

                                                                                                                      Figure B1 Use of RS latch to debounce a mechanical switch

                                                                                                                      69

                                                                                                                      • 01-ldst-Outer title
                                                                                                                        • Practical Workbook
                                                                                                                        • Logic Design amp Switching Theory I
                                                                                                                          • Dept of Computer amp Information Systems Engineering
                                                                                                                            • NED University of Engineering amp Technology
                                                                                                                            • Karachi ndash 75270 Pakistan
                                                                                                                              • 02-ldst-inner Title
                                                                                                                                • Practical Workbook
                                                                                                                                • Logic Design amp Switching Theory I
                                                                                                                                  • Dept of Computer amp Information Systems Engineering
                                                                                                                                    • NED University of Engineering amp Technology
                                                                                                                                    • Karachi ndash 75270 Pakistan
                                                                                                                                      • 03-ldst-general info
                                                                                                                                      • 04-ldst-introduction
                                                                                                                                      • 05-Table of Contents
                                                                                                                                        • CONTENTS
                                                                                                                                          • Lab Session No Object Page No
                                                                                                                                          • 1
                                                                                                                                          • Also implementing and testing the given circuit on a bread board
                                                                                                                                            • Working with Electronics Workbench
                                                                                                                                              • Driving a seven segment display using 7447 7448 driver IC
                                                                                                                                                • Designing a modulus-5 asynchronous up-counter using JK-FF
                                                                                                                                                  • Experimenting with 74194 4-bit bidirectional universal shift register
                                                                                                                                                      • 13
                                                                                                                                                          • 06-ldst-Exp01
                                                                                                                                                            • Lab Session 01
                                                                                                                                                            • OBJECT
                                                                                                                                                              • 1 Bread board
                                                                                                                                                              • 2 5 V - power supply
                                                                                                                                                              • 3 Multimeter
                                                                                                                                                              • 4 Logic probe
                                                                                                                                                              • 5 LEDs with resistors
                                                                                                                                                              • 6 Connecting wires
                                                                                                                                                              • 8 Following ICs and their datasheets
                                                                                                                                                                • THEORY
                                                                                                                                                                  • Logic Gates
                                                                                                                                                                  • 1 The AND Gate ndash An AND gatersquos output is 1 if and only if all its inputs are 1 If A and B are two inputs to an AND gate then output F of the gate is given as F = AB
                                                                                                                                                                  • 2 The OR Gate - An OR gatersquos output is 1 if at least one of its input is 1 If A and B are two inputs to an OR gate then output F of the gate is given as F = A+B
                                                                                                                                                                  • 3 The NOT Gate (Inverter) ndash Its output is 1 when its input is 0 and its output is 0 when the input is 1 ie it complements a digital variable If A is the input to a NOT gate then output F of the gate is given as
                                                                                                                                                                  • 4 The NAND Gate ndash Its output is 1 if at least one of its input is 0 This gate performs the same logic as an AND gate followed by an inverter If A and B are two inputs to a NAND gate then output F of the gate is given as
                                                                                                                                                                    • 5 The NOR Gate - The output of a NOR gate is 1 if and only if all its inputs are 0 This gate performs the same logic function as an OR gate followed by an inverter If A and B are two inputs to a NAND gate then output F of the gate is given as
                                                                                                                                                                        • DATA SHEETS
                                                                                                                                                                          • Logic expression for the given logic diagram __________________________________
                                                                                                                                                                              • 07-ldst-exp02
                                                                                                                                                                                • Working with Electronics Workbench
                                                                                                                                                                                  • 08-ldst-exp03
                                                                                                                                                                                    • Designing Half and Full Adder Circuits
                                                                                                                                                                                      • COMPONENTS AND APPARATUS REQUIRED
                                                                                                                                                                                        • 1 Following ICs and their Datasheets
                                                                                                                                                                                        • 7408 Quad 2-input AND Gate
                                                                                                                                                                                        • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                          • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                          • Connecting wires Switches
                                                                                                                                                                                            • THEORY
                                                                                                                                                                                                • IMPLEMENTATION AND OBSERVATIONS
                                                                                                                                                                                                  • 09-ldst-Exp04
                                                                                                                                                                                                    • Lab Session 04
                                                                                                                                                                                                    • 1 Digital ICs and their Datasheets
                                                                                                                                                                                                    • 7408 Quad 2-input AND Gate
                                                                                                                                                                                                    • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                      • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                      • Connecting wires Switches
                                                                                                                                                                                                      • PROCEDURE
                                                                                                                                                                                                      • REDUCTION OF LOGIC EXPRESSION USING KARNAUGH MAP
                                                                                                                                                                                                      • OBSERVATIONS
                                                                                                                                                                                                      • RESULT
                                                                                                                                                                                                          • 10-ldst-Exp05
                                                                                                                                                                                                            • Lab Session 05
                                                                                                                                                                                                            • 1 Following ICs and their Datasheets
                                                                                                                                                                                                            • 7408 Quad 2-input AND Gate
                                                                                                                                                                                                            • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                              • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                              • (100 Ω) Connecting wires Switches
                                                                                                                                                                                                              • THEORY
                                                                                                                                                                                                                • IMPLEMENTATION AND OBSERVATIONS
                                                                                                                                                                                                                  • 11-ldst-Exp06
                                                                                                                                                                                                                    • OBJECT
                                                                                                                                                                                                                    • 1 Following ICs and their Datasheets
                                                                                                                                                                                                                    • 7408 Quad 2-input AND Gates or 7411 Triple 3-input AND Gates
                                                                                                                                                                                                                    • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                      • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                                      • Connecting wires Switches
                                                                                                                                                                                                                        • Figure 62 Circuit Diagram for 4 x 1 Multiplexer
                                                                                                                                                                                                                        • Implementation and Observations
                                                                                                                                                                                                                          • Circuit Diagram
                                                                                                                                                                                                                            • ACTIVITY
                                                                                                                                                                                                                              • 12-ldst-exp07
                                                                                                                                                                                                                                • 1 Following ICs and their Datasheets
                                                                                                                                                                                                                                • 7408 Quad 2-input or 7411 Triple 3-input AND Gates
                                                                                                                                                                                                                                • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                                  • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                                                  • Connecting wires Switches
                                                                                                                                                                                                                                    • THEORY
                                                                                                                                                                                                                                        • Figure 72 Circuit Diagram for 2 x 4 Decoder 1 x 4 Demultiplexer
                                                                                                                                                                                                                                        • Implementation and Observations
                                                                                                                                                                                                                                          • Circuit Diagram
                                                                                                                                                                                                                                            • ACTIVITY
                                                                                                                                                                                                                                              • 13-ldst-Exp08
                                                                                                                                                                                                                                                • OBJECT
                                                                                                                                                                                                                                                • 1 Following ICs and their Datasheets
                                                                                                                                                                                                                                                • 7408 Quad 2-input or 7421 Dual 4-input AND Gates
                                                                                                                                                                                                                                                • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                                                  • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                                                                  • Connecting wires Switches
                                                                                                                                                                                                                                                    • THEORY
                                                                                                                                                                                                                                                        • Figure 81 Circuit Diagram for 4 x 2 Priority Encoder
                                                                                                                                                                                                                                                        • Implementation and Observations
                                                                                                                                                                                                                                                          • Therefore if GS A2 A1 and A0 are all low then it shows that line 0 is selected and if E0 A2 A1 and A0 are all low then it shows that none of the inputs selected E0 and GS cannot be in the same state provided that E1 is enabled
                                                                                                                                                                                                                                                          • Circuit Diagram
                                                                                                                                                                                                                                                            • ACTIVITY
                                                                                                                                                                                                                                                              • 14-ldst-exp09
                                                                                                                                                                                                                                                                • OBJECT
                                                                                                                                                                                                                                                                • 1 Following ICs and their Datasheets
                                                                                                                                                                                                                                                                • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                                                                  • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                                                                                  • Connecting wires Switches
                                                                                                                                                                                                                                                                    • THEORY
                                                                                                                                                                                                                                                                      • Parity Generator
                                                                                                                                                                                                                                                                        • Let x y and z be the three bits that constitute the message and are the input to the Odd Parity Generator Circuit Since it is an odd parity system the bit P is generated so as to make the total number of 1s odd (including P) The function P can be expressed as follows
                                                                                                                                                                                                                                                                        • Figure 91 Circuit Diagram for a 3-bit Parity Generator
                                                                                                                                                                                                                                                                          • C = x Ο y Ο z Ο P
                                                                                                                                                                                                                                                                            • Implementation and Observations
                                                                                                                                                                                                                                                                              • ACTIVITY
                                                                                                                                                                                                                                                                                  • 15-ldst-exp10
                                                                                                                                                                                                                                                                                    • Driving a seven segment display using 7447 7448 driver IC
                                                                                                                                                                                                                                                                                    • COMPONENTS AND APPARATUS REQUIRED
                                                                                                                                                                                                                                                                                    • 1 Following ICs and their Datasheets
                                                                                                                                                                                                                                                                                    • 7447 7448 BCD to Seven Segment Driver
                                                                                                                                                                                                                                                                                    • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                                                                                      • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches
                                                                                                                                                                                                                                                                                        • THEORY
                                                                                                                                                                                                                                                                                        • Seven Segment Displays
                                                                                                                                                                                                                                                                                        • CIRCUIT DIAGRAM
                                                                                                                                                                                                                                                                                        • Figure 102 Circuit diagram for 7447driving a common-anode display
                                                                                                                                                                                                                                                                                            • IMPLEMENTATION AND OBSERVATIONS
                                                                                                                                                                                                                                                                                              • Decimal Digit
                                                                                                                                                                                                                                                                                              • BCD Inputs
                                                                                                                                                                                                                                                                                              • Seven Segment Outputs
                                                                                                                                                                                                                                                                                              • D
                                                                                                                                                                                                                                                                                              • C
                                                                                                                                                                                                                                                                                              • B
                                                                                                                                                                                                                                                                                              • A
                                                                                                                                                                                                                                                                                              • a
                                                                                                                                                                                                                                                                                              • b
                                                                                                                                                                                                                                                                                              • c
                                                                                                                                                                                                                                                                                              • d
                                                                                                                                                                                                                                                                                              • e
                                                                                                                                                                                                                                                                                              • f
                                                                                                                                                                                                                                                                                              • g
                                                                                                                                                                                                                                                                                              • 0
                                                                                                                                                                                                                                                                                              • 0
                                                                                                                                                                                                                                                                                              • 0
                                                                                                                                                                                                                                                                                              • 0
                                                                                                                                                                                                                                                                                              • 0
                                                                                                                                                                                                                                                                                              • 1
                                                                                                                                                                                                                                                                                              • 0
                                                                                                                                                                                                                                                                                              • 0
                                                                                                                                                                                                                                                                                              • 0
                                                                                                                                                                                                                                                                                              • 1
                                                                                                                                                                                                                                                                                              • 2
                                                                                                                                                                                                                                                                                              • 0
                                                                                                                                                                                                                                                                                              • 0
                                                                                                                                                                                                                                                                                              • 1
                                                                                                                                                                                                                                                                                              • 0
                                                                                                                                                                                                                                                                                              • 3
                                                                                                                                                                                                                                                                                              • 0
                                                                                                                                                                                                                                                                                              • 0
                                                                                                                                                                                                                                                                                              • 1
                                                                                                                                                                                                                                                                                              • 1
                                                                                                                                                                                                                                                                                              • 4
                                                                                                                                                                                                                                                                                              • 0
                                                                                                                                                                                                                                                                                              • 1
                                                                                                                                                                                                                                                                                              • 0
                                                                                                                                                                                                                                                                                              • 0
                                                                                                                                                                                                                                                                                              • 5
                                                                                                                                                                                                                                                                                              • 0
                                                                                                                                                                                                                                                                                              • 1
                                                                                                                                                                                                                                                                                              • 0
                                                                                                                                                                                                                                                                                              • 1
                                                                                                                                                                                                                                                                                              • 6
                                                                                                                                                                                                                                                                                              • 0
                                                                                                                                                                                                                                                                                              • 1
                                                                                                                                                                                                                                                                                              • 1
                                                                                                                                                                                                                                                                                              • 0
                                                                                                                                                                                                                                                                                              • 7
                                                                                                                                                                                                                                                                                              • 0
                                                                                                                                                                                                                                                                                              • 1
                                                                                                                                                                                                                                                                                              • 1
                                                                                                                                                                                                                                                                                              • 1
                                                                                                                                                                                                                                                                                              • 8
                                                                                                                                                                                                                                                                                              • 1
                                                                                                                                                                                                                                                                                              • 0
                                                                                                                                                                                                                                                                                              • 0
                                                                                                                                                                                                                                                                                              • 0
                                                                                                                                                                                                                                                                                              • 9
                                                                                                                                                                                                                                                                                              • 1
                                                                                                                                                                                                                                                                                              • 0
                                                                                                                                                                                                                                                                                              • 0
                                                                                                                                                                                                                                                                                              • 1
                                                                                                                                                                                                                                                                                                • ACTIVITY
                                                                                                                                                                                                                                                                                                  • 16-ldst-exp11
                                                                                                                                                                                                                                                                                                    • Lab Session 11
                                                                                                                                                                                                                                                                                                      • OBJECT
                                                                                                                                                                                                                                                                                                      • COMPONENTS AND APPARATUS REQUIRED
                                                                                                                                                                                                                                                                                                        • 1 Following ICs and their Datasheets
                                                                                                                                                                                                                                                                                                        • 7473 7476 JK Flip-Flop
                                                                                                                                                                                                                                                                                                        • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                                                                                                          • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                                                                                                                          • Connecting wires Switches
                                                                                                                                                                                                                                                                                                            • THEORY
                                                                                                                                                                                                                                                                                                                • Flip-Flop
                                                                                                                                                                                                                                                                                                                • JK Flip-Flop
                                                                                                                                                                                                                                                                                                                  • Circuit Diagram
                                                                                                                                                                                                                                                                                                                    • Observations
                                                                                                                                                                                                                                                                                                                      • ACTIVITY
                                                                                                                                                                                                                                                                                                                          • 17-ldst-exp12
                                                                                                                                                                                                                                                                                                                            • Lab Session 12
                                                                                                                                                                                                                                                                                                                              • OBJECT
                                                                                                                                                                                                                                                                                                                              • GIVEN STATE DIAGRAM
                                                                                                                                                                                                                                                                                                                              • Figure 121 State Diagram
                                                                                                                                                                                                                                                                                                                              • COMPONENTS AND APPARATUS REQUIRED
                                                                                                                                                                                                                                                                                                                                • 1 Following ICs and their Datasheets
                                                                                                                                                                                                                                                                                                                                • 7474 D Flip-Flop
                                                                                                                                                                                                                                                                                                                                • ICs of basic gates (AND OR NOT XOR etc) as required
                                                                                                                                                                                                                                                                                                                                • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                                                                                                                                  • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                                                                                                                                                  • Connecting wires Switches
                                                                                                                                                                                                                                                                                                                                    • THEORY
                                                                                                                                                                                                                                                                                                                                        • Sequential Circuits
                                                                                                                                                                                                                                                                                                                                          • 18-ldst-exp13
                                                                                                                                                                                                                                                                                                                                            • Lab Session 13
                                                                                                                                                                                                                                                                                                                                              • Designing a modulo-5 asynchronous up-counter using JK-FF
                                                                                                                                                                                                                                                                                                                                                • 1 Following ICs and their Datasheets
                                                                                                                                                                                                                                                                                                                                                • 7400 Quad 2-input or 7410 Triple 3-input NAND Gates
                                                                                                                                                                                                                                                                                                                                                • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                                                                                                                                                  • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                                                                                                                                                                  • Connecting wires Switches
                                                                                                                                                                                                                                                                                                                                                    • THEORY
                                                                                                                                                                                                                                                                                                                                                        • Figure 131 A Mod-5 Asynchronous Up Counter
                                                                                                                                                                                                                                                                                                                                                        • Implementation and Observations
                                                                                                                                                                                                                                                                                                                                                          • ACTIVITY
                                                                                                                                                                                                                                                                                                                                                              • 19-ldst-exp14
                                                                                                                                                                                                                                                                                                                                                                • Experimenting with 74194 4-bit bidirectional universal shift register
                                                                                                                                                                                                                                                                                                                                                                • 1 Following ICs and their Datasheets
                                                                                                                                                                                                                                                                                                                                                                • 74194 4-bit bidirectional universal shift register
                                                                                                                                                                                                                                                                                                                                                                • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                                                                                                                                                                  • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                                                                                                                                                                                  • Connecting wires Switches
                                                                                                                                                                                                                                                                                                                                                                    • THEORY
                                                                                                                                                                                                                                                                                                                                                                      • Shift Registers
                                                                                                                                                                                                                                                                                                                                                                      • Bidirectional Shift Registers
                                                                                                                                                                                                                                                                                                                                                                      • Universal Shift Registers
                                                                                                                                                                                                                                                                                                                                                                        • S1
                                                                                                                                                                                                                                                                                                                                                                          • Circuit Diagram
                                                                                                                                                                                                                                                                                                                                                                          • ACTIVITY
                                                                                                                                                                                                                                                                                                                                                                              • 20-ldst-exp15
                                                                                                                                                                                                                                                                                                                                                                                • COMPONENTS AND APPARATUS REQUIRED
                                                                                                                                                                                                                                                                                                                                                                                • 1 Parallel Port Connectors (DB-25) with Cable
                                                                                                                                                                                                                                                                                                                                                                                • 2 Personal Computer with Windows 98 and TurboC Compiler Installed
                                                                                                                                                                                                                                                                                                                                                                                • 3 Following ICs and their Datasheets
                                                                                                                                                                                                                                                                                                                                                                                • 74245 Octal Bus Transceivers with 3-State Outputs
                                                                                                                                                                                                                                                                                                                                                                                • 4 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                                                                                                                                                                                  • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                                                                                                                                                                                                    • Connecting wires Switches
                                                                                                                                                                                                                                                                                                                                                                                      • THEORY
                                                                                                                                                                                                                                                                                                                                                                                      • 3-State Logic
                                                                                                                                                                                                                                                                                                                                                                                        • Serial and Parallel Port Connectors
                                                                                                                                                                                                                                                                                                                                                                                        • Parallel Port Connector ndash DB-25
                                                                                                                                                                                                                                                                                                                                                                                          • Accessing parallel port through C Language Programming
                                                                                                                                                                                                                                                                                                                                                                                              • 21-ldst-appendixA
                                                                                                                                                                                                                                                                                                                                                                                              • 22-ldst-appendixB
                                                                                                                                                                                                                                                                                                                                                                                                • DEBOUNCING CIRCUITRY FOR MECHANICAL SWITCHES

                                                                                                                        Logic Design amp Switching Theory 1 Lab Session 15 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering program The remaining 4-bits will receive data from PC as entered by the user via keyboard

                                                                                                                        Circuit Diagram

                                                                                                                        Figure 154 Interface of 74245 to PC via Parallel Port

                                                                                                                        Procedure

                                                                                                                        1 Connect the DB-25 connector to the PC at one end and solder it to the circuit board at the other end

                                                                                                                        2 Connect various pins of the connector and 74245 according to the circuit diagram shown in figure 152

                                                                                                                        3 Using the functions listed in the previous section write a program in C language to operate various pins of the buffer The user interface of the program should provide option to the user whether to send or receive data from the port

                                                                                                                        4 Set DIR switch to 1 5 Try sending some data bits to the port The result should be displayed at the LEDs 6 Set DIR switch to 0 7 Set some binary 4-bit value through the switches Try reading it via parallel port

                                                                                                                        C Language Program

                                                                                                                        A program to access parallel port for data transfers

                                                                                                                        use header file include ltstdiohgt main program void main() define variable

                                                                                                                        62

                                                                                                                        Logic Design amp Switching Theory 1 Lab Session 15 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering unsigned int data=0 char choice while(1) printing option menu clrscr() printf(This program will send or receive a BCD digit from the parallel portn) printf(nPress your choice numbern) printf(n1 Send Data) printf(n2 Receive Data) printf(n3 Exitn) choice = getch() sending entered digit to the port if(choice == 1) input BCD digit printf(nEnter BCD digit to be sent to the port) data = getche() masking the first four bits data = data amp 0x0f sending to the port outportb(0x378data) printf(nThe BCD digit c has been sent to the port data) printing on screen the data received from the port else if(choice == 2) receiving data from the port data = inportb(0x378) masking the last four bits data = data amp 0xf0 shifting first four bits to make them the last four bits datagtgt=4 printf(nThe BCD digit set at the port is c data) exit else if(choice == 3) break key pressed is not in the menu else printf(nEnter valid choice number) printf(nnPress any key to continue) getch()

                                                                                                                        63

                                                                                                                        Logic Design amp Switching Theory 1 Lab Session 15 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                                                                        ACTIVITY 1 In the above circuit DIR and G΄ inputs are hardwired Connect them to status or

                                                                                                                        control pins of the parallel port connector and control their function through your software program Circuit Diagram Program Code ______________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________

                                                                                                                        ___________________________________________________________________________________________________________________________________________________

                                                                                                                        64

                                                                                                                        Logic Design amp Switching Theory 1 Lab Session 15 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                                                                        65

                                                                                                                        _____________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ _____________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ _______________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ _________________________________________________ _________________________________________________

                                                                                                                        Logic Design amp Switching Theory 1 Appendix A NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                                                                        Appendix A

                                                                                                                        PIN DIAGRAMS OF THE ICS REQUIRED FOR THE LABORATORY SESSIONS Consult the TTLIC data book for internal diagrams and electrical characteristics of these ICs 7400 Quad 2-Input NAND 7402 Quad 2-Input NOR

                                                                                                                        7404 Hex Inverter 7408 Quad 2-Input AND

                                                                                                                        7410 Triple 3-Input NAND 7411 Triple 3-Input AND

                                                                                                                        7421 Dual 4-Input AND 7432 Quad 2-Input OR

                                                                                                                        66

                                                                                                                        Logic Design amp Switching Theory 1 Appendix A NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                                                                        BCD-to-Seven Segm 7448 BCD-to-Seven Segment 7447 ent

                                                                                                                        Decoder (15V OC) Decoder (2kΩ pull-up output)

                                                                                                                        7473 Dual JK Flip-Flop 7474 Dual D-Type Flip-Flop

                                                                                                                        7476 Dual JK Flop-Flop -Bit Binary Full Adder 7483 4 with Fast Carry

                                                                                                                        86 Quad 2-Inpu 74138 3-to-8 Line 74 t Exclusive OR Decoder Demultiplexer

                                                                                                                        67

                                                                                                                        Logic Design amp Switching Theory 1 Appendix A NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                                                                        68

                                                                                                                        74148 8-to-3 Line 16-to-1 Line Data

                                                                                                                        Priority Encoder 74150 Selector Multiplexer

                                                                                                                        74245 Oct nsceivers Universal Shift Register (PIPO) (3-State)

                                                                                                                        74194 4-Bit Bidirectional al Bus Tra

                                                                                                                        Logic Design amp Switching Theory 1 Appendix B NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                                                                        Appendix B

                                                                                                                        DEBOUNCING CIRCUITRY FOR MECHANICAL SWITCHES Mechanical switches form the interface between human beings and computers or other digital systems For example a keyboard is a matrix of switches used to supply alphanumeric data to a computer Whatever the switch design it is a potential source of problems due to contact bounce The contact bounce creates a sense of narrow pulses when a switch is opened or closed An example of device whose operation would be adversely affected by contact bounce is a digital counter used to count the number of times a switch is depressed Eliminating the effects of contact bounce is called debouncing When data is entered into a computer via a keyboard a software debounce is often used This type of debouncing is a program that causes the computer to sample the switch terminal (ie to input data from it) many times in succession during the interval of time that contact bounce occurs If the data is sensed to be 1s (or 0s) for a specific number of consecutive samples then it is assumed that contact bounce has ended and the last value sensed is valid Hardware debouncing is the use of electronic circuitry to eliminate the effects of contact bounce There are numerous versions of such circuitry including those that use monostable multivibrators (one-shots) but the most straightforward is simply an RS latch Figure B1 shows the circuit When the switch is in position 1 R = 0 and S = 1 so the latch is set and the output (Q) is 1 When the switch is in position 0 R = 1and S = 0 so the latch is reset and the output is 0 When the switch is moved form one position to the other the latch changes state and bouncing occurs at either the R or the S input The bouncing does not affect the latch after it has change state An RS latch will remain set for example when its R input is 0 and its S input is alternately changed form 1 to 0

                                                                                                                        Figure B1 Use of RS latch to debounce a mechanical switch

                                                                                                                        69

                                                                                                                        • 01-ldst-Outer title
                                                                                                                          • Practical Workbook
                                                                                                                          • Logic Design amp Switching Theory I
                                                                                                                            • Dept of Computer amp Information Systems Engineering
                                                                                                                              • NED University of Engineering amp Technology
                                                                                                                              • Karachi ndash 75270 Pakistan
                                                                                                                                • 02-ldst-inner Title
                                                                                                                                  • Practical Workbook
                                                                                                                                  • Logic Design amp Switching Theory I
                                                                                                                                    • Dept of Computer amp Information Systems Engineering
                                                                                                                                      • NED University of Engineering amp Technology
                                                                                                                                      • Karachi ndash 75270 Pakistan
                                                                                                                                        • 03-ldst-general info
                                                                                                                                        • 04-ldst-introduction
                                                                                                                                        • 05-Table of Contents
                                                                                                                                          • CONTENTS
                                                                                                                                            • Lab Session No Object Page No
                                                                                                                                            • 1
                                                                                                                                            • Also implementing and testing the given circuit on a bread board
                                                                                                                                              • Working with Electronics Workbench
                                                                                                                                                • Driving a seven segment display using 7447 7448 driver IC
                                                                                                                                                  • Designing a modulus-5 asynchronous up-counter using JK-FF
                                                                                                                                                    • Experimenting with 74194 4-bit bidirectional universal shift register
                                                                                                                                                        • 13
                                                                                                                                                            • 06-ldst-Exp01
                                                                                                                                                              • Lab Session 01
                                                                                                                                                              • OBJECT
                                                                                                                                                                • 1 Bread board
                                                                                                                                                                • 2 5 V - power supply
                                                                                                                                                                • 3 Multimeter
                                                                                                                                                                • 4 Logic probe
                                                                                                                                                                • 5 LEDs with resistors
                                                                                                                                                                • 6 Connecting wires
                                                                                                                                                                • 8 Following ICs and their datasheets
                                                                                                                                                                  • THEORY
                                                                                                                                                                    • Logic Gates
                                                                                                                                                                    • 1 The AND Gate ndash An AND gatersquos output is 1 if and only if all its inputs are 1 If A and B are two inputs to an AND gate then output F of the gate is given as F = AB
                                                                                                                                                                    • 2 The OR Gate - An OR gatersquos output is 1 if at least one of its input is 1 If A and B are two inputs to an OR gate then output F of the gate is given as F = A+B
                                                                                                                                                                    • 3 The NOT Gate (Inverter) ndash Its output is 1 when its input is 0 and its output is 0 when the input is 1 ie it complements a digital variable If A is the input to a NOT gate then output F of the gate is given as
                                                                                                                                                                    • 4 The NAND Gate ndash Its output is 1 if at least one of its input is 0 This gate performs the same logic as an AND gate followed by an inverter If A and B are two inputs to a NAND gate then output F of the gate is given as
                                                                                                                                                                      • 5 The NOR Gate - The output of a NOR gate is 1 if and only if all its inputs are 0 This gate performs the same logic function as an OR gate followed by an inverter If A and B are two inputs to a NAND gate then output F of the gate is given as
                                                                                                                                                                          • DATA SHEETS
                                                                                                                                                                            • Logic expression for the given logic diagram __________________________________
                                                                                                                                                                                • 07-ldst-exp02
                                                                                                                                                                                  • Working with Electronics Workbench
                                                                                                                                                                                    • 08-ldst-exp03
                                                                                                                                                                                      • Designing Half and Full Adder Circuits
                                                                                                                                                                                        • COMPONENTS AND APPARATUS REQUIRED
                                                                                                                                                                                          • 1 Following ICs and their Datasheets
                                                                                                                                                                                          • 7408 Quad 2-input AND Gate
                                                                                                                                                                                          • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                            • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                            • Connecting wires Switches
                                                                                                                                                                                              • THEORY
                                                                                                                                                                                                  • IMPLEMENTATION AND OBSERVATIONS
                                                                                                                                                                                                    • 09-ldst-Exp04
                                                                                                                                                                                                      • Lab Session 04
                                                                                                                                                                                                      • 1 Digital ICs and their Datasheets
                                                                                                                                                                                                      • 7408 Quad 2-input AND Gate
                                                                                                                                                                                                      • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                        • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                        • Connecting wires Switches
                                                                                                                                                                                                        • PROCEDURE
                                                                                                                                                                                                        • REDUCTION OF LOGIC EXPRESSION USING KARNAUGH MAP
                                                                                                                                                                                                        • OBSERVATIONS
                                                                                                                                                                                                        • RESULT
                                                                                                                                                                                                            • 10-ldst-Exp05
                                                                                                                                                                                                              • Lab Session 05
                                                                                                                                                                                                              • 1 Following ICs and their Datasheets
                                                                                                                                                                                                              • 7408 Quad 2-input AND Gate
                                                                                                                                                                                                              • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                                • (100 Ω) Connecting wires Switches
                                                                                                                                                                                                                • THEORY
                                                                                                                                                                                                                  • IMPLEMENTATION AND OBSERVATIONS
                                                                                                                                                                                                                    • 11-ldst-Exp06
                                                                                                                                                                                                                      • OBJECT
                                                                                                                                                                                                                      • 1 Following ICs and their Datasheets
                                                                                                                                                                                                                      • 7408 Quad 2-input AND Gates or 7411 Triple 3-input AND Gates
                                                                                                                                                                                                                      • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                        • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                                        • Connecting wires Switches
                                                                                                                                                                                                                          • Figure 62 Circuit Diagram for 4 x 1 Multiplexer
                                                                                                                                                                                                                          • Implementation and Observations
                                                                                                                                                                                                                            • Circuit Diagram
                                                                                                                                                                                                                              • ACTIVITY
                                                                                                                                                                                                                                • 12-ldst-exp07
                                                                                                                                                                                                                                  • 1 Following ICs and their Datasheets
                                                                                                                                                                                                                                  • 7408 Quad 2-input or 7411 Triple 3-input AND Gates
                                                                                                                                                                                                                                  • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                                    • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                                                    • Connecting wires Switches
                                                                                                                                                                                                                                      • THEORY
                                                                                                                                                                                                                                          • Figure 72 Circuit Diagram for 2 x 4 Decoder 1 x 4 Demultiplexer
                                                                                                                                                                                                                                          • Implementation and Observations
                                                                                                                                                                                                                                            • Circuit Diagram
                                                                                                                                                                                                                                              • ACTIVITY
                                                                                                                                                                                                                                                • 13-ldst-Exp08
                                                                                                                                                                                                                                                  • OBJECT
                                                                                                                                                                                                                                                  • 1 Following ICs and their Datasheets
                                                                                                                                                                                                                                                  • 7408 Quad 2-input or 7421 Dual 4-input AND Gates
                                                                                                                                                                                                                                                  • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                                                    • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                                                                    • Connecting wires Switches
                                                                                                                                                                                                                                                      • THEORY
                                                                                                                                                                                                                                                          • Figure 81 Circuit Diagram for 4 x 2 Priority Encoder
                                                                                                                                                                                                                                                          • Implementation and Observations
                                                                                                                                                                                                                                                            • Therefore if GS A2 A1 and A0 are all low then it shows that line 0 is selected and if E0 A2 A1 and A0 are all low then it shows that none of the inputs selected E0 and GS cannot be in the same state provided that E1 is enabled
                                                                                                                                                                                                                                                            • Circuit Diagram
                                                                                                                                                                                                                                                              • ACTIVITY
                                                                                                                                                                                                                                                                • 14-ldst-exp09
                                                                                                                                                                                                                                                                  • OBJECT
                                                                                                                                                                                                                                                                  • 1 Following ICs and their Datasheets
                                                                                                                                                                                                                                                                  • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                                                                    • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                                                                                    • Connecting wires Switches
                                                                                                                                                                                                                                                                      • THEORY
                                                                                                                                                                                                                                                                        • Parity Generator
                                                                                                                                                                                                                                                                          • Let x y and z be the three bits that constitute the message and are the input to the Odd Parity Generator Circuit Since it is an odd parity system the bit P is generated so as to make the total number of 1s odd (including P) The function P can be expressed as follows
                                                                                                                                                                                                                                                                          • Figure 91 Circuit Diagram for a 3-bit Parity Generator
                                                                                                                                                                                                                                                                            • C = x Ο y Ο z Ο P
                                                                                                                                                                                                                                                                              • Implementation and Observations
                                                                                                                                                                                                                                                                                • ACTIVITY
                                                                                                                                                                                                                                                                                    • 15-ldst-exp10
                                                                                                                                                                                                                                                                                      • Driving a seven segment display using 7447 7448 driver IC
                                                                                                                                                                                                                                                                                      • COMPONENTS AND APPARATUS REQUIRED
                                                                                                                                                                                                                                                                                      • 1 Following ICs and their Datasheets
                                                                                                                                                                                                                                                                                      • 7447 7448 BCD to Seven Segment Driver
                                                                                                                                                                                                                                                                                      • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                                                                                        • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches
                                                                                                                                                                                                                                                                                          • THEORY
                                                                                                                                                                                                                                                                                          • Seven Segment Displays
                                                                                                                                                                                                                                                                                          • CIRCUIT DIAGRAM
                                                                                                                                                                                                                                                                                          • Figure 102 Circuit diagram for 7447driving a common-anode display
                                                                                                                                                                                                                                                                                              • IMPLEMENTATION AND OBSERVATIONS
                                                                                                                                                                                                                                                                                                • Decimal Digit
                                                                                                                                                                                                                                                                                                • BCD Inputs
                                                                                                                                                                                                                                                                                                • Seven Segment Outputs
                                                                                                                                                                                                                                                                                                • D
                                                                                                                                                                                                                                                                                                • C
                                                                                                                                                                                                                                                                                                • B
                                                                                                                                                                                                                                                                                                • A
                                                                                                                                                                                                                                                                                                • a
                                                                                                                                                                                                                                                                                                • b
                                                                                                                                                                                                                                                                                                • c
                                                                                                                                                                                                                                                                                                • d
                                                                                                                                                                                                                                                                                                • e
                                                                                                                                                                                                                                                                                                • f
                                                                                                                                                                                                                                                                                                • g
                                                                                                                                                                                                                                                                                                • 0
                                                                                                                                                                                                                                                                                                • 0
                                                                                                                                                                                                                                                                                                • 0
                                                                                                                                                                                                                                                                                                • 0
                                                                                                                                                                                                                                                                                                • 0
                                                                                                                                                                                                                                                                                                • 1
                                                                                                                                                                                                                                                                                                • 0
                                                                                                                                                                                                                                                                                                • 0
                                                                                                                                                                                                                                                                                                • 0
                                                                                                                                                                                                                                                                                                • 1
                                                                                                                                                                                                                                                                                                • 2
                                                                                                                                                                                                                                                                                                • 0
                                                                                                                                                                                                                                                                                                • 0
                                                                                                                                                                                                                                                                                                • 1
                                                                                                                                                                                                                                                                                                • 0
                                                                                                                                                                                                                                                                                                • 3
                                                                                                                                                                                                                                                                                                • 0
                                                                                                                                                                                                                                                                                                • 0
                                                                                                                                                                                                                                                                                                • 1
                                                                                                                                                                                                                                                                                                • 1
                                                                                                                                                                                                                                                                                                • 4
                                                                                                                                                                                                                                                                                                • 0
                                                                                                                                                                                                                                                                                                • 1
                                                                                                                                                                                                                                                                                                • 0
                                                                                                                                                                                                                                                                                                • 0
                                                                                                                                                                                                                                                                                                • 5
                                                                                                                                                                                                                                                                                                • 0
                                                                                                                                                                                                                                                                                                • 1
                                                                                                                                                                                                                                                                                                • 0
                                                                                                                                                                                                                                                                                                • 1
                                                                                                                                                                                                                                                                                                • 6
                                                                                                                                                                                                                                                                                                • 0
                                                                                                                                                                                                                                                                                                • 1
                                                                                                                                                                                                                                                                                                • 1
                                                                                                                                                                                                                                                                                                • 0
                                                                                                                                                                                                                                                                                                • 7
                                                                                                                                                                                                                                                                                                • 0
                                                                                                                                                                                                                                                                                                • 1
                                                                                                                                                                                                                                                                                                • 1
                                                                                                                                                                                                                                                                                                • 1
                                                                                                                                                                                                                                                                                                • 8
                                                                                                                                                                                                                                                                                                • 1
                                                                                                                                                                                                                                                                                                • 0
                                                                                                                                                                                                                                                                                                • 0
                                                                                                                                                                                                                                                                                                • 0
                                                                                                                                                                                                                                                                                                • 9
                                                                                                                                                                                                                                                                                                • 1
                                                                                                                                                                                                                                                                                                • 0
                                                                                                                                                                                                                                                                                                • 0
                                                                                                                                                                                                                                                                                                • 1
                                                                                                                                                                                                                                                                                                  • ACTIVITY
                                                                                                                                                                                                                                                                                                    • 16-ldst-exp11
                                                                                                                                                                                                                                                                                                      • Lab Session 11
                                                                                                                                                                                                                                                                                                        • OBJECT
                                                                                                                                                                                                                                                                                                        • COMPONENTS AND APPARATUS REQUIRED
                                                                                                                                                                                                                                                                                                          • 1 Following ICs and their Datasheets
                                                                                                                                                                                                                                                                                                          • 7473 7476 JK Flip-Flop
                                                                                                                                                                                                                                                                                                          • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                                                                                                            • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                                                                                                                            • Connecting wires Switches
                                                                                                                                                                                                                                                                                                              • THEORY
                                                                                                                                                                                                                                                                                                                  • Flip-Flop
                                                                                                                                                                                                                                                                                                                  • JK Flip-Flop
                                                                                                                                                                                                                                                                                                                    • Circuit Diagram
                                                                                                                                                                                                                                                                                                                      • Observations
                                                                                                                                                                                                                                                                                                                        • ACTIVITY
                                                                                                                                                                                                                                                                                                                            • 17-ldst-exp12
                                                                                                                                                                                                                                                                                                                              • Lab Session 12
                                                                                                                                                                                                                                                                                                                                • OBJECT
                                                                                                                                                                                                                                                                                                                                • GIVEN STATE DIAGRAM
                                                                                                                                                                                                                                                                                                                                • Figure 121 State Diagram
                                                                                                                                                                                                                                                                                                                                • COMPONENTS AND APPARATUS REQUIRED
                                                                                                                                                                                                                                                                                                                                  • 1 Following ICs and their Datasheets
                                                                                                                                                                                                                                                                                                                                  • 7474 D Flip-Flop
                                                                                                                                                                                                                                                                                                                                  • ICs of basic gates (AND OR NOT XOR etc) as required
                                                                                                                                                                                                                                                                                                                                  • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                                                                                                                                    • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                                                                                                                                                    • Connecting wires Switches
                                                                                                                                                                                                                                                                                                                                      • THEORY
                                                                                                                                                                                                                                                                                                                                          • Sequential Circuits
                                                                                                                                                                                                                                                                                                                                            • 18-ldst-exp13
                                                                                                                                                                                                                                                                                                                                              • Lab Session 13
                                                                                                                                                                                                                                                                                                                                                • Designing a modulo-5 asynchronous up-counter using JK-FF
                                                                                                                                                                                                                                                                                                                                                  • 1 Following ICs and their Datasheets
                                                                                                                                                                                                                                                                                                                                                  • 7400 Quad 2-input or 7410 Triple 3-input NAND Gates
                                                                                                                                                                                                                                                                                                                                                  • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                                                                                                                                                    • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                                                                                                                                                                    • Connecting wires Switches
                                                                                                                                                                                                                                                                                                                                                      • THEORY
                                                                                                                                                                                                                                                                                                                                                          • Figure 131 A Mod-5 Asynchronous Up Counter
                                                                                                                                                                                                                                                                                                                                                          • Implementation and Observations
                                                                                                                                                                                                                                                                                                                                                            • ACTIVITY
                                                                                                                                                                                                                                                                                                                                                                • 19-ldst-exp14
                                                                                                                                                                                                                                                                                                                                                                  • Experimenting with 74194 4-bit bidirectional universal shift register
                                                                                                                                                                                                                                                                                                                                                                  • 1 Following ICs and their Datasheets
                                                                                                                                                                                                                                                                                                                                                                  • 74194 4-bit bidirectional universal shift register
                                                                                                                                                                                                                                                                                                                                                                  • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                                                                                                                                                                    • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                                                                                                                                                                                    • Connecting wires Switches
                                                                                                                                                                                                                                                                                                                                                                      • THEORY
                                                                                                                                                                                                                                                                                                                                                                        • Shift Registers
                                                                                                                                                                                                                                                                                                                                                                        • Bidirectional Shift Registers
                                                                                                                                                                                                                                                                                                                                                                        • Universal Shift Registers
                                                                                                                                                                                                                                                                                                                                                                          • S1
                                                                                                                                                                                                                                                                                                                                                                            • Circuit Diagram
                                                                                                                                                                                                                                                                                                                                                                            • ACTIVITY
                                                                                                                                                                                                                                                                                                                                                                                • 20-ldst-exp15
                                                                                                                                                                                                                                                                                                                                                                                  • COMPONENTS AND APPARATUS REQUIRED
                                                                                                                                                                                                                                                                                                                                                                                  • 1 Parallel Port Connectors (DB-25) with Cable
                                                                                                                                                                                                                                                                                                                                                                                  • 2 Personal Computer with Windows 98 and TurboC Compiler Installed
                                                                                                                                                                                                                                                                                                                                                                                  • 3 Following ICs and their Datasheets
                                                                                                                                                                                                                                                                                                                                                                                  • 74245 Octal Bus Transceivers with 3-State Outputs
                                                                                                                                                                                                                                                                                                                                                                                  • 4 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                                                                                                                                                                                    • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                                                                                                                                                                                                      • Connecting wires Switches
                                                                                                                                                                                                                                                                                                                                                                                        • THEORY
                                                                                                                                                                                                                                                                                                                                                                                        • 3-State Logic
                                                                                                                                                                                                                                                                                                                                                                                          • Serial and Parallel Port Connectors
                                                                                                                                                                                                                                                                                                                                                                                          • Parallel Port Connector ndash DB-25
                                                                                                                                                                                                                                                                                                                                                                                            • Accessing parallel port through C Language Programming
                                                                                                                                                                                                                                                                                                                                                                                                • 21-ldst-appendixA
                                                                                                                                                                                                                                                                                                                                                                                                • 22-ldst-appendixB
                                                                                                                                                                                                                                                                                                                                                                                                  • DEBOUNCING CIRCUITRY FOR MECHANICAL SWITCHES

                                                                                                                          Logic Design amp Switching Theory 1 Lab Session 15 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering unsigned int data=0 char choice while(1) printing option menu clrscr() printf(This program will send or receive a BCD digit from the parallel portn) printf(nPress your choice numbern) printf(n1 Send Data) printf(n2 Receive Data) printf(n3 Exitn) choice = getch() sending entered digit to the port if(choice == 1) input BCD digit printf(nEnter BCD digit to be sent to the port) data = getche() masking the first four bits data = data amp 0x0f sending to the port outportb(0x378data) printf(nThe BCD digit c has been sent to the port data) printing on screen the data received from the port else if(choice == 2) receiving data from the port data = inportb(0x378) masking the last four bits data = data amp 0xf0 shifting first four bits to make them the last four bits datagtgt=4 printf(nThe BCD digit set at the port is c data) exit else if(choice == 3) break key pressed is not in the menu else printf(nEnter valid choice number) printf(nnPress any key to continue) getch()

                                                                                                                          63

                                                                                                                          Logic Design amp Switching Theory 1 Lab Session 15 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                                                                          ACTIVITY 1 In the above circuit DIR and G΄ inputs are hardwired Connect them to status or

                                                                                                                          control pins of the parallel port connector and control their function through your software program Circuit Diagram Program Code ______________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________

                                                                                                                          ___________________________________________________________________________________________________________________________________________________

                                                                                                                          64

                                                                                                                          Logic Design amp Switching Theory 1 Lab Session 15 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                                                                          65

                                                                                                                          _____________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ _____________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ _______________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ _________________________________________________ _________________________________________________

                                                                                                                          Logic Design amp Switching Theory 1 Appendix A NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                                                                          Appendix A

                                                                                                                          PIN DIAGRAMS OF THE ICS REQUIRED FOR THE LABORATORY SESSIONS Consult the TTLIC data book for internal diagrams and electrical characteristics of these ICs 7400 Quad 2-Input NAND 7402 Quad 2-Input NOR

                                                                                                                          7404 Hex Inverter 7408 Quad 2-Input AND

                                                                                                                          7410 Triple 3-Input NAND 7411 Triple 3-Input AND

                                                                                                                          7421 Dual 4-Input AND 7432 Quad 2-Input OR

                                                                                                                          66

                                                                                                                          Logic Design amp Switching Theory 1 Appendix A NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                                                                          BCD-to-Seven Segm 7448 BCD-to-Seven Segment 7447 ent

                                                                                                                          Decoder (15V OC) Decoder (2kΩ pull-up output)

                                                                                                                          7473 Dual JK Flip-Flop 7474 Dual D-Type Flip-Flop

                                                                                                                          7476 Dual JK Flop-Flop -Bit Binary Full Adder 7483 4 with Fast Carry

                                                                                                                          86 Quad 2-Inpu 74138 3-to-8 Line 74 t Exclusive OR Decoder Demultiplexer

                                                                                                                          67

                                                                                                                          Logic Design amp Switching Theory 1 Appendix A NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                                                                          68

                                                                                                                          74148 8-to-3 Line 16-to-1 Line Data

                                                                                                                          Priority Encoder 74150 Selector Multiplexer

                                                                                                                          74245 Oct nsceivers Universal Shift Register (PIPO) (3-State)

                                                                                                                          74194 4-Bit Bidirectional al Bus Tra

                                                                                                                          Logic Design amp Switching Theory 1 Appendix B NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                                                                          Appendix B

                                                                                                                          DEBOUNCING CIRCUITRY FOR MECHANICAL SWITCHES Mechanical switches form the interface between human beings and computers or other digital systems For example a keyboard is a matrix of switches used to supply alphanumeric data to a computer Whatever the switch design it is a potential source of problems due to contact bounce The contact bounce creates a sense of narrow pulses when a switch is opened or closed An example of device whose operation would be adversely affected by contact bounce is a digital counter used to count the number of times a switch is depressed Eliminating the effects of contact bounce is called debouncing When data is entered into a computer via a keyboard a software debounce is often used This type of debouncing is a program that causes the computer to sample the switch terminal (ie to input data from it) many times in succession during the interval of time that contact bounce occurs If the data is sensed to be 1s (or 0s) for a specific number of consecutive samples then it is assumed that contact bounce has ended and the last value sensed is valid Hardware debouncing is the use of electronic circuitry to eliminate the effects of contact bounce There are numerous versions of such circuitry including those that use monostable multivibrators (one-shots) but the most straightforward is simply an RS latch Figure B1 shows the circuit When the switch is in position 1 R = 0 and S = 1 so the latch is set and the output (Q) is 1 When the switch is in position 0 R = 1and S = 0 so the latch is reset and the output is 0 When the switch is moved form one position to the other the latch changes state and bouncing occurs at either the R or the S input The bouncing does not affect the latch after it has change state An RS latch will remain set for example when its R input is 0 and its S input is alternately changed form 1 to 0

                                                                                                                          Figure B1 Use of RS latch to debounce a mechanical switch

                                                                                                                          69

                                                                                                                          • 01-ldst-Outer title
                                                                                                                            • Practical Workbook
                                                                                                                            • Logic Design amp Switching Theory I
                                                                                                                              • Dept of Computer amp Information Systems Engineering
                                                                                                                                • NED University of Engineering amp Technology
                                                                                                                                • Karachi ndash 75270 Pakistan
                                                                                                                                  • 02-ldst-inner Title
                                                                                                                                    • Practical Workbook
                                                                                                                                    • Logic Design amp Switching Theory I
                                                                                                                                      • Dept of Computer amp Information Systems Engineering
                                                                                                                                        • NED University of Engineering amp Technology
                                                                                                                                        • Karachi ndash 75270 Pakistan
                                                                                                                                          • 03-ldst-general info
                                                                                                                                          • 04-ldst-introduction
                                                                                                                                          • 05-Table of Contents
                                                                                                                                            • CONTENTS
                                                                                                                                              • Lab Session No Object Page No
                                                                                                                                              • 1
                                                                                                                                              • Also implementing and testing the given circuit on a bread board
                                                                                                                                                • Working with Electronics Workbench
                                                                                                                                                  • Driving a seven segment display using 7447 7448 driver IC
                                                                                                                                                    • Designing a modulus-5 asynchronous up-counter using JK-FF
                                                                                                                                                      • Experimenting with 74194 4-bit bidirectional universal shift register
                                                                                                                                                          • 13
                                                                                                                                                              • 06-ldst-Exp01
                                                                                                                                                                • Lab Session 01
                                                                                                                                                                • OBJECT
                                                                                                                                                                  • 1 Bread board
                                                                                                                                                                  • 2 5 V - power supply
                                                                                                                                                                  • 3 Multimeter
                                                                                                                                                                  • 4 Logic probe
                                                                                                                                                                  • 5 LEDs with resistors
                                                                                                                                                                  • 6 Connecting wires
                                                                                                                                                                  • 8 Following ICs and their datasheets
                                                                                                                                                                    • THEORY
                                                                                                                                                                      • Logic Gates
                                                                                                                                                                      • 1 The AND Gate ndash An AND gatersquos output is 1 if and only if all its inputs are 1 If A and B are two inputs to an AND gate then output F of the gate is given as F = AB
                                                                                                                                                                      • 2 The OR Gate - An OR gatersquos output is 1 if at least one of its input is 1 If A and B are two inputs to an OR gate then output F of the gate is given as F = A+B
                                                                                                                                                                      • 3 The NOT Gate (Inverter) ndash Its output is 1 when its input is 0 and its output is 0 when the input is 1 ie it complements a digital variable If A is the input to a NOT gate then output F of the gate is given as
                                                                                                                                                                      • 4 The NAND Gate ndash Its output is 1 if at least one of its input is 0 This gate performs the same logic as an AND gate followed by an inverter If A and B are two inputs to a NAND gate then output F of the gate is given as
                                                                                                                                                                        • 5 The NOR Gate - The output of a NOR gate is 1 if and only if all its inputs are 0 This gate performs the same logic function as an OR gate followed by an inverter If A and B are two inputs to a NAND gate then output F of the gate is given as
                                                                                                                                                                            • DATA SHEETS
                                                                                                                                                                              • Logic expression for the given logic diagram __________________________________
                                                                                                                                                                                  • 07-ldst-exp02
                                                                                                                                                                                    • Working with Electronics Workbench
                                                                                                                                                                                      • 08-ldst-exp03
                                                                                                                                                                                        • Designing Half and Full Adder Circuits
                                                                                                                                                                                          • COMPONENTS AND APPARATUS REQUIRED
                                                                                                                                                                                            • 1 Following ICs and their Datasheets
                                                                                                                                                                                            • 7408 Quad 2-input AND Gate
                                                                                                                                                                                            • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                              • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                              • Connecting wires Switches
                                                                                                                                                                                                • THEORY
                                                                                                                                                                                                    • IMPLEMENTATION AND OBSERVATIONS
                                                                                                                                                                                                      • 09-ldst-Exp04
                                                                                                                                                                                                        • Lab Session 04
                                                                                                                                                                                                        • 1 Digital ICs and their Datasheets
                                                                                                                                                                                                        • 7408 Quad 2-input AND Gate
                                                                                                                                                                                                        • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                          • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                          • Connecting wires Switches
                                                                                                                                                                                                          • PROCEDURE
                                                                                                                                                                                                          • REDUCTION OF LOGIC EXPRESSION USING KARNAUGH MAP
                                                                                                                                                                                                          • OBSERVATIONS
                                                                                                                                                                                                          • RESULT
                                                                                                                                                                                                              • 10-ldst-Exp05
                                                                                                                                                                                                                • Lab Session 05
                                                                                                                                                                                                                • 1 Following ICs and their Datasheets
                                                                                                                                                                                                                • 7408 Quad 2-input AND Gate
                                                                                                                                                                                                                • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                  • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                                  • (100 Ω) Connecting wires Switches
                                                                                                                                                                                                                  • THEORY
                                                                                                                                                                                                                    • IMPLEMENTATION AND OBSERVATIONS
                                                                                                                                                                                                                      • 11-ldst-Exp06
                                                                                                                                                                                                                        • OBJECT
                                                                                                                                                                                                                        • 1 Following ICs and their Datasheets
                                                                                                                                                                                                                        • 7408 Quad 2-input AND Gates or 7411 Triple 3-input AND Gates
                                                                                                                                                                                                                        • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                          • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                                          • Connecting wires Switches
                                                                                                                                                                                                                            • Figure 62 Circuit Diagram for 4 x 1 Multiplexer
                                                                                                                                                                                                                            • Implementation and Observations
                                                                                                                                                                                                                              • Circuit Diagram
                                                                                                                                                                                                                                • ACTIVITY
                                                                                                                                                                                                                                  • 12-ldst-exp07
                                                                                                                                                                                                                                    • 1 Following ICs and their Datasheets
                                                                                                                                                                                                                                    • 7408 Quad 2-input or 7411 Triple 3-input AND Gates
                                                                                                                                                                                                                                    • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                                      • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                                                      • Connecting wires Switches
                                                                                                                                                                                                                                        • THEORY
                                                                                                                                                                                                                                            • Figure 72 Circuit Diagram for 2 x 4 Decoder 1 x 4 Demultiplexer
                                                                                                                                                                                                                                            • Implementation and Observations
                                                                                                                                                                                                                                              • Circuit Diagram
                                                                                                                                                                                                                                                • ACTIVITY
                                                                                                                                                                                                                                                  • 13-ldst-Exp08
                                                                                                                                                                                                                                                    • OBJECT
                                                                                                                                                                                                                                                    • 1 Following ICs and their Datasheets
                                                                                                                                                                                                                                                    • 7408 Quad 2-input or 7421 Dual 4-input AND Gates
                                                                                                                                                                                                                                                    • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                                                      • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                                                                      • Connecting wires Switches
                                                                                                                                                                                                                                                        • THEORY
                                                                                                                                                                                                                                                            • Figure 81 Circuit Diagram for 4 x 2 Priority Encoder
                                                                                                                                                                                                                                                            • Implementation and Observations
                                                                                                                                                                                                                                                              • Therefore if GS A2 A1 and A0 are all low then it shows that line 0 is selected and if E0 A2 A1 and A0 are all low then it shows that none of the inputs selected E0 and GS cannot be in the same state provided that E1 is enabled
                                                                                                                                                                                                                                                              • Circuit Diagram
                                                                                                                                                                                                                                                                • ACTIVITY
                                                                                                                                                                                                                                                                  • 14-ldst-exp09
                                                                                                                                                                                                                                                                    • OBJECT
                                                                                                                                                                                                                                                                    • 1 Following ICs and their Datasheets
                                                                                                                                                                                                                                                                    • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                                                                      • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                                                                                      • Connecting wires Switches
                                                                                                                                                                                                                                                                        • THEORY
                                                                                                                                                                                                                                                                          • Parity Generator
                                                                                                                                                                                                                                                                            • Let x y and z be the three bits that constitute the message and are the input to the Odd Parity Generator Circuit Since it is an odd parity system the bit P is generated so as to make the total number of 1s odd (including P) The function P can be expressed as follows
                                                                                                                                                                                                                                                                            • Figure 91 Circuit Diagram for a 3-bit Parity Generator
                                                                                                                                                                                                                                                                              • C = x Ο y Ο z Ο P
                                                                                                                                                                                                                                                                                • Implementation and Observations
                                                                                                                                                                                                                                                                                  • ACTIVITY
                                                                                                                                                                                                                                                                                      • 15-ldst-exp10
                                                                                                                                                                                                                                                                                        • Driving a seven segment display using 7447 7448 driver IC
                                                                                                                                                                                                                                                                                        • COMPONENTS AND APPARATUS REQUIRED
                                                                                                                                                                                                                                                                                        • 1 Following ICs and their Datasheets
                                                                                                                                                                                                                                                                                        • 7447 7448 BCD to Seven Segment Driver
                                                                                                                                                                                                                                                                                        • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                                                                                          • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches
                                                                                                                                                                                                                                                                                            • THEORY
                                                                                                                                                                                                                                                                                            • Seven Segment Displays
                                                                                                                                                                                                                                                                                            • CIRCUIT DIAGRAM
                                                                                                                                                                                                                                                                                            • Figure 102 Circuit diagram for 7447driving a common-anode display
                                                                                                                                                                                                                                                                                                • IMPLEMENTATION AND OBSERVATIONS
                                                                                                                                                                                                                                                                                                  • Decimal Digit
                                                                                                                                                                                                                                                                                                  • BCD Inputs
                                                                                                                                                                                                                                                                                                  • Seven Segment Outputs
                                                                                                                                                                                                                                                                                                  • D
                                                                                                                                                                                                                                                                                                  • C
                                                                                                                                                                                                                                                                                                  • B
                                                                                                                                                                                                                                                                                                  • A
                                                                                                                                                                                                                                                                                                  • a
                                                                                                                                                                                                                                                                                                  • b
                                                                                                                                                                                                                                                                                                  • c
                                                                                                                                                                                                                                                                                                  • d
                                                                                                                                                                                                                                                                                                  • e
                                                                                                                                                                                                                                                                                                  • f
                                                                                                                                                                                                                                                                                                  • g
                                                                                                                                                                                                                                                                                                  • 0
                                                                                                                                                                                                                                                                                                  • 0
                                                                                                                                                                                                                                                                                                  • 0
                                                                                                                                                                                                                                                                                                  • 0
                                                                                                                                                                                                                                                                                                  • 0
                                                                                                                                                                                                                                                                                                  • 1
                                                                                                                                                                                                                                                                                                  • 0
                                                                                                                                                                                                                                                                                                  • 0
                                                                                                                                                                                                                                                                                                  • 0
                                                                                                                                                                                                                                                                                                  • 1
                                                                                                                                                                                                                                                                                                  • 2
                                                                                                                                                                                                                                                                                                  • 0
                                                                                                                                                                                                                                                                                                  • 0
                                                                                                                                                                                                                                                                                                  • 1
                                                                                                                                                                                                                                                                                                  • 0
                                                                                                                                                                                                                                                                                                  • 3
                                                                                                                                                                                                                                                                                                  • 0
                                                                                                                                                                                                                                                                                                  • 0
                                                                                                                                                                                                                                                                                                  • 1
                                                                                                                                                                                                                                                                                                  • 1
                                                                                                                                                                                                                                                                                                  • 4
                                                                                                                                                                                                                                                                                                  • 0
                                                                                                                                                                                                                                                                                                  • 1
                                                                                                                                                                                                                                                                                                  • 0
                                                                                                                                                                                                                                                                                                  • 0
                                                                                                                                                                                                                                                                                                  • 5
                                                                                                                                                                                                                                                                                                  • 0
                                                                                                                                                                                                                                                                                                  • 1
                                                                                                                                                                                                                                                                                                  • 0
                                                                                                                                                                                                                                                                                                  • 1
                                                                                                                                                                                                                                                                                                  • 6
                                                                                                                                                                                                                                                                                                  • 0
                                                                                                                                                                                                                                                                                                  • 1
                                                                                                                                                                                                                                                                                                  • 1
                                                                                                                                                                                                                                                                                                  • 0
                                                                                                                                                                                                                                                                                                  • 7
                                                                                                                                                                                                                                                                                                  • 0
                                                                                                                                                                                                                                                                                                  • 1
                                                                                                                                                                                                                                                                                                  • 1
                                                                                                                                                                                                                                                                                                  • 1
                                                                                                                                                                                                                                                                                                  • 8
                                                                                                                                                                                                                                                                                                  • 1
                                                                                                                                                                                                                                                                                                  • 0
                                                                                                                                                                                                                                                                                                  • 0
                                                                                                                                                                                                                                                                                                  • 0
                                                                                                                                                                                                                                                                                                  • 9
                                                                                                                                                                                                                                                                                                  • 1
                                                                                                                                                                                                                                                                                                  • 0
                                                                                                                                                                                                                                                                                                  • 0
                                                                                                                                                                                                                                                                                                  • 1
                                                                                                                                                                                                                                                                                                    • ACTIVITY
                                                                                                                                                                                                                                                                                                      • 16-ldst-exp11
                                                                                                                                                                                                                                                                                                        • Lab Session 11
                                                                                                                                                                                                                                                                                                          • OBJECT
                                                                                                                                                                                                                                                                                                          • COMPONENTS AND APPARATUS REQUIRED
                                                                                                                                                                                                                                                                                                            • 1 Following ICs and their Datasheets
                                                                                                                                                                                                                                                                                                            • 7473 7476 JK Flip-Flop
                                                                                                                                                                                                                                                                                                            • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                                                                                                              • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                                                                                                                              • Connecting wires Switches
                                                                                                                                                                                                                                                                                                                • THEORY
                                                                                                                                                                                                                                                                                                                    • Flip-Flop
                                                                                                                                                                                                                                                                                                                    • JK Flip-Flop
                                                                                                                                                                                                                                                                                                                      • Circuit Diagram
                                                                                                                                                                                                                                                                                                                        • Observations
                                                                                                                                                                                                                                                                                                                          • ACTIVITY
                                                                                                                                                                                                                                                                                                                              • 17-ldst-exp12
                                                                                                                                                                                                                                                                                                                                • Lab Session 12
                                                                                                                                                                                                                                                                                                                                  • OBJECT
                                                                                                                                                                                                                                                                                                                                  • GIVEN STATE DIAGRAM
                                                                                                                                                                                                                                                                                                                                  • Figure 121 State Diagram
                                                                                                                                                                                                                                                                                                                                  • COMPONENTS AND APPARATUS REQUIRED
                                                                                                                                                                                                                                                                                                                                    • 1 Following ICs and their Datasheets
                                                                                                                                                                                                                                                                                                                                    • 7474 D Flip-Flop
                                                                                                                                                                                                                                                                                                                                    • ICs of basic gates (AND OR NOT XOR etc) as required
                                                                                                                                                                                                                                                                                                                                    • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                                                                                                                                      • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                                                                                                                                                      • Connecting wires Switches
                                                                                                                                                                                                                                                                                                                                        • THEORY
                                                                                                                                                                                                                                                                                                                                            • Sequential Circuits
                                                                                                                                                                                                                                                                                                                                              • 18-ldst-exp13
                                                                                                                                                                                                                                                                                                                                                • Lab Session 13
                                                                                                                                                                                                                                                                                                                                                  • Designing a modulo-5 asynchronous up-counter using JK-FF
                                                                                                                                                                                                                                                                                                                                                    • 1 Following ICs and their Datasheets
                                                                                                                                                                                                                                                                                                                                                    • 7400 Quad 2-input or 7410 Triple 3-input NAND Gates
                                                                                                                                                                                                                                                                                                                                                    • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                                                                                                                                                      • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                                                                                                                                                                      • Connecting wires Switches
                                                                                                                                                                                                                                                                                                                                                        • THEORY
                                                                                                                                                                                                                                                                                                                                                            • Figure 131 A Mod-5 Asynchronous Up Counter
                                                                                                                                                                                                                                                                                                                                                            • Implementation and Observations
                                                                                                                                                                                                                                                                                                                                                              • ACTIVITY
                                                                                                                                                                                                                                                                                                                                                                  • 19-ldst-exp14
                                                                                                                                                                                                                                                                                                                                                                    • Experimenting with 74194 4-bit bidirectional universal shift register
                                                                                                                                                                                                                                                                                                                                                                    • 1 Following ICs and their Datasheets
                                                                                                                                                                                                                                                                                                                                                                    • 74194 4-bit bidirectional universal shift register
                                                                                                                                                                                                                                                                                                                                                                    • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                                                                                                                                                                      • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                                                                                                                                                                                      • Connecting wires Switches
                                                                                                                                                                                                                                                                                                                                                                        • THEORY
                                                                                                                                                                                                                                                                                                                                                                          • Shift Registers
                                                                                                                                                                                                                                                                                                                                                                          • Bidirectional Shift Registers
                                                                                                                                                                                                                                                                                                                                                                          • Universal Shift Registers
                                                                                                                                                                                                                                                                                                                                                                            • S1
                                                                                                                                                                                                                                                                                                                                                                              • Circuit Diagram
                                                                                                                                                                                                                                                                                                                                                                              • ACTIVITY
                                                                                                                                                                                                                                                                                                                                                                                  • 20-ldst-exp15
                                                                                                                                                                                                                                                                                                                                                                                    • COMPONENTS AND APPARATUS REQUIRED
                                                                                                                                                                                                                                                                                                                                                                                    • 1 Parallel Port Connectors (DB-25) with Cable
                                                                                                                                                                                                                                                                                                                                                                                    • 2 Personal Computer with Windows 98 and TurboC Compiler Installed
                                                                                                                                                                                                                                                                                                                                                                                    • 3 Following ICs and their Datasheets
                                                                                                                                                                                                                                                                                                                                                                                    • 74245 Octal Bus Transceivers with 3-State Outputs
                                                                                                                                                                                                                                                                                                                                                                                    • 4 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                                                                                                                                                                                      • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                                                                                                                                                                                                        • Connecting wires Switches
                                                                                                                                                                                                                                                                                                                                                                                          • THEORY
                                                                                                                                                                                                                                                                                                                                                                                          • 3-State Logic
                                                                                                                                                                                                                                                                                                                                                                                            • Serial and Parallel Port Connectors
                                                                                                                                                                                                                                                                                                                                                                                            • Parallel Port Connector ndash DB-25
                                                                                                                                                                                                                                                                                                                                                                                              • Accessing parallel port through C Language Programming
                                                                                                                                                                                                                                                                                                                                                                                                  • 21-ldst-appendixA
                                                                                                                                                                                                                                                                                                                                                                                                  • 22-ldst-appendixB
                                                                                                                                                                                                                                                                                                                                                                                                    • DEBOUNCING CIRCUITRY FOR MECHANICAL SWITCHES

                                                                                                                            Logic Design amp Switching Theory 1 Lab Session 15 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                                                                            ACTIVITY 1 In the above circuit DIR and G΄ inputs are hardwired Connect them to status or

                                                                                                                            control pins of the parallel port connector and control their function through your software program Circuit Diagram Program Code ______________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________

                                                                                                                            ___________________________________________________________________________________________________________________________________________________

                                                                                                                            64

                                                                                                                            Logic Design amp Switching Theory 1 Lab Session 15 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                                                                            65

                                                                                                                            _____________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ _____________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ _______________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ _________________________________________________ _________________________________________________

                                                                                                                            Logic Design amp Switching Theory 1 Appendix A NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                                                                            Appendix A

                                                                                                                            PIN DIAGRAMS OF THE ICS REQUIRED FOR THE LABORATORY SESSIONS Consult the TTLIC data book for internal diagrams and electrical characteristics of these ICs 7400 Quad 2-Input NAND 7402 Quad 2-Input NOR

                                                                                                                            7404 Hex Inverter 7408 Quad 2-Input AND

                                                                                                                            7410 Triple 3-Input NAND 7411 Triple 3-Input AND

                                                                                                                            7421 Dual 4-Input AND 7432 Quad 2-Input OR

                                                                                                                            66

                                                                                                                            Logic Design amp Switching Theory 1 Appendix A NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                                                                            BCD-to-Seven Segm 7448 BCD-to-Seven Segment 7447 ent

                                                                                                                            Decoder (15V OC) Decoder (2kΩ pull-up output)

                                                                                                                            7473 Dual JK Flip-Flop 7474 Dual D-Type Flip-Flop

                                                                                                                            7476 Dual JK Flop-Flop -Bit Binary Full Adder 7483 4 with Fast Carry

                                                                                                                            86 Quad 2-Inpu 74138 3-to-8 Line 74 t Exclusive OR Decoder Demultiplexer

                                                                                                                            67

                                                                                                                            Logic Design amp Switching Theory 1 Appendix A NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                                                                            68

                                                                                                                            74148 8-to-3 Line 16-to-1 Line Data

                                                                                                                            Priority Encoder 74150 Selector Multiplexer

                                                                                                                            74245 Oct nsceivers Universal Shift Register (PIPO) (3-State)

                                                                                                                            74194 4-Bit Bidirectional al Bus Tra

                                                                                                                            Logic Design amp Switching Theory 1 Appendix B NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                                                                            Appendix B

                                                                                                                            DEBOUNCING CIRCUITRY FOR MECHANICAL SWITCHES Mechanical switches form the interface between human beings and computers or other digital systems For example a keyboard is a matrix of switches used to supply alphanumeric data to a computer Whatever the switch design it is a potential source of problems due to contact bounce The contact bounce creates a sense of narrow pulses when a switch is opened or closed An example of device whose operation would be adversely affected by contact bounce is a digital counter used to count the number of times a switch is depressed Eliminating the effects of contact bounce is called debouncing When data is entered into a computer via a keyboard a software debounce is often used This type of debouncing is a program that causes the computer to sample the switch terminal (ie to input data from it) many times in succession during the interval of time that contact bounce occurs If the data is sensed to be 1s (or 0s) for a specific number of consecutive samples then it is assumed that contact bounce has ended and the last value sensed is valid Hardware debouncing is the use of electronic circuitry to eliminate the effects of contact bounce There are numerous versions of such circuitry including those that use monostable multivibrators (one-shots) but the most straightforward is simply an RS latch Figure B1 shows the circuit When the switch is in position 1 R = 0 and S = 1 so the latch is set and the output (Q) is 1 When the switch is in position 0 R = 1and S = 0 so the latch is reset and the output is 0 When the switch is moved form one position to the other the latch changes state and bouncing occurs at either the R or the S input The bouncing does not affect the latch after it has change state An RS latch will remain set for example when its R input is 0 and its S input is alternately changed form 1 to 0

                                                                                                                            Figure B1 Use of RS latch to debounce a mechanical switch

                                                                                                                            69

                                                                                                                            • 01-ldst-Outer title
                                                                                                                              • Practical Workbook
                                                                                                                              • Logic Design amp Switching Theory I
                                                                                                                                • Dept of Computer amp Information Systems Engineering
                                                                                                                                  • NED University of Engineering amp Technology
                                                                                                                                  • Karachi ndash 75270 Pakistan
                                                                                                                                    • 02-ldst-inner Title
                                                                                                                                      • Practical Workbook
                                                                                                                                      • Logic Design amp Switching Theory I
                                                                                                                                        • Dept of Computer amp Information Systems Engineering
                                                                                                                                          • NED University of Engineering amp Technology
                                                                                                                                          • Karachi ndash 75270 Pakistan
                                                                                                                                            • 03-ldst-general info
                                                                                                                                            • 04-ldst-introduction
                                                                                                                                            • 05-Table of Contents
                                                                                                                                              • CONTENTS
                                                                                                                                                • Lab Session No Object Page No
                                                                                                                                                • 1
                                                                                                                                                • Also implementing and testing the given circuit on a bread board
                                                                                                                                                  • Working with Electronics Workbench
                                                                                                                                                    • Driving a seven segment display using 7447 7448 driver IC
                                                                                                                                                      • Designing a modulus-5 asynchronous up-counter using JK-FF
                                                                                                                                                        • Experimenting with 74194 4-bit bidirectional universal shift register
                                                                                                                                                            • 13
                                                                                                                                                                • 06-ldst-Exp01
                                                                                                                                                                  • Lab Session 01
                                                                                                                                                                  • OBJECT
                                                                                                                                                                    • 1 Bread board
                                                                                                                                                                    • 2 5 V - power supply
                                                                                                                                                                    • 3 Multimeter
                                                                                                                                                                    • 4 Logic probe
                                                                                                                                                                    • 5 LEDs with resistors
                                                                                                                                                                    • 6 Connecting wires
                                                                                                                                                                    • 8 Following ICs and their datasheets
                                                                                                                                                                      • THEORY
                                                                                                                                                                        • Logic Gates
                                                                                                                                                                        • 1 The AND Gate ndash An AND gatersquos output is 1 if and only if all its inputs are 1 If A and B are two inputs to an AND gate then output F of the gate is given as F = AB
                                                                                                                                                                        • 2 The OR Gate - An OR gatersquos output is 1 if at least one of its input is 1 If A and B are two inputs to an OR gate then output F of the gate is given as F = A+B
                                                                                                                                                                        • 3 The NOT Gate (Inverter) ndash Its output is 1 when its input is 0 and its output is 0 when the input is 1 ie it complements a digital variable If A is the input to a NOT gate then output F of the gate is given as
                                                                                                                                                                        • 4 The NAND Gate ndash Its output is 1 if at least one of its input is 0 This gate performs the same logic as an AND gate followed by an inverter If A and B are two inputs to a NAND gate then output F of the gate is given as
                                                                                                                                                                          • 5 The NOR Gate - The output of a NOR gate is 1 if and only if all its inputs are 0 This gate performs the same logic function as an OR gate followed by an inverter If A and B are two inputs to a NAND gate then output F of the gate is given as
                                                                                                                                                                              • DATA SHEETS
                                                                                                                                                                                • Logic expression for the given logic diagram __________________________________
                                                                                                                                                                                    • 07-ldst-exp02
                                                                                                                                                                                      • Working with Electronics Workbench
                                                                                                                                                                                        • 08-ldst-exp03
                                                                                                                                                                                          • Designing Half and Full Adder Circuits
                                                                                                                                                                                            • COMPONENTS AND APPARATUS REQUIRED
                                                                                                                                                                                              • 1 Following ICs and their Datasheets
                                                                                                                                                                                              • 7408 Quad 2-input AND Gate
                                                                                                                                                                                              • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                • Connecting wires Switches
                                                                                                                                                                                                  • THEORY
                                                                                                                                                                                                      • IMPLEMENTATION AND OBSERVATIONS
                                                                                                                                                                                                        • 09-ldst-Exp04
                                                                                                                                                                                                          • Lab Session 04
                                                                                                                                                                                                          • 1 Digital ICs and their Datasheets
                                                                                                                                                                                                          • 7408 Quad 2-input AND Gate
                                                                                                                                                                                                          • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                            • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                            • Connecting wires Switches
                                                                                                                                                                                                            • PROCEDURE
                                                                                                                                                                                                            • REDUCTION OF LOGIC EXPRESSION USING KARNAUGH MAP
                                                                                                                                                                                                            • OBSERVATIONS
                                                                                                                                                                                                            • RESULT
                                                                                                                                                                                                                • 10-ldst-Exp05
                                                                                                                                                                                                                  • Lab Session 05
                                                                                                                                                                                                                  • 1 Following ICs and their Datasheets
                                                                                                                                                                                                                  • 7408 Quad 2-input AND Gate
                                                                                                                                                                                                                  • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                    • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                                    • (100 Ω) Connecting wires Switches
                                                                                                                                                                                                                    • THEORY
                                                                                                                                                                                                                      • IMPLEMENTATION AND OBSERVATIONS
                                                                                                                                                                                                                        • 11-ldst-Exp06
                                                                                                                                                                                                                          • OBJECT
                                                                                                                                                                                                                          • 1 Following ICs and their Datasheets
                                                                                                                                                                                                                          • 7408 Quad 2-input AND Gates or 7411 Triple 3-input AND Gates
                                                                                                                                                                                                                          • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                            • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                                            • Connecting wires Switches
                                                                                                                                                                                                                              • Figure 62 Circuit Diagram for 4 x 1 Multiplexer
                                                                                                                                                                                                                              • Implementation and Observations
                                                                                                                                                                                                                                • Circuit Diagram
                                                                                                                                                                                                                                  • ACTIVITY
                                                                                                                                                                                                                                    • 12-ldst-exp07
                                                                                                                                                                                                                                      • 1 Following ICs and their Datasheets
                                                                                                                                                                                                                                      • 7408 Quad 2-input or 7411 Triple 3-input AND Gates
                                                                                                                                                                                                                                      • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                                        • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                                                        • Connecting wires Switches
                                                                                                                                                                                                                                          • THEORY
                                                                                                                                                                                                                                              • Figure 72 Circuit Diagram for 2 x 4 Decoder 1 x 4 Demultiplexer
                                                                                                                                                                                                                                              • Implementation and Observations
                                                                                                                                                                                                                                                • Circuit Diagram
                                                                                                                                                                                                                                                  • ACTIVITY
                                                                                                                                                                                                                                                    • 13-ldst-Exp08
                                                                                                                                                                                                                                                      • OBJECT
                                                                                                                                                                                                                                                      • 1 Following ICs and their Datasheets
                                                                                                                                                                                                                                                      • 7408 Quad 2-input or 7421 Dual 4-input AND Gates
                                                                                                                                                                                                                                                      • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                                                        • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                                                                        • Connecting wires Switches
                                                                                                                                                                                                                                                          • THEORY
                                                                                                                                                                                                                                                              • Figure 81 Circuit Diagram for 4 x 2 Priority Encoder
                                                                                                                                                                                                                                                              • Implementation and Observations
                                                                                                                                                                                                                                                                • Therefore if GS A2 A1 and A0 are all low then it shows that line 0 is selected and if E0 A2 A1 and A0 are all low then it shows that none of the inputs selected E0 and GS cannot be in the same state provided that E1 is enabled
                                                                                                                                                                                                                                                                • Circuit Diagram
                                                                                                                                                                                                                                                                  • ACTIVITY
                                                                                                                                                                                                                                                                    • 14-ldst-exp09
                                                                                                                                                                                                                                                                      • OBJECT
                                                                                                                                                                                                                                                                      • 1 Following ICs and their Datasheets
                                                                                                                                                                                                                                                                      • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                                                                        • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                                                                                        • Connecting wires Switches
                                                                                                                                                                                                                                                                          • THEORY
                                                                                                                                                                                                                                                                            • Parity Generator
                                                                                                                                                                                                                                                                              • Let x y and z be the three bits that constitute the message and are the input to the Odd Parity Generator Circuit Since it is an odd parity system the bit P is generated so as to make the total number of 1s odd (including P) The function P can be expressed as follows
                                                                                                                                                                                                                                                                              • Figure 91 Circuit Diagram for a 3-bit Parity Generator
                                                                                                                                                                                                                                                                                • C = x Ο y Ο z Ο P
                                                                                                                                                                                                                                                                                  • Implementation and Observations
                                                                                                                                                                                                                                                                                    • ACTIVITY
                                                                                                                                                                                                                                                                                        • 15-ldst-exp10
                                                                                                                                                                                                                                                                                          • Driving a seven segment display using 7447 7448 driver IC
                                                                                                                                                                                                                                                                                          • COMPONENTS AND APPARATUS REQUIRED
                                                                                                                                                                                                                                                                                          • 1 Following ICs and their Datasheets
                                                                                                                                                                                                                                                                                          • 7447 7448 BCD to Seven Segment Driver
                                                                                                                                                                                                                                                                                          • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                                                                                            • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches
                                                                                                                                                                                                                                                                                              • THEORY
                                                                                                                                                                                                                                                                                              • Seven Segment Displays
                                                                                                                                                                                                                                                                                              • CIRCUIT DIAGRAM
                                                                                                                                                                                                                                                                                              • Figure 102 Circuit diagram for 7447driving a common-anode display
                                                                                                                                                                                                                                                                                                  • IMPLEMENTATION AND OBSERVATIONS
                                                                                                                                                                                                                                                                                                    • Decimal Digit
                                                                                                                                                                                                                                                                                                    • BCD Inputs
                                                                                                                                                                                                                                                                                                    • Seven Segment Outputs
                                                                                                                                                                                                                                                                                                    • D
                                                                                                                                                                                                                                                                                                    • C
                                                                                                                                                                                                                                                                                                    • B
                                                                                                                                                                                                                                                                                                    • A
                                                                                                                                                                                                                                                                                                    • a
                                                                                                                                                                                                                                                                                                    • b
                                                                                                                                                                                                                                                                                                    • c
                                                                                                                                                                                                                                                                                                    • d
                                                                                                                                                                                                                                                                                                    • e
                                                                                                                                                                                                                                                                                                    • f
                                                                                                                                                                                                                                                                                                    • g
                                                                                                                                                                                                                                                                                                    • 0
                                                                                                                                                                                                                                                                                                    • 0
                                                                                                                                                                                                                                                                                                    • 0
                                                                                                                                                                                                                                                                                                    • 0
                                                                                                                                                                                                                                                                                                    • 0
                                                                                                                                                                                                                                                                                                    • 1
                                                                                                                                                                                                                                                                                                    • 0
                                                                                                                                                                                                                                                                                                    • 0
                                                                                                                                                                                                                                                                                                    • 0
                                                                                                                                                                                                                                                                                                    • 1
                                                                                                                                                                                                                                                                                                    • 2
                                                                                                                                                                                                                                                                                                    • 0
                                                                                                                                                                                                                                                                                                    • 0
                                                                                                                                                                                                                                                                                                    • 1
                                                                                                                                                                                                                                                                                                    • 0
                                                                                                                                                                                                                                                                                                    • 3
                                                                                                                                                                                                                                                                                                    • 0
                                                                                                                                                                                                                                                                                                    • 0
                                                                                                                                                                                                                                                                                                    • 1
                                                                                                                                                                                                                                                                                                    • 1
                                                                                                                                                                                                                                                                                                    • 4
                                                                                                                                                                                                                                                                                                    • 0
                                                                                                                                                                                                                                                                                                    • 1
                                                                                                                                                                                                                                                                                                    • 0
                                                                                                                                                                                                                                                                                                    • 0
                                                                                                                                                                                                                                                                                                    • 5
                                                                                                                                                                                                                                                                                                    • 0
                                                                                                                                                                                                                                                                                                    • 1
                                                                                                                                                                                                                                                                                                    • 0
                                                                                                                                                                                                                                                                                                    • 1
                                                                                                                                                                                                                                                                                                    • 6
                                                                                                                                                                                                                                                                                                    • 0
                                                                                                                                                                                                                                                                                                    • 1
                                                                                                                                                                                                                                                                                                    • 1
                                                                                                                                                                                                                                                                                                    • 0
                                                                                                                                                                                                                                                                                                    • 7
                                                                                                                                                                                                                                                                                                    • 0
                                                                                                                                                                                                                                                                                                    • 1
                                                                                                                                                                                                                                                                                                    • 1
                                                                                                                                                                                                                                                                                                    • 1
                                                                                                                                                                                                                                                                                                    • 8
                                                                                                                                                                                                                                                                                                    • 1
                                                                                                                                                                                                                                                                                                    • 0
                                                                                                                                                                                                                                                                                                    • 0
                                                                                                                                                                                                                                                                                                    • 0
                                                                                                                                                                                                                                                                                                    • 9
                                                                                                                                                                                                                                                                                                    • 1
                                                                                                                                                                                                                                                                                                    • 0
                                                                                                                                                                                                                                                                                                    • 0
                                                                                                                                                                                                                                                                                                    • 1
                                                                                                                                                                                                                                                                                                      • ACTIVITY
                                                                                                                                                                                                                                                                                                        • 16-ldst-exp11
                                                                                                                                                                                                                                                                                                          • Lab Session 11
                                                                                                                                                                                                                                                                                                            • OBJECT
                                                                                                                                                                                                                                                                                                            • COMPONENTS AND APPARATUS REQUIRED
                                                                                                                                                                                                                                                                                                              • 1 Following ICs and their Datasheets
                                                                                                                                                                                                                                                                                                              • 7473 7476 JK Flip-Flop
                                                                                                                                                                                                                                                                                                              • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                                                                                                                • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                                                                                                                                • Connecting wires Switches
                                                                                                                                                                                                                                                                                                                  • THEORY
                                                                                                                                                                                                                                                                                                                      • Flip-Flop
                                                                                                                                                                                                                                                                                                                      • JK Flip-Flop
                                                                                                                                                                                                                                                                                                                        • Circuit Diagram
                                                                                                                                                                                                                                                                                                                          • Observations
                                                                                                                                                                                                                                                                                                                            • ACTIVITY
                                                                                                                                                                                                                                                                                                                                • 17-ldst-exp12
                                                                                                                                                                                                                                                                                                                                  • Lab Session 12
                                                                                                                                                                                                                                                                                                                                    • OBJECT
                                                                                                                                                                                                                                                                                                                                    • GIVEN STATE DIAGRAM
                                                                                                                                                                                                                                                                                                                                    • Figure 121 State Diagram
                                                                                                                                                                                                                                                                                                                                    • COMPONENTS AND APPARATUS REQUIRED
                                                                                                                                                                                                                                                                                                                                      • 1 Following ICs and their Datasheets
                                                                                                                                                                                                                                                                                                                                      • 7474 D Flip-Flop
                                                                                                                                                                                                                                                                                                                                      • ICs of basic gates (AND OR NOT XOR etc) as required
                                                                                                                                                                                                                                                                                                                                      • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                                                                                                                                        • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                                                                                                                                                        • Connecting wires Switches
                                                                                                                                                                                                                                                                                                                                          • THEORY
                                                                                                                                                                                                                                                                                                                                              • Sequential Circuits
                                                                                                                                                                                                                                                                                                                                                • 18-ldst-exp13
                                                                                                                                                                                                                                                                                                                                                  • Lab Session 13
                                                                                                                                                                                                                                                                                                                                                    • Designing a modulo-5 asynchronous up-counter using JK-FF
                                                                                                                                                                                                                                                                                                                                                      • 1 Following ICs and their Datasheets
                                                                                                                                                                                                                                                                                                                                                      • 7400 Quad 2-input or 7410 Triple 3-input NAND Gates
                                                                                                                                                                                                                                                                                                                                                      • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                                                                                                                                                        • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                                                                                                                                                                        • Connecting wires Switches
                                                                                                                                                                                                                                                                                                                                                          • THEORY
                                                                                                                                                                                                                                                                                                                                                              • Figure 131 A Mod-5 Asynchronous Up Counter
                                                                                                                                                                                                                                                                                                                                                              • Implementation and Observations
                                                                                                                                                                                                                                                                                                                                                                • ACTIVITY
                                                                                                                                                                                                                                                                                                                                                                    • 19-ldst-exp14
                                                                                                                                                                                                                                                                                                                                                                      • Experimenting with 74194 4-bit bidirectional universal shift register
                                                                                                                                                                                                                                                                                                                                                                      • 1 Following ICs and their Datasheets
                                                                                                                                                                                                                                                                                                                                                                      • 74194 4-bit bidirectional universal shift register
                                                                                                                                                                                                                                                                                                                                                                      • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                                                                                                                                                                        • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                                                                                                                                                                                        • Connecting wires Switches
                                                                                                                                                                                                                                                                                                                                                                          • THEORY
                                                                                                                                                                                                                                                                                                                                                                            • Shift Registers
                                                                                                                                                                                                                                                                                                                                                                            • Bidirectional Shift Registers
                                                                                                                                                                                                                                                                                                                                                                            • Universal Shift Registers
                                                                                                                                                                                                                                                                                                                                                                              • S1
                                                                                                                                                                                                                                                                                                                                                                                • Circuit Diagram
                                                                                                                                                                                                                                                                                                                                                                                • ACTIVITY
                                                                                                                                                                                                                                                                                                                                                                                    • 20-ldst-exp15
                                                                                                                                                                                                                                                                                                                                                                                      • COMPONENTS AND APPARATUS REQUIRED
                                                                                                                                                                                                                                                                                                                                                                                      • 1 Parallel Port Connectors (DB-25) with Cable
                                                                                                                                                                                                                                                                                                                                                                                      • 2 Personal Computer with Windows 98 and TurboC Compiler Installed
                                                                                                                                                                                                                                                                                                                                                                                      • 3 Following ICs and their Datasheets
                                                                                                                                                                                                                                                                                                                                                                                      • 74245 Octal Bus Transceivers with 3-State Outputs
                                                                                                                                                                                                                                                                                                                                                                                      • 4 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                                                                                                                                                                                        • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                                                                                                                                                                                                          • Connecting wires Switches
                                                                                                                                                                                                                                                                                                                                                                                            • THEORY
                                                                                                                                                                                                                                                                                                                                                                                            • 3-State Logic
                                                                                                                                                                                                                                                                                                                                                                                              • Serial and Parallel Port Connectors
                                                                                                                                                                                                                                                                                                                                                                                              • Parallel Port Connector ndash DB-25
                                                                                                                                                                                                                                                                                                                                                                                                • Accessing parallel port through C Language Programming
                                                                                                                                                                                                                                                                                                                                                                                                    • 21-ldst-appendixA
                                                                                                                                                                                                                                                                                                                                                                                                    • 22-ldst-appendixB
                                                                                                                                                                                                                                                                                                                                                                                                      • DEBOUNCING CIRCUITRY FOR MECHANICAL SWITCHES

                                                                                                                              Logic Design amp Switching Theory 1 Lab Session 15 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                                                                              65

                                                                                                                              _____________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ _____________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ _______________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ _________________________________________________ _________________________________________________

                                                                                                                              Logic Design amp Switching Theory 1 Appendix A NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                                                                              Appendix A

                                                                                                                              PIN DIAGRAMS OF THE ICS REQUIRED FOR THE LABORATORY SESSIONS Consult the TTLIC data book for internal diagrams and electrical characteristics of these ICs 7400 Quad 2-Input NAND 7402 Quad 2-Input NOR

                                                                                                                              7404 Hex Inverter 7408 Quad 2-Input AND

                                                                                                                              7410 Triple 3-Input NAND 7411 Triple 3-Input AND

                                                                                                                              7421 Dual 4-Input AND 7432 Quad 2-Input OR

                                                                                                                              66

                                                                                                                              Logic Design amp Switching Theory 1 Appendix A NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                                                                              BCD-to-Seven Segm 7448 BCD-to-Seven Segment 7447 ent

                                                                                                                              Decoder (15V OC) Decoder (2kΩ pull-up output)

                                                                                                                              7473 Dual JK Flip-Flop 7474 Dual D-Type Flip-Flop

                                                                                                                              7476 Dual JK Flop-Flop -Bit Binary Full Adder 7483 4 with Fast Carry

                                                                                                                              86 Quad 2-Inpu 74138 3-to-8 Line 74 t Exclusive OR Decoder Demultiplexer

                                                                                                                              67

                                                                                                                              Logic Design amp Switching Theory 1 Appendix A NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                                                                              68

                                                                                                                              74148 8-to-3 Line 16-to-1 Line Data

                                                                                                                              Priority Encoder 74150 Selector Multiplexer

                                                                                                                              74245 Oct nsceivers Universal Shift Register (PIPO) (3-State)

                                                                                                                              74194 4-Bit Bidirectional al Bus Tra

                                                                                                                              Logic Design amp Switching Theory 1 Appendix B NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                                                                              Appendix B

                                                                                                                              DEBOUNCING CIRCUITRY FOR MECHANICAL SWITCHES Mechanical switches form the interface between human beings and computers or other digital systems For example a keyboard is a matrix of switches used to supply alphanumeric data to a computer Whatever the switch design it is a potential source of problems due to contact bounce The contact bounce creates a sense of narrow pulses when a switch is opened or closed An example of device whose operation would be adversely affected by contact bounce is a digital counter used to count the number of times a switch is depressed Eliminating the effects of contact bounce is called debouncing When data is entered into a computer via a keyboard a software debounce is often used This type of debouncing is a program that causes the computer to sample the switch terminal (ie to input data from it) many times in succession during the interval of time that contact bounce occurs If the data is sensed to be 1s (or 0s) for a specific number of consecutive samples then it is assumed that contact bounce has ended and the last value sensed is valid Hardware debouncing is the use of electronic circuitry to eliminate the effects of contact bounce There are numerous versions of such circuitry including those that use monostable multivibrators (one-shots) but the most straightforward is simply an RS latch Figure B1 shows the circuit When the switch is in position 1 R = 0 and S = 1 so the latch is set and the output (Q) is 1 When the switch is in position 0 R = 1and S = 0 so the latch is reset and the output is 0 When the switch is moved form one position to the other the latch changes state and bouncing occurs at either the R or the S input The bouncing does not affect the latch after it has change state An RS latch will remain set for example when its R input is 0 and its S input is alternately changed form 1 to 0

                                                                                                                              Figure B1 Use of RS latch to debounce a mechanical switch

                                                                                                                              69

                                                                                                                              • 01-ldst-Outer title
                                                                                                                                • Practical Workbook
                                                                                                                                • Logic Design amp Switching Theory I
                                                                                                                                  • Dept of Computer amp Information Systems Engineering
                                                                                                                                    • NED University of Engineering amp Technology
                                                                                                                                    • Karachi ndash 75270 Pakistan
                                                                                                                                      • 02-ldst-inner Title
                                                                                                                                        • Practical Workbook
                                                                                                                                        • Logic Design amp Switching Theory I
                                                                                                                                          • Dept of Computer amp Information Systems Engineering
                                                                                                                                            • NED University of Engineering amp Technology
                                                                                                                                            • Karachi ndash 75270 Pakistan
                                                                                                                                              • 03-ldst-general info
                                                                                                                                              • 04-ldst-introduction
                                                                                                                                              • 05-Table of Contents
                                                                                                                                                • CONTENTS
                                                                                                                                                  • Lab Session No Object Page No
                                                                                                                                                  • 1
                                                                                                                                                  • Also implementing and testing the given circuit on a bread board
                                                                                                                                                    • Working with Electronics Workbench
                                                                                                                                                      • Driving a seven segment display using 7447 7448 driver IC
                                                                                                                                                        • Designing a modulus-5 asynchronous up-counter using JK-FF
                                                                                                                                                          • Experimenting with 74194 4-bit bidirectional universal shift register
                                                                                                                                                              • 13
                                                                                                                                                                  • 06-ldst-Exp01
                                                                                                                                                                    • Lab Session 01
                                                                                                                                                                    • OBJECT
                                                                                                                                                                      • 1 Bread board
                                                                                                                                                                      • 2 5 V - power supply
                                                                                                                                                                      • 3 Multimeter
                                                                                                                                                                      • 4 Logic probe
                                                                                                                                                                      • 5 LEDs with resistors
                                                                                                                                                                      • 6 Connecting wires
                                                                                                                                                                      • 8 Following ICs and their datasheets
                                                                                                                                                                        • THEORY
                                                                                                                                                                          • Logic Gates
                                                                                                                                                                          • 1 The AND Gate ndash An AND gatersquos output is 1 if and only if all its inputs are 1 If A and B are two inputs to an AND gate then output F of the gate is given as F = AB
                                                                                                                                                                          • 2 The OR Gate - An OR gatersquos output is 1 if at least one of its input is 1 If A and B are two inputs to an OR gate then output F of the gate is given as F = A+B
                                                                                                                                                                          • 3 The NOT Gate (Inverter) ndash Its output is 1 when its input is 0 and its output is 0 when the input is 1 ie it complements a digital variable If A is the input to a NOT gate then output F of the gate is given as
                                                                                                                                                                          • 4 The NAND Gate ndash Its output is 1 if at least one of its input is 0 This gate performs the same logic as an AND gate followed by an inverter If A and B are two inputs to a NAND gate then output F of the gate is given as
                                                                                                                                                                            • 5 The NOR Gate - The output of a NOR gate is 1 if and only if all its inputs are 0 This gate performs the same logic function as an OR gate followed by an inverter If A and B are two inputs to a NAND gate then output F of the gate is given as
                                                                                                                                                                                • DATA SHEETS
                                                                                                                                                                                  • Logic expression for the given logic diagram __________________________________
                                                                                                                                                                                      • 07-ldst-exp02
                                                                                                                                                                                        • Working with Electronics Workbench
                                                                                                                                                                                          • 08-ldst-exp03
                                                                                                                                                                                            • Designing Half and Full Adder Circuits
                                                                                                                                                                                              • COMPONENTS AND APPARATUS REQUIRED
                                                                                                                                                                                                • 1 Following ICs and their Datasheets
                                                                                                                                                                                                • 7408 Quad 2-input AND Gate
                                                                                                                                                                                                • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                  • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                  • Connecting wires Switches
                                                                                                                                                                                                    • THEORY
                                                                                                                                                                                                        • IMPLEMENTATION AND OBSERVATIONS
                                                                                                                                                                                                          • 09-ldst-Exp04
                                                                                                                                                                                                            • Lab Session 04
                                                                                                                                                                                                            • 1 Digital ICs and their Datasheets
                                                                                                                                                                                                            • 7408 Quad 2-input AND Gate
                                                                                                                                                                                                            • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                              • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                              • Connecting wires Switches
                                                                                                                                                                                                              • PROCEDURE
                                                                                                                                                                                                              • REDUCTION OF LOGIC EXPRESSION USING KARNAUGH MAP
                                                                                                                                                                                                              • OBSERVATIONS
                                                                                                                                                                                                              • RESULT
                                                                                                                                                                                                                  • 10-ldst-Exp05
                                                                                                                                                                                                                    • Lab Session 05
                                                                                                                                                                                                                    • 1 Following ICs and their Datasheets
                                                                                                                                                                                                                    • 7408 Quad 2-input AND Gate
                                                                                                                                                                                                                    • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                      • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                                      • (100 Ω) Connecting wires Switches
                                                                                                                                                                                                                      • THEORY
                                                                                                                                                                                                                        • IMPLEMENTATION AND OBSERVATIONS
                                                                                                                                                                                                                          • 11-ldst-Exp06
                                                                                                                                                                                                                            • OBJECT
                                                                                                                                                                                                                            • 1 Following ICs and their Datasheets
                                                                                                                                                                                                                            • 7408 Quad 2-input AND Gates or 7411 Triple 3-input AND Gates
                                                                                                                                                                                                                            • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                              • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                                              • Connecting wires Switches
                                                                                                                                                                                                                                • Figure 62 Circuit Diagram for 4 x 1 Multiplexer
                                                                                                                                                                                                                                • Implementation and Observations
                                                                                                                                                                                                                                  • Circuit Diagram
                                                                                                                                                                                                                                    • ACTIVITY
                                                                                                                                                                                                                                      • 12-ldst-exp07
                                                                                                                                                                                                                                        • 1 Following ICs and their Datasheets
                                                                                                                                                                                                                                        • 7408 Quad 2-input or 7411 Triple 3-input AND Gates
                                                                                                                                                                                                                                        • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                                          • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                                                          • Connecting wires Switches
                                                                                                                                                                                                                                            • THEORY
                                                                                                                                                                                                                                                • Figure 72 Circuit Diagram for 2 x 4 Decoder 1 x 4 Demultiplexer
                                                                                                                                                                                                                                                • Implementation and Observations
                                                                                                                                                                                                                                                  • Circuit Diagram
                                                                                                                                                                                                                                                    • ACTIVITY
                                                                                                                                                                                                                                                      • 13-ldst-Exp08
                                                                                                                                                                                                                                                        • OBJECT
                                                                                                                                                                                                                                                        • 1 Following ICs and their Datasheets
                                                                                                                                                                                                                                                        • 7408 Quad 2-input or 7421 Dual 4-input AND Gates
                                                                                                                                                                                                                                                        • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                                                          • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                                                                          • Connecting wires Switches
                                                                                                                                                                                                                                                            • THEORY
                                                                                                                                                                                                                                                                • Figure 81 Circuit Diagram for 4 x 2 Priority Encoder
                                                                                                                                                                                                                                                                • Implementation and Observations
                                                                                                                                                                                                                                                                  • Therefore if GS A2 A1 and A0 are all low then it shows that line 0 is selected and if E0 A2 A1 and A0 are all low then it shows that none of the inputs selected E0 and GS cannot be in the same state provided that E1 is enabled
                                                                                                                                                                                                                                                                  • Circuit Diagram
                                                                                                                                                                                                                                                                    • ACTIVITY
                                                                                                                                                                                                                                                                      • 14-ldst-exp09
                                                                                                                                                                                                                                                                        • OBJECT
                                                                                                                                                                                                                                                                        • 1 Following ICs and their Datasheets
                                                                                                                                                                                                                                                                        • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                                                                          • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                                                                                          • Connecting wires Switches
                                                                                                                                                                                                                                                                            • THEORY
                                                                                                                                                                                                                                                                              • Parity Generator
                                                                                                                                                                                                                                                                                • Let x y and z be the three bits that constitute the message and are the input to the Odd Parity Generator Circuit Since it is an odd parity system the bit P is generated so as to make the total number of 1s odd (including P) The function P can be expressed as follows
                                                                                                                                                                                                                                                                                • Figure 91 Circuit Diagram for a 3-bit Parity Generator
                                                                                                                                                                                                                                                                                  • C = x Ο y Ο z Ο P
                                                                                                                                                                                                                                                                                    • Implementation and Observations
                                                                                                                                                                                                                                                                                      • ACTIVITY
                                                                                                                                                                                                                                                                                          • 15-ldst-exp10
                                                                                                                                                                                                                                                                                            • Driving a seven segment display using 7447 7448 driver IC
                                                                                                                                                                                                                                                                                            • COMPONENTS AND APPARATUS REQUIRED
                                                                                                                                                                                                                                                                                            • 1 Following ICs and their Datasheets
                                                                                                                                                                                                                                                                                            • 7447 7448 BCD to Seven Segment Driver
                                                                                                                                                                                                                                                                                            • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                                                                                              • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches
                                                                                                                                                                                                                                                                                                • THEORY
                                                                                                                                                                                                                                                                                                • Seven Segment Displays
                                                                                                                                                                                                                                                                                                • CIRCUIT DIAGRAM
                                                                                                                                                                                                                                                                                                • Figure 102 Circuit diagram for 7447driving a common-anode display
                                                                                                                                                                                                                                                                                                    • IMPLEMENTATION AND OBSERVATIONS
                                                                                                                                                                                                                                                                                                      • Decimal Digit
                                                                                                                                                                                                                                                                                                      • BCD Inputs
                                                                                                                                                                                                                                                                                                      • Seven Segment Outputs
                                                                                                                                                                                                                                                                                                      • D
                                                                                                                                                                                                                                                                                                      • C
                                                                                                                                                                                                                                                                                                      • B
                                                                                                                                                                                                                                                                                                      • A
                                                                                                                                                                                                                                                                                                      • a
                                                                                                                                                                                                                                                                                                      • b
                                                                                                                                                                                                                                                                                                      • c
                                                                                                                                                                                                                                                                                                      • d
                                                                                                                                                                                                                                                                                                      • e
                                                                                                                                                                                                                                                                                                      • f
                                                                                                                                                                                                                                                                                                      • g
                                                                                                                                                                                                                                                                                                      • 0
                                                                                                                                                                                                                                                                                                      • 0
                                                                                                                                                                                                                                                                                                      • 0
                                                                                                                                                                                                                                                                                                      • 0
                                                                                                                                                                                                                                                                                                      • 0
                                                                                                                                                                                                                                                                                                      • 1
                                                                                                                                                                                                                                                                                                      • 0
                                                                                                                                                                                                                                                                                                      • 0
                                                                                                                                                                                                                                                                                                      • 0
                                                                                                                                                                                                                                                                                                      • 1
                                                                                                                                                                                                                                                                                                      • 2
                                                                                                                                                                                                                                                                                                      • 0
                                                                                                                                                                                                                                                                                                      • 0
                                                                                                                                                                                                                                                                                                      • 1
                                                                                                                                                                                                                                                                                                      • 0
                                                                                                                                                                                                                                                                                                      • 3
                                                                                                                                                                                                                                                                                                      • 0
                                                                                                                                                                                                                                                                                                      • 0
                                                                                                                                                                                                                                                                                                      • 1
                                                                                                                                                                                                                                                                                                      • 1
                                                                                                                                                                                                                                                                                                      • 4
                                                                                                                                                                                                                                                                                                      • 0
                                                                                                                                                                                                                                                                                                      • 1
                                                                                                                                                                                                                                                                                                      • 0
                                                                                                                                                                                                                                                                                                      • 0
                                                                                                                                                                                                                                                                                                      • 5
                                                                                                                                                                                                                                                                                                      • 0
                                                                                                                                                                                                                                                                                                      • 1
                                                                                                                                                                                                                                                                                                      • 0
                                                                                                                                                                                                                                                                                                      • 1
                                                                                                                                                                                                                                                                                                      • 6
                                                                                                                                                                                                                                                                                                      • 0
                                                                                                                                                                                                                                                                                                      • 1
                                                                                                                                                                                                                                                                                                      • 1
                                                                                                                                                                                                                                                                                                      • 0
                                                                                                                                                                                                                                                                                                      • 7
                                                                                                                                                                                                                                                                                                      • 0
                                                                                                                                                                                                                                                                                                      • 1
                                                                                                                                                                                                                                                                                                      • 1
                                                                                                                                                                                                                                                                                                      • 1
                                                                                                                                                                                                                                                                                                      • 8
                                                                                                                                                                                                                                                                                                      • 1
                                                                                                                                                                                                                                                                                                      • 0
                                                                                                                                                                                                                                                                                                      • 0
                                                                                                                                                                                                                                                                                                      • 0
                                                                                                                                                                                                                                                                                                      • 9
                                                                                                                                                                                                                                                                                                      • 1
                                                                                                                                                                                                                                                                                                      • 0
                                                                                                                                                                                                                                                                                                      • 0
                                                                                                                                                                                                                                                                                                      • 1
                                                                                                                                                                                                                                                                                                        • ACTIVITY
                                                                                                                                                                                                                                                                                                          • 16-ldst-exp11
                                                                                                                                                                                                                                                                                                            • Lab Session 11
                                                                                                                                                                                                                                                                                                              • OBJECT
                                                                                                                                                                                                                                                                                                              • COMPONENTS AND APPARATUS REQUIRED
                                                                                                                                                                                                                                                                                                                • 1 Following ICs and their Datasheets
                                                                                                                                                                                                                                                                                                                • 7473 7476 JK Flip-Flop
                                                                                                                                                                                                                                                                                                                • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                                                                                                                  • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                                                                                                                                  • Connecting wires Switches
                                                                                                                                                                                                                                                                                                                    • THEORY
                                                                                                                                                                                                                                                                                                                        • Flip-Flop
                                                                                                                                                                                                                                                                                                                        • JK Flip-Flop
                                                                                                                                                                                                                                                                                                                          • Circuit Diagram
                                                                                                                                                                                                                                                                                                                            • Observations
                                                                                                                                                                                                                                                                                                                              • ACTIVITY
                                                                                                                                                                                                                                                                                                                                  • 17-ldst-exp12
                                                                                                                                                                                                                                                                                                                                    • Lab Session 12
                                                                                                                                                                                                                                                                                                                                      • OBJECT
                                                                                                                                                                                                                                                                                                                                      • GIVEN STATE DIAGRAM
                                                                                                                                                                                                                                                                                                                                      • Figure 121 State Diagram
                                                                                                                                                                                                                                                                                                                                      • COMPONENTS AND APPARATUS REQUIRED
                                                                                                                                                                                                                                                                                                                                        • 1 Following ICs and their Datasheets
                                                                                                                                                                                                                                                                                                                                        • 7474 D Flip-Flop
                                                                                                                                                                                                                                                                                                                                        • ICs of basic gates (AND OR NOT XOR etc) as required
                                                                                                                                                                                                                                                                                                                                        • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                                                                                                                                          • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                                                                                                                                                          • Connecting wires Switches
                                                                                                                                                                                                                                                                                                                                            • THEORY
                                                                                                                                                                                                                                                                                                                                                • Sequential Circuits
                                                                                                                                                                                                                                                                                                                                                  • 18-ldst-exp13
                                                                                                                                                                                                                                                                                                                                                    • Lab Session 13
                                                                                                                                                                                                                                                                                                                                                      • Designing a modulo-5 asynchronous up-counter using JK-FF
                                                                                                                                                                                                                                                                                                                                                        • 1 Following ICs and their Datasheets
                                                                                                                                                                                                                                                                                                                                                        • 7400 Quad 2-input or 7410 Triple 3-input NAND Gates
                                                                                                                                                                                                                                                                                                                                                        • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                                                                                                                                                          • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                                                                                                                                                                          • Connecting wires Switches
                                                                                                                                                                                                                                                                                                                                                            • THEORY
                                                                                                                                                                                                                                                                                                                                                                • Figure 131 A Mod-5 Asynchronous Up Counter
                                                                                                                                                                                                                                                                                                                                                                • Implementation and Observations
                                                                                                                                                                                                                                                                                                                                                                  • ACTIVITY
                                                                                                                                                                                                                                                                                                                                                                      • 19-ldst-exp14
                                                                                                                                                                                                                                                                                                                                                                        • Experimenting with 74194 4-bit bidirectional universal shift register
                                                                                                                                                                                                                                                                                                                                                                        • 1 Following ICs and their Datasheets
                                                                                                                                                                                                                                                                                                                                                                        • 74194 4-bit bidirectional universal shift register
                                                                                                                                                                                                                                                                                                                                                                        • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                                                                                                                                                                          • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                                                                                                                                                                                          • Connecting wires Switches
                                                                                                                                                                                                                                                                                                                                                                            • THEORY
                                                                                                                                                                                                                                                                                                                                                                              • Shift Registers
                                                                                                                                                                                                                                                                                                                                                                              • Bidirectional Shift Registers
                                                                                                                                                                                                                                                                                                                                                                              • Universal Shift Registers
                                                                                                                                                                                                                                                                                                                                                                                • S1
                                                                                                                                                                                                                                                                                                                                                                                  • Circuit Diagram
                                                                                                                                                                                                                                                                                                                                                                                  • ACTIVITY
                                                                                                                                                                                                                                                                                                                                                                                      • 20-ldst-exp15
                                                                                                                                                                                                                                                                                                                                                                                        • COMPONENTS AND APPARATUS REQUIRED
                                                                                                                                                                                                                                                                                                                                                                                        • 1 Parallel Port Connectors (DB-25) with Cable
                                                                                                                                                                                                                                                                                                                                                                                        • 2 Personal Computer with Windows 98 and TurboC Compiler Installed
                                                                                                                                                                                                                                                                                                                                                                                        • 3 Following ICs and their Datasheets
                                                                                                                                                                                                                                                                                                                                                                                        • 74245 Octal Bus Transceivers with 3-State Outputs
                                                                                                                                                                                                                                                                                                                                                                                        • 4 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                                                                                                                                                                                          • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                                                                                                                                                                                                            • Connecting wires Switches
                                                                                                                                                                                                                                                                                                                                                                                              • THEORY
                                                                                                                                                                                                                                                                                                                                                                                              • 3-State Logic
                                                                                                                                                                                                                                                                                                                                                                                                • Serial and Parallel Port Connectors
                                                                                                                                                                                                                                                                                                                                                                                                • Parallel Port Connector ndash DB-25
                                                                                                                                                                                                                                                                                                                                                                                                  • Accessing parallel port through C Language Programming
                                                                                                                                                                                                                                                                                                                                                                                                      • 21-ldst-appendixA
                                                                                                                                                                                                                                                                                                                                                                                                      • 22-ldst-appendixB
                                                                                                                                                                                                                                                                                                                                                                                                        • DEBOUNCING CIRCUITRY FOR MECHANICAL SWITCHES

                                                                                                                                Logic Design amp Switching Theory 1 Appendix A NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                                                                                Appendix A

                                                                                                                                PIN DIAGRAMS OF THE ICS REQUIRED FOR THE LABORATORY SESSIONS Consult the TTLIC data book for internal diagrams and electrical characteristics of these ICs 7400 Quad 2-Input NAND 7402 Quad 2-Input NOR

                                                                                                                                7404 Hex Inverter 7408 Quad 2-Input AND

                                                                                                                                7410 Triple 3-Input NAND 7411 Triple 3-Input AND

                                                                                                                                7421 Dual 4-Input AND 7432 Quad 2-Input OR

                                                                                                                                66

                                                                                                                                Logic Design amp Switching Theory 1 Appendix A NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                                                                                BCD-to-Seven Segm 7448 BCD-to-Seven Segment 7447 ent

                                                                                                                                Decoder (15V OC) Decoder (2kΩ pull-up output)

                                                                                                                                7473 Dual JK Flip-Flop 7474 Dual D-Type Flip-Flop

                                                                                                                                7476 Dual JK Flop-Flop -Bit Binary Full Adder 7483 4 with Fast Carry

                                                                                                                                86 Quad 2-Inpu 74138 3-to-8 Line 74 t Exclusive OR Decoder Demultiplexer

                                                                                                                                67

                                                                                                                                Logic Design amp Switching Theory 1 Appendix A NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                                                                                68

                                                                                                                                74148 8-to-3 Line 16-to-1 Line Data

                                                                                                                                Priority Encoder 74150 Selector Multiplexer

                                                                                                                                74245 Oct nsceivers Universal Shift Register (PIPO) (3-State)

                                                                                                                                74194 4-Bit Bidirectional al Bus Tra

                                                                                                                                Logic Design amp Switching Theory 1 Appendix B NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                                                                                Appendix B

                                                                                                                                DEBOUNCING CIRCUITRY FOR MECHANICAL SWITCHES Mechanical switches form the interface between human beings and computers or other digital systems For example a keyboard is a matrix of switches used to supply alphanumeric data to a computer Whatever the switch design it is a potential source of problems due to contact bounce The contact bounce creates a sense of narrow pulses when a switch is opened or closed An example of device whose operation would be adversely affected by contact bounce is a digital counter used to count the number of times a switch is depressed Eliminating the effects of contact bounce is called debouncing When data is entered into a computer via a keyboard a software debounce is often used This type of debouncing is a program that causes the computer to sample the switch terminal (ie to input data from it) many times in succession during the interval of time that contact bounce occurs If the data is sensed to be 1s (or 0s) for a specific number of consecutive samples then it is assumed that contact bounce has ended and the last value sensed is valid Hardware debouncing is the use of electronic circuitry to eliminate the effects of contact bounce There are numerous versions of such circuitry including those that use monostable multivibrators (one-shots) but the most straightforward is simply an RS latch Figure B1 shows the circuit When the switch is in position 1 R = 0 and S = 1 so the latch is set and the output (Q) is 1 When the switch is in position 0 R = 1and S = 0 so the latch is reset and the output is 0 When the switch is moved form one position to the other the latch changes state and bouncing occurs at either the R or the S input The bouncing does not affect the latch after it has change state An RS latch will remain set for example when its R input is 0 and its S input is alternately changed form 1 to 0

                                                                                                                                Figure B1 Use of RS latch to debounce a mechanical switch

                                                                                                                                69

                                                                                                                                • 01-ldst-Outer title
                                                                                                                                  • Practical Workbook
                                                                                                                                  • Logic Design amp Switching Theory I
                                                                                                                                    • Dept of Computer amp Information Systems Engineering
                                                                                                                                      • NED University of Engineering amp Technology
                                                                                                                                      • Karachi ndash 75270 Pakistan
                                                                                                                                        • 02-ldst-inner Title
                                                                                                                                          • Practical Workbook
                                                                                                                                          • Logic Design amp Switching Theory I
                                                                                                                                            • Dept of Computer amp Information Systems Engineering
                                                                                                                                              • NED University of Engineering amp Technology
                                                                                                                                              • Karachi ndash 75270 Pakistan
                                                                                                                                                • 03-ldst-general info
                                                                                                                                                • 04-ldst-introduction
                                                                                                                                                • 05-Table of Contents
                                                                                                                                                  • CONTENTS
                                                                                                                                                    • Lab Session No Object Page No
                                                                                                                                                    • 1
                                                                                                                                                    • Also implementing and testing the given circuit on a bread board
                                                                                                                                                      • Working with Electronics Workbench
                                                                                                                                                        • Driving a seven segment display using 7447 7448 driver IC
                                                                                                                                                          • Designing a modulus-5 asynchronous up-counter using JK-FF
                                                                                                                                                            • Experimenting with 74194 4-bit bidirectional universal shift register
                                                                                                                                                                • 13
                                                                                                                                                                    • 06-ldst-Exp01
                                                                                                                                                                      • Lab Session 01
                                                                                                                                                                      • OBJECT
                                                                                                                                                                        • 1 Bread board
                                                                                                                                                                        • 2 5 V - power supply
                                                                                                                                                                        • 3 Multimeter
                                                                                                                                                                        • 4 Logic probe
                                                                                                                                                                        • 5 LEDs with resistors
                                                                                                                                                                        • 6 Connecting wires
                                                                                                                                                                        • 8 Following ICs and their datasheets
                                                                                                                                                                          • THEORY
                                                                                                                                                                            • Logic Gates
                                                                                                                                                                            • 1 The AND Gate ndash An AND gatersquos output is 1 if and only if all its inputs are 1 If A and B are two inputs to an AND gate then output F of the gate is given as F = AB
                                                                                                                                                                            • 2 The OR Gate - An OR gatersquos output is 1 if at least one of its input is 1 If A and B are two inputs to an OR gate then output F of the gate is given as F = A+B
                                                                                                                                                                            • 3 The NOT Gate (Inverter) ndash Its output is 1 when its input is 0 and its output is 0 when the input is 1 ie it complements a digital variable If A is the input to a NOT gate then output F of the gate is given as
                                                                                                                                                                            • 4 The NAND Gate ndash Its output is 1 if at least one of its input is 0 This gate performs the same logic as an AND gate followed by an inverter If A and B are two inputs to a NAND gate then output F of the gate is given as
                                                                                                                                                                              • 5 The NOR Gate - The output of a NOR gate is 1 if and only if all its inputs are 0 This gate performs the same logic function as an OR gate followed by an inverter If A and B are two inputs to a NAND gate then output F of the gate is given as
                                                                                                                                                                                  • DATA SHEETS
                                                                                                                                                                                    • Logic expression for the given logic diagram __________________________________
                                                                                                                                                                                        • 07-ldst-exp02
                                                                                                                                                                                          • Working with Electronics Workbench
                                                                                                                                                                                            • 08-ldst-exp03
                                                                                                                                                                                              • Designing Half and Full Adder Circuits
                                                                                                                                                                                                • COMPONENTS AND APPARATUS REQUIRED
                                                                                                                                                                                                  • 1 Following ICs and their Datasheets
                                                                                                                                                                                                  • 7408 Quad 2-input AND Gate
                                                                                                                                                                                                  • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                    • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                    • Connecting wires Switches
                                                                                                                                                                                                      • THEORY
                                                                                                                                                                                                          • IMPLEMENTATION AND OBSERVATIONS
                                                                                                                                                                                                            • 09-ldst-Exp04
                                                                                                                                                                                                              • Lab Session 04
                                                                                                                                                                                                              • 1 Digital ICs and their Datasheets
                                                                                                                                                                                                              • 7408 Quad 2-input AND Gate
                                                                                                                                                                                                              • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                                • Connecting wires Switches
                                                                                                                                                                                                                • PROCEDURE
                                                                                                                                                                                                                • REDUCTION OF LOGIC EXPRESSION USING KARNAUGH MAP
                                                                                                                                                                                                                • OBSERVATIONS
                                                                                                                                                                                                                • RESULT
                                                                                                                                                                                                                    • 10-ldst-Exp05
                                                                                                                                                                                                                      • Lab Session 05
                                                                                                                                                                                                                      • 1 Following ICs and their Datasheets
                                                                                                                                                                                                                      • 7408 Quad 2-input AND Gate
                                                                                                                                                                                                                      • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                        • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                                        • (100 Ω) Connecting wires Switches
                                                                                                                                                                                                                        • THEORY
                                                                                                                                                                                                                          • IMPLEMENTATION AND OBSERVATIONS
                                                                                                                                                                                                                            • 11-ldst-Exp06
                                                                                                                                                                                                                              • OBJECT
                                                                                                                                                                                                                              • 1 Following ICs and their Datasheets
                                                                                                                                                                                                                              • 7408 Quad 2-input AND Gates or 7411 Triple 3-input AND Gates
                                                                                                                                                                                                                              • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                                • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                                                • Connecting wires Switches
                                                                                                                                                                                                                                  • Figure 62 Circuit Diagram for 4 x 1 Multiplexer
                                                                                                                                                                                                                                  • Implementation and Observations
                                                                                                                                                                                                                                    • Circuit Diagram
                                                                                                                                                                                                                                      • ACTIVITY
                                                                                                                                                                                                                                        • 12-ldst-exp07
                                                                                                                                                                                                                                          • 1 Following ICs and their Datasheets
                                                                                                                                                                                                                                          • 7408 Quad 2-input or 7411 Triple 3-input AND Gates
                                                                                                                                                                                                                                          • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                                            • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                                                            • Connecting wires Switches
                                                                                                                                                                                                                                              • THEORY
                                                                                                                                                                                                                                                  • Figure 72 Circuit Diagram for 2 x 4 Decoder 1 x 4 Demultiplexer
                                                                                                                                                                                                                                                  • Implementation and Observations
                                                                                                                                                                                                                                                    • Circuit Diagram
                                                                                                                                                                                                                                                      • ACTIVITY
                                                                                                                                                                                                                                                        • 13-ldst-Exp08
                                                                                                                                                                                                                                                          • OBJECT
                                                                                                                                                                                                                                                          • 1 Following ICs and their Datasheets
                                                                                                                                                                                                                                                          • 7408 Quad 2-input or 7421 Dual 4-input AND Gates
                                                                                                                                                                                                                                                          • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                                                            • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                                                                            • Connecting wires Switches
                                                                                                                                                                                                                                                              • THEORY
                                                                                                                                                                                                                                                                  • Figure 81 Circuit Diagram for 4 x 2 Priority Encoder
                                                                                                                                                                                                                                                                  • Implementation and Observations
                                                                                                                                                                                                                                                                    • Therefore if GS A2 A1 and A0 are all low then it shows that line 0 is selected and if E0 A2 A1 and A0 are all low then it shows that none of the inputs selected E0 and GS cannot be in the same state provided that E1 is enabled
                                                                                                                                                                                                                                                                    • Circuit Diagram
                                                                                                                                                                                                                                                                      • ACTIVITY
                                                                                                                                                                                                                                                                        • 14-ldst-exp09
                                                                                                                                                                                                                                                                          • OBJECT
                                                                                                                                                                                                                                                                          • 1 Following ICs and their Datasheets
                                                                                                                                                                                                                                                                          • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                                                                            • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                                                                                            • Connecting wires Switches
                                                                                                                                                                                                                                                                              • THEORY
                                                                                                                                                                                                                                                                                • Parity Generator
                                                                                                                                                                                                                                                                                  • Let x y and z be the three bits that constitute the message and are the input to the Odd Parity Generator Circuit Since it is an odd parity system the bit P is generated so as to make the total number of 1s odd (including P) The function P can be expressed as follows
                                                                                                                                                                                                                                                                                  • Figure 91 Circuit Diagram for a 3-bit Parity Generator
                                                                                                                                                                                                                                                                                    • C = x Ο y Ο z Ο P
                                                                                                                                                                                                                                                                                      • Implementation and Observations
                                                                                                                                                                                                                                                                                        • ACTIVITY
                                                                                                                                                                                                                                                                                            • 15-ldst-exp10
                                                                                                                                                                                                                                                                                              • Driving a seven segment display using 7447 7448 driver IC
                                                                                                                                                                                                                                                                                              • COMPONENTS AND APPARATUS REQUIRED
                                                                                                                                                                                                                                                                                              • 1 Following ICs and their Datasheets
                                                                                                                                                                                                                                                                                              • 7447 7448 BCD to Seven Segment Driver
                                                                                                                                                                                                                                                                                              • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                                                                                                • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches
                                                                                                                                                                                                                                                                                                  • THEORY
                                                                                                                                                                                                                                                                                                  • Seven Segment Displays
                                                                                                                                                                                                                                                                                                  • CIRCUIT DIAGRAM
                                                                                                                                                                                                                                                                                                  • Figure 102 Circuit diagram for 7447driving a common-anode display
                                                                                                                                                                                                                                                                                                      • IMPLEMENTATION AND OBSERVATIONS
                                                                                                                                                                                                                                                                                                        • Decimal Digit
                                                                                                                                                                                                                                                                                                        • BCD Inputs
                                                                                                                                                                                                                                                                                                        • Seven Segment Outputs
                                                                                                                                                                                                                                                                                                        • D
                                                                                                                                                                                                                                                                                                        • C
                                                                                                                                                                                                                                                                                                        • B
                                                                                                                                                                                                                                                                                                        • A
                                                                                                                                                                                                                                                                                                        • a
                                                                                                                                                                                                                                                                                                        • b
                                                                                                                                                                                                                                                                                                        • c
                                                                                                                                                                                                                                                                                                        • d
                                                                                                                                                                                                                                                                                                        • e
                                                                                                                                                                                                                                                                                                        • f
                                                                                                                                                                                                                                                                                                        • g
                                                                                                                                                                                                                                                                                                        • 0
                                                                                                                                                                                                                                                                                                        • 0
                                                                                                                                                                                                                                                                                                        • 0
                                                                                                                                                                                                                                                                                                        • 0
                                                                                                                                                                                                                                                                                                        • 0
                                                                                                                                                                                                                                                                                                        • 1
                                                                                                                                                                                                                                                                                                        • 0
                                                                                                                                                                                                                                                                                                        • 0
                                                                                                                                                                                                                                                                                                        • 0
                                                                                                                                                                                                                                                                                                        • 1
                                                                                                                                                                                                                                                                                                        • 2
                                                                                                                                                                                                                                                                                                        • 0
                                                                                                                                                                                                                                                                                                        • 0
                                                                                                                                                                                                                                                                                                        • 1
                                                                                                                                                                                                                                                                                                        • 0
                                                                                                                                                                                                                                                                                                        • 3
                                                                                                                                                                                                                                                                                                        • 0
                                                                                                                                                                                                                                                                                                        • 0
                                                                                                                                                                                                                                                                                                        • 1
                                                                                                                                                                                                                                                                                                        • 1
                                                                                                                                                                                                                                                                                                        • 4
                                                                                                                                                                                                                                                                                                        • 0
                                                                                                                                                                                                                                                                                                        • 1
                                                                                                                                                                                                                                                                                                        • 0
                                                                                                                                                                                                                                                                                                        • 0
                                                                                                                                                                                                                                                                                                        • 5
                                                                                                                                                                                                                                                                                                        • 0
                                                                                                                                                                                                                                                                                                        • 1
                                                                                                                                                                                                                                                                                                        • 0
                                                                                                                                                                                                                                                                                                        • 1
                                                                                                                                                                                                                                                                                                        • 6
                                                                                                                                                                                                                                                                                                        • 0
                                                                                                                                                                                                                                                                                                        • 1
                                                                                                                                                                                                                                                                                                        • 1
                                                                                                                                                                                                                                                                                                        • 0
                                                                                                                                                                                                                                                                                                        • 7
                                                                                                                                                                                                                                                                                                        • 0
                                                                                                                                                                                                                                                                                                        • 1
                                                                                                                                                                                                                                                                                                        • 1
                                                                                                                                                                                                                                                                                                        • 1
                                                                                                                                                                                                                                                                                                        • 8
                                                                                                                                                                                                                                                                                                        • 1
                                                                                                                                                                                                                                                                                                        • 0
                                                                                                                                                                                                                                                                                                        • 0
                                                                                                                                                                                                                                                                                                        • 0
                                                                                                                                                                                                                                                                                                        • 9
                                                                                                                                                                                                                                                                                                        • 1
                                                                                                                                                                                                                                                                                                        • 0
                                                                                                                                                                                                                                                                                                        • 0
                                                                                                                                                                                                                                                                                                        • 1
                                                                                                                                                                                                                                                                                                          • ACTIVITY
                                                                                                                                                                                                                                                                                                            • 16-ldst-exp11
                                                                                                                                                                                                                                                                                                              • Lab Session 11
                                                                                                                                                                                                                                                                                                                • OBJECT
                                                                                                                                                                                                                                                                                                                • COMPONENTS AND APPARATUS REQUIRED
                                                                                                                                                                                                                                                                                                                  • 1 Following ICs and their Datasheets
                                                                                                                                                                                                                                                                                                                  • 7473 7476 JK Flip-Flop
                                                                                                                                                                                                                                                                                                                  • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                                                                                                                    • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                                                                                                                                    • Connecting wires Switches
                                                                                                                                                                                                                                                                                                                      • THEORY
                                                                                                                                                                                                                                                                                                                          • Flip-Flop
                                                                                                                                                                                                                                                                                                                          • JK Flip-Flop
                                                                                                                                                                                                                                                                                                                            • Circuit Diagram
                                                                                                                                                                                                                                                                                                                              • Observations
                                                                                                                                                                                                                                                                                                                                • ACTIVITY
                                                                                                                                                                                                                                                                                                                                    • 17-ldst-exp12
                                                                                                                                                                                                                                                                                                                                      • Lab Session 12
                                                                                                                                                                                                                                                                                                                                        • OBJECT
                                                                                                                                                                                                                                                                                                                                        • GIVEN STATE DIAGRAM
                                                                                                                                                                                                                                                                                                                                        • Figure 121 State Diagram
                                                                                                                                                                                                                                                                                                                                        • COMPONENTS AND APPARATUS REQUIRED
                                                                                                                                                                                                                                                                                                                                          • 1 Following ICs and their Datasheets
                                                                                                                                                                                                                                                                                                                                          • 7474 D Flip-Flop
                                                                                                                                                                                                                                                                                                                                          • ICs of basic gates (AND OR NOT XOR etc) as required
                                                                                                                                                                                                                                                                                                                                          • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                                                                                                                                            • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                                                                                                                                                            • Connecting wires Switches
                                                                                                                                                                                                                                                                                                                                              • THEORY
                                                                                                                                                                                                                                                                                                                                                  • Sequential Circuits
                                                                                                                                                                                                                                                                                                                                                    • 18-ldst-exp13
                                                                                                                                                                                                                                                                                                                                                      • Lab Session 13
                                                                                                                                                                                                                                                                                                                                                        • Designing a modulo-5 asynchronous up-counter using JK-FF
                                                                                                                                                                                                                                                                                                                                                          • 1 Following ICs and their Datasheets
                                                                                                                                                                                                                                                                                                                                                          • 7400 Quad 2-input or 7410 Triple 3-input NAND Gates
                                                                                                                                                                                                                                                                                                                                                          • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                                                                                                                                                            • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                                                                                                                                                                            • Connecting wires Switches
                                                                                                                                                                                                                                                                                                                                                              • THEORY
                                                                                                                                                                                                                                                                                                                                                                  • Figure 131 A Mod-5 Asynchronous Up Counter
                                                                                                                                                                                                                                                                                                                                                                  • Implementation and Observations
                                                                                                                                                                                                                                                                                                                                                                    • ACTIVITY
                                                                                                                                                                                                                                                                                                                                                                        • 19-ldst-exp14
                                                                                                                                                                                                                                                                                                                                                                          • Experimenting with 74194 4-bit bidirectional universal shift register
                                                                                                                                                                                                                                                                                                                                                                          • 1 Following ICs and their Datasheets
                                                                                                                                                                                                                                                                                                                                                                          • 74194 4-bit bidirectional universal shift register
                                                                                                                                                                                                                                                                                                                                                                          • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                                                                                                                                                                            • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                                                                                                                                                                                            • Connecting wires Switches
                                                                                                                                                                                                                                                                                                                                                                              • THEORY
                                                                                                                                                                                                                                                                                                                                                                                • Shift Registers
                                                                                                                                                                                                                                                                                                                                                                                • Bidirectional Shift Registers
                                                                                                                                                                                                                                                                                                                                                                                • Universal Shift Registers
                                                                                                                                                                                                                                                                                                                                                                                  • S1
                                                                                                                                                                                                                                                                                                                                                                                    • Circuit Diagram
                                                                                                                                                                                                                                                                                                                                                                                    • ACTIVITY
                                                                                                                                                                                                                                                                                                                                                                                        • 20-ldst-exp15
                                                                                                                                                                                                                                                                                                                                                                                          • COMPONENTS AND APPARATUS REQUIRED
                                                                                                                                                                                                                                                                                                                                                                                          • 1 Parallel Port Connectors (DB-25) with Cable
                                                                                                                                                                                                                                                                                                                                                                                          • 2 Personal Computer with Windows 98 and TurboC Compiler Installed
                                                                                                                                                                                                                                                                                                                                                                                          • 3 Following ICs and their Datasheets
                                                                                                                                                                                                                                                                                                                                                                                          • 74245 Octal Bus Transceivers with 3-State Outputs
                                                                                                                                                                                                                                                                                                                                                                                          • 4 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                                                                                                                                                                                            • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                                                                                                                                                                                                              • Connecting wires Switches
                                                                                                                                                                                                                                                                                                                                                                                                • THEORY
                                                                                                                                                                                                                                                                                                                                                                                                • 3-State Logic
                                                                                                                                                                                                                                                                                                                                                                                                  • Serial and Parallel Port Connectors
                                                                                                                                                                                                                                                                                                                                                                                                  • Parallel Port Connector ndash DB-25
                                                                                                                                                                                                                                                                                                                                                                                                    • Accessing parallel port through C Language Programming
                                                                                                                                                                                                                                                                                                                                                                                                        • 21-ldst-appendixA
                                                                                                                                                                                                                                                                                                                                                                                                        • 22-ldst-appendixB
                                                                                                                                                                                                                                                                                                                                                                                                          • DEBOUNCING CIRCUITRY FOR MECHANICAL SWITCHES

                                                                                                                                  Logic Design amp Switching Theory 1 Appendix A NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                                                                                  BCD-to-Seven Segm 7448 BCD-to-Seven Segment 7447 ent

                                                                                                                                  Decoder (15V OC) Decoder (2kΩ pull-up output)

                                                                                                                                  7473 Dual JK Flip-Flop 7474 Dual D-Type Flip-Flop

                                                                                                                                  7476 Dual JK Flop-Flop -Bit Binary Full Adder 7483 4 with Fast Carry

                                                                                                                                  86 Quad 2-Inpu 74138 3-to-8 Line 74 t Exclusive OR Decoder Demultiplexer

                                                                                                                                  67

                                                                                                                                  Logic Design amp Switching Theory 1 Appendix A NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                                                                                  68

                                                                                                                                  74148 8-to-3 Line 16-to-1 Line Data

                                                                                                                                  Priority Encoder 74150 Selector Multiplexer

                                                                                                                                  74245 Oct nsceivers Universal Shift Register (PIPO) (3-State)

                                                                                                                                  74194 4-Bit Bidirectional al Bus Tra

                                                                                                                                  Logic Design amp Switching Theory 1 Appendix B NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                                                                                  Appendix B

                                                                                                                                  DEBOUNCING CIRCUITRY FOR MECHANICAL SWITCHES Mechanical switches form the interface between human beings and computers or other digital systems For example a keyboard is a matrix of switches used to supply alphanumeric data to a computer Whatever the switch design it is a potential source of problems due to contact bounce The contact bounce creates a sense of narrow pulses when a switch is opened or closed An example of device whose operation would be adversely affected by contact bounce is a digital counter used to count the number of times a switch is depressed Eliminating the effects of contact bounce is called debouncing When data is entered into a computer via a keyboard a software debounce is often used This type of debouncing is a program that causes the computer to sample the switch terminal (ie to input data from it) many times in succession during the interval of time that contact bounce occurs If the data is sensed to be 1s (or 0s) for a specific number of consecutive samples then it is assumed that contact bounce has ended and the last value sensed is valid Hardware debouncing is the use of electronic circuitry to eliminate the effects of contact bounce There are numerous versions of such circuitry including those that use monostable multivibrators (one-shots) but the most straightforward is simply an RS latch Figure B1 shows the circuit When the switch is in position 1 R = 0 and S = 1 so the latch is set and the output (Q) is 1 When the switch is in position 0 R = 1and S = 0 so the latch is reset and the output is 0 When the switch is moved form one position to the other the latch changes state and bouncing occurs at either the R or the S input The bouncing does not affect the latch after it has change state An RS latch will remain set for example when its R input is 0 and its S input is alternately changed form 1 to 0

                                                                                                                                  Figure B1 Use of RS latch to debounce a mechanical switch

                                                                                                                                  69

                                                                                                                                  • 01-ldst-Outer title
                                                                                                                                    • Practical Workbook
                                                                                                                                    • Logic Design amp Switching Theory I
                                                                                                                                      • Dept of Computer amp Information Systems Engineering
                                                                                                                                        • NED University of Engineering amp Technology
                                                                                                                                        • Karachi ndash 75270 Pakistan
                                                                                                                                          • 02-ldst-inner Title
                                                                                                                                            • Practical Workbook
                                                                                                                                            • Logic Design amp Switching Theory I
                                                                                                                                              • Dept of Computer amp Information Systems Engineering
                                                                                                                                                • NED University of Engineering amp Technology
                                                                                                                                                • Karachi ndash 75270 Pakistan
                                                                                                                                                  • 03-ldst-general info
                                                                                                                                                  • 04-ldst-introduction
                                                                                                                                                  • 05-Table of Contents
                                                                                                                                                    • CONTENTS
                                                                                                                                                      • Lab Session No Object Page No
                                                                                                                                                      • 1
                                                                                                                                                      • Also implementing and testing the given circuit on a bread board
                                                                                                                                                        • Working with Electronics Workbench
                                                                                                                                                          • Driving a seven segment display using 7447 7448 driver IC
                                                                                                                                                            • Designing a modulus-5 asynchronous up-counter using JK-FF
                                                                                                                                                              • Experimenting with 74194 4-bit bidirectional universal shift register
                                                                                                                                                                  • 13
                                                                                                                                                                      • 06-ldst-Exp01
                                                                                                                                                                        • Lab Session 01
                                                                                                                                                                        • OBJECT
                                                                                                                                                                          • 1 Bread board
                                                                                                                                                                          • 2 5 V - power supply
                                                                                                                                                                          • 3 Multimeter
                                                                                                                                                                          • 4 Logic probe
                                                                                                                                                                          • 5 LEDs with resistors
                                                                                                                                                                          • 6 Connecting wires
                                                                                                                                                                          • 8 Following ICs and their datasheets
                                                                                                                                                                            • THEORY
                                                                                                                                                                              • Logic Gates
                                                                                                                                                                              • 1 The AND Gate ndash An AND gatersquos output is 1 if and only if all its inputs are 1 If A and B are two inputs to an AND gate then output F of the gate is given as F = AB
                                                                                                                                                                              • 2 The OR Gate - An OR gatersquos output is 1 if at least one of its input is 1 If A and B are two inputs to an OR gate then output F of the gate is given as F = A+B
                                                                                                                                                                              • 3 The NOT Gate (Inverter) ndash Its output is 1 when its input is 0 and its output is 0 when the input is 1 ie it complements a digital variable If A is the input to a NOT gate then output F of the gate is given as
                                                                                                                                                                              • 4 The NAND Gate ndash Its output is 1 if at least one of its input is 0 This gate performs the same logic as an AND gate followed by an inverter If A and B are two inputs to a NAND gate then output F of the gate is given as
                                                                                                                                                                                • 5 The NOR Gate - The output of a NOR gate is 1 if and only if all its inputs are 0 This gate performs the same logic function as an OR gate followed by an inverter If A and B are two inputs to a NAND gate then output F of the gate is given as
                                                                                                                                                                                    • DATA SHEETS
                                                                                                                                                                                      • Logic expression for the given logic diagram __________________________________
                                                                                                                                                                                          • 07-ldst-exp02
                                                                                                                                                                                            • Working with Electronics Workbench
                                                                                                                                                                                              • 08-ldst-exp03
                                                                                                                                                                                                • Designing Half and Full Adder Circuits
                                                                                                                                                                                                  • COMPONENTS AND APPARATUS REQUIRED
                                                                                                                                                                                                    • 1 Following ICs and their Datasheets
                                                                                                                                                                                                    • 7408 Quad 2-input AND Gate
                                                                                                                                                                                                    • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                      • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                      • Connecting wires Switches
                                                                                                                                                                                                        • THEORY
                                                                                                                                                                                                            • IMPLEMENTATION AND OBSERVATIONS
                                                                                                                                                                                                              • 09-ldst-Exp04
                                                                                                                                                                                                                • Lab Session 04
                                                                                                                                                                                                                • 1 Digital ICs and their Datasheets
                                                                                                                                                                                                                • 7408 Quad 2-input AND Gate
                                                                                                                                                                                                                • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                  • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                                  • Connecting wires Switches
                                                                                                                                                                                                                  • PROCEDURE
                                                                                                                                                                                                                  • REDUCTION OF LOGIC EXPRESSION USING KARNAUGH MAP
                                                                                                                                                                                                                  • OBSERVATIONS
                                                                                                                                                                                                                  • RESULT
                                                                                                                                                                                                                      • 10-ldst-Exp05
                                                                                                                                                                                                                        • Lab Session 05
                                                                                                                                                                                                                        • 1 Following ICs and their Datasheets
                                                                                                                                                                                                                        • 7408 Quad 2-input AND Gate
                                                                                                                                                                                                                        • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                          • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                                          • (100 Ω) Connecting wires Switches
                                                                                                                                                                                                                          • THEORY
                                                                                                                                                                                                                            • IMPLEMENTATION AND OBSERVATIONS
                                                                                                                                                                                                                              • 11-ldst-Exp06
                                                                                                                                                                                                                                • OBJECT
                                                                                                                                                                                                                                • 1 Following ICs and their Datasheets
                                                                                                                                                                                                                                • 7408 Quad 2-input AND Gates or 7411 Triple 3-input AND Gates
                                                                                                                                                                                                                                • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                                  • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                                                  • Connecting wires Switches
                                                                                                                                                                                                                                    • Figure 62 Circuit Diagram for 4 x 1 Multiplexer
                                                                                                                                                                                                                                    • Implementation and Observations
                                                                                                                                                                                                                                      • Circuit Diagram
                                                                                                                                                                                                                                        • ACTIVITY
                                                                                                                                                                                                                                          • 12-ldst-exp07
                                                                                                                                                                                                                                            • 1 Following ICs and their Datasheets
                                                                                                                                                                                                                                            • 7408 Quad 2-input or 7411 Triple 3-input AND Gates
                                                                                                                                                                                                                                            • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                                              • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                                                              • Connecting wires Switches
                                                                                                                                                                                                                                                • THEORY
                                                                                                                                                                                                                                                    • Figure 72 Circuit Diagram for 2 x 4 Decoder 1 x 4 Demultiplexer
                                                                                                                                                                                                                                                    • Implementation and Observations
                                                                                                                                                                                                                                                      • Circuit Diagram
                                                                                                                                                                                                                                                        • ACTIVITY
                                                                                                                                                                                                                                                          • 13-ldst-Exp08
                                                                                                                                                                                                                                                            • OBJECT
                                                                                                                                                                                                                                                            • 1 Following ICs and their Datasheets
                                                                                                                                                                                                                                                            • 7408 Quad 2-input or 7421 Dual 4-input AND Gates
                                                                                                                                                                                                                                                            • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                                                              • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                                                                              • Connecting wires Switches
                                                                                                                                                                                                                                                                • THEORY
                                                                                                                                                                                                                                                                    • Figure 81 Circuit Diagram for 4 x 2 Priority Encoder
                                                                                                                                                                                                                                                                    • Implementation and Observations
                                                                                                                                                                                                                                                                      • Therefore if GS A2 A1 and A0 are all low then it shows that line 0 is selected and if E0 A2 A1 and A0 are all low then it shows that none of the inputs selected E0 and GS cannot be in the same state provided that E1 is enabled
                                                                                                                                                                                                                                                                      • Circuit Diagram
                                                                                                                                                                                                                                                                        • ACTIVITY
                                                                                                                                                                                                                                                                          • 14-ldst-exp09
                                                                                                                                                                                                                                                                            • OBJECT
                                                                                                                                                                                                                                                                            • 1 Following ICs and their Datasheets
                                                                                                                                                                                                                                                                            • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                                                                              • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                                                                                              • Connecting wires Switches
                                                                                                                                                                                                                                                                                • THEORY
                                                                                                                                                                                                                                                                                  • Parity Generator
                                                                                                                                                                                                                                                                                    • Let x y and z be the three bits that constitute the message and are the input to the Odd Parity Generator Circuit Since it is an odd parity system the bit P is generated so as to make the total number of 1s odd (including P) The function P can be expressed as follows
                                                                                                                                                                                                                                                                                    • Figure 91 Circuit Diagram for a 3-bit Parity Generator
                                                                                                                                                                                                                                                                                      • C = x Ο y Ο z Ο P
                                                                                                                                                                                                                                                                                        • Implementation and Observations
                                                                                                                                                                                                                                                                                          • ACTIVITY
                                                                                                                                                                                                                                                                                              • 15-ldst-exp10
                                                                                                                                                                                                                                                                                                • Driving a seven segment display using 7447 7448 driver IC
                                                                                                                                                                                                                                                                                                • COMPONENTS AND APPARATUS REQUIRED
                                                                                                                                                                                                                                                                                                • 1 Following ICs and their Datasheets
                                                                                                                                                                                                                                                                                                • 7447 7448 BCD to Seven Segment Driver
                                                                                                                                                                                                                                                                                                • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                                                                                                  • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches
                                                                                                                                                                                                                                                                                                    • THEORY
                                                                                                                                                                                                                                                                                                    • Seven Segment Displays
                                                                                                                                                                                                                                                                                                    • CIRCUIT DIAGRAM
                                                                                                                                                                                                                                                                                                    • Figure 102 Circuit diagram for 7447driving a common-anode display
                                                                                                                                                                                                                                                                                                        • IMPLEMENTATION AND OBSERVATIONS
                                                                                                                                                                                                                                                                                                          • Decimal Digit
                                                                                                                                                                                                                                                                                                          • BCD Inputs
                                                                                                                                                                                                                                                                                                          • Seven Segment Outputs
                                                                                                                                                                                                                                                                                                          • D
                                                                                                                                                                                                                                                                                                          • C
                                                                                                                                                                                                                                                                                                          • B
                                                                                                                                                                                                                                                                                                          • A
                                                                                                                                                                                                                                                                                                          • a
                                                                                                                                                                                                                                                                                                          • b
                                                                                                                                                                                                                                                                                                          • c
                                                                                                                                                                                                                                                                                                          • d
                                                                                                                                                                                                                                                                                                          • e
                                                                                                                                                                                                                                                                                                          • f
                                                                                                                                                                                                                                                                                                          • g
                                                                                                                                                                                                                                                                                                          • 0
                                                                                                                                                                                                                                                                                                          • 0
                                                                                                                                                                                                                                                                                                          • 0
                                                                                                                                                                                                                                                                                                          • 0
                                                                                                                                                                                                                                                                                                          • 0
                                                                                                                                                                                                                                                                                                          • 1
                                                                                                                                                                                                                                                                                                          • 0
                                                                                                                                                                                                                                                                                                          • 0
                                                                                                                                                                                                                                                                                                          • 0
                                                                                                                                                                                                                                                                                                          • 1
                                                                                                                                                                                                                                                                                                          • 2
                                                                                                                                                                                                                                                                                                          • 0
                                                                                                                                                                                                                                                                                                          • 0
                                                                                                                                                                                                                                                                                                          • 1
                                                                                                                                                                                                                                                                                                          • 0
                                                                                                                                                                                                                                                                                                          • 3
                                                                                                                                                                                                                                                                                                          • 0
                                                                                                                                                                                                                                                                                                          • 0
                                                                                                                                                                                                                                                                                                          • 1
                                                                                                                                                                                                                                                                                                          • 1
                                                                                                                                                                                                                                                                                                          • 4
                                                                                                                                                                                                                                                                                                          • 0
                                                                                                                                                                                                                                                                                                          • 1
                                                                                                                                                                                                                                                                                                          • 0
                                                                                                                                                                                                                                                                                                          • 0
                                                                                                                                                                                                                                                                                                          • 5
                                                                                                                                                                                                                                                                                                          • 0
                                                                                                                                                                                                                                                                                                          • 1
                                                                                                                                                                                                                                                                                                          • 0
                                                                                                                                                                                                                                                                                                          • 1
                                                                                                                                                                                                                                                                                                          • 6
                                                                                                                                                                                                                                                                                                          • 0
                                                                                                                                                                                                                                                                                                          • 1
                                                                                                                                                                                                                                                                                                          • 1
                                                                                                                                                                                                                                                                                                          • 0
                                                                                                                                                                                                                                                                                                          • 7
                                                                                                                                                                                                                                                                                                          • 0
                                                                                                                                                                                                                                                                                                          • 1
                                                                                                                                                                                                                                                                                                          • 1
                                                                                                                                                                                                                                                                                                          • 1
                                                                                                                                                                                                                                                                                                          • 8
                                                                                                                                                                                                                                                                                                          • 1
                                                                                                                                                                                                                                                                                                          • 0
                                                                                                                                                                                                                                                                                                          • 0
                                                                                                                                                                                                                                                                                                          • 0
                                                                                                                                                                                                                                                                                                          • 9
                                                                                                                                                                                                                                                                                                          • 1
                                                                                                                                                                                                                                                                                                          • 0
                                                                                                                                                                                                                                                                                                          • 0
                                                                                                                                                                                                                                                                                                          • 1
                                                                                                                                                                                                                                                                                                            • ACTIVITY
                                                                                                                                                                                                                                                                                                              • 16-ldst-exp11
                                                                                                                                                                                                                                                                                                                • Lab Session 11
                                                                                                                                                                                                                                                                                                                  • OBJECT
                                                                                                                                                                                                                                                                                                                  • COMPONENTS AND APPARATUS REQUIRED
                                                                                                                                                                                                                                                                                                                    • 1 Following ICs and their Datasheets
                                                                                                                                                                                                                                                                                                                    • 7473 7476 JK Flip-Flop
                                                                                                                                                                                                                                                                                                                    • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                                                                                                                      • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                                                                                                                                      • Connecting wires Switches
                                                                                                                                                                                                                                                                                                                        • THEORY
                                                                                                                                                                                                                                                                                                                            • Flip-Flop
                                                                                                                                                                                                                                                                                                                            • JK Flip-Flop
                                                                                                                                                                                                                                                                                                                              • Circuit Diagram
                                                                                                                                                                                                                                                                                                                                • Observations
                                                                                                                                                                                                                                                                                                                                  • ACTIVITY
                                                                                                                                                                                                                                                                                                                                      • 17-ldst-exp12
                                                                                                                                                                                                                                                                                                                                        • Lab Session 12
                                                                                                                                                                                                                                                                                                                                          • OBJECT
                                                                                                                                                                                                                                                                                                                                          • GIVEN STATE DIAGRAM
                                                                                                                                                                                                                                                                                                                                          • Figure 121 State Diagram
                                                                                                                                                                                                                                                                                                                                          • COMPONENTS AND APPARATUS REQUIRED
                                                                                                                                                                                                                                                                                                                                            • 1 Following ICs and their Datasheets
                                                                                                                                                                                                                                                                                                                                            • 7474 D Flip-Flop
                                                                                                                                                                                                                                                                                                                                            • ICs of basic gates (AND OR NOT XOR etc) as required
                                                                                                                                                                                                                                                                                                                                            • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                                                                                                                                              • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                                                                                                                                                              • Connecting wires Switches
                                                                                                                                                                                                                                                                                                                                                • THEORY
                                                                                                                                                                                                                                                                                                                                                    • Sequential Circuits
                                                                                                                                                                                                                                                                                                                                                      • 18-ldst-exp13
                                                                                                                                                                                                                                                                                                                                                        • Lab Session 13
                                                                                                                                                                                                                                                                                                                                                          • Designing a modulo-5 asynchronous up-counter using JK-FF
                                                                                                                                                                                                                                                                                                                                                            • 1 Following ICs and their Datasheets
                                                                                                                                                                                                                                                                                                                                                            • 7400 Quad 2-input or 7410 Triple 3-input NAND Gates
                                                                                                                                                                                                                                                                                                                                                            • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                                                                                                                                                              • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                                                                                                                                                                              • Connecting wires Switches
                                                                                                                                                                                                                                                                                                                                                                • THEORY
                                                                                                                                                                                                                                                                                                                                                                    • Figure 131 A Mod-5 Asynchronous Up Counter
                                                                                                                                                                                                                                                                                                                                                                    • Implementation and Observations
                                                                                                                                                                                                                                                                                                                                                                      • ACTIVITY
                                                                                                                                                                                                                                                                                                                                                                          • 19-ldst-exp14
                                                                                                                                                                                                                                                                                                                                                                            • Experimenting with 74194 4-bit bidirectional universal shift register
                                                                                                                                                                                                                                                                                                                                                                            • 1 Following ICs and their Datasheets
                                                                                                                                                                                                                                                                                                                                                                            • 74194 4-bit bidirectional universal shift register
                                                                                                                                                                                                                                                                                                                                                                            • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                                                                                                                                                                              • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                                                                                                                                                                                              • Connecting wires Switches
                                                                                                                                                                                                                                                                                                                                                                                • THEORY
                                                                                                                                                                                                                                                                                                                                                                                  • Shift Registers
                                                                                                                                                                                                                                                                                                                                                                                  • Bidirectional Shift Registers
                                                                                                                                                                                                                                                                                                                                                                                  • Universal Shift Registers
                                                                                                                                                                                                                                                                                                                                                                                    • S1
                                                                                                                                                                                                                                                                                                                                                                                      • Circuit Diagram
                                                                                                                                                                                                                                                                                                                                                                                      • ACTIVITY
                                                                                                                                                                                                                                                                                                                                                                                          • 20-ldst-exp15
                                                                                                                                                                                                                                                                                                                                                                                            • COMPONENTS AND APPARATUS REQUIRED
                                                                                                                                                                                                                                                                                                                                                                                            • 1 Parallel Port Connectors (DB-25) with Cable
                                                                                                                                                                                                                                                                                                                                                                                            • 2 Personal Computer with Windows 98 and TurboC Compiler Installed
                                                                                                                                                                                                                                                                                                                                                                                            • 3 Following ICs and their Datasheets
                                                                                                                                                                                                                                                                                                                                                                                            • 74245 Octal Bus Transceivers with 3-State Outputs
                                                                                                                                                                                                                                                                                                                                                                                            • 4 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                                                                                                                                                                                              • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                                                                                                                                                                                                                • Connecting wires Switches
                                                                                                                                                                                                                                                                                                                                                                                                  • THEORY
                                                                                                                                                                                                                                                                                                                                                                                                  • 3-State Logic
                                                                                                                                                                                                                                                                                                                                                                                                    • Serial and Parallel Port Connectors
                                                                                                                                                                                                                                                                                                                                                                                                    • Parallel Port Connector ndash DB-25
                                                                                                                                                                                                                                                                                                                                                                                                      • Accessing parallel port through C Language Programming
                                                                                                                                                                                                                                                                                                                                                                                                          • 21-ldst-appendixA
                                                                                                                                                                                                                                                                                                                                                                                                          • 22-ldst-appendixB
                                                                                                                                                                                                                                                                                                                                                                                                            • DEBOUNCING CIRCUITRY FOR MECHANICAL SWITCHES

                                                                                                                                    Logic Design amp Switching Theory 1 Appendix A NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                                                                                    68

                                                                                                                                    74148 8-to-3 Line 16-to-1 Line Data

                                                                                                                                    Priority Encoder 74150 Selector Multiplexer

                                                                                                                                    74245 Oct nsceivers Universal Shift Register (PIPO) (3-State)

                                                                                                                                    74194 4-Bit Bidirectional al Bus Tra

                                                                                                                                    Logic Design amp Switching Theory 1 Appendix B NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                                                                                    Appendix B

                                                                                                                                    DEBOUNCING CIRCUITRY FOR MECHANICAL SWITCHES Mechanical switches form the interface between human beings and computers or other digital systems For example a keyboard is a matrix of switches used to supply alphanumeric data to a computer Whatever the switch design it is a potential source of problems due to contact bounce The contact bounce creates a sense of narrow pulses when a switch is opened or closed An example of device whose operation would be adversely affected by contact bounce is a digital counter used to count the number of times a switch is depressed Eliminating the effects of contact bounce is called debouncing When data is entered into a computer via a keyboard a software debounce is often used This type of debouncing is a program that causes the computer to sample the switch terminal (ie to input data from it) many times in succession during the interval of time that contact bounce occurs If the data is sensed to be 1s (or 0s) for a specific number of consecutive samples then it is assumed that contact bounce has ended and the last value sensed is valid Hardware debouncing is the use of electronic circuitry to eliminate the effects of contact bounce There are numerous versions of such circuitry including those that use monostable multivibrators (one-shots) but the most straightforward is simply an RS latch Figure B1 shows the circuit When the switch is in position 1 R = 0 and S = 1 so the latch is set and the output (Q) is 1 When the switch is in position 0 R = 1and S = 0 so the latch is reset and the output is 0 When the switch is moved form one position to the other the latch changes state and bouncing occurs at either the R or the S input The bouncing does not affect the latch after it has change state An RS latch will remain set for example when its R input is 0 and its S input is alternately changed form 1 to 0

                                                                                                                                    Figure B1 Use of RS latch to debounce a mechanical switch

                                                                                                                                    69

                                                                                                                                    • 01-ldst-Outer title
                                                                                                                                      • Practical Workbook
                                                                                                                                      • Logic Design amp Switching Theory I
                                                                                                                                        • Dept of Computer amp Information Systems Engineering
                                                                                                                                          • NED University of Engineering amp Technology
                                                                                                                                          • Karachi ndash 75270 Pakistan
                                                                                                                                            • 02-ldst-inner Title
                                                                                                                                              • Practical Workbook
                                                                                                                                              • Logic Design amp Switching Theory I
                                                                                                                                                • Dept of Computer amp Information Systems Engineering
                                                                                                                                                  • NED University of Engineering amp Technology
                                                                                                                                                  • Karachi ndash 75270 Pakistan
                                                                                                                                                    • 03-ldst-general info
                                                                                                                                                    • 04-ldst-introduction
                                                                                                                                                    • 05-Table of Contents
                                                                                                                                                      • CONTENTS
                                                                                                                                                        • Lab Session No Object Page No
                                                                                                                                                        • 1
                                                                                                                                                        • Also implementing and testing the given circuit on a bread board
                                                                                                                                                          • Working with Electronics Workbench
                                                                                                                                                            • Driving a seven segment display using 7447 7448 driver IC
                                                                                                                                                              • Designing a modulus-5 asynchronous up-counter using JK-FF
                                                                                                                                                                • Experimenting with 74194 4-bit bidirectional universal shift register
                                                                                                                                                                    • 13
                                                                                                                                                                        • 06-ldst-Exp01
                                                                                                                                                                          • Lab Session 01
                                                                                                                                                                          • OBJECT
                                                                                                                                                                            • 1 Bread board
                                                                                                                                                                            • 2 5 V - power supply
                                                                                                                                                                            • 3 Multimeter
                                                                                                                                                                            • 4 Logic probe
                                                                                                                                                                            • 5 LEDs with resistors
                                                                                                                                                                            • 6 Connecting wires
                                                                                                                                                                            • 8 Following ICs and their datasheets
                                                                                                                                                                              • THEORY
                                                                                                                                                                                • Logic Gates
                                                                                                                                                                                • 1 The AND Gate ndash An AND gatersquos output is 1 if and only if all its inputs are 1 If A and B are two inputs to an AND gate then output F of the gate is given as F = AB
                                                                                                                                                                                • 2 The OR Gate - An OR gatersquos output is 1 if at least one of its input is 1 If A and B are two inputs to an OR gate then output F of the gate is given as F = A+B
                                                                                                                                                                                • 3 The NOT Gate (Inverter) ndash Its output is 1 when its input is 0 and its output is 0 when the input is 1 ie it complements a digital variable If A is the input to a NOT gate then output F of the gate is given as
                                                                                                                                                                                • 4 The NAND Gate ndash Its output is 1 if at least one of its input is 0 This gate performs the same logic as an AND gate followed by an inverter If A and B are two inputs to a NAND gate then output F of the gate is given as
                                                                                                                                                                                  • 5 The NOR Gate - The output of a NOR gate is 1 if and only if all its inputs are 0 This gate performs the same logic function as an OR gate followed by an inverter If A and B are two inputs to a NAND gate then output F of the gate is given as
                                                                                                                                                                                      • DATA SHEETS
                                                                                                                                                                                        • Logic expression for the given logic diagram __________________________________
                                                                                                                                                                                            • 07-ldst-exp02
                                                                                                                                                                                              • Working with Electronics Workbench
                                                                                                                                                                                                • 08-ldst-exp03
                                                                                                                                                                                                  • Designing Half and Full Adder Circuits
                                                                                                                                                                                                    • COMPONENTS AND APPARATUS REQUIRED
                                                                                                                                                                                                      • 1 Following ICs and their Datasheets
                                                                                                                                                                                                      • 7408 Quad 2-input AND Gate
                                                                                                                                                                                                      • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                        • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                        • Connecting wires Switches
                                                                                                                                                                                                          • THEORY
                                                                                                                                                                                                              • IMPLEMENTATION AND OBSERVATIONS
                                                                                                                                                                                                                • 09-ldst-Exp04
                                                                                                                                                                                                                  • Lab Session 04
                                                                                                                                                                                                                  • 1 Digital ICs and their Datasheets
                                                                                                                                                                                                                  • 7408 Quad 2-input AND Gate
                                                                                                                                                                                                                  • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                    • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                                    • Connecting wires Switches
                                                                                                                                                                                                                    • PROCEDURE
                                                                                                                                                                                                                    • REDUCTION OF LOGIC EXPRESSION USING KARNAUGH MAP
                                                                                                                                                                                                                    • OBSERVATIONS
                                                                                                                                                                                                                    • RESULT
                                                                                                                                                                                                                        • 10-ldst-Exp05
                                                                                                                                                                                                                          • Lab Session 05
                                                                                                                                                                                                                          • 1 Following ICs and their Datasheets
                                                                                                                                                                                                                          • 7408 Quad 2-input AND Gate
                                                                                                                                                                                                                          • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                            • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                                            • (100 Ω) Connecting wires Switches
                                                                                                                                                                                                                            • THEORY
                                                                                                                                                                                                                              • IMPLEMENTATION AND OBSERVATIONS
                                                                                                                                                                                                                                • 11-ldst-Exp06
                                                                                                                                                                                                                                  • OBJECT
                                                                                                                                                                                                                                  • 1 Following ICs and their Datasheets
                                                                                                                                                                                                                                  • 7408 Quad 2-input AND Gates or 7411 Triple 3-input AND Gates
                                                                                                                                                                                                                                  • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                                    • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                                                    • Connecting wires Switches
                                                                                                                                                                                                                                      • Figure 62 Circuit Diagram for 4 x 1 Multiplexer
                                                                                                                                                                                                                                      • Implementation and Observations
                                                                                                                                                                                                                                        • Circuit Diagram
                                                                                                                                                                                                                                          • ACTIVITY
                                                                                                                                                                                                                                            • 12-ldst-exp07
                                                                                                                                                                                                                                              • 1 Following ICs and their Datasheets
                                                                                                                                                                                                                                              • 7408 Quad 2-input or 7411 Triple 3-input AND Gates
                                                                                                                                                                                                                                              • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                                                • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                                                                • Connecting wires Switches
                                                                                                                                                                                                                                                  • THEORY
                                                                                                                                                                                                                                                      • Figure 72 Circuit Diagram for 2 x 4 Decoder 1 x 4 Demultiplexer
                                                                                                                                                                                                                                                      • Implementation and Observations
                                                                                                                                                                                                                                                        • Circuit Diagram
                                                                                                                                                                                                                                                          • ACTIVITY
                                                                                                                                                                                                                                                            • 13-ldst-Exp08
                                                                                                                                                                                                                                                              • OBJECT
                                                                                                                                                                                                                                                              • 1 Following ICs and their Datasheets
                                                                                                                                                                                                                                                              • 7408 Quad 2-input or 7421 Dual 4-input AND Gates
                                                                                                                                                                                                                                                              • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                                                                • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                                                                                • Connecting wires Switches
                                                                                                                                                                                                                                                                  • THEORY
                                                                                                                                                                                                                                                                      • Figure 81 Circuit Diagram for 4 x 2 Priority Encoder
                                                                                                                                                                                                                                                                      • Implementation and Observations
                                                                                                                                                                                                                                                                        • Therefore if GS A2 A1 and A0 are all low then it shows that line 0 is selected and if E0 A2 A1 and A0 are all low then it shows that none of the inputs selected E0 and GS cannot be in the same state provided that E1 is enabled
                                                                                                                                                                                                                                                                        • Circuit Diagram
                                                                                                                                                                                                                                                                          • ACTIVITY
                                                                                                                                                                                                                                                                            • 14-ldst-exp09
                                                                                                                                                                                                                                                                              • OBJECT
                                                                                                                                                                                                                                                                              • 1 Following ICs and their Datasheets
                                                                                                                                                                                                                                                                              • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                                                                                • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                                                                                                • Connecting wires Switches
                                                                                                                                                                                                                                                                                  • THEORY
                                                                                                                                                                                                                                                                                    • Parity Generator
                                                                                                                                                                                                                                                                                      • Let x y and z be the three bits that constitute the message and are the input to the Odd Parity Generator Circuit Since it is an odd parity system the bit P is generated so as to make the total number of 1s odd (including P) The function P can be expressed as follows
                                                                                                                                                                                                                                                                                      • Figure 91 Circuit Diagram for a 3-bit Parity Generator
                                                                                                                                                                                                                                                                                        • C = x Ο y Ο z Ο P
                                                                                                                                                                                                                                                                                          • Implementation and Observations
                                                                                                                                                                                                                                                                                            • ACTIVITY
                                                                                                                                                                                                                                                                                                • 15-ldst-exp10
                                                                                                                                                                                                                                                                                                  • Driving a seven segment display using 7447 7448 driver IC
                                                                                                                                                                                                                                                                                                  • COMPONENTS AND APPARATUS REQUIRED
                                                                                                                                                                                                                                                                                                  • 1 Following ICs and their Datasheets
                                                                                                                                                                                                                                                                                                  • 7447 7448 BCD to Seven Segment Driver
                                                                                                                                                                                                                                                                                                  • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                                                                                                    • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches
                                                                                                                                                                                                                                                                                                      • THEORY
                                                                                                                                                                                                                                                                                                      • Seven Segment Displays
                                                                                                                                                                                                                                                                                                      • CIRCUIT DIAGRAM
                                                                                                                                                                                                                                                                                                      • Figure 102 Circuit diagram for 7447driving a common-anode display
                                                                                                                                                                                                                                                                                                          • IMPLEMENTATION AND OBSERVATIONS
                                                                                                                                                                                                                                                                                                            • Decimal Digit
                                                                                                                                                                                                                                                                                                            • BCD Inputs
                                                                                                                                                                                                                                                                                                            • Seven Segment Outputs
                                                                                                                                                                                                                                                                                                            • D
                                                                                                                                                                                                                                                                                                            • C
                                                                                                                                                                                                                                                                                                            • B
                                                                                                                                                                                                                                                                                                            • A
                                                                                                                                                                                                                                                                                                            • a
                                                                                                                                                                                                                                                                                                            • b
                                                                                                                                                                                                                                                                                                            • c
                                                                                                                                                                                                                                                                                                            • d
                                                                                                                                                                                                                                                                                                            • e
                                                                                                                                                                                                                                                                                                            • f
                                                                                                                                                                                                                                                                                                            • g
                                                                                                                                                                                                                                                                                                            • 0
                                                                                                                                                                                                                                                                                                            • 0
                                                                                                                                                                                                                                                                                                            • 0
                                                                                                                                                                                                                                                                                                            • 0
                                                                                                                                                                                                                                                                                                            • 0
                                                                                                                                                                                                                                                                                                            • 1
                                                                                                                                                                                                                                                                                                            • 0
                                                                                                                                                                                                                                                                                                            • 0
                                                                                                                                                                                                                                                                                                            • 0
                                                                                                                                                                                                                                                                                                            • 1
                                                                                                                                                                                                                                                                                                            • 2
                                                                                                                                                                                                                                                                                                            • 0
                                                                                                                                                                                                                                                                                                            • 0
                                                                                                                                                                                                                                                                                                            • 1
                                                                                                                                                                                                                                                                                                            • 0
                                                                                                                                                                                                                                                                                                            • 3
                                                                                                                                                                                                                                                                                                            • 0
                                                                                                                                                                                                                                                                                                            • 0
                                                                                                                                                                                                                                                                                                            • 1
                                                                                                                                                                                                                                                                                                            • 1
                                                                                                                                                                                                                                                                                                            • 4
                                                                                                                                                                                                                                                                                                            • 0
                                                                                                                                                                                                                                                                                                            • 1
                                                                                                                                                                                                                                                                                                            • 0
                                                                                                                                                                                                                                                                                                            • 0
                                                                                                                                                                                                                                                                                                            • 5
                                                                                                                                                                                                                                                                                                            • 0
                                                                                                                                                                                                                                                                                                            • 1
                                                                                                                                                                                                                                                                                                            • 0
                                                                                                                                                                                                                                                                                                            • 1
                                                                                                                                                                                                                                                                                                            • 6
                                                                                                                                                                                                                                                                                                            • 0
                                                                                                                                                                                                                                                                                                            • 1
                                                                                                                                                                                                                                                                                                            • 1
                                                                                                                                                                                                                                                                                                            • 0
                                                                                                                                                                                                                                                                                                            • 7
                                                                                                                                                                                                                                                                                                            • 0
                                                                                                                                                                                                                                                                                                            • 1
                                                                                                                                                                                                                                                                                                            • 1
                                                                                                                                                                                                                                                                                                            • 1
                                                                                                                                                                                                                                                                                                            • 8
                                                                                                                                                                                                                                                                                                            • 1
                                                                                                                                                                                                                                                                                                            • 0
                                                                                                                                                                                                                                                                                                            • 0
                                                                                                                                                                                                                                                                                                            • 0
                                                                                                                                                                                                                                                                                                            • 9
                                                                                                                                                                                                                                                                                                            • 1
                                                                                                                                                                                                                                                                                                            • 0
                                                                                                                                                                                                                                                                                                            • 0
                                                                                                                                                                                                                                                                                                            • 1
                                                                                                                                                                                                                                                                                                              • ACTIVITY
                                                                                                                                                                                                                                                                                                                • 16-ldst-exp11
                                                                                                                                                                                                                                                                                                                  • Lab Session 11
                                                                                                                                                                                                                                                                                                                    • OBJECT
                                                                                                                                                                                                                                                                                                                    • COMPONENTS AND APPARATUS REQUIRED
                                                                                                                                                                                                                                                                                                                      • 1 Following ICs and their Datasheets
                                                                                                                                                                                                                                                                                                                      • 7473 7476 JK Flip-Flop
                                                                                                                                                                                                                                                                                                                      • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                                                                                                                        • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                                                                                                                                        • Connecting wires Switches
                                                                                                                                                                                                                                                                                                                          • THEORY
                                                                                                                                                                                                                                                                                                                              • Flip-Flop
                                                                                                                                                                                                                                                                                                                              • JK Flip-Flop
                                                                                                                                                                                                                                                                                                                                • Circuit Diagram
                                                                                                                                                                                                                                                                                                                                  • Observations
                                                                                                                                                                                                                                                                                                                                    • ACTIVITY
                                                                                                                                                                                                                                                                                                                                        • 17-ldst-exp12
                                                                                                                                                                                                                                                                                                                                          • Lab Session 12
                                                                                                                                                                                                                                                                                                                                            • OBJECT
                                                                                                                                                                                                                                                                                                                                            • GIVEN STATE DIAGRAM
                                                                                                                                                                                                                                                                                                                                            • Figure 121 State Diagram
                                                                                                                                                                                                                                                                                                                                            • COMPONENTS AND APPARATUS REQUIRED
                                                                                                                                                                                                                                                                                                                                              • 1 Following ICs and their Datasheets
                                                                                                                                                                                                                                                                                                                                              • 7474 D Flip-Flop
                                                                                                                                                                                                                                                                                                                                              • ICs of basic gates (AND OR NOT XOR etc) as required
                                                                                                                                                                                                                                                                                                                                              • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                                                                                                                                                • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                                                                                                                                                                • Connecting wires Switches
                                                                                                                                                                                                                                                                                                                                                  • THEORY
                                                                                                                                                                                                                                                                                                                                                      • Sequential Circuits
                                                                                                                                                                                                                                                                                                                                                        • 18-ldst-exp13
                                                                                                                                                                                                                                                                                                                                                          • Lab Session 13
                                                                                                                                                                                                                                                                                                                                                            • Designing a modulo-5 asynchronous up-counter using JK-FF
                                                                                                                                                                                                                                                                                                                                                              • 1 Following ICs and their Datasheets
                                                                                                                                                                                                                                                                                                                                                              • 7400 Quad 2-input or 7410 Triple 3-input NAND Gates
                                                                                                                                                                                                                                                                                                                                                              • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                                                                                                                                                                • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                                                                                                                                                                                • Connecting wires Switches
                                                                                                                                                                                                                                                                                                                                                                  • THEORY
                                                                                                                                                                                                                                                                                                                                                                      • Figure 131 A Mod-5 Asynchronous Up Counter
                                                                                                                                                                                                                                                                                                                                                                      • Implementation and Observations
                                                                                                                                                                                                                                                                                                                                                                        • ACTIVITY
                                                                                                                                                                                                                                                                                                                                                                            • 19-ldst-exp14
                                                                                                                                                                                                                                                                                                                                                                              • Experimenting with 74194 4-bit bidirectional universal shift register
                                                                                                                                                                                                                                                                                                                                                                              • 1 Following ICs and their Datasheets
                                                                                                                                                                                                                                                                                                                                                                              • 74194 4-bit bidirectional universal shift register
                                                                                                                                                                                                                                                                                                                                                                              • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                                                                                                                                                                                • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                                                                                                                                                                                                • Connecting wires Switches
                                                                                                                                                                                                                                                                                                                                                                                  • THEORY
                                                                                                                                                                                                                                                                                                                                                                                    • Shift Registers
                                                                                                                                                                                                                                                                                                                                                                                    • Bidirectional Shift Registers
                                                                                                                                                                                                                                                                                                                                                                                    • Universal Shift Registers
                                                                                                                                                                                                                                                                                                                                                                                      • S1
                                                                                                                                                                                                                                                                                                                                                                                        • Circuit Diagram
                                                                                                                                                                                                                                                                                                                                                                                        • ACTIVITY
                                                                                                                                                                                                                                                                                                                                                                                            • 20-ldst-exp15
                                                                                                                                                                                                                                                                                                                                                                                              • COMPONENTS AND APPARATUS REQUIRED
                                                                                                                                                                                                                                                                                                                                                                                              • 1 Parallel Port Connectors (DB-25) with Cable
                                                                                                                                                                                                                                                                                                                                                                                              • 2 Personal Computer with Windows 98 and TurboC Compiler Installed
                                                                                                                                                                                                                                                                                                                                                                                              • 3 Following ICs and their Datasheets
                                                                                                                                                                                                                                                                                                                                                                                              • 74245 Octal Bus Transceivers with 3-State Outputs
                                                                                                                                                                                                                                                                                                                                                                                              • 4 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                                                                                                                                                                                                • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                                                                                                                                                                                                                  • Connecting wires Switches
                                                                                                                                                                                                                                                                                                                                                                                                    • THEORY
                                                                                                                                                                                                                                                                                                                                                                                                    • 3-State Logic
                                                                                                                                                                                                                                                                                                                                                                                                      • Serial and Parallel Port Connectors
                                                                                                                                                                                                                                                                                                                                                                                                      • Parallel Port Connector ndash DB-25
                                                                                                                                                                                                                                                                                                                                                                                                        • Accessing parallel port through C Language Programming
                                                                                                                                                                                                                                                                                                                                                                                                            • 21-ldst-appendixA
                                                                                                                                                                                                                                                                                                                                                                                                            • 22-ldst-appendixB
                                                                                                                                                                                                                                                                                                                                                                                                              • DEBOUNCING CIRCUITRY FOR MECHANICAL SWITCHES

                                                                                                                                      Logic Design amp Switching Theory 1 Appendix B NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering

                                                                                                                                      Appendix B

                                                                                                                                      DEBOUNCING CIRCUITRY FOR MECHANICAL SWITCHES Mechanical switches form the interface between human beings and computers or other digital systems For example a keyboard is a matrix of switches used to supply alphanumeric data to a computer Whatever the switch design it is a potential source of problems due to contact bounce The contact bounce creates a sense of narrow pulses when a switch is opened or closed An example of device whose operation would be adversely affected by contact bounce is a digital counter used to count the number of times a switch is depressed Eliminating the effects of contact bounce is called debouncing When data is entered into a computer via a keyboard a software debounce is often used This type of debouncing is a program that causes the computer to sample the switch terminal (ie to input data from it) many times in succession during the interval of time that contact bounce occurs If the data is sensed to be 1s (or 0s) for a specific number of consecutive samples then it is assumed that contact bounce has ended and the last value sensed is valid Hardware debouncing is the use of electronic circuitry to eliminate the effects of contact bounce There are numerous versions of such circuitry including those that use monostable multivibrators (one-shots) but the most straightforward is simply an RS latch Figure B1 shows the circuit When the switch is in position 1 R = 0 and S = 1 so the latch is set and the output (Q) is 1 When the switch is in position 0 R = 1and S = 0 so the latch is reset and the output is 0 When the switch is moved form one position to the other the latch changes state and bouncing occurs at either the R or the S input The bouncing does not affect the latch after it has change state An RS latch will remain set for example when its R input is 0 and its S input is alternately changed form 1 to 0

                                                                                                                                      Figure B1 Use of RS latch to debounce a mechanical switch

                                                                                                                                      69

                                                                                                                                      • 01-ldst-Outer title
                                                                                                                                        • Practical Workbook
                                                                                                                                        • Logic Design amp Switching Theory I
                                                                                                                                          • Dept of Computer amp Information Systems Engineering
                                                                                                                                            • NED University of Engineering amp Technology
                                                                                                                                            • Karachi ndash 75270 Pakistan
                                                                                                                                              • 02-ldst-inner Title
                                                                                                                                                • Practical Workbook
                                                                                                                                                • Logic Design amp Switching Theory I
                                                                                                                                                  • Dept of Computer amp Information Systems Engineering
                                                                                                                                                    • NED University of Engineering amp Technology
                                                                                                                                                    • Karachi ndash 75270 Pakistan
                                                                                                                                                      • 03-ldst-general info
                                                                                                                                                      • 04-ldst-introduction
                                                                                                                                                      • 05-Table of Contents
                                                                                                                                                        • CONTENTS
                                                                                                                                                          • Lab Session No Object Page No
                                                                                                                                                          • 1
                                                                                                                                                          • Also implementing and testing the given circuit on a bread board
                                                                                                                                                            • Working with Electronics Workbench
                                                                                                                                                              • Driving a seven segment display using 7447 7448 driver IC
                                                                                                                                                                • Designing a modulus-5 asynchronous up-counter using JK-FF
                                                                                                                                                                  • Experimenting with 74194 4-bit bidirectional universal shift register
                                                                                                                                                                      • 13
                                                                                                                                                                          • 06-ldst-Exp01
                                                                                                                                                                            • Lab Session 01
                                                                                                                                                                            • OBJECT
                                                                                                                                                                              • 1 Bread board
                                                                                                                                                                              • 2 5 V - power supply
                                                                                                                                                                              • 3 Multimeter
                                                                                                                                                                              • 4 Logic probe
                                                                                                                                                                              • 5 LEDs with resistors
                                                                                                                                                                              • 6 Connecting wires
                                                                                                                                                                              • 8 Following ICs and their datasheets
                                                                                                                                                                                • THEORY
                                                                                                                                                                                  • Logic Gates
                                                                                                                                                                                  • 1 The AND Gate ndash An AND gatersquos output is 1 if and only if all its inputs are 1 If A and B are two inputs to an AND gate then output F of the gate is given as F = AB
                                                                                                                                                                                  • 2 The OR Gate - An OR gatersquos output is 1 if at least one of its input is 1 If A and B are two inputs to an OR gate then output F of the gate is given as F = A+B
                                                                                                                                                                                  • 3 The NOT Gate (Inverter) ndash Its output is 1 when its input is 0 and its output is 0 when the input is 1 ie it complements a digital variable If A is the input to a NOT gate then output F of the gate is given as
                                                                                                                                                                                  • 4 The NAND Gate ndash Its output is 1 if at least one of its input is 0 This gate performs the same logic as an AND gate followed by an inverter If A and B are two inputs to a NAND gate then output F of the gate is given as
                                                                                                                                                                                    • 5 The NOR Gate - The output of a NOR gate is 1 if and only if all its inputs are 0 This gate performs the same logic function as an OR gate followed by an inverter If A and B are two inputs to a NAND gate then output F of the gate is given as
                                                                                                                                                                                        • DATA SHEETS
                                                                                                                                                                                          • Logic expression for the given logic diagram __________________________________
                                                                                                                                                                                              • 07-ldst-exp02
                                                                                                                                                                                                • Working with Electronics Workbench
                                                                                                                                                                                                  • 08-ldst-exp03
                                                                                                                                                                                                    • Designing Half and Full Adder Circuits
                                                                                                                                                                                                      • COMPONENTS AND APPARATUS REQUIRED
                                                                                                                                                                                                        • 1 Following ICs and their Datasheets
                                                                                                                                                                                                        • 7408 Quad 2-input AND Gate
                                                                                                                                                                                                        • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                          • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                          • Connecting wires Switches
                                                                                                                                                                                                            • THEORY
                                                                                                                                                                                                                • IMPLEMENTATION AND OBSERVATIONS
                                                                                                                                                                                                                  • 09-ldst-Exp04
                                                                                                                                                                                                                    • Lab Session 04
                                                                                                                                                                                                                    • 1 Digital ICs and their Datasheets
                                                                                                                                                                                                                    • 7408 Quad 2-input AND Gate
                                                                                                                                                                                                                    • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                      • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                                      • Connecting wires Switches
                                                                                                                                                                                                                      • PROCEDURE
                                                                                                                                                                                                                      • REDUCTION OF LOGIC EXPRESSION USING KARNAUGH MAP
                                                                                                                                                                                                                      • OBSERVATIONS
                                                                                                                                                                                                                      • RESULT
                                                                                                                                                                                                                          • 10-ldst-Exp05
                                                                                                                                                                                                                            • Lab Session 05
                                                                                                                                                                                                                            • 1 Following ICs and their Datasheets
                                                                                                                                                                                                                            • 7408 Quad 2-input AND Gate
                                                                                                                                                                                                                            • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                              • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                                              • (100 Ω) Connecting wires Switches
                                                                                                                                                                                                                              • THEORY
                                                                                                                                                                                                                                • IMPLEMENTATION AND OBSERVATIONS
                                                                                                                                                                                                                                  • 11-ldst-Exp06
                                                                                                                                                                                                                                    • OBJECT
                                                                                                                                                                                                                                    • 1 Following ICs and their Datasheets
                                                                                                                                                                                                                                    • 7408 Quad 2-input AND Gates or 7411 Triple 3-input AND Gates
                                                                                                                                                                                                                                    • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                                      • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                                                      • Connecting wires Switches
                                                                                                                                                                                                                                        • Figure 62 Circuit Diagram for 4 x 1 Multiplexer
                                                                                                                                                                                                                                        • Implementation and Observations
                                                                                                                                                                                                                                          • Circuit Diagram
                                                                                                                                                                                                                                            • ACTIVITY
                                                                                                                                                                                                                                              • 12-ldst-exp07
                                                                                                                                                                                                                                                • 1 Following ICs and their Datasheets
                                                                                                                                                                                                                                                • 7408 Quad 2-input or 7411 Triple 3-input AND Gates
                                                                                                                                                                                                                                                • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                                                  • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                                                                  • Connecting wires Switches
                                                                                                                                                                                                                                                    • THEORY
                                                                                                                                                                                                                                                        • Figure 72 Circuit Diagram for 2 x 4 Decoder 1 x 4 Demultiplexer
                                                                                                                                                                                                                                                        • Implementation and Observations
                                                                                                                                                                                                                                                          • Circuit Diagram
                                                                                                                                                                                                                                                            • ACTIVITY
                                                                                                                                                                                                                                                              • 13-ldst-Exp08
                                                                                                                                                                                                                                                                • OBJECT
                                                                                                                                                                                                                                                                • 1 Following ICs and their Datasheets
                                                                                                                                                                                                                                                                • 7408 Quad 2-input or 7421 Dual 4-input AND Gates
                                                                                                                                                                                                                                                                • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                                                                  • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                                                                                  • Connecting wires Switches
                                                                                                                                                                                                                                                                    • THEORY
                                                                                                                                                                                                                                                                        • Figure 81 Circuit Diagram for 4 x 2 Priority Encoder
                                                                                                                                                                                                                                                                        • Implementation and Observations
                                                                                                                                                                                                                                                                          • Therefore if GS A2 A1 and A0 are all low then it shows that line 0 is selected and if E0 A2 A1 and A0 are all low then it shows that none of the inputs selected E0 and GS cannot be in the same state provided that E1 is enabled
                                                                                                                                                                                                                                                                          • Circuit Diagram
                                                                                                                                                                                                                                                                            • ACTIVITY
                                                                                                                                                                                                                                                                              • 14-ldst-exp09
                                                                                                                                                                                                                                                                                • OBJECT
                                                                                                                                                                                                                                                                                • 1 Following ICs and their Datasheets
                                                                                                                                                                                                                                                                                • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                                                                                  • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                                                                                                  • Connecting wires Switches
                                                                                                                                                                                                                                                                                    • THEORY
                                                                                                                                                                                                                                                                                      • Parity Generator
                                                                                                                                                                                                                                                                                        • Let x y and z be the three bits that constitute the message and are the input to the Odd Parity Generator Circuit Since it is an odd parity system the bit P is generated so as to make the total number of 1s odd (including P) The function P can be expressed as follows
                                                                                                                                                                                                                                                                                        • Figure 91 Circuit Diagram for a 3-bit Parity Generator
                                                                                                                                                                                                                                                                                          • C = x Ο y Ο z Ο P
                                                                                                                                                                                                                                                                                            • Implementation and Observations
                                                                                                                                                                                                                                                                                              • ACTIVITY
                                                                                                                                                                                                                                                                                                  • 15-ldst-exp10
                                                                                                                                                                                                                                                                                                    • Driving a seven segment display using 7447 7448 driver IC
                                                                                                                                                                                                                                                                                                    • COMPONENTS AND APPARATUS REQUIRED
                                                                                                                                                                                                                                                                                                    • 1 Following ICs and their Datasheets
                                                                                                                                                                                                                                                                                                    • 7447 7448 BCD to Seven Segment Driver
                                                                                                                                                                                                                                                                                                    • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                                                                                                      • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches
                                                                                                                                                                                                                                                                                                        • THEORY
                                                                                                                                                                                                                                                                                                        • Seven Segment Displays
                                                                                                                                                                                                                                                                                                        • CIRCUIT DIAGRAM
                                                                                                                                                                                                                                                                                                        • Figure 102 Circuit diagram for 7447driving a common-anode display
                                                                                                                                                                                                                                                                                                            • IMPLEMENTATION AND OBSERVATIONS
                                                                                                                                                                                                                                                                                                              • Decimal Digit
                                                                                                                                                                                                                                                                                                              • BCD Inputs
                                                                                                                                                                                                                                                                                                              • Seven Segment Outputs
                                                                                                                                                                                                                                                                                                              • D
                                                                                                                                                                                                                                                                                                              • C
                                                                                                                                                                                                                                                                                                              • B
                                                                                                                                                                                                                                                                                                              • A
                                                                                                                                                                                                                                                                                                              • a
                                                                                                                                                                                                                                                                                                              • b
                                                                                                                                                                                                                                                                                                              • c
                                                                                                                                                                                                                                                                                                              • d
                                                                                                                                                                                                                                                                                                              • e
                                                                                                                                                                                                                                                                                                              • f
                                                                                                                                                                                                                                                                                                              • g
                                                                                                                                                                                                                                                                                                              • 0
                                                                                                                                                                                                                                                                                                              • 0
                                                                                                                                                                                                                                                                                                              • 0
                                                                                                                                                                                                                                                                                                              • 0
                                                                                                                                                                                                                                                                                                              • 0
                                                                                                                                                                                                                                                                                                              • 1
                                                                                                                                                                                                                                                                                                              • 0
                                                                                                                                                                                                                                                                                                              • 0
                                                                                                                                                                                                                                                                                                              • 0
                                                                                                                                                                                                                                                                                                              • 1
                                                                                                                                                                                                                                                                                                              • 2
                                                                                                                                                                                                                                                                                                              • 0
                                                                                                                                                                                                                                                                                                              • 0
                                                                                                                                                                                                                                                                                                              • 1
                                                                                                                                                                                                                                                                                                              • 0
                                                                                                                                                                                                                                                                                                              • 3
                                                                                                                                                                                                                                                                                                              • 0
                                                                                                                                                                                                                                                                                                              • 0
                                                                                                                                                                                                                                                                                                              • 1
                                                                                                                                                                                                                                                                                                              • 1
                                                                                                                                                                                                                                                                                                              • 4
                                                                                                                                                                                                                                                                                                              • 0
                                                                                                                                                                                                                                                                                                              • 1
                                                                                                                                                                                                                                                                                                              • 0
                                                                                                                                                                                                                                                                                                              • 0
                                                                                                                                                                                                                                                                                                              • 5
                                                                                                                                                                                                                                                                                                              • 0
                                                                                                                                                                                                                                                                                                              • 1
                                                                                                                                                                                                                                                                                                              • 0
                                                                                                                                                                                                                                                                                                              • 1
                                                                                                                                                                                                                                                                                                              • 6
                                                                                                                                                                                                                                                                                                              • 0
                                                                                                                                                                                                                                                                                                              • 1
                                                                                                                                                                                                                                                                                                              • 1
                                                                                                                                                                                                                                                                                                              • 0
                                                                                                                                                                                                                                                                                                              • 7
                                                                                                                                                                                                                                                                                                              • 0
                                                                                                                                                                                                                                                                                                              • 1
                                                                                                                                                                                                                                                                                                              • 1
                                                                                                                                                                                                                                                                                                              • 1
                                                                                                                                                                                                                                                                                                              • 8
                                                                                                                                                                                                                                                                                                              • 1
                                                                                                                                                                                                                                                                                                              • 0
                                                                                                                                                                                                                                                                                                              • 0
                                                                                                                                                                                                                                                                                                              • 0
                                                                                                                                                                                                                                                                                                              • 9
                                                                                                                                                                                                                                                                                                              • 1
                                                                                                                                                                                                                                                                                                              • 0
                                                                                                                                                                                                                                                                                                              • 0
                                                                                                                                                                                                                                                                                                              • 1
                                                                                                                                                                                                                                                                                                                • ACTIVITY
                                                                                                                                                                                                                                                                                                                  • 16-ldst-exp11
                                                                                                                                                                                                                                                                                                                    • Lab Session 11
                                                                                                                                                                                                                                                                                                                      • OBJECT
                                                                                                                                                                                                                                                                                                                      • COMPONENTS AND APPARATUS REQUIRED
                                                                                                                                                                                                                                                                                                                        • 1 Following ICs and their Datasheets
                                                                                                                                                                                                                                                                                                                        • 7473 7476 JK Flip-Flop
                                                                                                                                                                                                                                                                                                                        • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                                                                                                                          • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                                                                                                                                          • Connecting wires Switches
                                                                                                                                                                                                                                                                                                                            • THEORY
                                                                                                                                                                                                                                                                                                                                • Flip-Flop
                                                                                                                                                                                                                                                                                                                                • JK Flip-Flop
                                                                                                                                                                                                                                                                                                                                  • Circuit Diagram
                                                                                                                                                                                                                                                                                                                                    • Observations
                                                                                                                                                                                                                                                                                                                                      • ACTIVITY
                                                                                                                                                                                                                                                                                                                                          • 17-ldst-exp12
                                                                                                                                                                                                                                                                                                                                            • Lab Session 12
                                                                                                                                                                                                                                                                                                                                              • OBJECT
                                                                                                                                                                                                                                                                                                                                              • GIVEN STATE DIAGRAM
                                                                                                                                                                                                                                                                                                                                              • Figure 121 State Diagram
                                                                                                                                                                                                                                                                                                                                              • COMPONENTS AND APPARATUS REQUIRED
                                                                                                                                                                                                                                                                                                                                                • 1 Following ICs and their Datasheets
                                                                                                                                                                                                                                                                                                                                                • 7474 D Flip-Flop
                                                                                                                                                                                                                                                                                                                                                • ICs of basic gates (AND OR NOT XOR etc) as required
                                                                                                                                                                                                                                                                                                                                                • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                                                                                                                                                  • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                                                                                                                                                                  • Connecting wires Switches
                                                                                                                                                                                                                                                                                                                                                    • THEORY
                                                                                                                                                                                                                                                                                                                                                        • Sequential Circuits
                                                                                                                                                                                                                                                                                                                                                          • 18-ldst-exp13
                                                                                                                                                                                                                                                                                                                                                            • Lab Session 13
                                                                                                                                                                                                                                                                                                                                                              • Designing a modulo-5 asynchronous up-counter using JK-FF
                                                                                                                                                                                                                                                                                                                                                                • 1 Following ICs and their Datasheets
                                                                                                                                                                                                                                                                                                                                                                • 7400 Quad 2-input or 7410 Triple 3-input NAND Gates
                                                                                                                                                                                                                                                                                                                                                                • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                                                                                                                                                                  • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                                                                                                                                                                                  • Connecting wires Switches
                                                                                                                                                                                                                                                                                                                                                                    • THEORY
                                                                                                                                                                                                                                                                                                                                                                        • Figure 131 A Mod-5 Asynchronous Up Counter
                                                                                                                                                                                                                                                                                                                                                                        • Implementation and Observations
                                                                                                                                                                                                                                                                                                                                                                          • ACTIVITY
                                                                                                                                                                                                                                                                                                                                                                              • 19-ldst-exp14
                                                                                                                                                                                                                                                                                                                                                                                • Experimenting with 74194 4-bit bidirectional universal shift register
                                                                                                                                                                                                                                                                                                                                                                                • 1 Following ICs and their Datasheets
                                                                                                                                                                                                                                                                                                                                                                                • 74194 4-bit bidirectional universal shift register
                                                                                                                                                                                                                                                                                                                                                                                • 2 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                                                                                                                                                                                  • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                                                                                                                                                                                                  • Connecting wires Switches
                                                                                                                                                                                                                                                                                                                                                                                    • THEORY
                                                                                                                                                                                                                                                                                                                                                                                      • Shift Registers
                                                                                                                                                                                                                                                                                                                                                                                      • Bidirectional Shift Registers
                                                                                                                                                                                                                                                                                                                                                                                      • Universal Shift Registers
                                                                                                                                                                                                                                                                                                                                                                                        • S1
                                                                                                                                                                                                                                                                                                                                                                                          • Circuit Diagram
                                                                                                                                                                                                                                                                                                                                                                                          • ACTIVITY
                                                                                                                                                                                                                                                                                                                                                                                              • 20-ldst-exp15
                                                                                                                                                                                                                                                                                                                                                                                                • COMPONENTS AND APPARATUS REQUIRED
                                                                                                                                                                                                                                                                                                                                                                                                • 1 Parallel Port Connectors (DB-25) with Cable
                                                                                                                                                                                                                                                                                                                                                                                                • 2 Personal Computer with Windows 98 and TurboC Compiler Installed
                                                                                                                                                                                                                                                                                                                                                                                                • 3 Following ICs and their Datasheets
                                                                                                                                                                                                                                                                                                                                                                                                • 74245 Octal Bus Transceivers with 3-State Outputs
                                                                                                                                                                                                                                                                                                                                                                                                • 4 Digital Trainer DT-01 or the following components
                                                                                                                                                                                                                                                                                                                                                                                                  • Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
                                                                                                                                                                                                                                                                                                                                                                                                    • Connecting wires Switches
                                                                                                                                                                                                                                                                                                                                                                                                      • THEORY
                                                                                                                                                                                                                                                                                                                                                                                                      • 3-State Logic
                                                                                                                                                                                                                                                                                                                                                                                                        • Serial and Parallel Port Connectors
                                                                                                                                                                                                                                                                                                                                                                                                        • Parallel Port Connector ndash DB-25
                                                                                                                                                                                                                                                                                                                                                                                                          • Accessing parallel port through C Language Programming
                                                                                                                                                                                                                                                                                                                                                                                                              • 21-ldst-appendixA
                                                                                                                                                                                                                                                                                                                                                                                                              • 22-ldst-appendixB
                                                                                                                                                                                                                                                                                                                                                                                                                • DEBOUNCING CIRCUITRY FOR MECHANICAL SWITCHES

                                                                                                                                        top related